Induced resistance to aphid cotton on colored cotton cultivars

Abstract

The aim of this study was to evaluate the resistance induced by chemical inducers on cultivars of colored cotton. The cotton was planted in pots and kept in a climate-controlled room (28±2^oC daytime temperature, 25±2^oC night temperature, 70±10 % R.H.; and 12 hours of photoperiod). Silicon and acibenzolar-S-methyl were applied to the plants that were offered to Aphis gossypii afterwards. The bioassays were conducted in a randomized design in a factorial arrangement, with three cultivars of cotton and two resistance inducers, with ten repetitions. The biological parameters observed were: ninfal mortality, duration of nymphal stage, and pre-reproductive, reproductive and post-reproductive periods, longevity and total number of nymphs produced. The lignin and phenol content in the leaves were quantified. The longest duration of the nymphal period, the lower number of nymphs produced, and the major mortality were observed in the ASM treatment. Silicon and ASM promoted an increase in lignin content in the cv. BRS Verde. Thus, the ASM application affected negatively biological parameters of A. gossypii, by increasing the lignin content in plants. The cv. BRS Verde is a better cutivar to be used, because it accumulated higher lignina and phenol contents.