Leaf angle, light interception and chlorophyll contents of bean and soybean grown in integrated cropping systems

This study aimed to evaluate the dynamics of solar radiation and the morphological and physiological responses of bean and soybean plants grown in two integrated cultivation systems and under full sun. Two experiments were conducted in southern Brazil, one with beans (in-season) and the other with soybeans (off-season). The experimental design used was randomised blocks in a bifactorial 2 × 2 arrangement with an additional treatment, characterised by two forest arrangements (6 × 6 m and 12 × 12 m); two forest species (Peltophorum dubium and Eucalyptus urograndis); and full sun, with three repetitions. The transmissivity of solar radiation, intercepted solar radiation, leaf inclination angle, light extinction coefficient (k), and chlorophyll content (a, b, total, and a/b ratio) were measured. The dynamics of solar radiation were modified by the arrangement of trees and the canopy characteristics of the forest species. Shading significantly influenced the levels of chlorophyll a, b, and total chlorophyll, while no variation was observed in the angle of inclination of the leaves. It is recommended to cultivate beans intercropped with the forest species E. urograndis in the 12 × 12 intercropped arrangement, while for soybean cultivation, intercropping with the two forest species studied in the 12 × 12 intercropped arrangement is recommended.