Composto orgânico na nodulação natural e crescimento inicial de feijão guandu (Cajanus cajan L.)

Abstract

Pigeon pea (Cajanus cajan L.) is an important legume that is widely used in Brazil as green manure, wind breaker, in addition to being useful for both human and animal food. Given its significant importance, the objective was to verify the effect of organic fertilizer doses on natural nodulation and initial growth of Cajanus cajan. The experiment was carried out in the greenhouse of the Federal University of Recôncavo da Bahia (UFRB) of the Center for Agricultural, Environmental and Biological Sciences (CCAAB), arranged in a completely randomized experimental design. The treatments consisted of five proportions of organic compost:soil (0:100, 20:80, 40:60, 60:40 and 80:20%) (v: v), with 17 replications, totaling 85 experimental units. The soil used to compose the substrates was the Distrocohesive Yellow Latosol, collected on the UFRB Campus at a depth of 40 cm. The organic compost was produced in the same institution, from the compost pile formed from tree trimmings, cattle and goat manure, in a 3:1:1 ratio. Ninety days after sowing, the following evaluations were performed: chlorophyll (a, h and total), height, number of leaves, stem diameter, root length and number of nodules. Subsequently, the plants were segmented into shoots and roots, placed in a greenhouse, and the dry matter mass and the ratio between shoot and root dry mass and nodule dry mass were measured. The use of organic compost inhibited the natural nodulation of Cajanus cajan. The organic compound influenced the chlorophyll a, b and total index, height growth, leaf number, stem diameter, root length and shoot, root and total dry matter. Cajanus cajan plants cultivated with organic compost showed better development than those cultivated in substrate consisting only of soil. Plants cultivated in substrate consisting of an average of 20% organic compost added to 80% of soil showed higher yields, and this substrate formulation is recommended for the initial growth of Cajanus cajan.