The Effect of Silicon on Quantitative and Physiological Characteristics of Borage (Borago officinalis L.) under Irrigation Regimes

In order to investigate the effects of irrigation regimes and foliar silicon spraying on quantitative and physiological characteristics of borage (Borago officinalis), an experiment is conducted as split plot based on randomized complete block design with three replications during 2014 at the University of Zabol research farm in Zahak. Treatments include irrigation regimes at three levels; (90%, 70%, and 50% FC) comprising the main-treatments and four levels of silicon sprying including spraying in the form of sodium silicate (Na2SiO3) (0, 2, 4, and 6 mM) as sub-treatments. The results indicate that the highest amount of proline is obtained from the interaction of irrigation regime with 50% of field capacity, without the use of silicon at the rate of 0.7847 mg.g-1. Based on the results of average comparison, the highest amount of chlorophyll a (15.919 mg/g fresh weight), chlorophyll b (7.14 mg/g fresh weight), from the interaction of irrigation regime 70% of field capacity and application of 2 mM silicon, as well as number of flowers per plant, total dry yield of plant (520 kg.ha-1) and biological yield (1187 520 kg.ha-1) Per hectare), 70% and 50% of field capacity and application of 6 mM silicon are obtained from the interaction effect of irrigation regime, respectively. Overall, the results suggest that silicon application mitigate drought stress impact and led to increasing drought tolerance of borage. Since flower and flowering branches of plant has economic value and application of 4 mM silicon acid is recommended to obtain the greatest flower yield under drought stress conditions.