Adubos verdes influenciam o cultivo de Campomanesia adamantium (Cambess.) O. Berg, espécie nativa do cerrado

Abstract

For the preservation of medicinal plants from the Cerrado, their proper management in situ or ex situ cultivation is essential. Among the Cerrado species, Campomanesia adamantium (guavira) has been exploited in its habitat to consume its fruits and leaves, whose medicinal properties are anti-inflammatory, andiarreic and antimicrobial, which, added to the burning and deforestation, lead it to the risk of extinction. Therefore, studies on its cultivation are necessary for the conservation of the species. Among the management, the use of plants as green manures contributes to the proper use of natural resources, maximization of space with species of different habits and the use of organic materials. Thus, the aim of this work was to evaluate the growth and production of guavira plants cultivated with green manures and the influence on the chemical and microbiological attributes of the soil. The guavira plant was studied in soil under plant cover with three species of perennial green manures: Stylosanthes macrocephala (Stylozanthes), Pueraria phaseoloides (tropical kudzu) and Calopogonium mucunoides (calopogonium) and a semi-perennial Cajanus cajan (guandu beans), besides the witnesses spontaneous vegetation and exposed soil (grass). The six treatments were arranged in the experimental design of randomized blocks, with four repetitions. Two cuts of green manures were made, the first at 180 days after sowing (DAS), and the second, from regrowth, at 360 DAS. The cultivation cycle of guavira plants was 730 days after transplanting. The calopogonium plants and spontaneous vegetation had bigger dry masses in the second cut. The concentration of N was higher in the masses of the stylozanthes, calopogonium, tropical kudzu and guandu beans in the first cut and in the mass of tropical kudzu in the second cut. The calopogonium plants had higher P content in the second cut. The green manures, except for the guandu beans, had higher K content in the first cut and the higher Ca content was in the mass of the stylozanthes in both cuts. Calopogonium and spontaneous vegetation had higher Mg content. The mass of the calopogonium plants had fast decomposition and shorter half-life in both cuts. The soil with calopogonium and tropical kudzu had higher P content after the second cut. The highest K content in the soil was with tropical kudzu in the first cut and with guandu beans and spontaneous vegetation in the second cut. After the second cut there was a greater action of microorganisms in the biochemical process of decomposition of organic waste, with the increase of C-BMS and qMIC and the reduction of C-CO2 and qCO2. Guavira plants had higher perspiration rate when grown with guandu beans and higher stomach conductivity and photosynthetic rate with green manures, except with spontaneous vegetation. The highest instantaneous efficiency of water use and the intrinsic efficiency of water use in guavira plants were with stylozanthes and higher instantaneous efficiency of carboxylation with calopogonium and guandu beans. The maximum photosynthetic rate of guavira plants (15.13 µmol m-2 s -1 ) occurred at 483 DAT; the minimum intercellular concentration of CO2 (144.54 µmol mol-1 ), at 392 DAT; the minimum perspiration rate (5.79 mmol m-2 s -1 ), at 82 DAT; and minimum stomach conductance (0.22 mol m-2 s -1 ), at 55 DAT. The maximum instantaneous carboxylation efficiency (0.03 mol m-2 s-1) of guavira plants occurred at 155 DAT; the minimum chlorophyll index at (13.25), 430 DAT and minimum total chlorophyll index at (19.25), 418 DAT. As for the concentration of nutrients in the leaves of guavira plants, they had a higher N content when cultivated with calopogonium and P, with stylozanthes, guandu beans and spontaneous vegetation; higher K content with all green manures, except with spontaneous vegetation and exposed soil. The highest height of guavira plants occurred with stylozanthes and the diameter of the stem, with calopogonium and stylozanthes. The largest fresh mass of the leaves occurred with calopogonium, and the largest dry mass occurred with calopogonium and stylozanthes. The largest fresh and dry mass of the stems occurred with stylozanthes. The foliar area of guavira plants was larger in cultivation with calopogonium. Guavira plants responded positively to the use of green calopogonium manure, with increased leaf production.