Estudos fisiológicos e bioquímicos de cultivares de amendoim (Arachis hypogaea L.) submetidas à deficiência hídrica

Abstract

Belonging to Leguminoseae Family, peanut is a very important crop to the food industry, because its high oil and protein contents essential for nutrition. The market enlargement due to the high industry demand and mainly the biodiesel production brings news and favorable perspectives to expand this crop in the semi-arid region of Brazilian northeastern. However, the low water availability is the main limiting factor to agriculture expansion in these areas. Although peanut crop shows well adapted to water deficit conditions, there are still so much to be studied to improve its potential and performance in the semi-arid areas. Thus, an experiment was carried out in greenhouse conditions aiming to evaluate some physiological and biochemical parameters of two peanuts cultivars under water deficit. A randomized experimental design was used in a factorial 2 (cultivars) x 3 (water treatments), with six replications. The cultivars studied were BR1 and BRS Havana. The water treatments were: daily watering, five days intervals of watering and water withholding. Growth analysis was accomplished over all the experimental period. At the end of the experiment, leaf water potential and relative water content was measured. For the biochemical analyses, leaf and root tissues were collected to the determination of total soluble carbohydrates, amino acids, protein and free proline. For growth analysis, the plants were separated in leaves, stems and roots to determination of dry matter. Leaf area, root:shoot ratioand biomass allocation were calculated. The obtained data were submitted to variance analysis and the means were compared by Tukey Multiple Range Test (P<0.05). Soluble arbohydrates, proteins, amino acids and free proline contents increased with the water deficiency in the leaves and roots of peanut cultivars. Plants water relations were influenced by water deficit reducing leaf water potential to more negative values. The growth of the peanuts cultivars was reduced proportionally to water availability, with marked varietal differences. The cultivar BR1 is more adapted to water deficiency conditions by showing physiological mechanisms capable to accumulate more organics solutes osmotically actives, reducing its leaf water potential to more negatives values, and for showing less growth alterations.