弱光下氮素配施对杂交水稻氮磷钾吸收分配的效应研究

Effects of Nitrogen Application on NPK Uptake and Distribution in Hybrid Rice Under Weak Light

近几十年来长江中下游地区日照时数和总辐射量不断减少,极端阴雨寡照天气发生频率明显增加,造成水稻生长季弱光胁迫,研究弱光逆境对水稻生长的影响机理及调控途径对国家粮食安全具有重要意义。本文以弱光研究中常用的杂交籼稻品种汕优63为供试材料,通过水培盆栽试验,从水稻移栽至成熟收获期进行了3种光照强度(L0、L1和L2分别为自然光、遮1层光和遮2层光)、3种氮素水平(N1、N2和N3分别为7、21、35 mg·kg-1N)及其互作的处理,研究了弱光下氮素配施对杂交水稻氮磷钾吸收分配的效应。结果表明:除了拔节期植株含钾率呈现L1>L2>L0,各时期水稻植株含氮、磷、钾率均表现为L2>L1>L0。成熟期N2、N3供氮水平下弱光促进氮、磷元素在叶片和茎鞘部位残留;N1、N3水平下,弱光均不同程度提高茎鞘钾素积累;高氮弱光促进了主要养分在水稻营养器官中的积累。施氮量对植株N、P吸收的最大效应期均在抽穗期,而对K吸收的最大效应期则在拔节期;光氮互作效应对N、P、K吸收的影响效应随着生育期的推进而渐增,均在成熟期达到最大。在N2、N3施氮水平下,氮收获指数均呈现L2<L1<L0趋势;弱光降低了磷、钾收获指数,氮素增量配施促使其下降趋势更加显著。由此可见,氮肥配施量必须与光强相匹配,如果水稻生育期总体光强较弱,宜减量施氮,如光强较强,宜增量施氮。

In recent decades,total intensity and hours of sunshine decrease in the area of Lower-Middle Reaches of the Yangtze River. Moreover,rainy weather in the seasons of rice growing often causes weak light stress. So it＇s of great significance for national food security to study the effects of weak light stress on the growth of rice. Under hydroponic pot conditions,with Hybrid Indica rice Shanyou 63 as experimental material,two elements including light intensity（L0、L1and L2） and nitrogen supply（N1、N2 and N3 represent 7、21 and 35 mg·kg^-1 respectively） were conducted to study effects of nitrogen application on major nutrient element uptake and distribution under weak light. The results showed that in addition to the potassium rate in rice presenting as L1 〉L2 〉L0 at elongation stage,the content of nitrogen（N）,phosphorus（P） and potassium（K） in plants were characterized by L2〉 L1 〉L0 at each key period of rice. At maturity stage,under nitrogen level of N2 and N3,weak light promoted accumulation of N and P in leaf and stem sheath;under N1,N3 level,weak light improved K residue in stem accumulation in rice vegetative organs. The maximum effective phase of N application on absorption of N and P were heading stage（F = 335. 67^＊＊、194. 15^＊＊）,while the biggest effective phase for the K absorption was jointing stage（F = 522. 25^＊＊）. Interactive effects of light intensity and nitrogen supply on N,P,K absorption increased gradually with the development of growth period,reaching the maximum at the mature period. Then we concluded that we should reduce the application of nitrogen fertilizer if the overall light intensity is weak. On the contrary,we should increase the application of nitrogen fertilizer if the overall light intensity is strong. This indicated that the amount of nitrogen fertilizer must match the light intensity accordingly.