Respostas fisiológicas em cultivares de soja submetidas ao alagamento em diferentes estádios

Abstract

The soybean is one of the most important agricultural products in Brazil, the second in world production. The soil high tolerance to excess of moisture and the rapid recovery after flooding are important characteristics of this culture. However, the oxygen, deficiency resulting from excess of water is one factor that may cause reduction in soybean productivity. This study aimed to evaluate the behavior of three soybeans cultivars upon flooding at various stages of development, based on dry matter production, carbohydrate metabolism and some anaerobic enzymes activities. The experiment was conducted at the Federal University of Lavras, Brazil, in 2007. Cultivars BRS 267, BRS 257 and BRS 213 were submitted to 15 days of flooding, for stages V6 and V8 and 11 days for stage R4. Results indicated a reduction in the production of dry matter for the treatments flooded BRS 267 in the stage V8 and for varieties BRS 257 and BRS 213, V6 stage the latter being the most tolerant to flooding, once exhibited a lower reduction in dry matter compaired to control. The flooding also lead to an increase of total soluble sugars and starch levels in the leaves, as well as to an increase in the activity of the enzymes alcohol dehydrogenase and pyruvate decarboxylase, in all three evaluated cultivars. Nom significant differences were observed for the lactate dehydrogenase enzyme activity. These results indicate a different behavior when comparing the three cultivars.