Investigation of the effects of plastic pollution and salt stress on some ecophysiological properties in watermelon (Citrillus lanatus (Thunb.) Matsum. & Nakai)

Plastics released into the environment through waste, industrial activities, and agricultural practices degrade into various forms of microplastics due to their polymer structures, which are resistant to decomposition and take a long time to break down in nature. In agricultural ecosystems, the main contributors to microplastics are fertilizers, pesticides, and mulchs. Microplastics can affect soil structure, microbial activity, and plant-soil interactions, leading to negative impacts on agricultural production. Salinity, which is the accumulation of soluble salts in soils at high levels, is currently a significant factor threatening agricultural ecosystems. Salinity affects plant growth and yield due to reduced water uptake and altered nutrient absorption. In this study, the individual and combined effects of plastic pollution and salt stress on certain ecophysiological traits of watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) were investigated. Microplastics were obtained by cutting polyethylene mulch film into 2.5×4 mm pieces. A total of 12 experimental sets were established, in which microplastics and salt were applied separately and in combination. Stem diameter, number of leaves, shoot/root length, shoot/root fresh and dry weight, chlorophyll a, chlorophyll b, total chlorophyll, shoot and root water content, root/shoot ratio were taken into consideration as ecophysiological properties. The results of the study revealed that both microplastic and salt treatments caused significant variations in all measured ecophysiological traits. It was observed that the effects of microplastic and salt treatments on the ecophysiological traits were different. The plant responses also varied depending on whether microplastic and salt were applied individually or in combination.