Fisiologia da planta doente e controle biológico da fusariose da pimenta - do - reino (Piper nigrum L.) no campo.

Abstract

The black pepper (Piper Nigrum L.) is a plant belonging to Piperaceae family, which has high productivity and has great economic value, allowing this activity to be highly profitable. Brazil is the third largest pepper producer in the world and the state of Pará is the second largest national producer. Despite the importance of the black pepper cultivation in regional, national and internationl scenario, there’s a lack o knowledge that guarantees the sustaintable and economical production of the culture. Among the factors that limit crop productivity, fusariosis stands out. The presente study aimed to estimate the damage of fusariosis based on visual severity, on the photosynthetic apparatus and on the yield of Apra and Guajarina cultivars in the field and to evaluate the efficiency of the Trichoderma asperellum mix in reducing the severity of the desease. The experiment was carried out in field conditions with a randomized block design. The evaluations for severity, productivity and gas exchange were carried out in rainy and dry periods in two cultivars of black pepper, Apra and Guajarina, with symptoms of fusariosis, forming 4 treatments with 20 plants each. The data were subjected to analysis of variance and the treatment means were compared using the Tukey test (p <0.05). In the presente study, fusariosis negatively affected the severity variables, A, gs, Ci, E, A/E, Fv’/Fm’,ΦPSII, qP, NPQ and the yield of cultivars according to the period. The Apra cultivar indicates a greater productive potential, however in the presence of conditions favorable to fusariosis it is more susceptible to the disease. The severity of fusariosis was higher in the rainy seasons than in the dry seasons, regardless of the cultivar. The cultivar Apra showed a higher degree of susceptibility to fusariosis than the cultivar Guajarina, being in the rainy seasons in 10 units and 4 units in the dry period, based on the diagrammatic scale of disease severity. In the rainy seasons, liquid photosynthesis (A) reduced 12% in cv. Apra and 50% in cv. Guajarina compared to healthy plants, while in the dry period the reduction in A in cv. Apra was 68% and in cv. Guajarina reduction was 91%. For Stomatal conductance (gs), in the rainy seasons cv. Apra reduced by 50%, while in cv. Guajarina was 45%. In the dry period there was a reduction in gas of 59% in cv. Apra and 48% in cv. Guajarina in relation to healthy plants. The substomatic concentration of CO2 (Ci) in the rainy seasons reduced 59% in cv. Apra, however in cv. Guajarina Ci increased by 35% in relation to healthy plants. In the dry period Ci increased in cultivars under stress, where in Apra cv. It increased by 47% and in cv. Guajarina 131% in relation to healthy plants respectively. The efficiency of water use (A / E) was differentiated only in the rainy seasons, with na increase of 98% for cv. Apra. In healthy plants, the average dry pepper yield per plant was 2.86 kg, while in sick plants it was only 0.93 kg, regardless of the cultivar. The presente study indicates that there was an increase in productivity and a reduction in severity when a mix of T. asperellum was applied. The application of T. asperellum can be used as an alternative to Sustainable management of pepper production in the kingdom.