Soybean development under soil water deficit

One of the main factors affecting soybean development is water deficiency, especially when it occurs during the flowering and pods filling stages. Thus, this study aimed to evaluate the soybean development under soil water deficit in different phenological phases, under soil and climatic conditions of Bom Jesus, Piaui State, Brazil. The test was conducted at Sao Luiz Farm, located 3 km from Bom Jesus  to  PI, during the period from August to December, 2014. The test was conducted with a drip irrigation system using drip tape with 0.3 m between emitters and nominal flow of 1.6 L h to 1. The water deficit was applied in the vegetative development stages (treatment I), flowering and grains filling (treatment II) and grain maturation (treatment III), compared to the control treatment (full irrigation throughout the cycle). Plant height, number of green leaves, leaf area index and plant dry matter were evaluated. The water deficit in the flowering and pod filling stages inhibited the BRS Sambaiba RR cultivar growth, contributing to a reduction of up to 33.2, 34.7, 41.3 and 13.7% of plant height, number of leaves, leaf area index and total dry mass, respectively compared to the control. Key words: Glycine max, water balance, water availability.