黄淮海地区农业集约化和机械化发展导致土壤紧实问题日益加重,限制玉米产量的进一步提升。明确不同品种玉米根系和地上部生长对土壤紧实胁迫的差异性响应特征,可为该区玉米高产栽培提供理论依据。本研究选用3个玉米品种,采用机械碾压的...黄淮海地区农业集约化和机械化发展导致土壤紧实问题日益加重,限制玉米产量的进一步提升。明确不同品种玉米根系和地上部生长对土壤紧实胁迫的差异性响应特征,可为该区玉米高产栽培提供理论依据。本研究选用3个玉米品种,采用机械碾压的方法在同一田块模拟无紧实胁迫(NC:no compaction stress,容重1.0~1.3 g cm^(-3))、中度紧实胁迫(MC:moderate compaction stress,容重1.4~1.5 g cm^(-3))和重度紧实胁迫(HC:heavy compaction stress,容重>1.6 g cm^(-3))3个紧实程度处理,定量解析不同程度土壤紧实胁迫下不同品种玉米根冠生长各指标及产量的变化规律。结果表明,与NC相比,MC和HC处理导致玉米减产3.8%~10.3%和12.5%~33.3%。玉米根冠生长及产量形成对土壤紧实胁迫的响应存在基因型差异。MC处理下,DK517的根长、根干重及根冠比较ZD958和DH605分别提高6.0%和14.0%、15.7%和29.6%、18.8%和24.8%,但最大叶面积指数、植株总干物重和产量无显著差异;HC处理下,DK517的根长和根干重较ZD958和DH605分别提高8.4%和22.5%、29.6%和57.8%,且最大叶面积指数、植株总干物重和根冠比分别提高4.6%和15.5%、3.7%和20.9%、28.0%和32.1%,因此产量分别增加7.5%和27.2%。相关分析表明,土壤容重和贯穿阻力与玉米根冠生长各指标和产量呈显著负相关关系(P<0.01)。综上所述,土壤紧实胁迫会显著抑制玉米根系和地上部生长而造成减产,但不同品种玉米根冠生长对不同程度土壤紧实胁迫的响应存在着差异,重度土壤紧实胁迫下根冠生长均具有优势的品种能够维持较高的产量,研究结果可为玉米品种改良和土壤紧实下耕作措施优化提供理论依据。展开更多
Stem respiration is an important part of the activity of a tree and is an important source of CO2 evolution from a forest ecosystem. Presently, no standard methods are available for the accurate estimation of total st...Stem respiration is an important part of the activity of a tree and is an important source of CO2 evolution from a forest ecosystem. Presently, no standard methods are available for the accurate estimation of total stem CO2 efflux from a forest. In the current study, a 33-year-old (by the year 2001) larch (Larix gmelini Rupr.) plantation was measured throughout 2001-2002 to analyze its monthly and seasonal patterns of stem respiration. Stem respiration rate was also measured at different heights, at different daily intervals and any variation in the larch plantation was recorded. The relationship between stem temperature, growth status and respiration rate was analyzed. Higher respiration rates were recorded in upper reaches of the larch tree throughout the season and these were affected partially by temperature difference. Midday depression was found in the diurnal changes in stem respiration. In the morning, but not in the afternoon, stem respiration was positively correlated with stem temperature. The reason for this variation may be attributed to water deficit, which was stronger in the afternoon. In the larch plantation, a maximum 7-fold variation in stem respiration was found. The growth status (such as mean growth rate of stem and canopy projection area) instead of stem temperature difference was positively correlated with this large variation. An S-model (sigmoid curve) or Power model shows the greatest regression of the field data. In the courses of seasonal and annual changes of stem respiration, peak values were observed in July of both years, but substantial interannual differences in magnitude were observed. An exponential model can clearly show this regression of the temperature-respiration relationship. In our results, Q(10) values ranged from 2.22 in 2001 to 3.53 in 2002. Therefore, estimation of total stem CO2 efflux only by a constant Q(10) value may give biased results. More parameters of growth status and water status should be considered for more accurate estimation.展开更多
A field experiment using a split-plot randomized complete block design with three replications was carried out to determine relationships between spectral indices and wheat grain yield （GY）, to compare the performan...A field experiment using a split-plot randomized complete block design with three replications was carried out to determine relationships between spectral indices and wheat grain yield （GY）, to compare the performance of four vegetation indices （VIs） for GY prediction, and to study the feasibility of VI to estimate grain protein content （GPC） in winter wheat. Two typical winter wheat （Triticum aestivum L.） cultivars ＇Xuzhou 26＇ （high protein content） and ＇Huaimai 18＇ （low protein content） were used as the main plot treatments and four N rates, i.e., 0, 120, 210, and 300 kg N ha^-1, as the sub-plot treatments. Increasing soil N supply significantly increased GY and GPC （P ≤ 0.05）. For the two cultivars combined, significant and positive correlations were found between four VIs and GY, with the strongest relationship observed when using the green ratio vegetation index （GRVI） at mid-filling. Cumulative VI estimates improved yield predictions substantially, with the best interval being heading to maturity stage. Similar results were found between VI and grain protein yield. However, when using cumulative VI, GPC showed no significant improvement. The strong relationship between leaf N status and GPC （R2 =0.9144 for ＇Xuzhou 26＇ and R2 = 0.8285 for ＇Huaimai 18＇） indicated that canopy spectra could be used to predict GPC. The strong fit between estimated and observed GPC （R2 = 0.7939） indicated that remote sensing techniques were potentially useful predictors of grain protein content and quality in wheat.展开更多
