BIOESTIMULANTES E SEUS EFEITOS NOS COMPONENTES DA PRODUÇÃO, NAS TROCAS GASOSAS E NA EFICIÊNCIA DE USO DA ÁGUA NO TOMATEIRO SOB RESTRIÇÃO HÍDRICA

Abstract

Agronomic efficiency studies of biostimulants that can grant plant resistance in periods of water deficit is of fundamental importance to decrease yield losses, especially tomatoes whose production requires plenty of water. Therefore, the action of biostimulants on gas exchange, on water use efficiency, and on components for production in tomato cultivated under water deficit was evaluated. The experiment was carried out under a climate greenhouse with temperature, photoperiod, and relative humidity control. The experiment was in (2 x 4) +2 factorial scheme, two soil water percentage intervals (80-100% and 50-70% in soil field capacity), four biostimulants (three pre-commercial and one commercial), and two control treatments without biostimulant application, one for each water condition in soil. The biostimulants evaluated were from different groups, one based on active microorganism, one based on amino acids, and the two others based on humic substances. The treatments were arranged in a randomized block design (RBD) (four blocks) and two plants per plot, making a total of eighty experimental units. Gas exchange, plant water use efficiency, dry mass, and yield of tomato were characteristics evaluated. The use of biostimulants in plants under water stress provided total tomato yield similar to treatments without stress. However, the use of biostimulants in optimal soil water conditions has not promoted increasing in yield. The difference in the soil water amount affected the carbon fractions, and the biostimulant effects were most evident in 80-100% field vii capacity (FC), and the humic substances (HS) treatment was with 9.49% Carbon (C) in soil. There was higher efficiency of instantaneous and intrinsic water use by tomato plant treated with amino acids (AA) and SH biostimulants under lower water supply condition. Biostimulants showed promising results in tomato stress attenuation when cultivated under water deficit conditions.