Application frequency and dosage of mepiquat chloride as a growth regulator for coker cotton variety in Ecuador

Abstract

The aim of this research was to determine the appropriate time and dose of application of mepiquat chloride (MC), as a plant growth regulator (PGR), in the Coker cotton commercial variety. This field trial was carried out during February-August 2020 in La Teodomira experimental farm of the National Institute of Agricultural Research (INIAP, Lodana, Manabí, Ecuador), with three periods of application and four doses of growth regulator in addition to control (without regulator). A randomized complete block design in additive factorial arrangement was used, with four repetitions. The variables, such as plant height (cm), stem diameter (cm), plant height increase (cm/day) in productive stage, apical internodes length (cm), leaf greenness index (SPAD), total number of branches/plant, total number of flower buds/plant, total number of cotton bolls/ plant, weight (g) of ten unopened cotton bolls (g) and yield of raw cotton (kg ha-1), were recorded. The data obtained were subjected to ANOVA, and comparison of means was done by Tukey’s test (P<0.05). The results indicated that the application of mepiquat chloride at 50 days after sowing (DAS) performed better in most of the agronomic and productive variables evaluated in this study. The leaf greenness index variable reported higher values with doses greater than 300 mL. The application of the MC, allowed to reduce the height of the plants, contributing to the good structure of the plant, efficiently using its nutritional resources. When the growth regulator was applied at a single time, that is at 50 DAS, the best average yield of raw cotton was obtained (4,642 kg ha-1). Meanwhile, the most efficient dose was that of 300 mL of MC, with which the highest yield (4,613 kg ha-1) of raw cotton was obtained.