中后期追施15N对水稻氮素积累与分配的影响

在田间条件下 ,采用 1 5 N微区法 ,研究中、后期施肥对稻株体内氮素积累与分配的影响。结果表明 :1随着氮肥施用时期的推迟 ,茎、叶等营养器官干物重明显下降 ,而穗干物重下降幅度较小 ,且其占全株干重的比例提高。 2稻株含氮率随氮肥施用时期推迟有提高的趋势 ;与施促花肥相比 ,施用粒肥绿叶及叶鞘中的氮素积累量明显下降 ,而茎、穗中氮累积量则略有增加。 3在稻株不同器官中 ,穗、绿叶 (包括叶鞘 )对穗粒肥氮的积累能力最强 ,但随穗粒肥施用时期的推迟 ,穗部积累的肥料氮及其占全株的比例增加 ,而绿叶则呈相反的趋势。 4稻株对促花肥、保花肥、粒肥氮的回收率 (利用率 )分别为 32 .7%、30 .0 %及 2 3.7%。

EFFECT OF NITROGEN FERTILIZER APPLIED AT MIDDLE AND LATE GROWING STAGES ON 15N UPTAKE AND DISTRIBUTION IN RICE (ORYZA SATIVA L.)

Isotopic 15 N micro plot experiment was conducted under field condition to investigate the effect and uptake of nitrogen applied at middle and late growing stages of rice. Results showed that nitrogen timing had an obvious effect on dry matter accumulation, fertilizer N uptake and its distribution in different parts of rice plant. With delayed fertilizer application dry weight of vegetative parts of rice plant (e.g. stalk and leaf) decreased obviously while spike dry weight decreased slightly. Compared with spikelet promoting fertilizer, amount of nitrogen accumulated in green leaf and leaf sheath decreased by 31.5% and by 37.70%, respectively, while that of stalk and spike increased slightly. Of total amount of 15 N accumulated in whole rice plant, green leaf (including its sheath) and spike accounted for 40% and 50%, respectively. Delayed fertilizer N application also resulted in the increase of 15 N uptake by spike and the decrease of that by green leaf. In this experiment, 15 N recovery of applied as spkelet promoting, spikelet sustaining and grain fertilizer was 32.7%, 30.0% and 23.7%, respectively.