Morphophysiological aspects of bean plants cultivated with natural reactive phosphate and solubilizing and growth promoting microorganisms

Abstract

Beans (Phaseolus vulgaris L.) are an economically important crop, being part of the daily meal of a large part of the Brazilian population. One of the most common problems in bean cultivation is the low availability and low mobility of phosphorus. Among the strategies to improve the acquisition of phosphorus from the soil, the association of plants with microorganisms that promote growth and/or phosphate solubilizers stands out, since the efficiency of phosphate fertilizers depends directly on the microbial action in their cycle. Thus, the objective of this study was to evaluate physiological, morphological and biochemical characteristics in bean plants cultivated with the presence or absence of reactive natural phosphate associated or not with seed inoculation with different efficient microorganisms. The experiment was carried out in a greenhouse with a completely randomized design, consisting of eight treatments and four replications. The treatments were composed of: i) control, and application of ii) Azospirillum brasilense, iii) Bacillus subtilis and Bacillus megaterium, iv) efficient microorganisms (ME), v) reactive natural phosphate (RNP), vi) RNP + A. brasilense, vii) RNP + Bacillus, and viii) RNP + ME. Gas exchange and material collection to determine height, stem diameter, dry matter, acid phosphatase activity and P content were performed 55 days after sowing. The treatment RNP + A. brasilense and other microorganisms contributed to a higher photosynthetic rate and transpiration in bean plants. The treatments RNP + ME and RNP + Bacillus promoted greater plant height and stem diameter, respectively. The shoot dry matter was higher in the RNP + ME treatment, in relation to the other treatments. Acid phosphatase activity was higher in the area of ​​bean plants exposed to reactive natural phosphate, and in the roots of plants exposed to treatment with species of the genus Bacillus. It was possible to verify that the application of microorganisms with natural phosphate, despite not causing an increase in the P content of the shoot, favored the conditions of growth and production of bean plants.