بررسی پتانسیل استفاده از تفاله موم زنبور عسل به عنوان بستر کاشت گاوزبان اروپایی (Borago officinalis) در رژیم های مختلف آبیاری

In order to investigate the effect of using beeswax waste in combination with other organic matter as a substrate on some growth, physiological and biochemical parameters of borage in different irrigation regimes, an experiment was conducted in a factorial arrangement based on completely randomized design with three replications in 2017. The experimental treatments were irrigation interval in three levels (2, 4 and 6 day) and substrate in 8 levels (soil + wax in ratio of 3-1, soil + wax 4-1, soil + leaf-soil 3-1, soil + leaf-soil 4-1, soil + cow manure 3-1, soil + cow manure + wax 3-0.5-0.5, soil + leaf-soil + wax 3-0.5-0.5 and soil). The results showed that plant dry matter and height, carotenoid and proline contents, catalase (CAT), ascorbate peroxidase (APX) and lipids peroxidation (MDA) were affected by simple and interaction effects of irrigation regimes and planting substrates (P≤0.05). The membrane permeability and photochemical efficiency of photosystem II were influenced by the simple effects of both treatments. The content of chlorophyll a was only affected by irrigation regime and any treatments had significant effect on chlorophyll b contents. The photochemical efficiency of photosystem II, chlorophyll a and carotenoid contents were significantly decreased with increasing irrigation intervals. All of the organic substrates could mitigate the drought stress related to increasing the irrigation interval from 2 to 4 days. In both stress and non stress conditions, wax substrate in ratio of 3-1 had the highest dry matter, height, carotenoid contents and photochemical efficiency of photosystem II, with the lowest proline and MDA contents. Other wax containing substrates also showed satisfactory conditions in terms of plant growth indices and stress resistance for irrigation intervals of 4 and 6 days. The activity rate of CAT and APX enzymes were elevated with increasing irrigation interval in the soil + wax substrate with the ratio of 3-1, 4-1, wax + soil + peat, soil + leaf-soil 3-1 and 1-4. In other words, the two Enzymes have an effective role for improving drought stress resistance in the mentioned substrates. Therefore, it seems that the wax containing substrates are recommendable under drought stress conditions, and it is more efficient by enhancing the wax ratio in the planting substrate composition.