Abstract

Salt stress is abiotic stress that directly affects the gas exchange and redox metabolism of the plants. However, some studies claim that the combination of potassium-phosphorus fertilization may increase salt tolerance in plants. In this context, the objective of this study was to evaluate gas exchange and the antioxidant enzyme activity responses to combined potassium-phosphorus fertilization in the tissues of West Indian cherry during the fructification phase, 240 days after application of treatments (DAT) in the second year of brackish water irrigation production. The treatments were distributed in randomized blocks, in a 5 × 4 factorial scheme, with five levels of irrigation water electrical conductivity – (ECw equal to 0.6 – control, 1.4; 2.2; 3.0 or 3.8 dS m⁻¹) and four potassium-phosphorus fertilization combinations, 200/120; 170/102; 120/72 or 90/54 g K₂O/P₂O₅ plant⁻¹ per year, with three replicates. Irrigation water salinity impaired the gas exchange, showing a reduction of 47.94, 47.21, and 43.92% in the stomatal conductance, transpiration, and CO₂ assimilation, respectively. In contrast, it increased the antioxidant metabolism, mainly the catalase enzyme activity (+ 67.7%). The average weight of fruits was increased by 85% in the combination of 90/54 under 1.4 dS m⁻¹. Although the average number of fruits, in same combination (90/54) was 37% lower compared to high salinities. The threshold water salinity (1.12 dS m⁻¹) indicates that West Indian cherry is a salt sensitive crop.

摘要

盐胁迫是直接影响植物气体交换和氧化还原代谢的非生物胁迫。然而，一些研究声称钾磷施肥的组合可能会增加植物的耐盐性。在此背景下，本研究的目的是评估在第二次应用处理 (DAT) 后 240 天，西印度樱桃组织中的气体交换和抗氧化酶活性对组合钾-磷施肥的反应。年咸水灌溉产量。处理以 5 × 4 因子方案随机分布，具有五个灌溉水电导率水平 - （ECw 等于 0.6 - 对照，1.4；2.2；3.0 或 3.8 dS m ^-1) 和四种钾磷施肥组合，200/120；170/102；每年 120/72 或 90/54 g K ₂ O/P ₂ O ₅植物^-1，重复 3 次。_{灌溉水盐度损害了气体交换，气孔导度、蒸腾作用和CO 2}同化分别降低了47.94%、47.21%和43.92% 。相反，它增加了抗氧化代谢，主要是过氧化氢酶活性（+ 67.7%）。在 1.4 dS m ^-1下，90/54 组合的果实平均重量增加了 85% 。尽管与高盐度相比，相同组合（90/54）的平均水果数量减少了 37%。阈值水盐度 (1.12 dS m ^-1) 表明西印度樱桃是一种盐敏感作物。