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The regular water supply during life cycle is essential to determine the yield in the legumes. In semiarid environments, the irregular rainfall and high temperature influence the phenology of crops impairing the yield. Peanut is an oleaginous crop with broad adaptation to tropical and semiarid climates, but yield is often harmed when plants face water irregularities during reproductive phase. The recommendation of cultivars tolerant to environments with water-limitation is indispensable to farmers in order to ensure reasonable production when drought settles down. Here, we evaluating peanut bred lines in order to assess drought tolerance based on physiological and yield traits, in greenhouse and field assays. In greenhouse experiment, 2 genotypes (BR 1, drought tolerant and the sensible LViPE-06) and 2 descendant bred lines (earliness-LBM Branco and a mid-runner, LBR Branco) were submitted to 21 days of total water supression. Diffusive resistance, transpiration and leaf water potential were measured by porometer (LI 1600), from fully expanded leaves at mid canopy. Root length was also measured at final period of water stress. Further, in a 2-year field experiment carried out in semiarid environment (Barbalha, CE, Brazil), the genotypes were evaluated under rainfed and irrigation, aiming to estimating the yield trait and the efficiency of drought tolerance. Physiological and yield traits of all genotypes were altered under water stress and significant responses were observed. Both top lines showed physiological ability to tolerance to drought, but LBM Branco, an earliness and upright line, was classified as drought tolerant showing behavior near to BR 1. The losses in pod and seed yield were low, comparing to runner parent (LViPE-06). LBR Branco showed an intermediary performance between parents and was classified as moderately tolerant. Based on physiological and agronomic performances, LBM Branco can later be recommended for management in semiarid environment.

-Seven biochemical descriptors were used to estimate the genotypic variability of peanut in response to moderate water stress. Six genotypes, constituted by four lines and two cultivars, were grown in pots, each containing two plants. At 15 days after emergence (DAE), the treatment differentiation was carried out: Control-plants maintained with daily watering, and Stress-plants submitted to water stress by complete suspension of watering for 15 days. The experimental design was completely randomized with factorial scheme 6 x 2 (genotype x water treatments), with five replications. The biochemical variables evaluated were: catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), free proline, total carbohydrates, soluble proteins, and amino acids. Results obtained by biochemical analysis and estimation of genotypic variability indicated that proline is the most appropriate descriptor for selecting genotypes tolerant to water stress, which led to identification of L81V and L108V as promising lines for drought tolerance breeding program. Keywords:Arachis hypogaea L. Antioxidative enzymes. Organic solutes. Drought tolerance. VARIABILIDADE GENOTÍPICA DE AMENDOIM EM RESPOSTA A ESTRESSE HÍDRICO BASEADA EM DESCRITORES BIOQUÍMICOSRESUMO -Sete descritores bioquímicos foram utilizados para estimar a variabilidade genotípica de linhagens de amendoim submetidas a estresse hídrico moderado. Seis genótipos, sendo quatro linhagens e duas cultivares, foram cultivados em vasos, cada um contendo duas plantas e mantidas em casa de vegetação. Aos 15 dias após a emergência, procedeu-se a diferenciação dos tratamentos: Controle, as plantas mantidas com rega diariamente; Estresse, as plantas submetidas à suspensão total de rega durante 15 dias. O delineamento experimental foi inteiramente casualizado, com esquema fatorial 6 x 2 (genótipos x tratamentos hídricos), com cinco repetições. As variáveis bioquímicas avaliadas foram: catalase (CAT), ascorbato peroxidase (APX), guaiacol peroxidase (GPX), prolina livre, carboidratos totais, proteínas solúveis e aminoácidos. Baseado nos resultados das análises bioquímicas e de estimativa da variabilidade genotípica, a prolina demonstrou ser o descritor mais adequado para seleção de genótipos tolerantes ao estresse hídrico, contribuindo para indicar as linhagens L81V e L108V como mais promissoras, para um programa de melhoramento visando tolerância à seca. Palavras-chave:Arachis hypogaea L. Enzimas antioxidativas. Solutos orgânicos. Tolerância à seca.