Semidwarf breeding has boosted crop production and is a well-known outcome from the first Green Revolution. The Green Revolution gene Semidwarf 1(SD1), which modulates gibberellic acid(GA) biosynthesis, plays a princi...Semidwarf breeding has boosted crop production and is a well-known outcome from the first Green Revolution. The Green Revolution gene Semidwarf 1(SD1), which modulates gibberellic acid(GA) biosynthesis, plays a principal role in determining rice plant height. Mutations in SD1 reduce rice plant height and promote lodging resistance and fertilizer tolerance to increase grain production. The plant height mediated by SD1 also favors grain yield under certain conditions. However, it is not yet known whether the function of SD1 in upland rice promotes adaptation and grain production. In this study, the plant height and grain yield of irrigated and upland rice were comparatively analyzed under paddy and dryland conditions. In response to dryland environments, rice requires a reduction in plant height to cope with water deficits. Upland rice accessions had greater plant heights than their irrigated counterparts under both paddy and dryland conditions, and appropriately reducing plant height could improve adaptability to dryland environments and maintain high grain yield formation. Moreover, upland rice cultivars with thicker stem diameters had stronger lodging resistance, which addresses the lodging problem. Knockout of SD1 in the upland rice cultivar IRAT104 reduced the plant height and grain yield, demonstrating that the adjustment of plant height mediated by SD1 could increase grain production in dryland fields. In addition, an SD1 genetic diversity analysis verified that haplotype variation causes phenotypic variation in plant height. During the breeding history of rice, SD1 allelic mutations were selected from landraces to improve the grain yield of irrigated rice cultivars, and this selection was accompanied by a reduction in plant height. Thus, five known mutant alleles were analyzed to verify that functional SD1 is required for upland rice production. All these results suggest that SD1 might have undergone artificial positive selection in upland rice, which provides further insights concerning greater plant height in upland rice breeding.展开更多
Upland rice shows dryland adaptation in the form of a deeper and denser root system and greater drought resistance than its counterpart,irrigated rice.Our previous study revealed a difference in the frequency of the O...Upland rice shows dryland adaptation in the form of a deeper and denser root system and greater drought resistance than its counterpart,irrigated rice.Our previous study revealed a difference in the frequency of the OsNCED2 gene between upland and irrigated populations.A nonsynonymous mutation(C to T,from irrigated to upland rice)may have led to functional variation fixed by artificial selection,but the exact biological function in dryland adaptation is unclear.In this study,transgenic and association analysis indicated that the domesticated fixed mutation caused functional variation in OsNCED2,increasing ABA levels,root development,and drought tolerance in upland rice under dryland conditions.OsNCED2-overexpressing rice showed increased reactive oxygen species-scavenging abilities and transcription levels of many genes functioning in stress response and development that may regulate root development and drought tolerance.OsNCED2^(T)-NILs showed a denser root system and drought resistance,promoting the yield of rice under dryland conditions.OsNCED2^(T)may confer dryland adaptation in upland rice and may find use in breeding dryland-adapted,water-saving rice.展开更多
The effects of mulching mode on population physiology and ecology of rice were studied using a combination P88S/1128 as the material under three mulching cultivation modes including plastic film mulching, straw mulchi...The effects of mulching mode on population physiology and ecology of rice were studied using a combination P88S/1128 as the material under three mulching cultivation modes including plastic film mulching, straw mulching and liquid film mulching, as well as bare cultivation (control). The results indicated that mulching mode had significant effects on micro-meteorological factors and individual growth of rice, as shown by an increase of relative humidity, a better internal micro-meteorological environment of rice population, a significant reduction under the rice canopy temperature, especially during high-temperature periods. Rice plants under mulching cultivation conditions displayed a stronger transpiration and lower leaf temperature, thereby improving the ability of anti-high temperature stress and markedly increasing the photosynthetic rate. Furthermore, the yield components of rice were significantly optimized under mulching cultivation, of which with plastic film mulching displayed the highest grain number per panicle and seed-setting rate, and a yield increase of 16.81% compared with the control; and with straw mulching displayed an increase of effective panicle number and a 9.59% increase of total yield compared to the control.展开更多
The planting of upland rice is one cropping option in area with limited water availability and low soil fertility in North and Northeast Thailand.The varietal selection was determined by grain yield potential,wide ada...The planting of upland rice is one cropping option in area with limited water availability and low soil fertility in North and Northeast Thailand.The varietal selection was determined by grain yield potential,wide adaptation,and good stability.This study was aimed at evaluation of indigenous upland rice germplasm for yield and yield stability in multi-locations.Thirty-six upland rice genotypes collected from six provinces of the North and Northeast Thailand and one check variety(Sewmaejan) were assessed under five locations in the rainy seasons of 2009 and 2010.The experiment was laid out in a randomized complete block design with three replications.The genotype grain yield was highly affected by location(59.90%),followed by genotypes(G)×location(L) interaction(12.80%) and genotype(6.79%).The most suitable location for the genotype evaluation was L3(Khon Kaen-KKU10) which associated with stability of grain yield for all genotypes.Furthermore,biplot and regression analysis indicated that genotype numbers 6(Jaowmong 1),10(Neawmong 1),18(Neawdum 1),19(Leamna),20(Prayaleamkang),32(Kunwang 2),and 33(Kunwang 3) showed great yield stability over five locations.The genotypes will be applicant for upland rice production area and parental base in breeding program.展开更多
