Efeitos do uso de microrganismos eficientes na formação de mudas do porta-enxerto poncirus trifoliata (L.) Raf e no desenvolvimento de plantas jovens de laranja valência (citrus sinensis) e tangor murcott (citrus sinensis x citrus reticulata)

Abstract

Brazil is the world's largest citrus producer. This prominent position has demanded from the Brazilian citrus sector the use of high amounts of synthetic pesticide and fertilizers, which cause environmental impact, reduce the financial return and increase their dependence on external agricultural inputs. Among the alternatives to increase the development of agricultural crops and increase their sustainability there are the Efficient Microorganisms (EM) technology. The EM inoculants consist of a mixture of bacteria and fungi that coexist synergistically in a certain medium. Although there are studies indicating the benefits of using EM in several agricultural crops, in citrus crops these are still scarce.The present study aimed to evaluate the effect of the EM in the growing of seedlings of the Poncirus trifoliata (L.) Raf rootstock, and in the development of young plants of Valencia orange (Citrus sinensis) and Murcott tangor (Citrus sinensis x Citrus reticulata), in order to support the development of technologies for organic production of citrus seedlings. The experiments were conducted in a greenhouse condition, at the Federal University of Fronteira Sul, Campus Erechim / RS. Were used EM obtained from “homemade” technology of capture and multiplication (native efficient microorganisms - EMN) and a commercial formulation of efficient microorganisms (EM1®). The experimental design used was completely randomized (DIC). For the experiment with the Poncirus trifoliata rootstock three treatments were used (commercial product EM1®, EMN and control), with 3 (three) repetitions per treatment and 12 (twelve) plants per experimental unit. The experiment with the Valencia orange and the Murcott tangor was conducted independently for each culture, using the factorial scheme 3x2, where the first factor was the commercial product EM1®, native efficient microorganisms (EMN) and control treatments. The second factor consisted of 2 (two) mulch situations, one with oat straw (Avena sativa) and another with straw from spontaneous vegetation. The experiment with Valencia orange and Murcott tangor was conducted with 5 (five) replications per treatment and 1 (one) plant per experimental unit. The dosage used for both EM1® and EMN, in all experiments, was 16.65 l / ha of activated inoculant. The inoculant based on native efficient microorganisms (EMN) showed greater microbial diversity when compared to commercial product EM1®. The EM1® and EMN increased the stem diameter at the level of grafting of the Poncirus trifoliata rootstock. The commercial product EM1® increased the pivoting root system the Poncirus trifoliata rootstock. The use of microbial inoculants EM1® and EMN did not modify the permanence time of the oat and fallow straw columns arranged on the soil cultivated with the cultures of Valencia orange and Murcott tangor. Increases in stem diameter and plant height, both by EM1® and EMN treatments in the young Valencia orange and Murcott tangor plants, were verified until 240 days after seedling planting. The results obtained with analysis of dry mass of Valencia orange and Murcott tangor plants, indicate that positive effects resulting from the use of EM1® and EMN inoculants can be obtained by cultivating the respective cultures in a system covered with oat straw.