打顶后喷施油菜素内酯和生长素对烤烟田间生长、碳氮代谢及烟叶品质的影响

Effects of brassinolide and auxin on growth, carbon and nitrogen metabolism and tobacco quality of flue-cured tobacco leaves after topping

通过田间试验研究了打顶后喷施油菜素内酯(BR)和生长素(IAA)对烤烟田间生长、碳氮代谢及烟叶品质的影响。试验共设置6个处理,分别为:T1,清水;T2,10 mg?kg?1 BR;T3,10 mg?kg?1 IAA;T4,20 mg?kg?1 IAA;T5,10 mg?kg?1 IAA+10 mg?kg?1 BR;T6,20 mg?kg?1 IAA+10 mg?kg?1 BR。在打顶当天、打顶后15 d和30 d时测定烟株顶部5片烟叶的叶面积和各部位的干物质重,在打顶当天、打顶后10 d、20 d、30 d时测定烟株碳氮代谢关键酶的活性。结果表明:1)打顶后喷施油菜素内酯和生长素能不同程度地促进上部烟叶开片,促进烟株根系生长,提高上部烟叶的产量,且以二者同时喷施时效果较好;2)除对照处理外,各处理的硝酸还原酶和谷氨酰胺合成酶活性均表现为先升高后降低,蔗糖转化酶和淀粉酶活性均表现为先降低后略微升高的变化趋势,说明打顶后喷施油菜素内酯和生长素能增强烟株的碳氮代谢强度,但在一定程度上推迟了烟叶成熟落黄时期,延长了生育期;3)打顶后喷施油菜素内酯和生长素可以有效提高烟叶钾含量、钾氯比、有机钾指数,并降低中、上部烟叶的烟碱和氯含量,且以对上部叶的作用效果最为明显,以二者同时施用时作用效果最好;4)处理T6(20 mg?kg?1 IAA+10 mg?kg?1 BR)促进烟株生长和提高烟叶品质的效果最佳,能使上部烟叶的钾含量、钾氯比、有机钾指数相对于对照T1分别提高40.9%、68.5%和0.524,使氯含量和烟碱分别降低16.2%和16.3%。总的来看,打顶后喷施油菜素内酯和生长素可以促进烟株生长,增强碳氮代谢,提高烟叶钾含量、钾氯比和有机钾指数,降低烟碱和氯含量,进而提高烟叶的产质量。

A field experiment was conducted in Jiyuan Tobacco Area of Henan Province, to study the effects of brassinosteroid（BR） and auxin（indole acetic acid, IAA） on growth, carbon and nitrogen metabolism and leaves quality of flue-cured tobacco. The aim of the experiment was to explore the rational managements of flue-cured tobacco after topping in the study area. The experiment included 6 treatments, which were spraying water（T1）, spraying 10 mg·kg·1 BR（T2）, spraying 10 mg·kg·1 IAA（T3）, spraying 20 mg·kg·1 IAA（T4）, spraying 10 mg·kg·1 IAA and 10 mg·kg·1 BR（T5） and spraying 20 mg·kg·1IAA and 10 mg·kg·1 BR（T6）, after topping of tobacco. The area of the top 5 leaves, dry matter of different organs of flue-tobacco were investigated at the day of topping, 15 days and 30 days after topping, the activities of enzymes relative to carbon and nitrogen metabolism of flue-cured tobacco were investigated at the day of topping and 10 days, 20 days, and 30 days after topping. The results showed that： 1） spaying BR and IAA after topping promoted leaves expansion, root growth, upper leaves production. Combined spring of BR and IAA showed better effect. 2） Under BA and IAA treatments, nitrate reductase and glutamine synthetase activities first raised then dropped, while invertase and amylase activities first decreased then slightly increased. This suggested that spaying BR and IAA after topping enhanced carbon and nitrogen metabolism, delayed tobacco maturity and fall time of yellow to a certain extent. Correspondingly, the growth period of tobacco with BR and IAA spraying was extended. 3） Spaying BR and IAA after topping effectively increased potassium content, potassiumchlorine ratio and organic potassium index of tobacco leaves. The nicotine and chlorine contents of middle and upper leaves were reduced by spraying BR and IAA, especially for the upper leaves. Applying both BR and IAA at the same time showed best effects on leaves quality. 4） Among five BR and IAA treatments, T6（IAA 20 mg·kg·1 ＋ BR 10 mg·kg·1） was best for tobacco growth and leave quality improvement. Compared with treatment T1, treatment T6 increased potassium content, potassium-chloride ratio and organic potassium index by 40.9%, 68.5% and 0.524; decreased contents of chlorine and nicotine by 16.2% and 16.3% of the upper leaves, respectively. From these results, it was conclude that spaying BR and IAA after topping promoted growth, enhanced carbon and nitrogen metabolism, improved production and quality of flue-cured tobacco. Spraying IAA 20 mg·kg·1 ＋ BR 10 mg·kg·1 was the optimum for tobacco cultivation of the study area.