Dinâmica da radiação solar, crescimento e produtividade de culturas anuais em sistemas agroflorestais

Abstract

The simultaneous cultivation of agricultural and forest species can result in changes in the interactions of the plant community, generating microclimatic changes within the understory and thus modifying the growth and productivity characteristics of the crops in consortium. Therefore, this research aimed to evaluate the dynamics of solar radiation, morphological characteristics, growth, radiation use efficiency and yield of bean and soybean, grown in succession under two arrangements of agroforestry systems and in full sun, and oats grown in agroforestry systems. The research was carried out from 2017 to 2018, in the city of Frederico Westphalen, Rio Grande do Sul, Brazil, with a geographical location of 27º23’48 ”S, 53º25’45” W at 480 m altitude. The experimental design used for the crops of bean and soybean was randomized complete blocks in a 2 x 2 factorial scheme with additional treatment, with two plant arrangements and two forest species and full sun, with three repetitions. The experimental design used for the cultivation of oats was randomized blocks in a 4 x 2 factorial scheme, with four agroforestry systems and two crop years, with three replications. The variables evaluated were: dynamics of solar radiation, growth, morphology and yield of annual crops. The use of different arrangements of plants and forest species changes the dynamics of radiation in the understory. Shading significantly influenced the content of chlorophyll a, chlorophyll b, total chlorophyll of plants and the chlorophyll a/b ratio, while no significance was observed in the angle of inclination of the leaves of bean and soybean. Shading also affected the characteristics of growth, yield and radiation use efficiency from bean and soybean. For oats it was found that higher levels of shading reduced the growth and yield of the crop, increased the efficiency in the use of solar radiation, number of stomata and the crude protein content. Based on the results obtained in this study, it is possible to recommend the cultivation of bean and oats in agroforestry systems. However, for soybean, due to the reduced yield obtained in agroforestry systems, new research should be developed in order to study more spaced arrangements and the insertion of culture in the initial years of implementation of agroforestry and, thus, to make the cultivation of the crop viable in agroforestry systems.