Rice (</span><i><span style="font-family:Verdana;">Oryza</span></i> <i><span style="font-family:Verdana;">sativa</span></i></span><spa...Rice (</span><i><span style="font-family:Verdana;">Oryza</span></i> <i><span style="font-family:Verdana;">sativa</span></i></span><span style="font-family:""> </span><span style="font-family:Verdana;">L</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">) is the main staple cereal crops for half of the world’s population which is predicted to exceed 9 billion by the 2050. Rice production needs to be doubled to meet the future demand of rice eating countries. To ensure the food security of growing population, sustainable rice production is needed. To achieve the expected yield, better understanding of the rice root systems will be required. A panel of rice cultivars, collected from Bangladesh Rice Research Institute (BRRI) </span><span style="font-family:Verdana;">were</span><span style="font-family:""><span style="font-family:Verdana;"> assessed through two established </span><span style="font-family:Verdana;">screening methods. Deep and shallow rooted cultivars were identified</span><span style="font-family:Verdana;"> through </span><span style="font-family:Verdana;">hydroponic screening and soil filled rhizotron method. In hydroponic</span><span style="font-family:Verdana;"> screening method, one way analysis of variance (ANOVA) revealed 99.13% variation explained by the genotype (P < 0.001). At the same time, ANOVA revealed 73.37% variation explained by the genotype in soil filled glass rhizotron method (P < 0.001). When comparing the data of root traits obtained from hydroponic and rhizotron experiments, 4 cultivars were identified as </span><span style="font-family:Verdana;">deep rooted cultivars, which would be very promising cultivars for rice</span><span style="font-family:Verdana;"> breeding programmes in drought prone regions.展开更多
Aims Water level is one of the most important determinants of the distri-bution and composition of submersed aquatic vegetation in shal-low lakes.Without changes in nutrient loading,large-scale declines in submerged m...Aims Water level is one of the most important determinants of the distri-bution and composition of submersed aquatic vegetation in shal-low lakes.Without changes in nutrient loading,large-scale declines in submerged macrophytes in shallow lakes are largely attributed to strong external or internal forces,including changes in water level.As a winter-active submerged macrophyte,Potamogeton crispus has important functions in aquatic ecosystem.The objec-tives of our study were to reveal the effects of water depths on the germination,growth,reproduction and morphological changes of P.crispus under natural environmental conditions;identify the optimum water depth range for colonization of P.crispus;and pre-dict the succession course for P.crispus in Lake Taihu.Methods A long-term in situ experiment was performed to study the effects of water depth on the growth and morphology of P.crispus across the entire life cycle.Plants were grown in the improved cross type of rhizotrons for 30 weeks at three different water depths(60,120 and 200 cm)in Dongtaihu Bay of Lake Taihu.We measured the plant height,root length,the length and width of leaves and counted the numbers of leaves,ramets,turion spikes and roots of each plant on each observation day during the experiment.Important Findings Water depths ranging from 60 to 120 cm were favourable for above-ground vegetation growth,root tissue growth and the reproductive ability of P.crispus.At water depth of 200 cm or beyond,the distri-bution of P.crispus will be limited in the following year because of the lack of turion formation and the severe inhibition of ramet pro-duction.The relationship between above-ground biomass and growth time at three different water depths fits a logistic growth curve well(P<0.001).The rapid growth and distribution with high density of P.crispus at water depth near 60 cm during the reproductive stage is not favourable for growth of other submerged species.So a continuous water depth of~60-120 cm is the optimum growth depth range for the conservation and restoration of P.crispus in Lake Taihu.In addi-tion,the morphological parameters values acquired can replace or provide the ranges for the value of GmaxSB(the maximum growth rate of submerged plants,in the unit of d^(−1))obtained via calibration in the control equations of submerged plant growth in the Eco-Taihu model,which is a three-dimensional ecological model of Lake Taihu.展开更多
