Efficiency of cover materials in preventing evaporation in drought - stressed soybeans grown in pots

PALAVRAS-CHAVE Glycine max L. Merrill Temperatura foliar Déficit hídrico Perda de água. ABSTRACT: There are few studies in the specific literature on the use of cover materials to control evaporation in drought-stressed plants grown in pots under greenhouse conditions. The use of these materials is of great importance to ensure that water loss occurs only through transpiration. Thus this study aimed to investigate the efficiency of different cover materials – polyethylene, marble, polystyrene, and polyvinyl chloride (PVC) – in controlling evaporation in black and in silver pots cultivated with the soybean cultivar BR 16 and subjected to drought under greenhouse conditions. The plants were kept at 100% field capacity until they reached the V3 stage. The different cover materials were then applied to the substrate surface, irrigation was suspended, and the plants were evaluated with regard to water loss and temperature of leaf and substrate for nine consecutive days. The experiment was repeated without plants to assess evaporation. Substrate water potential was measured on the last day in both experiments. Although all the cover materials showed uniformity between the replicates with respect to water loss, polyethylene and PVC presented higher substrate water potential and leaf turgor after nine days of suspended irrigation; however, PVC led to soil compactions, restricting its use. Therefore, among the materials tested, polyethylene is the most suitable to control evaporation in pots cultivated with soybean plants subjected to drought, with no influence of pot color.