The role of wheat ears as a source of nitrogen （N） and carbon （C） in the grain filling process has barely been studied. To resolve this question, five wheat genotypes were labeled with 15N-enriched nutrient soluti...The role of wheat ears as a source of nitrogen （N） and carbon （C） in the grain filling process has barely been studied. To resolve this question, five wheat genotypes were labeled with 15N-enriched nutrient solution. N remobilization and absorption were estimated via the nitrogen isotope composition of total organic matter and Rubisco. Gas exchange analyses showed that ear photosynthesis contributed substantially to grain filling in spite of the great loss of C due to respiration. Of the total kernel N, 64.7% was derived from the N acquired between sowing and anthesis, while the remaining 35.3% was derived from the N acquired between anthesis and maturity. In addition, 1.87 times more N was remobilized to the developing kernel from the ear than from the flag leaf. The higher yielding genotypes showed an increased N remobflization to the kernel compared to the lower yielding genotypes. In addition, the higher yielding genotypes remobilized more N from the ears to the kernel than the lower yielding genotypes, while the lower yielding genotypes remobilized more N from the flag leaf to the kernel. Therefore, the ears contribute significantly toward fulfilling C and N demands during grain filling.展开更多
干旱区农业土地开发利用对土壤碳库的源汇效应一直存有争议,为研究该过程对土壤剖面碳存储作用,该文以新疆三工河流域阜北农场不同土地开发利用时段的农田为研究对象,对比分析近50 a 0~200 cm土壤剖面有机碳和无机碳分布格局及其变化。...干旱区农业土地开发利用对土壤碳库的源汇效应一直存有争议,为研究该过程对土壤剖面碳存储作用,该文以新疆三工河流域阜北农场不同土地开发利用时段的农田为研究对象,对比分析近50 a 0~200 cm土壤剖面有机碳和无机碳分布格局及其变化。结果表明:土壤碳含量随利用年限增加而增大,但有机碳与无机碳变化趋势相反;长期的农业土地利用显著影响0~80 cm土壤碳的分布,其变异性在80~100 cm有明显的突变现象,即变异系数均减小40%以上;无机碳与有机碳的比例随土层深度和利用年限增加,变化率从荒地的0.028到50 a的0.088(P<0.01),增幅达2.14倍;随土地利用年限,有机碳和无机碳的碳储效应在土层间与时间尺度上不同,但剖面土壤碳密度为典型的碳汇进程。研究可为干旱区农业土地开发提供依据。展开更多
基金supported by Breeding to Optimise Chinese Agriculture (OPTICHINA) (Coordination and support action: FP7-KBBE-2010-4, 266045)the projects AGL 2011-30386C02-02 and AGL 2013-44147-R funded by the Spanish Ministry of Economy and Competitiveness+1 种基金a Ramon y Cajal research grant funded by the Spanish Ministry of Economy and Competitivenessa Basque Country Postdoctoral Fellowship funded by the Department of Culture and Linguistic Politics of the Basque Country Government
文摘The role of wheat ears as a source of nitrogen （N） and carbon （C） in the grain filling process has barely been studied. To resolve this question, five wheat genotypes were labeled with 15N-enriched nutrient solution. N remobilization and absorption were estimated via the nitrogen isotope composition of total organic matter and Rubisco. Gas exchange analyses showed that ear photosynthesis contributed substantially to grain filling in spite of the great loss of C due to respiration. Of the total kernel N, 64.7% was derived from the N acquired between sowing and anthesis, while the remaining 35.3% was derived from the N acquired between anthesis and maturity. In addition, 1.87 times more N was remobilized to the developing kernel from the ear than from the flag leaf. The higher yielding genotypes showed an increased N remobflization to the kernel compared to the lower yielding genotypes. In addition, the higher yielding genotypes remobilized more N from the ears to the kernel than the lower yielding genotypes, while the lower yielding genotypes remobilized more N from the flag leaf to the kernel. Therefore, the ears contribute significantly toward fulfilling C and N demands during grain filling.
