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以‘津优4号’(热敏感型)和‘美国保尔’(耐热型)黄瓜幼苗为试材,研究了叶面喷施褪黑素对高温胁迫条件下黄瓜幼苗氮代谢的影响。结果显示,高温胁迫下,(1)两种黄瓜幼苗硝态氮含量先升高后降低,‘津优4号’总氮和氨态氮含量先下降后持续升高,而‘美国保尔’总氮和氨态氮含量持续上升;(2)两种黄瓜幼苗硝酸还原酶(NR)活性均先上升后下降,而谷氨酰胺合成酶(GS)、谷氨酸合成酶(GOGAT)和谷氨酸脱氢酶(GDH)均持续下降,‘美国保尔’的4种酶活性下降幅度显著低于‘津优4号’。研究结果表明,叶面喷施褪黑素可有效缓解高温胁迫对NR、GS、GOGAT和GDH的抑制作用,显著增加硝态氮含量,降低氨态氮含量,减轻氨态氮积累对黄瓜幼苗造成的毒害作用,增强高温胁迫条件下黄瓜幼苗氮素的代谢能力,减轻高温胁迫对黄瓜幼苗造成的伤害,提高黄瓜幼苗抵御高温胁迫的能力。
Effects of foliar application of melatonin on nitrogen metabolism of cucumber seedlings under high temperature stress were studied using ’Jinyou No.4’ (heat-sensitive) and ’American Paul’ (heat-tolerant) cucumber seedlings. The results showed that under high temperature stress, (1) the contents of nitrate nitrogen in seedlings of two cucumbers increased firstly and then decreased, while the content of total nitrogen and ammonia nitrogen of ’Jinyou 4’ (2) Nitrate reductase (NR) activity of both cucumber seedlings increased firstly and then decreased, but glutamine synthetase (GS), glutamate synthase (GOGAT) (GDH) decreased continuously. The decrease of four enzymes in ’Paul’ was significantly lower than that of ’Jinyou 4’. The results showed that foliar application of melatonin could effectively alleviate the inhibitory effect of high temperature stress on NR, GS, GOGAT and GDH, significantly increase the content of nitrate nitrogen, reduce the content of ammonia nitrogen, and reduce the accumulation of ammonia nitrogen on cucumber seedlings , And enhanced the ability of nitrogen metabolism of cucumber seedlings under high temperature stress, reduced the damage of cucumber seedlings caused by high temperature stress, and improved the ability of cucumber seedlings to resist high temperature stress.