The Irrigation of Fordhook Giant/Swisschard (Beta vulgaris var cicla) and Mustard (Brassica juncea) Spinach Vegetables with Saline Water

Spinach is an important leafy green vegetable that contains large quantities of bioactive compounds and nutrients that are not common to most other vegetables, such as
-coumaric acid derivatives that exhibit strong antioxidant activity and glucuronic acid derivatives of flavonoids. Saline irrigation water is becoming an important water source as fresh water is fast becoming a scarce resource in many areas of the world, including Eswatini. This shortage is true, especially in arid and semi-arid regions. A study to test the response of two varieties of spinach (Fordhook Giant and Mustard) to salinity was conducted in a field pot experiment at the Faculty of Agriculture at the Luyengo Campus of the University of Eswatini. The treatments were laid in a randomized block design (RCBD). The experiment consisted of four treatments, each replicated twelve times. Treatments were salinity levels of 0.0 dS/m, 1.5 dS/m, 2.0 dS/m and 3.5 dS/m. All the treatments were subjected to similar agronomic practices. Spinach was grown and observed for a period of five weeks. Plant height was measured and the number of leaves was counted weekly throughout the experiment. Treatment means were separated by the Student’s t test at the 0.05 level of probability using the ANOVA. Significant differences (P < 0.05) between salinity treatments were obtained for plant height beginning in week 2 but were more pronounced in week 3, 4 and week 5. Visual observation showed that levels of salinity beyond 2.0 dS/m affected the leaf colour of both varieties of spinach. No significant differences were obtained for the number of leaves. There were, however, clear significant differences between spinach irrigated with non-saline irrigation water compared to saline irrigation water. It was concluded that irrigating spinach with saline water having a salinity of more than 2.0 dS/m drastically reduced plant growth, although it did not affect the number of leaves under the experimental conditions. The study also concluded that the growth of mustard spinach was better than that of Fordhook Giant at low salinity levels indicating a slight tolerance. It may be recommended that farmers prioritize growing Mustard spinach as the first choice followed by Fordhook Giant under similar conditions.