化控措施对直播晚稻抽穗扬花期低温胁迫的缓解效应

直播晚稻抽穗扬花期易遭受寒露风危害,影响产量与品质。利用自然低温条件,以陵两优722和中早35为试验材料,设置T1（芸苔素内酯+赤霉素）、T2（芸苔素内酯+赤霉素+磷酸二氢钾）、T3（赤霉素+磷酸二氢钾）和对照（CK,清水）4个处理,研究化学调控剂对直播晚稻遭遇寒露风危害的缓解作用。结果表明,在寒露风危害下,喷施不同化学调控剂均可有效缩短水稻抽穗时间,与CK相比,陵两优722和中早35生育期平均缩短了2.5d,其中,T1生育期均缩短1d,T2分别缩短3d和5d,T3分别缩短2d和4d,喷施化学调控剂还可有效减缓叶绿素相对值（SPAD值）与净光合速率（P_n）的下降,CK的SPAD值较第1次测定最大下降幅度平均为6.55%,T1、T2和T3分别为3.50%、4.22%和3.77%;CK的P_n较第1次测定最大下降幅度平均为10.59%,T1、T2和T3分别为5.96%、1.22%和3.36%。喷施化学调控剂不仅能稳定结实率与千粒重,且产量、稻米加工品质及外观品质均优于CK,与CK相比,陵两优722与中早35在T1处理下结实率分别提高8.17%与2.31%,T2分别提高6.20%与5.36%,T3分别提高7.88%与6.31%;千粒重则仅T2有促进作用,陵两优722与中早35较CK分别提高了1.67%与2.92%;与CK相比,陵两优722和中早35在T1处理产量平均提升9.01%,T2平均提升20.69%,T3平均提升19.01%,出糙率、精米率与整精米率较CK均明显提高,垩白度与垩白粒率明显降低。总体而言,磷酸二氢钾、赤霉素和0.01%芸苔素内酯混合液（T2）对水稻低温胁迫的缓解效果最明显。

Study on Relieving Cold Stress of Direct-Seeded Late Rice at Heading Stage by Chemical Control

Cold-dew wind stress has an influence on yield and quality by direct-seeding late rice during the heading stage. Lingliangyou 722 and Zhongzao 35 was used as materials, and four treatments of T1 (brassinolide + gibberellin), T2 (potassium dihydrogen phosphate + gibberellin + brassinolide), and T3 (gibberllin + potassium dihydrogen phosphate), and CK (water) as a control, the effects of chemical control on the cold-dew wind in direct-seeded late rice in the natural low temperature were researched. The results showed that the spraying of different chemical regulators could effectively shorten the heading time of rice. Compared with CK, the average growth period of Lingliangyou 722 and Zhongzao 35 was 2.5d shorter, all varieties were reduced 1d under T1 treatment ; T2 was reduced 3d and 5d; T3 was reduced 2d and 4d. The falling range of SPAD value and the net photosynthetic rate (P_n) was smaller by using chemical control. Compared with the first time, the SPAD value of the maximal reduction average decreased by 6.55%; the average decrease of T1, T2, and T3 were 3.50%, 4.22%, and 3.77%, respectively; The average of P_n decreased by 10.59%, T1 decreased by 5.96%, T2 decreased by 1.22%, T3 decreased by 3.36%. Not only seed setting rate and 1000-grain weight were stabilized by using chemical control, but also yield, milling quality, and appearance quality were better than CK. Compared with seed setting rate of CK, T1 of Lingliangyou 722 and Zhongzao 35 increased by 8.17% and 2.31%, T2 increased by 6.20%, 5.36%, T3 increased by 7.88% and 6.31%; Only T2 increased by 1000-grain weight, Lingliangyou 722 and Zhongzao 35 increased 1.67% and 2.92%; Compared with yield of CK, T1 average increased by 9.01%, T2 increased by 20.69%, T3 increased by 19.01%; Compared with CK, brown rice rate, milled rice rate and head rice rate were increased by chemical control, chalkiness and chalkiness rate were decreased by chemical control. Overall, potassium dihydrogen phosphate, gibberellin, and 0.01% brassinolide mixture of T2 was the best for relieving the low-temperature stress of rice.