Comportamento Ecofisiológico e Fitopatológico de bananeiras (Musa sp.) em solo artificialmente infestado por Fusarium oxysporum f sp cubense (E.F. Smith) sn. & Hansen, nas condições da Amazônia Oriental.

Abstract

Eventhough the tropical areas have environmental potentialities to banana production, there are few researches about the relationship between biophysics varieties and the environmental factors as well as phytopathologics aspects. In Brazil, this is the first research linking physiologics, ecologics, and phytopathologics aspects in banana plants. On this way, this research had , as purpose, to evaluate banana plant ecophysiologic and phytopathologic behavior, when in soil artificially infested with Fusarium oxysporum f.sp. cubense, at rainy and dry periods, in Belém — Pará metropolitan medium region. Eight banana plant cultivars (“Mysoure”, “Yangambi”, “Ouro-da-mata”, “Maçã”, “Thap maeo”, “PV 0344”, “PA 0322”, and “PA 1203”) were cultured on yellow latosoil, medium texture, obeying the experimental curve of blocks casually. In field conditions, height increasing, transpiration, stomatal conductance, normal leaves number, leaves lifetime, leaves emission velocity, total leaf area, photossynthetic rate, and productivity were mensured on healthy plants and plants infested with Panama disease. In laboratory, the water leaf relative content, total soluble carbohidrates and total soluble proteins contents , and leaves stomatal density were determined. The results showed that transpiration and stomatal conductance were reduced since leaf 4 (dry period) and leaf 5 (rainy period), on basipetal way. The transpiration increased since first hours in the morning, until the noon, decreasing during the afternoon. Stomal conductance decreased, gradually, since first hours in the morning. Both Transpiration and Stomatal Conductance got almost insignificant values in the end of afternoon, and also suffered drastic reduction, at dry period, and vapour pressure deficit, in soils which had grate water content, was the variable that had more influence on closing stomatal. Transpiration and stomatal conductance, on abaxial surface, were superior than the one's observated on adaxial surface, and that one had a stomatal density upper than the last, at least, about four times. At dry period, the water soil avaiability seems to have more influence than vapour pressure deficit on closing stomatal mechanism, because it carried out high influence on the leaves water content reduction. Also, there was a reduction on the normal leaves number and on total leaf area, eventhough the leaves emission velocity had been similar to the one observed at rainy period. There was a reduction on photosynthetic rate, transpiration, and stomatal conductance, in desease plants, only when Panama disease Symptoms occurred. chlorophill a , chlorophill b , and chlorophill (a+tb ) contents didn't have differences between the cultivars, however, with the evolution on desease symptoms, it was verified that it happened, simultaneousiy, degradation of chlorophill a and chlorophill b, as well as, others photossynthetic units. The solubles carbohidrates content increased significantly at dry period, but the solubles proteins content didn't change between both periods. On the other side, reductions on these compounds content occurr in disease plants, and carbohidrates content were more rapidly altered than proteins contents. All banana plant cultivars showed low productivities, and “PA 1203” had higher potential of productivity.