Aims Root interactions between neighbour plants represent a fundamental aspect of the competitive dynamics in pure stand and mixed cropping systems.The comprehension of such phenomena places big methodological challen...Aims Root interactions between neighbour plants represent a fundamental aspect of the competitive dynamics in pure stand and mixed cropping systems.The comprehension of such phenomena places big methodological challenges,and still needs clarification.The objectives of this work were(i)to test if a species with coloured roots can be used to examine the interaction in a legume-non-legume intercropping system;(ii)to verify the importance of initial root growth on the successive root development ofmixture component plants;(iii)to test if the root interaction in the shallowlayers has consequences for deep root growth and(iv)to compare the effect of intraspecific and interspecific competition on root development and biomass growth.Methods A detailed study on root growth and interaction was carried out using rhizotron tubes where two legume species were grown in pure stands or were intercropped with red beet,a variety of Beta vulgaris L.with clear red roots.Within the rhizotrons,the three species were grown either without competitors,with two plants of the same species to measure intraspecific competition or with one legume and one red beet plant to study interspecific competition.The use of mixtures where one component has clearly coloured roots,together with several scalar measurements of root depth and proliferation,allowed the measurement of the root system of each species when grown in the mixtures.Important findings The use of rhizotron tubes coupled with species with coloured roots represented a valuable method to study the belowground interaction in mixed cropping systems.The initial root growth was a very important feature for the subsequent dominance of a species and it was not related to seed dimension.Initial root growth was also important because the root interactions in the shallower soil layers were found to influence the root growth in deeper soil.The root system of the red beet showed much faster and deeper growth than that of the legumes,and made red beet the dominant component in the mixtures while the legume root system was confined to the shallower soil layer.Intraspecific competition was well tolerated by the legumes,but it was limiting for the highly competitive red beet.The outcome of root interaction between neighbour plants was confirmed to be speciesspecific as it changed according to the intensity of the competitive effect/response of each species of the mixture:both legumes were slightly affected by the intraspecific and highly affected by interspecific competition while red beet was more affected by intraspecific competition but strongly dominant when intercropped with legumes.展开更多
文摘Rice (</span><i><span style="font-family:Verdana;">Oryza</span></i> <i><span style="font-family:Verdana;">sativa</span></i></span><span style="font-family:""> </span><span style="font-family:Verdana;">L</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">) is the main staple cereal crops for half of the world’s population which is predicted to exceed 9 billion by the 2050. Rice production needs to be doubled to meet the future demand of rice eating countries. To ensure the food security of growing population, sustainable rice production is needed. To achieve the expected yield, better understanding of the rice root systems will be required. A panel of rice cultivars, collected from Bangladesh Rice Research Institute (BRRI) </span><span style="font-family:Verdana;">were</span><span style="font-family:""><span style="font-family:Verdana;"> assessed through two established </span><span style="font-family:Verdana;">screening methods. Deep and shallow rooted cultivars were identified</span><span style="font-family:Verdana;"> through </span><span style="font-family:Verdana;">hydroponic screening and soil filled rhizotron method. In hydroponic</span><span style="font-family:Verdana;"> screening method, one way analysis of variance (ANOVA) revealed 99.13% variation explained by the genotype (P < 0.001). At the same time, ANOVA revealed 73.37% variation explained by the genotype in soil filled glass rhizotron method (P < 0.001). When comparing the data of root traits obtained from hydroponic and rhizotron experiments, 4 cultivars were identified as </span><span style="font-family:Verdana;">deep rooted cultivars, which would be very promising cultivars for rice</span><span style="font-family:Verdana;"> breeding programmes in drought prone regions.
基金Natural Science Foundation of China(NSFC41230853)the Key Deployment Project of the Chinese Academy of Sciences(KZZD-EW-10)+1 种基金the China National Fund for Water Pollution Control and Management Project(2014ZX07101-011)the Research Culture Funds of Anhui Normal University(2012rcpy056).
