赤霉素喷施量及时期对水稻穗层整齐度和产量的影响

Effects of spraying exogenous gibberellin(GA_3) at heading stage on heading uniformity and yield of rice

为探明叶面肥(赤霉素与磷酸二氢钾混合液)中不同赤霉素(GA3)剂量和喷施时期对水稻花期低温的调控效果,以遭受低温危害的中稻迟熟品种杂交稻培两优537和常规稻鄂中5号为材料,在叶面喷施3kg/hm2磷酸二氢钾的基础上,按每公顷添加0.0(A0)、7.5(A1)、15.0(A2)、22.5(A3)、30.0(A4)、37.5g(A5)的GA3分别于破口期(B1)、始穗期(B2)、抽穗期(B3)、齐穗期(B4)施用,考查水稻抽穗动态、穗层整齐度、产量及其构成。结果表明:GA3用量控制在15.0～22.5g/hm2,且在B1或B2期施用有利于提高水稻的千粒重、穗实粒数和结实率,缩短出穗的时间,进而提高产量,而在B3或B4喷施,则要适当加大GA3喷施的剂量;加大GA3的处理或在抽穗早期喷施均能提高水稻穗层的整齐度,但前者会影响籽粒的灌浆,降低千粒重。在叶面肥中增加GA3可以提高水稻对低温的抗性,其中GA315.0～22.5g/hm2是较为适当的喷施剂量,而对于因下雨等原因导致必须在抽穗后期喷施时,可适当加大GA3的剂量。

To explore the controlling effect of different dosages of gibberellin（GA3） contained in the foliar fertilizer mingled by potassium dihydrogen phosphate and gibberellin（GA3） and the spraying times of gibberellin（GA3） at heading stage on the resistance of rice to low temperature stress during the flowering period,two rice cultivars matured lately and sensitive to low-temperature stress at heading stage,hybrid ＇Peiliangyou 537＇ and conventional ＇Ezhong 5＇,were used as experimental materials in this study.Twenty four adjustment patterns including the supplement of 0.0（A0）,7.5（A1）,15.0（A2）,22.5（A3）,30.0（A4）,37.5 g（A5） of GA3 based on 3.0 g/hm2 potassium dihydrogen phosphate and the spraying time at spike initial appearance stage（B1）,initial heading stage（B2）,heading stage（B3）,full heading stage（B4） were adopted,thereafter heading dynamics,uniformity of panicle layer,yield and yield components of rice were investigated.The results showed that the 1 000-grains weight,grains per panicle,rate of seed setting,heading time and yield of rice under the patterns with spraying dosage of GA3 at 15.0-22.5 g/hm2 and the spraying time at B1 or B2 were better than those under other patterns and spraying times.However,under spraying the foliar fertilizer at B3 or B4,high rice yield requires the increase of spraying dosage.Increasing of spraying dosage or earlier spray time during heading period could improve the uniformity of rice panicle layer,but the former would diminish grain-filling and decrease 1000-grain weight.The addition of GA3 in the fertilizer can increase the resistance of rice to low temperature,in which the appropriate dosage of GA3 is 15.0-22.5 g/hm2.The increased dosage of GA3 may be useful to improve rice yield when the foliar fertilizer spraying time is delayed due to rain.