Varalu is an early maturing rice variety widely grown in the rainfed ecosystem preferred for its grain type and cooking quality.However,the yield of Varalu is substantially low since it is being affected by reproducti...Varalu is an early maturing rice variety widely grown in the rainfed ecosystem preferred for its grain type and cooking quality.However,the yield of Varalu is substantially low since it is being affected by reproductive drought stress along with the blast disease.The genetic improvement of Varalu was done by introgressing a major yield QTL,qDTY_(12.1),along with two major blast resistance genes i.e.Pi54 and Pi1 through marker-assisted backcross breeding.Both traits were transferred till BC_(2) generation and intercrossing was followed to pyramid the two traits.Stringent foreground selection was carried out using linked markers as well as peak markers(RM28099,RM28130,RM511 and RM28163)for the targeted QTL(qDTY_(12.1)),RM206 for Pi54 and RM224 for Pi1.Extensive background selection was done using genome-wide SSR markers.Six best lines(MSM-36,MSM-49,MSM-53,MSM-57,MSM-60 and MSM-63)having qDTY_(12.1) and two blast resistance genes in homozygous condition with recurrent parent genome of 95.0%-96.5% having minimal linkage drag of about 0.1 to 0.7 Mb were identified.These lines showed yield advantage under drought stress as well as irrigated conditions.MSM-36 showed better performance in the national coordinated trials conducted across India,which indicated that improved lines of Varalu expected to replace Varalu and may have an important role in sustaining rice production.The present study demonstrated the successful marker-assisted pyramiding strategy for introgression of genes/QTLs conferring biotic stress resistance and yield under abiotic stress in rice.展开更多
The demand for rice to meet the dietary need in low-income countries is expected to witness an exponential rise as the population increases.Meeting the rice demand domestically has remained challenging due to signific...The demand for rice to meet the dietary need in low-income countries is expected to witness an exponential rise as the population increases.Meeting the rice demand domestically has remained challenging due to significant yield loss caused by several biotic and abiotic factors.Among these factors,one of the most important is the high weed pressure that ravages the upland rice ecology.In Nigeria,several independent weed control techniques,such as physical,chemical and cultural methods,have been recommended and adopted for weed control across varying rice upland ecologies.However,outcomes of these approaches when used independently have not consistently led to an increase in yield.There remains an outstanding deficit between the actual yield and the potential rice yield.This review aimed to identify potential research gaps,and quest effective and sustainable weed management strategies in smallholder upland rice farming systems in Nigeria.A critical analysis of studies suggests the potential of sustainable weed management practices if adopted and adapted smartly in different upland ecologies in Nigeria.Competitiveness of upland rice against weeds can be enhanced through strategic integration of weed competitive cultivars,optimum nitrogen application timings(within weed-free periods),uniform plant spacing,and high seeding rates,with conventional herbicide/manual weed control practices.However,such management practices can only be engaged where inputs are supplied on time and the technical know-how is extended to farmers.The review equally highlights potential research gaps for further studies.展开更多
Genome-wide association study(GWAS)was performed for 16 agronomic traits including nitrogen use efficiency(NUE)and yield-related components using a panel of 190 mainly japonica rice varieties and a set of 38390 single...Genome-wide association study(GWAS)was performed for 16 agronomic traits including nitrogen use efficiency(NUE)and yield-related components using a panel of 190 mainly japonica rice varieties and a set of 38390 single nucleotide polymorphism(SNP)markers.This panel was evaluated under rainfed upland conditions in Madagascar in two consecutive cropping seasons with two contrasted nitrogen input levels.Using another set of five grain traits,we identified previously known genes(GW5,GS3,Awn1 and Glabrous1),thus validating the pertinence and accuracy of our datasets for GWAS.A total of 369 significant associations were detected between SNPs and agronomic traits,gathered into 46 distinct haplotype groups and 28 isolated markers.Few association signals were identified for the complex quantitative trait NUE,however,larger number of quantitative trait loci(QTLs)were detected for its component traits,with 10 and 2 association signals for nitrogen utilization efficiency and nitrogen uptake efficiency,respectively.Several detected association signals co-localized with genes involved in nitrogen transport or nitrogen remobilization within 100 kb.The present study thus confirmed the potential of GWAS to identify candidate genes and new loci associated with agronomic traits.However,because of the quantitative and complex nature of NUE-related traits,GWAS might have not captured a large number of QTLs with limited effects.展开更多
To develop basis for strategic or arranged decision making towards crop yield improvement in Thailand, a new method in which crop models could be used is essential. Therefore, the objective of this study was to measur...To develop basis for strategic or arranged decision making towards crop yield improvement in Thailand, a new method in which crop models could be used is essential. Therefore, the objective of this study was to measure cultivar specific parameters by using DSSAT (v4.7) Cropping Simulation Model (CSM) with five upland rice genotypes namely Dawk Pa-yawm, Mai Tahk, Bow Leb Nahng, Dawk Kha 50 and Dawk Kahm. Experiment was laid out in a Completely Randomized Design (CRD) with split plot design. Results showed that five upland rice genotypes had significantly affected each other by different temperature treatments (28°C, 30°C, 32°C) with grain yield, tops weight, harvest index, flowering, and maturity date. At the same time, all the phenological traits had highly significant variation with the genotypes. The cultivar specific parameters obtained by using a temperature tolerant cultivar (Basmati 385) with five upland genotypes involved in the DSSAT4.7-CSM. Model evaluation results indicated that utilizing the estimated cultivar coefficient parameters, model simulated well with varying temperature treatments as indicated by the agreement index (d-statistic) closer to unity. Hence, it was estimated that model calibration and evaluation was realistic in the limits of test cropping seasons and that CSM fitted with cultivar specific parameters can be used in simulation studies for investigation, farm managing or decision making. This electronic document is a “live” template. The various components of your paper [title, text, heads, etc.] are already defined on the style sheet, as illustrated by the portions given in this document.展开更多
Slash-and-burn agriculture is the common practice for upland rice intercropping system in Sierra Leone and it has been blamed for the loss of forest vegetation across the country. Shortening of the fallow period in th...Slash-and-burn agriculture is the common practice for upland rice intercropping system in Sierra Leone and it has been blamed for the loss of forest vegetation across the country. Shortening of the fallow period in the Eastern region of Sierra Leone has implications on agricultural food production and the persistence of the remaining tropical rainforest. This study was therefore undertaken to assess: 1) the extent of reduction of the fallow period in the Nongowa Chiefdom of Kenema District;2) the causes of reduction in the fallow period;3) farmers’ perception of the relevance of fallow period and the implications of reduction of fallow period on crop production. The study revealed a drastic reduction of the fallow period in the chiefdom with a mean of 3.8 years which falls far below the country mean fallow period of 8.8 years as estimated by FAO. Farmers pointed out that the reduction of the fallow period was as a result of land scarcity due to competing land uses such as large scale commercial agriculture, logging, mining, charcoal burning and expansion of settlements. Farmers agreed that a fallow period of at least 10 years is necessary for upland rice production. Farmers were aware of the impact of reduction of the fallow period on upland rice production and were able to estimate rice yields based on the age of the fallow. Also, farmers have attempted to adapt to the constraints posed by shorter fallow periods by selection of rice varieties to suit the length of the fallow periods.展开更多
