Caracterização de cultivares de feijoeiro submetidas a baixas temperaturas durante do florescimento

Abstract

Common bean has great nutritional, economic and social importance, but itsproduction can be affected by adverse climatic factors, such as the occurrence of lowtemperatures. Cold stress can impair the germination and emergence of the crop, if itoccurs at the beginning of the cycle of the plants. When cold stress occur at the endof the cycle of the plants, the yield components can be directly affected. In bothcases, losses in productivity can be observed. This work aimed to verify the responseof common bean cultivars to cold stress during the flowering phase. For this, sevencommon bean cultivars were sown in pots and grown in a greenhouse with atemperature between 15 and 35°C until the R6 stage, when half of the pots weretransferred to a climatic chamber for plant growth under a temperature of 5 to 9°Cfor three days, and a 12 hours photoperiod. After this period, the plant material wascollected for analysis of concentrations of total soluble sugars and proline andenzymatic activity. The plants were kept in a greenhouse until physiological maturity,when their yield components were caused. It was the test of grouping means for thephysiological and agronomic traits and principal component analysis were performed.In general, cold stress caused a drop in yield components of cultivars, increasedproline synthesis and enzyme activity of catalase. The yield component most affectedby cold was the number of pods per plant. A lower activity of the enzyme superoxidedismutase in the cold offers tolerance of the cultivars to this stress. BRSMGMadrepérola and IAC Imperador were the cultivars most sensitive to cold stress, thegreatest reduction in yield components, while ANFc 9 and ANfp 110 were moretolerant, showing that they have adaptive mechanisms at low temperatures.