Aspectos fisiológicos e produtivos de gramíneas adaptadas ao semiárido submetidas a déficit hídrico

Abstract

In environments of semi-arid regions, where water restriction is the main limiting factor for agricultural production, cultivation of drought tolerant species is one of the most viable alternatives to food and dry matter production. One of the main aptitudes in these areas is livestock, however, it is necessary to have fodder plants capable of surviving and producing biomass under drought conditions. In order to study alternatives for forage production in semi-arid environments, the present study aimed to evaluate the levels of photosynthetic pigments in three grass species tolerant to water deficit. The experiment was carried out in a greenhouse at the Universidade Federal Rural de Pernambuco, Recife-PE. Plants of Cenchrus ciliaris, Urochloa mosambicensis, Andropogon gayanus were grown in six levels of pot capacity (100, 85, 70, 55, 40 e 25% of pot capacity - PC) with four evaluation times (5, 15, 25, 35 days after stress - DAS) for the variables related to the photosynthetic pigments and two times(20 and 40 DAS) for the gas exchanges. The experimental design was done in randomized blocks with a triple factorial arrangement. The decrease in moisture levels implied a significant reduction of most of the variables related to the gas exchange, suggesting that this could be one of the first processes to be impaired in the plant with the reduction of the availability of water in the soil. The chlorophyll a and b contents decreased throughout the evaluations while the fluorescence parameters showed higher overload on the remaining chlorophylls, most evidently from the 25 DAE in both cuts. Urochloa mosambicensis and Andropogon guayanus, were the most promising species.