Mitigation of reproductive structure abortion in shaded cotton by an auxin precursor.

• Grant number: 25/03682-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2025
• End date: April 30, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Fábio Rafael Echer
• Grantee: Claudio Maticolli Costa
• Host Institution: Pró-Reitoria de Pesquisa e Pós-Graduação. Universidade do Oeste Paulista (UNOESTE). Presidente Prudente , SP, Brazil

Abstract

The cotton plant (Gossypium hirsutum L.) plays a crucial role in both the global and Brazilian economies, with Brazil being the third-largest producer and the world's leading exporter of cotton fiber. In the country, most of the production is concentrated in the Central-West region, where climatic conditions are highly favorable for cultivation. However, shading caused by prolonged periods of cloudiness and intense rainfall during the flowering phase significantly reduces photosynthesis and compromises the fixation of reproductive structures, leading to flower and fruit abortion and, consequently, reduced productivity. To mitigate these impacts, this study aims to evaluate the exogenous application of tryptophan, an auxin precursor, under different shading levels. The experimental design will follow a randomized block arrangement in a 3×4 factorial scheme, with three shading levels (0%, 30%, and 50%) and four tryptophan doses: 0, 15, 30, and 60 g ha¿¹ of the commercial product. The research will be conducted under irrigated conditions and will assess parameters such as reproductive structure retention, the number of bolls, productivity, and fiber quality. At harvest, the number of plants and bolls will be counted, and all bolls present in a 2-meter row within the useful area of each plot will be manually collected. Additionally, three plants from each plot will be selected for reproductive structure mapping, where plant height, number of nodes, and the presence of bolls at each fruiting position-divided into thirds (P1, P2, and P3+)-on each branch will be recorded. The data obtained will be subjected to variance and regression analysis, and for significant effects, means will be compared using Tukey's test at a 5% significance level (p < 0.05).