Shifting cultivation,popularly known as jhum,is a dominant form of agriculture in the Chattogram Hill Tracts(CHT)of Bangladesh with upland rice being the major component of the system.The region is known for its rice ...Shifting cultivation,popularly known as jhum,is a dominant form of agriculture in the Chattogram Hill Tracts(CHT)of Bangladesh with upland rice being the major component of the system.The region is known for its rice biodiversity,which is under threat.This study was an attempt to explore the extent of rice biodiversity and variation in rice yields observing 81 randomly selected shifting cultivation plots from 26 dispersedly located mountainous villages in four sub-districts of Bandarban,one of three districts of the CHT.A total of 28 landraces of upland rice was grown in shifting cultivation.Highest number of landraces(16)was found in sub-district Thanchi.Three landraces most frequently observed were Gunda,Maemonsing and Sadabinni.Rice grain yield varied between 1.421 t ha-1 and 3.442 t ha-1 across landraces with the highest being recorded for Patobi.Landrace Dilon the lowest yield.Relative performance of landraces Kobrokbinni,Maemonsing,Monthon,Patobi and PD were superior to standard BRRI dhan83 and Gunda in relation to grain yield.Some of these landraces having wider adaptability may be released as varieties.展开更多
The upland rice is grown in most Brazilian states. However, in many of them the yield obtained is low. The choice of cultivar more suited to a particular environment can contribute to increased productivity of this cr...The upland rice is grown in most Brazilian states. However, in many of them the yield obtained is low. The choice of cultivar more suited to a particular environment can contribute to increased productivity of this crop. This research aimed to evaluate the performance of a hybrid cultivar of upland rice (Ecco) and five conventional cultivars (BRS Monarca, BRS Primavera, AN Cambará, BRS Sertaneja and BRS MG Curinga) in two environments (Vilhena and Cerejeiras). The tests were conducted in the agricultural year 2010/2011. We evaluated the following characteristics: tillering, panicle number per unit area, number of filled grains per panicle sterile, mass of grains per panicle, 1000 grain weight, grain yield (kg·ha-1) and whole grain yield. There was no cultivar x environment interaction for all traits. Greater tillering, higher panicle number per area, higher productivity and yield of whole grains in the municipality of Cerejeiras were observed, while the highest number of sterile grains per panicle was obtained in Vilhena. The hybrid Ecco highlighted in relation to all other cultivars is in relation to tillering, panicle number per area and grain yield. The municipality of Cerejeiras is the most suitable for the cultivation of upland rice.展开更多
Worldwide, approximately 27 million ha of rice are grown in upland rather than paddy fields, and is subject to drought stress. To counter this stress, it is desirable to breed new rice cultivars with improved drought ...Worldwide, approximately 27 million ha of rice are grown in upland rather than paddy fields, and is subject to drought stress. To counter this stress, it is desirable to breed new rice cultivars with improved drought tolerance. For breeding purposes, especially for breeding upland rice, it is desirable to develop a simple and accurate method to evaluate rice drought tolerance. We describe a new method that can be used to evaluate efficiently the drought tolerance degree(DTD) of upland rice cultivars, and call it the DTD method.DTD is defined as the mean of the ratios of green leaf length to total leaf length of the top three leaves in every rice seedling after drought treatment, and thus takes values from zero to one. To test whether the DTD method works effectively to evaluate drought tolerance of upland rice cultivars, we determined the DTD values of 13 upland rice cultivars showing varying degrees of drought tolerance in drought-tolerance trials. The idrl-1 mutant, which displayed the strongest drought tolerance of the 13 cultivars as identified by drought-tolerance trials under severe drought stress, had the highest DTD value and297-28, displaying the weakest drought tolerance, had the lowest DTD value. Further analyses of water potential, survival rate, panicles per plant, spikelets per panicle, seed setting rate, yield per plant, and contents of proline, chlorophyll, and malondialdehyde(MDA) indicated that DTD values are in general correlated with the values of these traits,making this new method useful for assessing the drought tolerance of upland rice cultivars.These results show that the DTD method is a simple, direct and relatively accurate evaluation method for drought-tolerance breeding of upland rice.展开更多
Mycorrhizal status of rice under upland conditions was studied using potted seedlings. Percentage of arbuscular mycorrhizal fungi (AMF) root colonization varied between 17.35% and 37.18% over an age series of 7 to 70 ...Mycorrhizal status of rice under upland conditions was studied using potted seedlings. Percentage of arbuscular mycorrhizal fungi (AMF) root colonization varied between 17.35% and 37.18% over an age series of 7 to 70 days old rice plants. AMF root colonization was increased up to 35-42 days, beyond which the root colonization steadily declined. The vesicles appeared after two weeks and reached their maximum intensity on the 35th day. The arbuscules were formed late on the 42nd day (2.93%) and slightly varied up to the 70th day (3.03%). Higher dosage of urea application suppressed plant growth whereas the superphosphate treatment had no marked impact on plant growth. Generally, application of these agrochemicals registered less influence on the hyphal colonization of AMF in rice plants, whereas arbuscular colonization was adversely affected by higher dosages of fertilizers. There were pronounced decreases in both the plant growth and their AMF colonization due to the application of systemic fungicides, carbendazim and thiophanate methyl. The application of single sprays of fungicides was less deleterious over multiple sprays.展开更多
To further improve upland rice varieties Huhan 3 and Huhan 7,seed samples were sent to outer space with two recoverable spaceships for approximately 1 and 5 d and were propagated for 7 and 5 generations,respectively.P...To further improve upland rice varieties Huhan 3 and Huhan 7,seed samples were sent to outer space with two recoverable spaceships for approximately 1 and 5 d and were propagated for 7 and 5 generations,respectively.Phenotypic analysis revealed that the morphological traits and the protein and amylose contents of grains changed.Characterization of genomic mutations by the gene-associated simple sequence repeat (SSR) and insertion-delete (InDel) markers indicated that the mutation pattern was very complex.Most of the mutations occurred at the 3′or 5′-end of the fragments in the simple sequence repeat fragment.Reverse transcription-polymerase chain reaction (RT-PCR) assay showed that mutations in those parts of the SSR affected their gene expression,indicating that gene associated markers would be helpful to isolate functional genes.Field survey for breeding also revealed that more lines with high yield,high quality and drought-tolerance could be selected through aerospace breeding.The results indicate that aerospace mutagenesis resulted in molecular variation,as well as physiological and morphological changes for rice breeding.展开更多
