Work

Differential drought tolerance in two commercial açaí cultivars: Insights from gas exchange, chlorophyll fluorescence, and antioxidant responses

Year: 2026

Type: article

Abstract: The effects of water deficit on leaf gas exchange, chlorophyll fluorescence, and antioxidant enzyme activity were evaluated in two açaí cultivars (BRS-PA and BRS-PD) to assess potential differences in drought tolerance. Plants were compared under full irrigation (Control) and under water deficit marked by predawn leaf water potential around – 2.3 MPa. In both cultivars, drought caused similar decreases in net CO₂ assimilation rate ( A ), stomatal conductance, Rubisco instantaneous carboxylation efficiency, and transpiration, accompanied by increases in substomatal CO₂ concentration and instantaneous water-use efficiency. In both cultivars, maximum photochemical efficiency of PSII remained unaffected, but actual quantum yield and photochemical quenching declined under stress. The ratio between electron transport rate and A increased by 219% in BRS-PA and 130% in BRS-PD. Chlorophyll a and b, and carotenoids were more strongly reduced in BRS-PD. Superoxide dismutase increased in both cultivars, while ascorbate peroxidase remained unchanged. Catalase activity declined by 40% only in BRS-PD. Lipid peroxidation rose by around 280% in both cultivars, but foliar H₂O₂ accumulation was greater in BRS-PA (37%) than in BRS-PD (21%). Therefore, under the imposed water deficit conditions, cultivars BRS-PA and BRS-PD exhibited comparable overall physiological performance, however, BRS-PD displayed subtle advantages in photoprotective and antioxidant adjustments, potentially conferring greater resilience to prolonged or severe drought than BRS-PA.

Source: Trees

DOI: 10.1007/s00468-026-02759-6