文摘黄淮海地区农业集约化和机械化发展导致土壤紧实问题日益加重,限制玉米产量的进一步提升。明确不同品种玉米根系和地上部生长对土壤紧实胁迫的差异性响应特征,可为该区玉米高产栽培提供理论依据。本研究选用3个玉米品种,采用机械碾压的方法在同一田块模拟无紧实胁迫(NC:no compaction stress,容重1.0~1.3 g cm^(-3))、中度紧实胁迫(MC:moderate compaction stress,容重1.4~1.5 g cm^(-3))和重度紧实胁迫(HC:heavy compaction stress,容重>1.6 g cm^(-3))3个紧实程度处理,定量解析不同程度土壤紧实胁迫下不同品种玉米根冠生长各指标及产量的变化规律。结果表明,与NC相比,MC和HC处理导致玉米减产3.8%~10.3%和12.5%~33.3%。玉米根冠生长及产量形成对土壤紧实胁迫的响应存在基因型差异。MC处理下,DK517的根长、根干重及根冠比较ZD958和DH605分别提高6.0%和14.0%、15.7%和29.6%、18.8%和24.8%,但最大叶面积指数、植株总干物重和产量无显著差异;HC处理下,DK517的根长和根干重较ZD958和DH605分别提高8.4%和22.5%、29.6%和57.8%,且最大叶面积指数、植株总干物重和根冠比分别提高4.6%和15.5%、3.7%和20.9%、28.0%和32.1%,因此产量分别增加7.5%和27.2%。相关分析表明,土壤容重和贯穿阻力与玉米根冠生长各指标和产量呈显著负相关关系(P<0.01)。综上所述,土壤紧实胁迫会显著抑制玉米根系和地上部生长而造成减产,但不同品种玉米根冠生长对不同程度土壤紧实胁迫的响应存在着差异,重度土壤紧实胁迫下根冠生长均具有优势的品种能够维持较高的产量,研究结果可为玉米品种改良和土壤紧实下耕作措施优化提供理论依据。
文摘研究了广东电白巨尾桉和刚果12号桉无性系0.5、1.5、2、3和4年生林木的冠幅生长。试图探索其各年龄阶段的适宜密度,为营造桉树速生丰产林确定造林密度,抚育间伐和经营管理等提供科学依据。结果表明,巨尾桉冠幅与胸径的回归方程为:Y=1.6983+0.1032X r=0.4756。显著性 F 检验为显著。刚果12号桉冠幅与胸径的回归方程为:Y=0.9235+0.1317X r=0.8344^(**) 显著性 F
文摘Stem respiration is an important part of the activity of a tree and is an important source of CO2 evolution from a forest ecosystem. Presently, no standard methods are available for the accurate estimation of total stem CO2 efflux from a forest. In the current study, a 33-year-old (by the year 2001) larch (Larix gmelini Rupr.) plantation was measured throughout 2001-2002 to analyze its monthly and seasonal patterns of stem respiration. Stem respiration rate was also measured at different heights, at different daily intervals and any variation in the larch plantation was recorded. The relationship between stem temperature, growth status and respiration rate was analyzed. Higher respiration rates were recorded in upper reaches of the larch tree throughout the season and these were affected partially by temperature difference. Midday depression was found in the diurnal changes in stem respiration. In the morning, but not in the afternoon, stem respiration was positively correlated with stem temperature. The reason for this variation may be attributed to water deficit, which was stronger in the afternoon. In the larch plantation, a maximum 7-fold variation in stem respiration was found. The growth status (such as mean growth rate of stem and canopy projection area) instead of stem temperature difference was positively correlated with this large variation. An S-model (sigmoid curve) or Power model shows the greatest regression of the field data. In the courses of seasonal and annual changes of stem respiration, peak values were observed in July of both years, but substantial interannual differences in magnitude were observed. An exponential model can clearly show this regression of the temperature-respiration relationship. In our results, Q(10) values ranged from 2.22 in 2001 to 3.53 in 2002. Therefore, estimation of total stem CO2 efflux only by a constant Q(10) value may give biased results. More parameters of growth status and water status should be considered for more accurate estimation.
基金Project supported by the National Natural Science Foundation of China (No.30400278)National High Technology Research and Development Program (863 Program) of China (No.2006AA10Z129)
文摘A field experiment using a split-plot randomized complete block design with three replications was carried out to determine relationships between spectral indices and wheat grain yield （GY）, to compare the performance of four vegetation indices （VIs） for GY prediction, and to study the feasibility of VI to estimate grain protein content （GPC） in winter wheat. Two typical winter wheat （Triticum aestivum L.） cultivars ＇Xuzhou 26＇ （high protein content） and ＇Huaimai 18＇ （low protein content） were used as the main plot treatments and four N rates, i.e., 0, 120, 210, and 300 kg N ha^-1, as the sub-plot treatments. Increasing soil N supply significantly increased GY and GPC （P ≤ 0.05）. For the two cultivars combined, significant and positive correlations were found between four VIs and GY, with the strongest relationship observed when using the green ratio vegetation index （GRVI） at mid-filling. Cumulative VI estimates improved yield predictions substantially, with the best interval being heading to maturity stage. Similar results were found between VI and grain protein yield. However, when using cumulative VI, GPC showed no significant improvement. The strong relationship between leaf N status and GPC （R2 =0.9144 for ＇Xuzhou 26＇ and R2 = 0.8285 for ＇Huaimai 18＇） indicated that canopy spectra could be used to predict GPC. The strong fit between estimated and observed GPC （R2 = 0.7939） indicated that remote sensing techniques were potentially useful predictors of grain protein content and quality in wheat.
