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以内单314为材料,研究施氮量对超高产春玉米不同层位叶片花粒期光合特性及产量的影响。结果表明,施氮量低于439.8 kg/hm2时,同一层位叶片叶绿素相对含量(SPAD)、净光合速率(Pn)、光系统Ⅱ(PSⅡ)的最大光化学效率(Fv/Fm)均表现出随施氮量增加而增高的趋势;当施氮量超出439.8 kg/hm2时,各层位叶片的SPAD、Pn、Fv/Fm降低,且叶位越低降幅越大。同一施氮水平下,不同层位叶片SPAD、Pn、Fv/Fm花粒期变化不同,上位叶片自散粉后0～20 d相对稳定或略有上升,21～40 d迅速降低;中位叶片整个花粒期缓慢降低;下位叶片自散粉后0～20 d缓慢降低,21～40 d后迅速降低。当施氮量为439.8 kg/hm2时,超高产春玉米花粒期不同层位叶片衰老得到延缓,利于其花粒期干物质积累和产量形成,是实现超高产的重要基础。
The single 314 was used to study the effects of nitrogen rate on photosynthetic characteristics and grain yield of different layers of spring maize in ultra-high yield. The results showed that the maximum photochemical efficiency (Fv / Fm) of SPAD, Pn and PSⅡ in the same layer were all shown when the nitrogen application rate was lower than 439.8 kg / hm2 When N rate exceeded 439.8 kg / hm2, the SPAD, Pn, Fv / Fm of the leaves in all layers decreased and the lower the leaf position, the greater the decline. Under the same nitrogen level, the change of pollen period of SPAD, Pn and Fv / Fm was different in different layers. The upper leaves were relatively stable or slightly increased from 0 to 20 days after 0 ~ 20 d and decreased rapidly from 21 to 40 days. The pollen stage decreased slowly. The lower leaves self-loose powder slowly decreased from 0 to 20 days and rapidly decreased after 21 to 40 days. When the nitrogen application rate was 439.8 kg / hm2, leaf senescence in different layers of the super high-yield spring maize was postponed, which was conducive to the accumulation of dry matter and the yield formation at the anthesis, which was an important basis for achieving high yield.