氮肥对夏玉米穗粒数形成的影响

设立不同基肥施氮量、不同施氮时期、雌穗小花肥和吐丝肥不同氮量共3个试验,从氮肥用量和施用时期考察氮肥影响穗粒数形成的生理原因。结果表明,氮肥通过影响植株生长发育和光合生产能力来影响穗粒数形成。不同施氮方式主要影响籽粒结实率,对分化的花丝数和花粉活力影响不大。在保证基肥用量的基础上,雌穗小花分化期适量增施氮肥提高了粒数决定关键期的植株生长速率和叶片光合能力,可获得较高的穗粒数。在基肥和雌穗小花肥充足的基础上,吐丝期增施氮肥不仅对植株物质积累和同化物供应促进作用不大,反而可能由于氮代谢对碳水化合物的竞争,降低了穗粒数。

Effect of Nitrogen Supply on the Kernel Number Determination in Summer Maize

The physiology of nitrogen effects on kernel number(KN) determination in summer maize was investigated by adopting field trails of different nitrogen supply amount and time.The results showed that nitrogen influenced KN mainly by plant growth and leaf sucrose supply in the critical period of grain number determination.The increased KN by nitrogen was mainly due to the reduced kernel abortion while spikelet number and pollen activity were not influenced.Increasing the nitrogen supply during early and middle growth stage improved the assimilate and nitrogen level of plant,so as to enhance dry matter production and plant growth rate,which was helpful to kernel growth.Increasing the nitrogen supply in the silking stage had no effect on the dry matter production,but the assimilate supply for kernel growth was reduced due to the competition between carbon and nitrogen metabolism.