HIGHLIGHTS:
Application of proline attenuates the deleterious effect of water deficit in cowpea.
The use of salicylic acid reduces antioxidant enzyme activity in cowpea.
Salicylic acid increases protein concentrations in cowpea under water stress.
ABSTRACT
Exogenous applications of chemical compounds stimulate changes in plant metabolism and promote tolerance to different environmental stresses, including water deficit. This study aimed to evaluate the ability of salicylic acid (SA) and proline (PRO) to reduce water stress in a traditional variety of cowpea in a typical Brazilian semiarid climate. A completely randomized design was used in a 2 × 4 factorial scheme, with five replicates. Two irrigation regimes were evaluated corresponding to 100% (W100) and 50% of daily evapotranspiration (W50), respectively, with the addition of the following four attenuators: control (distilled water), SA (550 mg L-1), PRO (690 mg L-1), and 690 mg L-1 PRO + 550 mg L-1 SA. The treatments promoted changes in osmotic and antioxidant metabolism, which may contribute to the tolerance mechanisms of cowpea plants to water stress. The application of SA increased osmoregulator synthesis and protein concentrations, and modulated antioxidant enzyme activity in the cowpea plants under water stress. PRO concentrations increased synergistically in plants treated with PRO and SA, particularly in 50% of water replacement.
Key words:
Vigna unguiculata L. (Walp); total free amino acids; antioxidative metabolism; water deficiency
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P - Precipitation; Tm - Mean air temperature; Tn - Minimum air temperature; Tx - Maximum air temperature; RH - Mean relative air humidity; E - Daily evaporation; DHS - Daily heat stroke obtained by radiometry; S - Sowing; Spr - Spray (Spr); PMC - Plant material collection for biochemical analysis
The same lowercase letters for the same water replacement regime indicate no difference among the attenuators according to Tukey tests (p ≤ 0.05). The same uppercase letters indicate no significant differences between water replacement regimes within each attenuator based on the F-test (p ≤ 0.05). Vertical bars represent the standard error of the mean (n = 5)
The same lowercase letters for the same water replacement regime indicate no difference among the attenuators according to Tukey tests (p ≤ 0.05). The same uppercase letters indicate no significant differences between water replacement regimes with each attenuator based on the F-test (p ≤ 0.05). Vertical bars represent the standard error of the mean (n = 5)