A total of 17 simple sequence repeat(SSR) markers linked to QTLs(qDTYs) governing grain yield under reproductive stage(RS) drought stress were used to assess the genetic relationship and prospecting new donors for q D...A total of 17 simple sequence repeat(SSR) markers linked to QTLs(qDTYs) governing grain yield under reproductive stage(RS) drought stress were used to assess the genetic relationship and prospecting new donors for q DTYs among 32 popular upland rice genotypes. These SSR markers generated a total of 36 alleles with an average allele count of 2.1 per locus. Polymorphic information content value of the markers ranged from 0.376 to 0.662 with an average value of 0.484. The expected heterozyogosity ranged from 0.381 to 0.632. STRUCTURE analysis divided the 32 genotypes into three sub-populations. Subsequent phenotyping revealed that all the tolerant genotypes were grouped into one sub-population, whereas the moderately tolerant and susceptible genotypes were grouped into separate sub-populations. Phylogenetic tree constructed by the unweighted neighbour-joining method also divided the genotypes into three clusters. The grouping pattern of genotypes into the clusters was similar to that into the STRUCTURE analysis, on the basis of drought tolerance level. The average value of genetic dissimilarity coefficient among the genotypes was observed to be 0.486. Furthermore, by combining genotyping data with phenotyping data, 16 new donors for 6 qDTYs were identified.展开更多
Luang Prabang Province is located within the area recognized as the center of rice(Oryza sativa L.) diversity in Lao PDR. This study reported on grain quality characteristics of 60 upland rice seed samples sharing 49 ...Luang Prabang Province is located within the area recognized as the center of rice(Oryza sativa L.) diversity in Lao PDR. This study reported on grain quality characteristics of 60 upland rice seed samples sharing 49 variety names collected from 6 villages in Luang Prabang in 2015. Most of the samples has non-pigmented pericarp, while red pericarp was found in four samples and purple in five samples. Almost all of the samples were of large grain type, with glutinous endosperm in 70% and non-glutinous endosperm in 30%. The brown(unpolished) rice was found with a wide range of grain nutritional quality, including protein(9.2% ± 0.9%), Fe(15.9 ± 6.9 mg/kg), Zn(19.6 ± 2.1 mg/kg), anthocyanin(0.774 ± 0.880 mg/g), and anti-oxidative capacity(2.071 ± 1.373 mg/g). The varieties sharing similar names had similar morphological characteristics but varied in nutritional concentration, with required confirmation in genetic variation analysis. This study found that some rice varieties with high grain quality may benefit the farmers directly or could be used in varietal improvement programs.展开更多
The grain quality of 100 upland/ahu rice genotypes from Assam,India was assessed.The characteristics measured were grain length,grain width,cooked grain length,cooked grain width,grain elongation ratio after cooking,g...The grain quality of 100 upland/ahu rice genotypes from Assam,India was assessed.The characteristics measured were grain length,grain width,cooked grain length,cooked grain width,grain elongation ratio after cooking,grain widening ratio after cooking,alkali spreading value,gel consistency,as well as starch,amylose,amylopectin and total soluble sugar contents.Considerable genetic variability among the 100 rice genotypes was observed for the characteristics under study.Analysis of variance revealed highly significant differences among the genotypes for all the characteristics.The difference between genotypic coefficient of variation(GCV)and phenotypic coefficient of variation(PCV)was very small for all the characteristics analyzed.High GCV and PCV were found in the characteristic of total soluble sugar content followed by alkali spreading value.The high values for these traits signify the scope for selection to develop superior genotypes.High heritability was recorded in all the characteristics analyzed along with diverse genetic advance which varied from 9.71%to 52.83%.The characteristic of total soluble sugar content showed high heritability with high genetic advance,whereas alkali spreading value and grain widening ratio presented high heritability with moderate genetic advance.This implies that these characteristics are mainly under additive gene effects and could be relied upon further selection based on phenotypic performance.The genotypic correlation coefficient was higher than the phenotypic correlation coefficient,indicating strong inherent associations among the characteristics studied.展开更多
The difference in protein content, MDH,POD and COD isozymes have been seenbetween lowland rice roots and upland rice roots during root growth and development. High pro-tein content has been examined in upland rice roo...The difference in protein content, MDH,POD and COD isozymes have been seenbetween lowland rice roots and upland rice roots during root growth and development. High pro-tein content has been examined in upland rice roots,but isozyme bands in lowland rice roots aremore than that in upland rice roots.Total area of POD isozyme bands at seedling and tilleringstages of upland rice is larger than that of lowland rice.The POD isozymes zymogram in the rootof upland rice is more stable compared with that of lowland rice.More COD isozyme numbershave been showed in roots of upland rice,but the relative activity of COD isozyme in roots of up-land rice at the seedling and tillering stages is lower than that of lowland rice.COD<sub>7</sub> band can beshown in upland rice root at flowering stage,but it is absent in lowland rice.Therefore,COD<sub>7</sub>,band can be taken as an index for resistance of the upland rice to drought environment.展开更多
Productivity potentials of upland rice landraces (URLs) are continuously compromised by scanty water supply due to competing priorities for irrigations and fluctuations in agro-ecological conditions peculiar to low-in...Productivity potentials of upland rice landraces (URLs) are continuously compromised by scanty water supply due to competing priorities for irrigations and fluctuations in agro-ecological conditions peculiar to low-input farming systems. A growing demand for rice amidst decline in productive agricultural areas plunges into an urgent contribution of marginal areas critical in attaining food sufficiency among Filipino households. Agronomic performances of URLs locally found in Catanduanes province, Philippines were evaluated in a replicated trial utilizing three URLs: Kamanang [1], Kadari [2] and Bulaw [3]. The experimental set-up was closely monitored for consistent dry moisture content and zero fertilizer application. Results were significant for traditional upland landraces: Kamanang and Kadari, scored in terms of higher germination rate, increment plant height and the number of tillers during the vegetative stage. Leaf color gradations, although statistically not significant across cultivars, were suggestive of varying adaptive performance between traditional cultivars subjected to low-input system. Putative low-input responsive lines indicated by the higher survival percentage and overall agronomic responses were selected from the study site. Screened lines took part of the advance population which would be potentially able to tolerate poor soil conditions (i.e. poor storehouse of water and nutrients) especially in areas with edaphological constraints and changing rainfall distribution pattern. The development of putative drought tolerant lines among URLs forms the most economical solution implicated to areas with limited access to agricultural interventions.展开更多
