Plant Growth Promoter Effects on the Growth and Yield of Transplanted Cotton in Northern Jiangxi

Objective] This study aimed to investigate the effects of six plant growth promoters on the growth and development of cotton (Gossypium hirsutum L.), and to determine which is most beneficial for enhancing cotton yield in northern Jiangxi Province, China. Methods] Foliar treatments of naphthalene acetic acid, gibberellin, cytokinin, brassinolide, sodium polyphenol sodium and amine fresh ester were applied at the three-leaf, squaring, first flowering and peak flowering stages of transplanted cotton in the northern Jiangxi region. Cotton growth and development in response to these promoters were investigated, and a pure water spray served as the control. Yield, yield component and agronomic trait data were collected during various growth periods. Results] Cytokinin and sodium nitrate significantly facilitated the growth of cotton during the early and middle seasons. A more rapid boll setting was achieved by sodium nitrophenolate during the peak flowering stage. Amines promoted cotton growth throughout the plant’s lifecycle, and the plant leaf area and biomass values were the greatest among all the treatments. The brassinolide treatment resulted in a stronger resistance to adverse environmental stresses, and it produced larger bolls and higher cotton yields. Although naphthalene acetic acid had little effects on the growth and development of cotton during the early and middle seasons, a final yield increase was evident. Gibberellin negatively affected the late growth of cotton and led to smaller plant architectural structures and boll weights. The combination of brassinolide and amine fresh ester did not present any advantage over their independent applications. Conclusion] The growth and development of cotton were significantly increased by the independent foliar applications of six plant promoters at the seedling, squaring, first flowering and peak flowering stages, resulting in seed cotton yield increases of 2.43%–10.4% under seedling transplanting conditions in northern Jiangxi Province. Therefore, we suggest that cytokinin or sodium nitrophenolate can be applied at the cotton seedling and squaring stages and that brassinolide or amine ester can be applied at the flowering and fruiting stage