Effects of defoliation on grain yield and water use of winter wheat
Effects of defoliation on grain yield and water use of winter wheat
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DOI：
10.1017/s0021859609990542
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发表时间：
2009-12
期刊：
影响因子：
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通讯作者：
L. Shao;Xiying Zhang;A. Hideki;W. Tsuji;Suying Chen
中科院分区：
文献类型：
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作者：
L. Shao;Xiying Zhang;A. Hideki;W. Tsuji;Suying Chen
摘要 进行了田间和盆栽实验，以研究脱叶对作物性能的影响以及使用脱叶作为保持土壤水分的方法的可能性。该研究于 2006 年至 2008 年期间进行，涵盖华北平原冬小麦 (Triticum aestivum L.) 的两个生长季。在以下作物阶段和条件下，对田间冬小麦实施三种程度的落叶（轻度、中度和重度）：抽穗期、缺水条件下的花期以及两级或三级灌溉的花期。安排了在两种水况下进行三个脱叶水平的额外盆栽实验。结果表明，脱叶强度和脱叶时间均显着降低了粮食产量。在潮湿条件下，减少量超过20%，而在干燥条件下，减少量为c。 12%。抽穗期落叶的产量下降幅度大于花期落叶，主要是由于籽粒重量下降所致。轻度落叶（保留顶部三片叶子）不会影响谷物产量。中度落叶（保留顶部两片叶子）略微降低了谷物产量。在潮湿条件下，由于开花期严重落叶，表土剖面中的根长密度显着降低，但在干燥条件下却增加了。中度和轻度落叶条件下，谷物的干物质再利用增加，收获指数（HI）相对较高。在所有土壤湿度条件下，落叶后剩余叶片的光合速率均增强。虽然落叶减少了季节性用水（ET），但产量下降幅度远大于严重落叶下ET的下降，导致水分利用效率（WUE）降低。结果表明，通过去除树叶来保持土壤湿度可能不是一个经济的选择。在本研究条件下，冬小麦的WUE并没有因落叶而得到改善；然而，在非常干燥的条件下，落叶导致的蒸散量减少可能有助于作物生存。
SUMMARY Field and pot experiments were conducted to investigate the effects of defoliation on crop performance and the possibility of using defoliation as a method for conserving soil moisture. The study was conducted during 2006–2008, over two growing seasons of winter wheat (Triticum aestivum L.) in the North China Plain. Three levels of defoliation (mild, moderate and severe) were imposed on winter wheat in the field during the following crop phases and conditions: at heading, at anthesis under water deficit conditions and at anthesis under two or three levels of irrigation. Additional pot experiments with three levels of defoliation under two water regimes were arranged. The results showed that both the intensity of defoliation and the timing of defoliation significantly reduced grain production. Under wet conditions the reduction was over 20%, while under dry conditions the reduction was c. 12%. Yield reduction was greater for defoliation at heading than at anthesis and it was mainly caused by a reduction in kernel weight. Mild defoliation (top three leaves retained) did not affect grain yield. Moderate defoliation (top two leaves retained) slightly reduced grain production. Root length density in the topsoil profile was significantly reduced by severe defoliation at anthesis under wet conditions, but it increased under dry conditions. Dry matter remobilization to grains under moderate and mild defoliation was increased and resulted in a relatively higher harvest index (HI). The photosynthetic rate of the leaves remaining after defoliation was enhanced under all soil moisture conditions. Although defoliation reduced the seasonal water use (ET), the yield reduction was much greater than the reduction in ET under severe defoliation, resulting in lower water use efficiency (WUE). The results show that conserving soil moisture by removing leaves might not be an economic choice. Under the conditions of the present study, the WUE of winter wheat was not improved by defoliation; however, in very dry conditions the reduction in ET by defoliation might help the crop survive.