基金supported by grants from the National Natural Science Foundation of China(32272079 and 32060474)the Yunnan Provincial Science and Technology Department,China(202101AS070001 and 202201BF070001-011)。
文摘Semidwarf breeding has boosted crop production and is a well-known outcome from the first Green Revolution. The Green Revolution gene Semidwarf 1(SD1), which modulates gibberellic acid(GA) biosynthesis, plays a principal role in determining rice plant height. Mutations in SD1 reduce rice plant height and promote lodging resistance and fertilizer tolerance to increase grain production. The plant height mediated by SD1 also favors grain yield under certain conditions. However, it is not yet known whether the function of SD1 in upland rice promotes adaptation and grain production. In this study, the plant height and grain yield of irrigated and upland rice were comparatively analyzed under paddy and dryland conditions. In response to dryland environments, rice requires a reduction in plant height to cope with water deficits. Upland rice accessions had greater plant heights than their irrigated counterparts under both paddy and dryland conditions, and appropriately reducing plant height could improve adaptability to dryland environments and maintain high grain yield formation. Moreover, upland rice cultivars with thicker stem diameters had stronger lodging resistance, which addresses the lodging problem. Knockout of SD1 in the upland rice cultivar IRAT104 reduced the plant height and grain yield, demonstrating that the adjustment of plant height mediated by SD1 could increase grain production in dryland fields. In addition, an SD1 genetic diversity analysis verified that haplotype variation causes phenotypic variation in plant height. During the breeding history of rice, SD1 allelic mutations were selected from landraces to improve the grain yield of irrigated rice cultivars, and this selection was accompanied by a reduction in plant height. Thus, five known mutant alleles were analyzed to verify that functional SD1 is required for upland rice production. All these results suggest that SD1 might have undergone artificial positive selection in upland rice, which provides further insights concerning greater plant height in upland rice breeding.
基金This work was supported by the National Natural Science Foundation of China(U1602266,32060474,and 31601274)grants from the Yunnan Provincial Science and Technology Department(202005AF150009 and 202101AS070001).
文摘Upland rice shows dryland adaptation in the form of a deeper and denser root system and greater drought resistance than its counterpart,irrigated rice.Our previous study revealed a difference in the frequency of the OsNCED2 gene between upland and irrigated populations.A nonsynonymous mutation(C to T,from irrigated to upland rice)may have led to functional variation fixed by artificial selection,but the exact biological function in dryland adaptation is unclear.In this study,transgenic and association analysis indicated that the domesticated fixed mutation caused functional variation in OsNCED2,increasing ABA levels,root development,and drought tolerance in upland rice under dryland conditions.OsNCED2-overexpressing rice showed increased reactive oxygen species-scavenging abilities and transcription levels of many genes functioning in stress response and development that may regulate root development and drought tolerance.OsNCED2^(T)-NILs showed a denser root system and drought resistance,promoting the yield of rice under dryland conditions.OsNCED2^(T)may confer dryland adaptation in upland rice and may find use in breeding dryland-adapted,water-saving rice.
基金supported by the Major Science and Technology Capture Project in the Eleventh Five-Year Plan in Hunan Province, China titled 'Super high yielding hybrid rice cultivation technology research and demonstration'the National Great Science and Technology Support Plan, Chinathe National Science and Technology Project for Food Production, China
文摘The effects of mulching mode on population physiology and ecology of rice were studied using a combination P88S/1128 as the material under three mulching cultivation modes including plastic film mulching, straw mulching and liquid film mulching, as well as bare cultivation (control). The results indicated that mulching mode had significant effects on micro-meteorological factors and individual growth of rice, as shown by an increase of relative humidity, a better internal micro-meteorological environment of rice population, a significant reduction under the rice canopy temperature, especially during high-temperature periods. Rice plants under mulching cultivation conditions displayed a stronger transpiration and lower leaf temperature, thereby improving the ability of anti-high temperature stress and markedly increasing the photosynthetic rate. Furthermore, the yield components of rice were significantly optimized under mulching cultivation, of which with plastic film mulching displayed the highest grain number per panicle and seed-setting rate, and a yield increase of 16.81% compared with the control; and with straw mulching displayed an increase of effective panicle number and a 9.59% increase of total yield compared to the control.
基金supported by the Plant Breeding Research Centre for Sustainable Agriculture and Research Center of Agricultural Biotechnology for Sustainable Economy,Khon Kaen University,Thailandthe Faculty of Agriculture at Khon Kaen University for providing financial support for manuscript preparation activities
文摘The planting of upland rice is one cropping option in area with limited water availability and low soil fertility in North and Northeast Thailand.The varietal selection was determined by grain yield potential,wide adaptation,and good stability.This study was aimed at evaluation of indigenous upland rice germplasm for yield and yield stability in multi-locations.Thirty-six upland rice genotypes collected from six provinces of the North and Northeast Thailand and one check variety(Sewmaejan) were assessed under five locations in the rainy seasons of 2009 and 2010.The experiment was laid out in a randomized complete block design with three replications.The genotype grain yield was highly affected by location(59.90%),followed by genotypes(G)×location(L) interaction(12.80%) and genotype(6.79%).The most suitable location for the genotype evaluation was L3(Khon Kaen-KKU10) which associated with stability of grain yield for all genotypes.Furthermore,biplot and regression analysis indicated that genotype numbers 6(Jaowmong 1),10(Neawmong 1),18(Neawdum 1),19(Leamna),20(Prayaleamkang),32(Kunwang 2),and 33(Kunwang 3) showed great yield stability over five locations.The genotypes will be applicant for upland rice production area and parental base in breeding program.
