Eficiência fotoquímica de plantas de bananeira submetidas à aplicação de cal virgem sobre a folhas

Abstract

The temperature, high relative humidity and rainfall are directly related to the growth of the banana plant. The commitment of these effects has been researched using photochemical efficiency measures. Although the banana plant is a typical tropical plant, can present physiological damage by high temperatures, especially in times of drought. Therefore, the present study aims evaluate the effects of applying of the virgin lime in the leaves of banana plants on the photochemical efficiency in two seasons climate (dry and rainy).The experiment was realized at the Nucleo for Agronomic Biotechnology, of the State University of Maranhão, São Luís, where the variety of banana used was the FHIA-18. Four plants were sprayed with a suspension of 5% of virgin lime and the control treatment with same number of plants received no product application. The determination of the measurements was made the times of the 8 am, 12 pm, 4 p.m. The chlorophyll a fluorescence was measured by IRGA equipment and Pocket PEA and chlorophyll content by SPAD-502. We used a randomized block design (RBD) with 4 (four) repetitions in a 3x2 factorial arrangement. The tests performed were Kruskall – Wallis, to evaluate schedules and the two climatic seasons, the test of Man-Whittney, to evaluate the two treatments, at the 5% level and the Tukey test, at 5%, to compare means between the two periods. The parameters evaluated were: F0 (initial fluorescence), Fm (maximal fluorescence), Fv (variable fluorescence) and Fv/Fm (maximum quantum yield). There was no significant difference for F0, Fm and Fv in the dry season for plants exposed to application of lime at all schedules of day. In rainy season the F0, showed a drop in last hour of day, in relation to others. The Fm, in dry season, were different at all schedules the day in rainy season, there was a growing trend the averages in the plants without cal in schedules 8 am and 4 pm. This same variable and in rainy season, there was an increasing of averages without virgin lime in 8 am and 4 pm. In both periods the values of photochemical efficiency (Fv/Fm) were between 0.75-0.81; what does means that no their photodamage. The plants with virgin lime, throughout the period of assessment, showed SPAD values higher than those plants without virgin lime, particularly in the rainy season, comprising indices between 35-50. The lime was effective in maintaining stable maximal fluorescence throughout the day and can assist chlorophyll fluorescence as an auxiliary tool in the management of banana.