Effect of irrigation using saline and magnetized water on some botanical characteristics of cowpea plant (Vigna unguiculata L. Walp)

A two-year pot experiments were conducted at the farm of Agricultural Botany Department, Faculty of Agriculture, Al-Azhar University, Assiut, Egypt, during the summer seasons of 2021 and 2022. The aim of the present investigation is to study the effect of irrigation using saline and magnetic (i.e., a technique for mitigation the harmful effects of saline water) water on some morphological, physiological and productivity characteristics of two cultivars of cowpea plant (Cream 7 and Kafr El-Shekh). Irrigation water treatments were done using salinity levels at 4000, 5000 and 6000 mgl^-1 as well as the magnetic treatment of saline irrigation water at the same concentrations compared to the control (tap water) .The results showed that irrigation with saline water at 4000, 5000 and 6000 mgl^-1) as well as magnetic water were decreased the morphological, physiological and productivity characteristics during the two study seasons compared to the control. Results also showed that the use of increasing saline water levels led to a significant decrease in all morphological characteristics i.e., plant length (cm), number of leaves plant^-1 leaf area (cm²) plant^-1, branches number plant^-1, roots dry weight, stems and leaves dry weights (g). The same results also, showed a decrease in the physiological characteristics i.e., chlorophyll A, B, total chlorophyll and total carotenoids (mg g^-1 F.W) as well as the nitrogen (N), phosphorus (P) and potassium (K) contents. A reverse trend was observed in sodium (Na) and chloride (Cl) in the leaves content. Also, there was a noticeable decrease in yield characteristics i.e., number of pods plant^-1, pods dry weight plant^-1 (g), weight of 100 seeds (g), number of seeds plant^-1, dry weight of seeds plant^-1 (g)) compared to the control during the two growing seasons. Data indicated that salinity at 6000 and 5000 followed by 4000 mg l^-1 respectively, had the most effects on the occurrence of a clear decrease in the studied characteristics compared to the control with the two cultivars during the two seasons. On the other side, using magnetized water of the salinity at 4000, 5000 and 6000 mg l^-1, results showed remarkable positive effects for all previous morphological, physiological and productivity characteristics compared to using of saline water with the two cultivars especially Kafr El-Shekh cultivar during the two growing seasons. Finally, the study confirms that the using of magnetic treatment of saline water until a concentration of 6000 mg l^-1 has reduced the harmful effects of salt stress on the morphological, physiological and yield characteristics of the cowpea plant especially Kafr El-Shekh cultivar.