文摘Varalu is an early maturing rice variety widely grown in the rainfed ecosystem preferred for its grain type and cooking quality.However,the yield of Varalu is substantially low since it is being affected by reproductive drought stress along with the blast disease.The genetic improvement of Varalu was done by introgressing a major yield QTL,qDTY_(12.1),along with two major blast resistance genes i.e.Pi54 and Pi1 through marker-assisted backcross breeding.Both traits were transferred till BC_(2) generation and intercrossing was followed to pyramid the two traits.Stringent foreground selection was carried out using linked markers as well as peak markers(RM28099,RM28130,RM511 and RM28163)for the targeted QTL(qDTY_(12.1)),RM206 for Pi54 and RM224 for Pi1.Extensive background selection was done using genome-wide SSR markers.Six best lines(MSM-36,MSM-49,MSM-53,MSM-57,MSM-60 and MSM-63)having qDTY_(12.1) and two blast resistance genes in homozygous condition with recurrent parent genome of 95.0%-96.5% having minimal linkage drag of about 0.1 to 0.7 Mb were identified.These lines showed yield advantage under drought stress as well as irrigated conditions.MSM-36 showed better performance in the national coordinated trials conducted across India,which indicated that improved lines of Varalu expected to replace Varalu and may have an important role in sustaining rice production.The present study demonstrated the successful marker-assisted pyramiding strategy for introgression of genes/QTLs conferring biotic stress resistance and yield under abiotic stress in rice.
文摘The demand for rice to meet the dietary need in low-income countries is expected to witness an exponential rise as the population increases.Meeting the rice demand domestically has remained challenging due to significant yield loss caused by several biotic and abiotic factors.Among these factors,one of the most important is the high weed pressure that ravages the upland rice ecology.In Nigeria,several independent weed control techniques,such as physical,chemical and cultural methods,have been recommended and adopted for weed control across varying rice upland ecologies.However,outcomes of these approaches when used independently have not consistently led to an increase in yield.There remains an outstanding deficit between the actual yield and the potential rice yield.This review aimed to identify potential research gaps,and quest effective and sustainable weed management strategies in smallholder upland rice farming systems in Nigeria.A critical analysis of studies suggests the potential of sustainable weed management practices if adopted and adapted smartly in different upland ecologies in Nigeria.Competitiveness of upland rice against weeds can be enhanced through strategic integration of weed competitive cultivars,optimum nitrogen application timings(within weed-free periods),uniform plant spacing,and high seeding rates,with conventional herbicide/manual weed control practices.However,such management practices can only be engaged where inputs are supplied on time and the technical know-how is extended to farmers.The review equally highlights potential research gaps for further studies.
基金supported jointly by Cariplo(Italia)and Agropolis(France)Foundations(Grant No.1201-006).
文摘Genome-wide association study(GWAS)was performed for 16 agronomic traits including nitrogen use efficiency(NUE)and yield-related components using a panel of 190 mainly japonica rice varieties and a set of 38390 single nucleotide polymorphism(SNP)markers.This panel was evaluated under rainfed upland conditions in Madagascar in two consecutive cropping seasons with two contrasted nitrogen input levels.Using another set of five grain traits,we identified previously known genes(GW5,GS3,Awn1 and Glabrous1),thus validating the pertinence and accuracy of our datasets for GWAS.A total of 369 significant associations were detected between SNPs and agronomic traits,gathered into 46 distinct haplotype groups and 28 isolated markers.Few association signals were identified for the complex quantitative trait NUE,however,larger number of quantitative trait loci(QTLs)were detected for its component traits,with 10 and 2 association signals for nitrogen utilization efficiency and nitrogen uptake efficiency,respectively.Several detected association signals co-localized with genes involved in nitrogen transport or nitrogen remobilization within 100 kb.The present study thus confirmed the potential of GWAS to identify candidate genes and new loci associated with agronomic traits.However,because of the quantitative and complex nature of NUE-related traits,GWAS might have not captured a large number of QTLs with limited effects.
文摘To develop basis for strategic or arranged decision making towards crop yield improvement in Thailand, a new method in which crop models could be used is essential. Therefore, the objective of this study was to measure cultivar specific parameters by using DSSAT (v4.7) Cropping Simulation Model (CSM) with five upland rice genotypes namely Dawk Pa-yawm, Mai Tahk, Bow Leb Nahng, Dawk Kha 50 and Dawk Kahm. Experiment was laid out in a Completely Randomized Design (CRD) with split plot design. Results showed that five upland rice genotypes had significantly affected each other by different temperature treatments (28°C, 30°C, 32°C) with grain yield, tops weight, harvest index, flowering, and maturity date. At the same time, all the phenological traits had highly significant variation with the genotypes. The cultivar specific parameters obtained by using a temperature tolerant cultivar (Basmati 385) with five upland genotypes involved in the DSSAT4.7-CSM. Model evaluation results indicated that utilizing the estimated cultivar coefficient parameters, model simulated well with varying temperature treatments as indicated by the agreement index (d-statistic) closer to unity. Hence, it was estimated that model calibration and evaluation was realistic in the limits of test cropping seasons and that CSM fitted with cultivar specific parameters can be used in simulation studies for investigation, farm managing or decision making. This electronic document is a “live” template. The various components of your paper [title, text, heads, etc.] are already defined on the style sheet, as illustrated by the portions given in this document.
文摘Slash-and-burn agriculture is the common practice for upland rice intercropping system in Sierra Leone and it has been blamed for the loss of forest vegetation across the country. Shortening of the fallow period in the Eastern region of Sierra Leone has implications on agricultural food production and the persistence of the remaining tropical rainforest. This study was therefore undertaken to assess: 1) the extent of reduction of the fallow period in the Nongowa Chiefdom of Kenema District;2) the causes of reduction in the fallow period;3) farmers’ perception of the relevance of fallow period and the implications of reduction of fallow period on crop production. The study revealed a drastic reduction of the fallow period in the chiefdom with a mean of 3.8 years which falls far below the country mean fallow period of 8.8 years as estimated by FAO. Farmers pointed out that the reduction of the fallow period was as a result of land scarcity due to competing land uses such as large scale commercial agriculture, logging, mining, charcoal burning and expansion of settlements. Farmers agreed that a fallow period of at least 10 years is necessary for upland rice production. Farmers were aware of the impact of reduction of the fallow period on upland rice production and were able to estimate rice yields based on the age of the fallow. Also, farmers have attempted to adapt to the constraints posed by shorter fallow periods by selection of rice varieties to suit the length of the fallow periods.