文摘Aims Water level is one of the most important determinants of the distri-bution and composition of submersed aquatic vegetation in shal-low lakes.Without changes in nutrient loading,large-scale declines in submerged macrophytes in shallow lakes are largely attributed to strong external or internal forces,including changes in water level.As a winter-active submerged macrophyte,Potamogeton crispus has important functions in aquatic ecosystem.The objec-tives of our study were to reveal the effects of water depths on the germination,growth,reproduction and morphological changes of P.crispus under natural environmental conditions;identify the optimum water depth range for colonization of P.crispus;and pre-dict the succession course for P.crispus in Lake Taihu.Methods A long-term in situ experiment was performed to study the effects of water depth on the growth and morphology of P.crispus across the entire life cycle.Plants were grown in the improved cross type of rhizotrons for 30 weeks at three different water depths(60,120 and 200 cm)in Dongtaihu Bay of Lake Taihu.We measured the plant height,root length,the length and width of leaves and counted the numbers of leaves,ramets,turion spikes and roots of each plant on each observation day during the experiment.Important Findings Water depths ranging from 60 to 120 cm were favourable for above-ground vegetation growth,root tissue growth and the reproductive ability of P.crispus.At water depth of 200 cm or beyond,the distri-bution of P.crispus will be limited in the following year because of the lack of turion formation and the severe inhibition of ramet pro-duction.The relationship between above-ground biomass and growth time at three different water depths fits a logistic growth curve well(P<0.001).The rapid growth and distribution with high density of P.crispus at water depth near 60 cm during the reproductive stage is not favourable for growth of other submerged species.So a continuous water depth of~60-120 cm is the optimum growth depth range for the conservation and restoration of P.crispus in Lake Taihu.In addi-tion,the morphological parameters values acquired can replace or provide the ranges for the value of GmaxSB(the maximum growth rate of submerged plants,in the unit of d^(−1))obtained via calibration in the control equations of submerged plant growth in the Eco-Taihu model,which is a three-dimensional ecological model of Lake Taihu.
文摘Aims Root interactions between neighbour plants represent a fundamental aspect of the competitive dynamics in pure stand and mixed cropping systems.The comprehension of such phenomena places big methodological challenges,and still needs clarification.The objectives of this work were(i)to test if a species with coloured roots can be used to examine the interaction in a legume-non-legume intercropping system;(ii)to verify the importance of initial root growth on the successive root development ofmixture component plants;(iii)to test if the root interaction in the shallowlayers has consequences for deep root growth and(iv)to compare the effect of intraspecific and interspecific competition on root development and biomass growth.Methods A detailed study on root growth and interaction was carried out using rhizotron tubes where two legume species were grown in pure stands or were intercropped with red beet,a variety of Beta vulgaris L.with clear red roots.Within the rhizotrons,the three species were grown either without competitors,with two plants of the same species to measure intraspecific competition or with one legume and one red beet plant to study interspecific competition.The use of mixtures where one component has clearly coloured roots,together with several scalar measurements of root depth and proliferation,allowed the measurement of the root system of each species when grown in the mixtures.Important findings The use of rhizotron tubes coupled with species with coloured roots represented a valuable method to study the belowground interaction in mixed cropping systems.The initial root growth was a very important feature for the subsequent dominance of a species and it was not related to seed dimension.Initial root growth was also important because the root interactions in the shallower soil layers were found to influence the root growth in deeper soil.The root system of the red beet showed much faster and deeper growth than that of the legumes,and made red beet the dominant component in the mixtures while the legume root system was confined to the shallower soil layer.Intraspecific competition was well tolerated by the legumes,but it was limiting for the highly competitive red beet.The outcome of root interaction between neighbour plants was confirmed to be speciesspecific as it changed according to the intensity of the competitive effect/response of each species of the mixture:both legumes were slightly affected by the intraspecific and highly affected by interspecific competition while red beet was more affected by intraspecific competition but strongly dominant when intercropped with legumes.
