Efeito da aplicação de boro, silício e ácido salicílico nos pigmentos foliares do algodoeiro

Abstract

The foliar application of the micronutrient boron (B), the beneficial element silicon (Si), and the plant hormone salicylic acid (SA) has shown promising results in scientific research on the development of cotton plants grown under B deficiency. Thus, the objective of this study was to investigate the impact of the individual and combined application of B, Si, and SA on foliar pigment content in cotton plants. Additionally, the study aimed to determine the ideal number of applications of these nutrients and substances that would lead to a significant increase in the concentrations of these pigments, to better understand the interaction between these elements and their effect on the biosynthesis and accumulation of chlorophyll and carotenoids in cotton leaves. Furthermore, a field experiment was conducted using the cotton cultivar FM 906 GLT during the 2022/2023 growing season, in a randomized complete block design with seven treatments. The treatments consisted of Control (water), B, Si, SA, SA+B, SA+Si, and SA+B+Si, applied foliarly with four replications. Four foliar applications were carried out, starting at the reproductive stage B1, at intervals of 7 to 11 days. Before each application, leaf samples were collected (fifth fully expanded leaf) and the chlorophyll and carotenoid content were analyzed. Plants treated with B, Si, SA, SA+B, SA+Si, or B+Si+SA showed higher chlorophyll and carotenoid contents compared to the control, with significant differences among the treatments. It can be concluded that from the second application onwards, there was a positive effect on chlorophyll and carotenoid pigments, mainly from Si and SA. However, from the third application, the B+Si+SA treatment had a more prominent effect. This trend can be attributed to the cumulative effect of B, Si, and SA, which started from the second application, intensified in the third and fourth applications, with particular emphasis on the combined application of the three elements.