基金The work was partially funded by a grant from theMinistry of Science and Technology, Government of Bangladesh.
文摘Shifting cultivation,popularly known as jhum,is a dominant form of agriculture in the Chattogram Hill Tracts(CHT)of Bangladesh with upland rice being the major component of the system.The region is known for its rice biodiversity,which is under threat.This study was an attempt to explore the extent of rice biodiversity and variation in rice yields observing 81 randomly selected shifting cultivation plots from 26 dispersedly located mountainous villages in four sub-districts of Bandarban,one of three districts of the CHT.A total of 28 landraces of upland rice was grown in shifting cultivation.Highest number of landraces(16)was found in sub-district Thanchi.Three landraces most frequently observed were Gunda,Maemonsing and Sadabinni.Rice grain yield varied between 1.421 t ha-1 and 3.442 t ha-1 across landraces with the highest being recorded for Patobi.Landrace Dilon the lowest yield.Relative performance of landraces Kobrokbinni,Maemonsing,Monthon,Patobi and PD were superior to standard BRRI dhan83 and Gunda in relation to grain yield.Some of these landraces having wider adaptability may be released as varieties.
文摘The upland rice is grown in most Brazilian states. However, in many of them the yield obtained is low. The choice of cultivar more suited to a particular environment can contribute to increased productivity of this crop. This research aimed to evaluate the performance of a hybrid cultivar of upland rice (Ecco) and five conventional cultivars (BRS Monarca, BRS Primavera, AN Cambará, BRS Sertaneja and BRS MG Curinga) in two environments (Vilhena and Cerejeiras). The tests were conducted in the agricultural year 2010/2011. We evaluated the following characteristics: tillering, panicle number per unit area, number of filled grains per panicle sterile, mass of grains per panicle, 1000 grain weight, grain yield (kg·ha-1) and whole grain yield. There was no cultivar x environment interaction for all traits. Greater tillering, higher panicle number per area, higher productivity and yield of whole grains in the municipality of Cerejeiras were observed, while the highest number of sterile grains per panicle was obtained in Vilhena. The hybrid Ecco highlighted in relation to all other cultivars is in relation to tillering, panicle number per area and grain yield. The municipality of Cerejeiras is the most suitable for the cultivation of upland rice.
基金supported by the National Key Research and Development Program of China(2016YFD0100600)the Fundamental Research Funds for the Central Universities (KYTZ201402, KYRC201409) to H.La
文摘Worldwide, approximately 27 million ha of rice are grown in upland rather than paddy fields, and is subject to drought stress. To counter this stress, it is desirable to breed new rice cultivars with improved drought tolerance. For breeding purposes, especially for breeding upland rice, it is desirable to develop a simple and accurate method to evaluate rice drought tolerance. We describe a new method that can be used to evaluate efficiently the drought tolerance degree(DTD) of upland rice cultivars, and call it the DTD method.DTD is defined as the mean of the ratios of green leaf length to total leaf length of the top three leaves in every rice seedling after drought treatment, and thus takes values from zero to one. To test whether the DTD method works effectively to evaluate drought tolerance of upland rice cultivars, we determined the DTD values of 13 upland rice cultivars showing varying degrees of drought tolerance in drought-tolerance trials. The idrl-1 mutant, which displayed the strongest drought tolerance of the 13 cultivars as identified by drought-tolerance trials under severe drought stress, had the highest DTD value and297-28, displaying the weakest drought tolerance, had the lowest DTD value. Further analyses of water potential, survival rate, panicles per plant, spikelets per panicle, seed setting rate, yield per plant, and contents of proline, chlorophyll, and malondialdehyde(MDA) indicated that DTD values are in general correlated with the values of these traits,making this new method useful for assessing the drought tolerance of upland rice cultivars.These results show that the DTD method is a simple, direct and relatively accurate evaluation method for drought-tolerance breeding of upland rice.
文摘Mycorrhizal status of rice under upland conditions was studied using potted seedlings. Percentage of arbuscular mycorrhizal fungi (AMF) root colonization varied between 17.35% and 37.18% over an age series of 7 to 70 days old rice plants. AMF root colonization was increased up to 35-42 days, beyond which the root colonization steadily declined. The vesicles appeared after two weeks and reached their maximum intensity on the 35th day. The arbuscules were formed late on the 42nd day (2.93%) and slightly varied up to the 70th day (3.03%). Higher dosage of urea application suppressed plant growth whereas the superphosphate treatment had no marked impact on plant growth. Generally, application of these agrochemicals registered less influence on the hyphal colonization of AMF in rice plants, whereas arbuscular colonization was adversely affected by higher dosages of fertilizers. There were pronounced decreases in both the plant growth and their AMF colonization due to the application of systemic fungicides, carbendazim and thiophanate methyl. The application of single sprays of fungicides was less deleterious over multiple sprays.
基金supported by the National High-Technology Research and Development Program of China(Grant No.2010AA101805)National Key Technology R&D Program of China(Grant No.2013ZX08001-003)Shanghai Agricultural Science and Technology Key Projects,China(Grant No.2009-6-4-2)
文摘To further improve upland rice varieties Huhan 3 and Huhan 7,seed samples were sent to outer space with two recoverable spaceships for approximately 1 and 5 d and were propagated for 7 and 5 generations,respectively.Phenotypic analysis revealed that the morphological traits and the protein and amylose contents of grains changed.Characterization of genomic mutations by the gene-associated simple sequence repeat (SSR) and insertion-delete (InDel) markers indicated that the mutation pattern was very complex.Most of the mutations occurred at the 3′or 5′-end of the fragments in the simple sequence repeat fragment.Reverse transcription-polymerase chain reaction (RT-PCR) assay showed that mutations in those parts of the SSR affected their gene expression,indicating that gene associated markers would be helpful to isolate functional genes.Field survey for breeding also revealed that more lines with high yield,high quality and drought-tolerance could be selected through aerospace breeding.The results indicate that aerospace mutagenesis resulted in molecular variation,as well as physiological and morphological changes for rice breeding.
