Preliminary Research On The Compensatory Effects Of Nitrogen Deficiency In Double-season Super Hybird Rice Varieties

Nitrogen was one of the most important and active controlled factor that affectthe yield of the rice, but the current of widespread low nitrogen use efficiency andinconspicuous yield effect in our country. Resolved the problem must be determinedthe nitrogen critical period, efficient and dull period. But the premise was to identifythe nitrogen demanded critical period and sensitive stage. This test selected potentialyield excellent early super hybrid rice varieties GanXin203and late super hybrid ricevarieties WuFengYou T025, planted in the barrel test under normal supply water, thewhole growth period was divided into five stages: seeding stage, tillering stage,panicle stage, heading stage and milky stage, studied on nitrogen deficiency atdifferent stages, next growth stages supplied the same amount, double amountnitrogen, the influence on dry matter accumulation, nitrogen accumulation,distribution and utilization, and yield formation of double-season of super hybrid ricevarieties, known the nitrogen deficiency compensation effect. The results showedthat:1.Yileld per plant and its component factors to the double-season of super hybridrice varieties. The sensitive stage of nitrogen and nitrogen demanded critical period ofyield per plant in the double-season super hybrid rice varieties was from the tilleringstage to panicle stage, validity of nitrogen deficiency compensation was from tilleringstage to heading stage;Plant effective panicle nitrogen deficiency sensitive period andnitrogen demanded critical period was tillering stage, validity of nitrogen deficiencycompensation was from tillering stage to heading stage; Per plant and grain weightnitrogen deficiency sensitive period and nitrogen demanded critical period waspanicle stage, validity of nitrogen deficiency compensation was from panicle stage toheading stage;Seed setting rate nitrogen deficiency sensitive period and nitrogendemanded critical period was panicle stage,validity of nitrogen deficiencycompensation was not manifested;Harvest index nitrogen dediciency sensitive periodand nitrogen demanded critical period was panicle stage, validity of nitrogendeficiency compensation was from panicle stage to heading stage.2.Dry matter accumulation and SPAD value of leaves. Different growth stagesof n itrogen deficiency treatment in double-season super hybrid rice varieties showedthat：in the maturity stage,parts of stem, leaf and panicle had the highest dry biomassin the panicle stage, milky stage, seedling stage without nitrogen treatment. Nitrogendeficiency in the seeding stage;The SPAD was no significant difference among thetreatments with the advance of growing stages.3.Nitrogen accumulation and its distribution and utilization in the stem, leaf, panicle. Panicle stage nitrogen deficiency treatment, NPE,NHI of the double-seasonof super hybrid rice varieties were higher than other treatment; Milky stage with nonitrogen treatment, its TNR,PFP of the double-season of super hybrid rice varietieswere higher than other treatments; Seedling stage nitrogen deficiency, its NUE of thedouble-season super hybrid rice varieties was higher than other treatments; Paniclestage nitrogen deficiency, the uptake of the stem and leaf in the double-season superhybrid rice varieties was higher than other treatments; Seedling stage nitrogendeficiency, the uptake of the panicle in the double-season super hybrid rice varietieswas higher than other treatments; Panicle stage nitrogen deficiency, the numbers ofthe tillers in the double-season super hybrid rice varieties was higher than othertreatments.4.According to the results of this study we think:choose the new varieties fromthe stable yield of double-season super hybrid rice varieties should have strongtillering ability,because the tillering ability was the main source of compensationeffect of rice plants,foundation of effective panicle number per plantformation;Rational use of nitrogen deficiency compensation effect in the cultivationcould realize the optimization of nitrogen management,but we should also recognizethe compensation effect was limited and timeliness.