大豆群体冠层翻叶生理效应及其对花荚形成的影响

It was the key of super-high yielding in soybean that to establish the population structure with high photosynthetic efficiency. Previous the soybean population main studied the relationship of leaf area index, photosynthetic potential, photosynthetic rate, dry matter accumulation and yield etc., but the systematic study on the effect of photosynthetic performance of canopy and yield was a little in the leaf position (erect, horizontal etc.) of canopy. Leaf area index of the population was high with high-yield soybean in field, at the same time, canopy of soybean often appears the phenomenon of “turn leaf”. Light condition has been changed when the leaf was turned on the middle and upper nodes of main-stem of soybean, which will effect on photosynthetic performance of canopy and flowers and pods formation in soybean. At present, the occurrence rules and physiological effect of “turn leaf” and its impact on yield was unknown. This project is planned for the range of yield 4.5-6.4t/hm2 in the field, and to compare different medium maturity varieties of soybean, and comparing the difference of morphology (including ultrastructure), photosynthetic rate, chlorophyll fluorescence, RuBPcase activity and SOD activity etc. of the “turn” and not “turn” leaf on the middle and upper nodes of soybean under nitrogen fertilizer and density treatment. To study the effect of “turn leaf” on that in flower and pod number of same nodal point near this leaf and to prove important insights into the formation and physiological effect of “turn leaf” of soybean, and to reveal the physiological mechanism on the yield effect of soybean, and further to study the effective measures for the prevention “turn leaf”, providing theoretical basis for super-high yielding breeding and cultivation of soybean.

建立高光效群体结构是大豆超高产的关键。以往对大豆群体研究多集中在叶面积指数、光合势、光合速率与干物质积累和产量的关系分析等方面。群体冠层叶片的着生态势（直立、水平等）对冠层光合性能和产量影响的系统研究很少。高产条件下群体叶面积指数大，大豆冠层常出现“翻叶”现象。大豆主茎中、上部节位“翻叶”改变叶片光照条件后，将对冠层的光合性能和花荚形成产生影响。目前，对“翻叶”发生规律及其生理效应和对产量的影响均不清楚。本项目拟在田间产量4.5-6.4t/hm2的范围内，比较不同中熟大豆品种、及其氮肥和密度处理的中、上部节“翻叶”与未”翻叶”叶片的形态（包括超微结构）、光合速率、叶绿素荧光参数、RuBP羧化酶活性、 超氧化物歧化酶活性等的差异，研究“翻叶”对其相邻节位花荚数的影响，探明大豆“翻叶”成因和生理效应，揭示“翻叶”对大豆产量影响的生理机制，研究减少大豆“翻叶”的技术。为大豆超高产提供理论依据。

我国大豆消费高度依靠进口，国产大豆供不应求，急需提高我国大豆单产水平。塑造高光效群体结构是提高大豆产量的前提条件。部分大豆品种冠层顶部叶片翻叶率较高，改变了大豆群体冠层结构，影响大豆产量形成。鼓粒期是大豆产量形成的关键时期。在新疆高产条件下研究春大豆鼓粒期冠层顶部翻叶率品种间差异的原因；研究大豆冠层顶部叶片持续翻叶后光合速率、蒸腾速率、抗氧化酶活性等生理指标的变化规律；研究持续翻叶后叶片结构变化；研究大豆冠层顶部叶片持续翻转后对相应节位粒重的影响；研究新疆超高产大豆冠层结构。研究结果表明，不同春大豆品种间在鼓粒期冠层顶部1-4节叶片的翻叶率在0～26.5%之间，大豆冠层顶部叶片单叶面积大、比叶重小及叶型指数低的叶片翻转率较高，反之，叶片翻转率低或不发生翻叶；不同品种冠层顶部叶片远轴面短时间内的光合速率较近轴面平均降低31.7%，下降幅度因品种而异；人工模拟试验，持续翻叶0～10 d叶片SOD、POD、CAT酶活性高于对照，翻叶10～20 d低于对照；翻叶后叶片丙二醛含量较对照叶片持续增加，降低叶片可溶性蛋白质含量；翻叶0～20 d叶片近轴面净光合速率较对照叶近轴面33.3%～41.5%，大幅降低叶片可溶性糖含量；持续翻叶降低叶片光合速率是叶片远轴面光合速率低于近轴面和翻叶加速叶片衰老进程的共同作用结果；在高温和强光条件下，持续翻叶加速衰老是叶片膜脂过氧化进程加速的结果；翻叶蒸腾速率比对照低5.6 %～28.9 %，叶片温度却比对照高7.2 %～8.1 %；持续翻叶后叶肉细胞结构失去完整性，降低总电子受体容量、并使PSII中受体侧和供体侧的放氧复合体(OEC)失活和电子之间的不平衡；始粒期翻叶后同节位粒重降低10.38～22.4%。大豆鼓粒期冠层顶部持续翻叶大幅度降低叶片光合速率和蒸腾速率，叶片吸收光能过剩和叶温增高，导致加速叶片衰老，对大豆高产不利。研究结果丰富了大豆高产冠层结构的内容。