The effects of selenium and silisium applications on reducing irrigation water-induced salinity stress in bean plant

Excess salinity, osmotic stress, harmful effects of toxic ions and ion imbalance negatively affect plant growth and development. Legumes, including beans, are classified as salt-sensitive plant species as they were significantly affected by salt stress, one of the abiotic stress factors. In recent years, researches on the use of elements such as silisium and selenium to reduce salinity stress have been increasing. However, no study has been found in the world literature that shows the effects of these elements on reducing salinity stress in bean plants. The main purpose of this study was to determine whether the negative effects of salinity stress on growth, yield and quality parameters of bean (Phaseolus vulgaris L.) plant could be reduced by silisium or selenium applications. The research was realized for two growing seasons between March-2019 and March-2021, in weighing lysimeters under a rain-out shelter at Akdeniz University. In the study, two different experiments with similar two factors (irrigation water salinity and silisium or selenium) were set up. Four different irrigation water salinity levels including control (0.6 dS/m), low (1.6 dS/m), medium (3.0 dS/m) and high (4.8 dS/m) as the first factor treatments were investigated in both experiments. In addition, three different foliar application dosage of silisium (0, 56 and 112 mg Si/L) and selenium (0, 5 and 20 mg Se/L) which were thought to increase the response of the bean plant to salinity stress, were considered as the second factor in the experiments. At the end of the experiment, plant water consumption, soil salinity and drainage water salinity and yield parameters as pod length, number of pod, number of seed, wet and dry biological yield, vegetative dry weight, pod dry weight and seed dry weight were determined. In addition to these, organic acid components (tartaric acid, oxalic acid, malic acid, maloic acid, shikimic acid, ascorbic acid, acetic acid, citric acid, maleic acid, fumaric acid and succinic acid) of the plant samples were analyzed. Finally, salinity threshold and relative yield decrease values were determined separately for each foliar application dose of silisium and selenium. In general, salinity, as the main factor, has a significant negative effect on parameters including plant water consumption, growth and yield in bean plants in both years. However, it has been shown that foliar application of silisium and selenium, which are suggested to be used to reduce salinity stress in many plants, did not show, in general, a statistically positive trend for almost all growth, yield and quality parameters in bean. Compared to the control salinity treatment, it was revealed that the application of 112 mg Si/L to the bean plant slightly increased the salinity threshold, while the application of 20 mg Se/L did not affect the salinity threshold value at a significant level, but this application had a very low positive effect on the slope value, which expresses the decrease in yield after the threshold salinity. When evaluated in general, it was concluded that foliar application of silisium and selenium under studied concentartions had minor effect than expected in improving the tolerance of salinity stress to growth, yield and quality parameters in bean plants.