基金funded by ICAR-National Rice Research Institute(NRRI)
文摘A total of 17 simple sequence repeat(SSR) markers linked to QTLs(qDTYs) governing grain yield under reproductive stage(RS) drought stress were used to assess the genetic relationship and prospecting new donors for q DTYs among 32 popular upland rice genotypes. These SSR markers generated a total of 36 alleles with an average allele count of 2.1 per locus. Polymorphic information content value of the markers ranged from 0.376 to 0.662 with an average value of 0.484. The expected heterozyogosity ranged from 0.381 to 0.632. STRUCTURE analysis divided the 32 genotypes into three sub-populations. Subsequent phenotyping revealed that all the tolerant genotypes were grouped into one sub-population, whereas the moderately tolerant and susceptible genotypes were grouped into separate sub-populations. Phylogenetic tree constructed by the unweighted neighbour-joining method also divided the genotypes into three clusters. The grouping pattern of genotypes into the clusters was similar to that into the STRUCTURE analysis, on the basis of drought tolerance level. The average value of genetic dissimilarity coefficient among the genotypes was observed to be 0.486. Furthermore, by combining genotyping data with phenotyping data, 16 new donors for 6 qDTYs were identified.
基金financial support provided by the International Development Research Center(IDRC)the Southeast Asian Regional Center for Graduate Study and Research in Agriculture(SEARCA)the National Research University Program of Thailand’s Commission on Higher Education
文摘Luang Prabang Province is located within the area recognized as the center of rice(Oryza sativa L.) diversity in Lao PDR. This study reported on grain quality characteristics of 60 upland rice seed samples sharing 49 variety names collected from 6 villages in Luang Prabang in 2015. Most of the samples has non-pigmented pericarp, while red pericarp was found in four samples and purple in five samples. Almost all of the samples were of large grain type, with glutinous endosperm in 70% and non-glutinous endosperm in 30%. The brown(unpolished) rice was found with a wide range of grain nutritional quality, including protein(9.2% ± 0.9%), Fe(15.9 ± 6.9 mg/kg), Zn(19.6 ± 2.1 mg/kg), anthocyanin(0.774 ± 0.880 mg/g), and anti-oxidative capacity(2.071 ± 1.373 mg/g). The varieties sharing similar names had similar morphological characteristics but varied in nutritional concentration, with required confirmation in genetic variation analysis. This study found that some rice varieties with high grain quality may benefit the farmers directly or could be used in varietal improvement programs.
文摘The grain quality of 100 upland/ahu rice genotypes from Assam,India was assessed.The characteristics measured were grain length,grain width,cooked grain length,cooked grain width,grain elongation ratio after cooking,grain widening ratio after cooking,alkali spreading value,gel consistency,as well as starch,amylose,amylopectin and total soluble sugar contents.Considerable genetic variability among the 100 rice genotypes was observed for the characteristics under study.Analysis of variance revealed highly significant differences among the genotypes for all the characteristics.The difference between genotypic coefficient of variation(GCV)and phenotypic coefficient of variation(PCV)was very small for all the characteristics analyzed.High GCV and PCV were found in the characteristic of total soluble sugar content followed by alkali spreading value.The high values for these traits signify the scope for selection to develop superior genotypes.High heritability was recorded in all the characteristics analyzed along with diverse genetic advance which varied from 9.71%to 52.83%.The characteristic of total soluble sugar content showed high heritability with high genetic advance,whereas alkali spreading value and grain widening ratio presented high heritability with moderate genetic advance.This implies that these characteristics are mainly under additive gene effects and could be relied upon further selection based on phenotypic performance.The genotypic correlation coefficient was higher than the phenotypic correlation coefficient,indicating strong inherent associations among the characteristics studied.
文摘The difference in protein content, MDH,POD and COD isozymes have been seenbetween lowland rice roots and upland rice roots during root growth and development. High pro-tein content has been examined in upland rice roots,but isozyme bands in lowland rice roots aremore than that in upland rice roots.Total area of POD isozyme bands at seedling and tilleringstages of upland rice is larger than that of lowland rice.The POD isozymes zymogram in the rootof upland rice is more stable compared with that of lowland rice.More COD isozyme numbershave been showed in roots of upland rice,but the relative activity of COD isozyme in roots of up-land rice at the seedling and tillering stages is lower than that of lowland rice.COD<sub>7</sub> band can beshown in upland rice root at flowering stage,but it is absent in lowland rice.Therefore,COD<sub>7</sub>,band can be taken as an index for resistance of the upland rice to drought environment.
文摘Productivity potentials of upland rice landraces (URLs) are continuously compromised by scanty water supply due to competing priorities for irrigations and fluctuations in agro-ecological conditions peculiar to low-input farming systems. A growing demand for rice amidst decline in productive agricultural areas plunges into an urgent contribution of marginal areas critical in attaining food sufficiency among Filipino households. Agronomic performances of URLs locally found in Catanduanes province, Philippines were evaluated in a replicated trial utilizing three URLs: Kamanang [1], Kadari [2] and Bulaw [3]. The experimental set-up was closely monitored for consistent dry moisture content and zero fertilizer application. Results were significant for traditional upland landraces: Kamanang and Kadari, scored in terms of higher germination rate, increment plant height and the number of tillers during the vegetative stage. Leaf color gradations, although statistically not significant across cultivars, were suggestive of varying adaptive performance between traditional cultivars subjected to low-input system. Putative low-input responsive lines indicated by the higher survival percentage and overall agronomic responses were selected from the study site. Screened lines took part of the advance population which would be potentially able to tolerate poor soil conditions (i.e. poor storehouse of water and nutrients) especially in areas with edaphological constraints and changing rainfall distribution pattern. The development of putative drought tolerant lines among URLs forms the most economical solution implicated to areas with limited access to agricultural interventions.
