Effect of irrigation interval and silicon on some morpho-physiological and biochemical properties of basil (Ocimum basilicum L.)

In order to investigate the effect of irrigation interval and silicon on growth, yield and oil content, total phenols and antioxidant activity of basil, an experiment was carried out at research greenhouse of Faculty of Agriculture, Lorestan University, Iran, in 2016. The research was carried out in pots as a factorial experiment based on a completely randomized design with four replications. Factors consisted of irrigation in three intervals of 4, 7 and 9 days (according to soil water content of 90%, 75% and 60% field capacity, respectively) and weekly foliar application of 0, 1 and 2 mM potassium silicate. Results showed that increasing irrigation interval decreased growth, and increased water use efficiency. Silicon alleviated the stress effects and improved growth parameters and application of 2 mM potassium silicate increased stress tolerance index. Both higher irrigation intervals and foliar application of silicon increased oil content and total phenols.Moreover, increasing irrigation intervals increased antioxidant activity and the maximum activity was found in plants irrigated every 9 d and foliar sprayed with 2 mM potassium silicate. Correlation coefficient indices showed that oil content had significant positive correlations with root length, total phenols and stress tolerance index and a negative correlation with IC50. Overall, results showed that increase in irrigation interval induced drought stress and consequently decreased the growth parameters measured in this experiment and application of potassium silicate alleviated the effects of drought and improved plant tolerance to drought stress and it increased oil content, oil yield and antioxidant activity.