杂交早稻吸氮特性与产量形成的初步研究

研究了在不同施氮水平下,杂交早稻吸氮特性及其与产量形成的关系。结果表明;杂交早稻威优49亩产500千克左右,植株每亩总吸氮量平均为9.78千克,其中土壤供氮量占52.45%。杂交早稻一生中前期吸氮量占50.72%,中期占31.08%,后期占18.30%,以中期施氮对叶片含氮率影响最大。在高氮水平下,中期施氮导致茎鞘醣含量急剧下降。抽穗前植株吸氮量与每亩发育颖花数呈极显著正相关,但结实率受每朵颖花占有抽穗前醣量的影响。最适 LAI 为6.5～7.5。

STUDIES ON THE CHARACTERISTICS OF NITROGEN ABSORPTION AND THE YIELD FORMATION IN EARLY HYBRID RICE

The relationship between the characteristics of nitrogen(N)absorption and theyield formation was studied under different N levels.The main results obtained aresummarized as follows:The total amount of the N absorption was 9.78 Kg/mu whenthe grain yield of the early hybrid rice,V49,was about 500Kg/mu.And theamount of N supplied by soil was 52.45% of the total amount.The amount ofN absorption was 50.72% in the early stage,31.08% and 18.30% in the middleand later stages respectively.The N content of the leaf was affected more sig-nificantly by the N applied in the middle stage than that in other stages,and theN applied in the middle stage caused a dramatic decrease of the amount of carbo-hydrate in leaf-sheath and stem under high N level.There was a close correlationbetween the amount of N absorption before heading and the number of developedspikelets,but the filled grain percentage was affected by the carbohydrate amountof each spikelet before heading.The optimum LAI was 6.5 to 7.5.