水稻生育后期外源赤霉素调控稻草饲用品质的机理研究

本研究利用两优培九(迟熟中籼)和南粳44(早熟晚粳)两个水稻品种,开花后15d喷施45g/hm~2赤霉素(GA),在处理后第3和14天采集水稻倒1叶样品,分析其中内源激素GA,吲哚乙酸(IAA)和脱落酸(ABA)]的含量及与衰老相关指标丙二醛(MDA)含量、超氧化物歧化酶(SOD)和过氧化物歧化酶(POD)活性,并在收获时采集稻草样品分析饲用品质和青贮品质,分析外源GA调控稻草饲用品质的机理。结果表明外施GA后籼稻品种两优培九和粳稻品种南粳44稻草的饲用品质得到显著改善,衰老进程放缓;但是籼稻和粳稻品种间存在显著差异:两优培九GA处理组稻草的单茎绿叶面积增加幅度极显著高于南粳44(P0.01),稻草中的非结构性碳水化合物(NSC)和粗蛋白(CP)增加幅度也显著高于南粳44(P0.05),叶片中的MDA含量显著低于对照(P0.05),SOD和POD活性显著高于对照(P0.05),且增加幅度高于南粳44,叶片中的GA含量和GA/ABA均显著高于对照(P0.05),且高于南粳44。这说明水稻生育后期喷施外源GA能显著改善稻草饲用品质,主要通过减少MDA的积累量,提高SOD和POD活性,提高内源GA含量及GA/ABA来实现,但对衰老进程较快的籼稻品种两优培九的效果优于粳稻品种南粳44。

Effects of gibberellic acid on forage quality of rice (Oryza sativa)straw

In this study,two different rice (Oryza sativa )varieties,Liangyoupeijiu (late maturing indica)and Nanjing 44 (early maturing japonica),were used to investigate the mechanisms of gibberellic acid (GA)regula-tion of the forage value of rice straw during late growth.GA was applied 15 days after anthesis at a rate of 45 g/ha.The endogenous plant hormones such as GA,3-indole acetic acid (IAA),and abscisic acid (ABA)], superoxide dismutase (SOD)and peroxidase (POD)activities,and malondialdehyde (MDA)content in the first top leaf were assessed on the 3rd d and 14th d after GA application.Forage quality and fermentation quali-ty of rice straw were also assessed after rice harvest.The results indicated that the forage value Liangyoupeijiu and Nanjing 44 were significantly improved by GA application as a result of reduced senescence.However, there were significant cultivar differences;the green leaf area per tiller of Liangyoupeijiu was significantly high-er than that of Nanjing 44 (P <0.01);nonstructural carbohydrates (NSC)and crude protein (CP)content in the straw of Liangyoupeijiu were significantly higher than those of Nanjing 44 (P <0.05).The MDA content of GA treated Liangyoupeijiu was significantly lower than that of the control (P <0.05),while the SOD and POD activities of GA treated plants were significantly higher than those of the control (P <0.05).The GA content and the GA∶ABA ratio of GA treated plants of Liangyoupeiju were significantly higher than those of the con-trol (P <0.05)and Nanjing 44.It was concluded that application of GA during late growth could significantly improve the forage quality of rice straw.The effects of GA were greater in Liangyoupeijiu than in Nanjing 44.