Application of bio stimulants in tomato subjected to water deficit: Physiological, enzymatic and production responses/Aplicacao de bioestimulantes em tomateiro submetido a deficiencia hidrica: Respostas fisiologicas, enzimaticas e produtivas

HIGHLIGHTS: The application of Seed+ and Crop+ biostimuiants reduced the damage caused by water stress in tomato plants. The mean productivity of tomato fruits increased with the use of biostimuiants regardless of the soil water condition. The application of biostimuiants significantly influenced the activity of the enzymes SOD and POD. The objective of this study was to evaluate the effect of the application of the biostimuiants Seed+ and Crop+ on physiological and production variables and on the activity of antioxidant enzymes (superoxide dismutase - SOD and guaiacol peroxidase - POD) in tomato plants subjected to two soil water conditions. The experiment was carried out in a greenhouse, in a 2 x 2 x 6 factorial scheme, with two times of application of the biostimuiants (flowering and fruiting), two soil water conditions (50 and 100% of soil water holding capacity) and six biostimuiants (control treatment; Seed+; Seed+ + Crop+ lx; Seed+ + Crop+ 2x; Crop+ lx; + Crop+ 2x). The exprimental design was completely randomized, with four repetitions. The biostimuiants Seed+ and Crop+ increased the quantum yield of photosystem II (Fv/Fm), regardless of the time of application and water condition of the soil. The biostimuiants Seed + Crop+ 2x and Crop+ 2x stood out in the pre-morning period, with an average Fv/Fm of 0.813, under the conditions testea. The highest SOD activity (372.12 U [mg.sup.-1] of protein) was obtained with Crop+ 2x biostimulant in fruiting and under water deficit. For POD, when under wafer deficit, the best results were obtained with the biostimuiants Seed+ + Crop+ 2x, Crop+ lx and Crop+ 2x in flowering (810.94; 691.19 and 921.59 U mg1 protein) and in fruiting (703.60; 800.01) and 972.62 U [mg.sup.-1] protein). Thus, the use of Seed+ and Crop+ biostimuiants can be an alternative to help mitigate the damage caused by water deficit in tomato crop. Key words: Solanum lycopersicum, water condition, oxidative stress Objetivou-se neste estudo avaliar o efeito da aplicacao dos bioestimulantes Seed+ e Crop+ nas variaveis fisiologicas e produtivas e na atividade de enzimas antioxidantes (superoxido dismutase - SOD e guaiacol peroxidase - POD) em plantas de tomateiro submetidas a duas condicoes hidricas do solo. O experimento foi conduzido em casa de vegetacao, em esquema fatorial 2 x 2 x 6, sendo duas epocas de aplicacao dos Dioestimulantes (florescimento e frutificacao), duas condicoes hidricas do solo (50 e 100% da capacidade de retencao de agua no s