Análise do conteúdo de pigmentos fotossintéticos, prolina e proteína em três variedades de feijão-nhemba (Vigna unguiculata (L.) Walp.) sob condições de stress hídrico durante a fase vegetativa"

Abstract

The water deficit in the soil is one of the problems that affects most of the cultivated areas, mainly in the semi-arid regions. The present work aimed to evaluate the effect of water stress on the content of photosynthetic pigments (chlorophylls, carotenoids and pheophytins), proline and soluble proteins in the leaves of three varieties of cowpea (IT82E-18, Tete-2 and motorized Timbawene ). The study was conducted in greenhouse conditions where 108 plants were subjected to two treatments; water stress and control (optimal irrigation conditions). Three harvests were carried out (four, seven and ten weeks after sowing). The content of chlorophyll a in the motifed Timbawene variety was not significantly affected by water stress (reduction of only 2.7%), while the varieties Tete-2 and IT82E = 18 suffered significant reductions (15.9% and 15.4%, respectively). The variety Timbawene moteado was the most effected by water stress, having suffered significant reductions in 14.4% (P = 0.002) and 25.6% (P = 0.010 ) of the chlorophyll b content in the fourth and seventh under water stress conditions, but the IT82E-18 variety suffered a reduction of only 1.14% and presented a higher average chlorophyll b content in relation to the other varieties for both treatments. carotenoid content, the IT82E-18 varieties were the most affected by water stress, with a reduction of 38.23%, followed by the variety Tete-2 with a reduction of 17.28%. However, the Timbawene moteado variety showed a positive response to the water deficit, increasing its carotenoid content by 2.9%. The IT82E-18 variety registered a significant increase in pheophytin a (8.8%) and pheophytin b (24.5%) under water stress conditions. . However, the motorized Timbawene variety suffered a 4.6% reduction in the content of phaeophytin a. Compared to their respective controls, the proline content increased by 38.9%, 38.3% and 40.5% for the IT82E-18, Tete-2 and Timbawene moteado, respectively, under water stress conditions. As for the protein content, water stress induced significant reductions for all varieties, with the Timbawene moteado (32.98%) and IT82E-18 (32.8%) varieties having suffered a greater reduction. (TRADUÇÃO NOSSA)