Co-Inoculação de microrganismos para a promoção de crescimento em mudas de palma de óleo

Abstract

Elaeis guineensis, popularly known as oil palm, is currently the most important palm tree in the world market for vegetable oils. However, the production of oil palm seedlings is considered one of the main obstacles in the cultivation system, since the seeds have slow and uneven germination, which results in the formation of seedlings with less vigor. The use of microbial technologies is considered a viable alternative to promote growth and increase the quality of seedlings. Beneficial microorganisms such as fungi and bacteria can induce changes in physiological responses that are associated with accelerated growth and shorter nursery time. Thus, the present study aims to evaluate the growth promotion through biometric responses, gas exchange and total chlorophyll content in oil palm seedlings inoculated with a mix of microorganisms (Bacillus amyloliquefaciens + Trichoderma asperellum). The experiment was conducted for 12 months under nursery conditions. Two treatments were used, consisting of Mix inoculation and a control (without inoculation). Data were subjected to the homogeneity of variances test and treatment means were compared by Student's t-test (P<0.05). Mix inoculation induced favorable responses in gas exchange parameters, except for stomatal conductance, which was not influenced. Increases were 15% for net photosynthesis (A), 24% for carboxylation efficiency (A/Ci) and 31% for efficient water use (A/E) compared to the control. Transpiration (E) and intercellular CO2 concentration were 8% and 13% lower in seedlings with Mix compared to the control. In biometric responses, mix induced increases of 24% for height, 47% for stem diameter and 15% for number of leaves compared to the control. Chlorophyll content (SPAD) also increased in seedlings with Mix, being 28% higher compared to the control. Therefore, the greater net assimilation of CO2 without changes in stomatal conductance indicates that the Mix of microorganisms can regulate the carboxylation activity of the Rubisco enzyme to increase carbon fixation and allocate it to the greater accumulation of biomass required for greater seedling growth.