打顶后涂抹生长素对棉花功能叶营养物质及脱落酸和细胞分裂素含量的调节作用
Effect of post-decapitation NAA-smearing on ABA and CTK content in the functional leaves of cotton plant
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摘要: 为了解新疆棉花栽培中打顶措施与棉花早衰间的关系, 在盆栽条件下研究了低氮(150 mg·kg-1)和高氮(500 mg·kg-1)条件下, 不打顶、打顶和打顶后涂抹生长素处理对棉花内源激素含量的影响。结果表明, 低氮水平下, 棉花打顶后功能叶片细胞分裂素(CTK)和可溶性蛋白质含量降低, 而脱落酸(ABA)和丙二醛(MDA)含量增加; 打顶后涂抹生长素处理CTK和可溶性蛋白质含量均比打顶和不打顶处理高, 而ABA含量低于打顶处理, 但仍比不打顶处理高。打顶处理ABA/CTK的比值均高于不打顶处理, 而打顶后涂抹外源生长素又使ABA/CTK比打顶处理有所降低。叶片MDA含量对不同打顶处理的响应与激素比值的响应表现出相似趋势。高氮水平下, 打顶或打顶后涂抹生长素处理的ABA含量高于不打顶处理。打顶处理在低氮条件下叶绿素含量均高于高氮条件。试验结果表明, 高氮处理的施氮量超过了棉花植株生长需要, 出现了ABA累积, 对植株生长产生抑制。低氮条件下, 打顶提高了棉花叶ABA的绝对含量、ABA/CTK和MDA含量, 表明打顶促进了棉花衰老, 而打顶后涂抹生长素在一定程度可延缓衰老进程。Abstract: A pot experiment was conducted to investigate the effect of decapitation (a conventional technique in cotton cultivation in Xinjiang) on the premature senility and contents of phytohormone, carbonhydrate and chlorophyll in the functional leaves of cotton plant under low (150 mg·kg-1) and high (500 mg·kg-1) nitrogen application. Compared with non-decapitated plants under low nitrogen application, CTK and soluble protein content decreases while ABA and MDA content increases in decapitated plants. Both CTK and soluble protein content increases when smeared with NAA after decapitation in relation to decapitation only or non-decapitation treatments. ABA content in plants smeared with NAA after decapitation is lower than in decapitation only, but is higher than in non-decapitation treatment. ABA/CTK ratio for cotton plant with decapitation treatment is higher than in non-decapitation or post-decapitation NAA-smearing treatments. Decapitation increases plant MDA content while MDA decreases in post-decapitation NAA-smearing treatment, compared with non-decapitation treatment. Under higher N supply, ABA content under decapitation or post-decapitation NAA-smearing treatment is higher than under non-decapitation treatment. Chlorophyll content in leaves under low N supply is higher than under high nitrogen supply. Accumulation of ABA under high nitrogen supply indicates that high N might inhibit plant growth. The increase in ABA and MDA content and in ABA/CTK ratio under decapitation with low N supply suggests that decapitation enhances premature senility of cotton plants. Post-decapitation NAA smearing, on the other hand, may delay premature senility.