Abstract

In order to study the effect of salicylic acid concentrations on the mitigation of salt stress in melon plants grown on a hydroponic system an experiment was conducted in a greenhouse at Pombal – PB, Brazil, using an NFT (Nutrient Film Technique) system. The experimental design was completely randomized, in a 4 × 4 factorial scheme, corresponding to four levels of electrical conductivity of the nutrient solution—ECns (2.1—control, 3.2, 4.3, and 5.4 dS m⁻¹) and four concentrations of salicylic acid—SA (0, 1.5, 3.0, and 4.5 mM), with six replicates. Salicylic acid at the concentration of 3.2 mM attenuated the effect of nutrient solution salinity on the fresh weight of melon fruits. The saline nutrient solution impairs gas exchange and the relative water content and increases the intercellular electrolyte leakage in the leaf blade of melon plants. However, salicylic acid attenuates the deleterious effects of salinity and attains a maximum yield of melon fruits of 23.82 t ha⁻¹ with foliar application of 1.5 mM at ECns of 3.1 dS m⁻¹. Salicylic acid stimulated the synthesis of total chlorophyll, the CO₂ assimilation rate, and the instantaneous water use efficiency of hydroponic melon up to a concentration of 4.5 mM. The results obtained indicate that the responses of the hydroponic melon plant grown with saline nutrient solution and the application of salicylic acid are not yet fully elucidated.

摘要

为了研究水杨酸浓度对在水培系统上生长的甜瓜植物减轻盐分胁迫的影响，在巴西 PB Pombal 的温室中使用 NFT（营养膜技术）系统进行了一项实验。实验设计是完全随机的，采用 4 × 4 阶乘方案，对应于营养液电导率的四个水平 - ECns（2.1 - 对照、3.2、4.3 和 5.4 dS m ^-1) 和四种浓度的水杨酸 - SA（0、1.5、3.0 和 4.5 mM），重复六次。浓度为3.2 mM的水杨酸减弱了营养液盐度对甜瓜果实鲜重的影响。盐水营养液会损害瓜类植物叶片中的气体交换和相对含水量，并增加细胞间电解质渗漏。然而，水杨酸减弱了盐度的有害影响，并在 ECns 为 3.1 dS m ^-1时叶面喷施 1.5 mM的甜瓜果实达到 23.82 t ha ^-1的最大产量。水杨酸刺激总叶绿素、CO _2的合成水培甜瓜的同化率和瞬时水分利用效率高达 4.5 mM 的浓度。获得的结果表明，水培甜瓜植株对含盐营养液和水杨酸施用的反应尚未完全阐明。