Physiological behavior of melon cultivars submitted to soil salinity1

Abstract

Melon is one of the most important vegetables for the Brazilian foreign trade. However, in semi-arid areas, the irregular rainfall, excessive use of fertilizers and, especially, poor quality water contribute to the soil salinization, becoming a limiting factor and damaging the photosynthetic apparatus, as well as affecting yield. This study aimed to evaluate the physiological behavior of melon cultivars submitted to soil salinity. For that, an experiment was conducted in a greenhouse, using a randomized block experimental design, in a 3 x 5 factorial scheme, with the first factor related to melon cultivars (Iracema, Goldex and Natal) and the second one related to soil salinity levels (0.3 dS m-1, 1.3 dS m-1, 2.3 dS m-1, 3.3 dS m-1 and 4.3 dS m-1 of electrical conductivity), with four replications. For soil salinization, a saturation extract with initial soil salinity of 0.3 dS m-1 was obtained, while the other levels were prepared by adding NaCl to the soil. The physiology of melon plants is negatively affected by the increased salinity in the soil. The evaluated cultivars do not show differences in tolerance for the physiological response to soil saline stress.

Morphophysiology and inorganic solutes in watermelon irrigated with brackish water in different planting systems

“…Decreases of 62.66%, 17.13%, 14.20%, and 23.65% were found for stomatal conductance (Figure 3A), CO 2 assimilation rate (Figure 3B), internal CO 2 concentration (Figure 3C), and transpiration rate (Figure 3D), respectively, when comparing the treatments with the lowest and highest salinity levels. The inhibition in stomatal conductance may be related to excess salts in the soil solution, causing a reduction in water absorption, promoting stomatal closure, and inhibiting leaf gas exchange (PARIHAR et al, 2015;SOUSA et al, 2018;SILVA et al, 2019). Similar results were found in other studies (RIBEIRO et al, 2020;FREITAS et al, 2021;FREIRE et al, 2021).…”

Use of hydrogen peroxide in acclimatization of melon to salinity of irrigation water

“…In contrast, iCE and WUE were not significantly influenced by either factor studied, possibly because they are mathematical relationships, such as the ratio between the carbon dioxide assimilation rate and intracellular CO 2 concentration (iCE), as well as the ratio between the CO 2 assimilation rate and conductance (WUE), as observed by Sousa et al (2018).…”

“…When analyzing the interaction between the electrical conductivity of irrigation water and H 2 O 2 concentrations, it was observed that the LA (Figure 2A), DMAP (Figure 2B), and P of melon plants (Figure 2C) subjected to ECw of 0.3 dS m -1 differed significantly from that of plants irrigated with water at 5.0 dS m -1 . This was due to high saline concentrations reducing melon growth and production (Sousa et al, 2018).…”

“…However, in semi-arid regions, such as Northeast Brazil, soil and climate conditions can increase the risk of soil salinization, particularly when poor quality water is used for irrigation. The amount of salt in irrigation water can impair the physicochemical properties of soils and reduce crop yields according to their degree of tolerance (Sousa et al, 2018).…”