Potencial de insumos biológicos no desenvolvimento de forrageiras

Abstract

The limitation of the productive capacity of the pastures due to the excessive pressure of grazing combined with the incorrect choice of forage and the low availability of nutrients in the soil favors the degradation of these areas. In view of the soil conservation scenario, the use of efficient forage plants in the production of biomass, microorganisms that promote plant growth and arbuscular mycorrhizal fungi, together with humic substances have been identified as key points for the recovery of degraded pastures. In this sense, the present study aimed to evaluate biotechnologies integrating the use of plant growth promoting bacteria (BPCV), arbuscular mycorrhizal fungi (FMA) and humic substances (SH), as a strategy to maximize the productivity of forages in two managements (SCA - without liming and fertilization and, CCA - with liming and fertilization). The four chapters were developed in a greenhouse. In chapter 1, the 2x2x5 factorial scheme with 4 repetitions, composed of Urochloa genotypes: U. brizantha cv. Marandu and U. decumbens cv. Basilisk inoculated with commercial product AzoTotal© and FMA, isolated or together and, in the treatment with biostimulant, was applied via SH spray (dose 40 mg L-1 C) extracted from vermicompost combined with strains of Herbaspirillum seropedicae - HIV206 and Herbaspirillum rubrisubalbicans - HCC101 and control. In CCA management, the highest MSPA was obtained with the application of SH+Herb. spp. The application of SH+Herb. spp. in the presence of liming and fertilization, showed greater accumulations of N, P, K and Ca. The use of biotechnologies positively influenced the physiological parameters. In chapter 2, in a randomized block, the effect of three biotechnologies and a control in inoculated marandu grass was evaluated isolated or together with AzoTotal© and SH+Herb. spp (dose 40 mg L-1 C) combined with strains - (HIV206 and HCC101) and control. Marandu grass under controlled conditions submitted to treatments T3 and T4 showed better performance in the evaluated parameters. There were improvements in physiological parameters when applying biofertilizers and biostimulants. In chapter 3, in a randomized block, the dose-response effect on Arachis pintoi cv. Amarillo MG 100 inoculated with Bradyrhizobium spp., where the treatments consisted of five concentrations of humic substances (SH): 0, 20, 40, 60, 80 mg L-1 of C, applied at 20 and 40 DAE, being evaluated the potential biomass production and nutrient concentration. The addition of SH enabled increased production of forage peanuts, accumulation of nutrients and increased quantum yield of photosystem II. The concentration of 40 mg L-1 of C made it possible to obtain maximum absorption of nutrients. In chapter 4, the 2x5 factorial scheme with 4 repetitions, consisting of: two managements (SCA - without liming and fertilization and, CCA - with liming and the 40% PK recommendation), for the evaluated biotechnologies, we tested: Bradyrhizobium spp.; FMA; SH (dose 40 mg L-1 C at 20 and 40 DAE) together with Bradyrhizobium spp. and, co-inoculation (Bradyrhizobium spp. and FMA). Biotechnologies had a positive influence on the dry mass of the aerial part and on gas exchange. The biotechnologies Bradyrhizobium spp. and SH+Brad. spp. provided greater dry root mass. Plants inoculated with R. clarum and co-inoculation showed higher accumulations of nutrients. The microbial activity was more intense in the soil under SCA management.