Análise da sensibilidade de duas cultivares de pimentão a diferentes condições de regime hídrico

Abstract

The present work was accomplished with the following objectives: (i) to evaluate the sensibility to different water regime of both, a hybrid (Fortuna Super) and of open pollination (Ikeda) bell pepper cultívar;(ii) to quantify water stress effects on yield; (iii) to monitor plant water status; and (iv) to analyze the improvements induced by greenhouse cultivation. The experiment was carried out inside a greenhouse at the Universidade Federal de Lavras, MG. The experimental design was completely randomized in a factorial outline with eight treatments consisting of two cultivars and four irrigation intervals (1, 2, 3 and 4 days), and four replications. Irrigation amount was computed based on pot weight difference. Evapotranspiration was computed as the amount of water lost by plants and soil. The following characteristics were evaluated: stem diameter and plant height; plant yield (total, commercial and rejects); fruit classification; number of fruits (total, commercial and rejects), diameter and length of the fruits, pulp thickness; fruit dry matter, and root dry matter. Physiologic parameters such as leaf water potential, perspiration, stomatic resistance, leaf temperature and plant leaf area were also analyzed. When considering total and commercial yield, fruit classification, number of commercial fruits, diameter and length of the fruits, and root dry matter, the hybrid Fortuna Super presented a better performance than the cultivar Ikeda. In terms of characteristics, plant height, stem diameter, total and commercial yield and number of commercial fruits, better performance was obtained under the two-day irrigation interval. As indicated by the number of commercial fruits and root dry matter, the three-day irrigation interval provided the greatest water stress sensibility. Considering that, only in the characteristic diameter and length of the fruits, there was significant effect among irrigation intervals and cultivar, it was verified that, for the diameter, cultivar Fortuna Super presented larger sensibility to the four-days irrigation interval and cultivar Ikeda presented larger sensibility to the mree-days irrigation interval; and for the length of the fruits, in two cultivars, there was a larger sensibility to the two-days irrigation interval. None of the studied factors (irrigation interval and cultivar) affected pulp thickness and fruit dry matter. Independently of the cultivars or irrigation interval, the values of the physiologic indicators stomatic resistance and leaf temperature were similar. Smaller irrigation intervals, one and two-days, that is to say, better water conditions, were responsible for larger values of the plants perspiration, as well as for área and leaf water potential. In relation to bell pepper greenhouse cultivation, it suggests a better preventive action to control insects and diseases and an effective system of temperature control inside the greenhouse in order to avoid high temperature amplitude.