产量15 000 kgha-1以上夏玉米灌浆期间的光合特性

 【目的】探讨产量15 000 kg?ha-1以上夏玉米籽粒灌浆期的光合特性及其与产量形成的关系。【方法】在多年高产试验基础上，选用3个具有高产潜力的玉米杂交种，采用78 000株/ha的密度大田种植。以地上生物量及其分配、果穗叶的光合特征参数来评价产量15 000 kg?ha-1以上的夏玉米光合生理活性；以Richards模型拟合籽粒灌浆过程。【结果】3个玉米杂交种均可实现15 000 kg?ha-1以上的高产，以先玉335（XY335）产量最高。对籽粒产量形成的Richards解析表明，籽粒灌浆启动快且高灌浆速率持续时间和生长活跃期（50 d以上）长的杂交种更容易实现高产。产量15 000 kg?ha-1以上3个杂交种表现出灌浆前期净光合速率、PEPCase活性和RuBPCase活性较高，后期净光合速率、叶面积指数和可溶性蛋白含量下降缓慢的特点，整个灌浆期间叶绿素a/b比值始终较高。3个杂交种中XY 335叶片光合生理活性最高，净光合速率和叶面积的高值持续期分别达50 d和60 d以上。【结论】在玉米高产高密度栽培条件下，重视叶片的光合生理活性的改善可提高光能利用效率，维持较高灌浆速率和较长活跃生长期，实现15 000 kg?ha-1以上的高产目标。

Photosynthetic Traits of over-15000 kgha-1 Summer Maize Hybrids during Grain Filling

【Objective】It is very important to study photosynthesis of super high-yielding maize hybrids, so a field trail was conducted to research the relation to photosynthetic traits and yield of over-15000 kg ha-1 summer maize hybrids during grain filling period. 【Method】Three summer maize hybrids (XY335, DH3632 and DH3806) were planted at 78000 plants ha-1 in National Corn Project Technology Research Center (Shandong) randomly. Above-ground biomass partitioning and photosynthetic characteristics of ear leaves were investigated to evaluate yield formation of three super high-yielding maize hybrids during grain filling period.【Result】Yields of three-type maize hybrids were over 15000 kg ha-1, and yield of XY335 was higher than that of DH3632 and DH3806 significantly (P＜0.05). Characteristic of grain filling analyzed by Richards equation showed XY335 had the higher grain-filling rate, the longer active growing period, and it reached the maximum grain-filling rate earlier than DH3632 and DH3806. The result indicated grain-filling traits like XY335 was favorable to high yield in the experiment. The leaves’ photosynthetic physiology quantity of XY335 was highest of the three-type hybrids. XY335 had high net photosynthetic rate (Pn), PEPCase activity, RuBPCase activity and chlorophyll a/b value after anthesis, and the leaf area index (LAI) and soluble protein content decreased slowly from 20d and 30d after flowering, respectively. 【Conclusion】To obtain 15000 kg ha-1 of super high-yielding breeding and cultivation in practice, we need to improve the leaves photosynthetic physiology quantity to maintain high grain-filling rate and long active growing period after anthesis, enhance the solar energy use efficiency.