Doses e épocas de aplicação foliar de sulfato de manganês associado a inoculação de Bacillus subtilis em Phaseolus vulgaris L.

Abstract

The cultivation of common beans (Phaseolus vulgaris L.) is of great importance in the Brazilian economy, due to its high nutritional value. An adequate and balanced supply of nutrients to beans can contribute to increasing the productivity and quality of the seeds produced. In this scenario, foliar fertilization becomes an important ally for the production of agricultural crops, as nutrients are absorbed quickly and efficiently. Despite the high technology adopted by producers, mineral nutrition is often neglected, especially in relation to micronutrients. In this sense, manganese constitutes an important micronutrient in bean cultivation, as it plays roles in the activation of enzymes, chlorophyll synthesis, photosynthesis, and consequently in grain production. Furthermore, the use of Plant Growth Promoting Rhizobacteria has been widely used, and among them, one of the most important is Bacillus subtilis. Therefore, the objective of this work was to evaluate the effects of different doses and times of foliar application of manganese sulfate (MnSO4), associated with inoculation of Bacillus subtilis on the production characteristics and physiological quality of bean seeds. The experiment was conducted under field and laboratory conditions, at the State University of Goiás located in the municipality of Ipameri. The experimental design was in randomized blocks, in a factorial scheme (5 x 2 + 1), consisting of five doses of manganese sulfate (0.0; 0.5; 1.0; 1.5; 2.0 L/ ha), and two application times (stage R5 – pre-flowering and stage R7 – pod formation), plus an additional treatment (control), with four replications. Bacillus subtilis was inoculated in the seed treatment at a dose of 400 ml for 50 kg of bean seeds. The cultivar used was TAA dama. The variables analyzed were: number of pods per plant; number of grains per plant; number of grains per pod; 100 grain dough; grain productivity; germination test; seedling length; and accelerated aging test. According to the results, the foliar application of manganese sulfate provided increases in the productivity of the bean crop, mainly at a dose of 2 L/ha. To increase productivity, foliar application of manganese sulfate does not depend on the time of application. Furthermore, inoculation of Bacillus subtilis with foliar application of manganese sulfate provided increases for most production characteristics, when compared to the control. Furthermore, as different doses of manganese sulfate had little interference in the physiological quality of bean seeds, only influencing the length of bean seedlings, according to the increase in doses.