非生物胁迫对棉花次生代谢及棉蚜种群消长的影响

盐碱、干旱等非生物胁迫影响棉花的次生代谢,而次生代谢可能影响棉株上的害虫发生。为明确非生物胁迫与次生代谢及棉蚜种群消长三者间的关系,以不同浓度氯化钠(NaCl)和聚乙醇(PEG)溶液分别处理棉苗,测定了棉叶组织内棉酚和可溶性糖含量的变化,并观察了棉蚜在被处理棉苗上的生长发育及繁殖情况。结果发现,100和200 mmol·L~(-1) NaCl处理棉苗的棉酚含量分别比不含NaCl的对照提高20%和53.5%,可溶性糖含量分别提高15.7%和46%。盐胁迫显著延长棉蚜的发育历期并降低繁殖率,100和200 mmol·L~(-1) NaCl处理的棉蚜若蚜期分别比对照延长6.4%和9.9%,单雌产蚜量分别减少22.6%和52.3%。干旱胁迫也影响棉花叶片棉酚和可溶性糖含量,质量分数2.5%和5%的PEG处理棉株的棉酚含量分别比对照提高39.7%和61.5%,可溶性糖含量分别提高14.2%和47.1%,生长在PEG处理棉株上的棉蚜的若蚜期分别延长7.4%和16.5%,单雌产蚜量分别减少26.8%和55.8%。叶片内棉酚和可溶性糖含量均与棉蚜若蚜期呈显著正相关,与棉蚜的产蚜量呈显著负相关。由此推断,盐碱、干旱等非生物胁迫增强了棉苗的次生代谢,导致棉酚和可溶性糖等次生代谢产物大量积累,抑制了棉蚜种群的消长。

Effects of Abiotic Stress on Cotton Secondary Metabolism and Cotton Aphid Population Dynamics

Abiotic stresses such as salinity and drought affect the secondary metabolism in cotton plants, which may further influence the occurrence of pests on the stressed plants. To determine the relationships of abiotic stress with secondary metabolism and cotton aphid population dynamics, we conducted an experiment to determine the gossypol and soluble sugar contents in cotton leaves stressed with different concentrations of NaCl and PEG (polyethylene glycol), respectively. The development and multiplication of cotton aphids on cotton seedlings were also studied. The results indicated that the gossypol contents in cotton leaves increased by 20% and 53.5% with 100 and 200 mmol·L^－1 of added NaCl, respectively. The soluble sugar contents increased by 15.7% and 46%. The developmental period of cotton aphids in salt-stressed plants was significantly extended, while the reproductive rate of cotton aphids was significantly reduced. The durations of the nymph stage under the 100 and 200 mmol·L^－1 NaCl treatments increased by 6.4% and 9.9%, relative to the control, respectively; The fecundity of the single female reduced by 22.6% and 52.3%, respectively; Accumulation of the gossypol and soluble sugar in cotton leaves was also enhanced by drought stress; The gossypol contents increased by 39.7% and 61.5%, and the soluble sugar contents increased by 14.2% and 47.1%, respectively. The durations of nymph stage of 2.5% (mass fraction) and 5% PEG treatments increased by 7.4% and 16.5%, relative to the control, respectively; The fecundity of the single female reduced by 26.8% and 55.8%, respectively. Correlation analysis indicated that the gossypol and soluble sugar contents in cotton leaves were positively correlated with the duration of the nymph stage and negatively correlated with the cumulative fecundity. Thus, salt stress enhanced secondary metabolismand increased accumulation of secondary metabolites such as gossypol and soluble sugar, which finally inhibited the population dynamics of cotton aphids.