Response of Acokanthera oblongifolia Hochst. Plants to Seaweeds Extract under Water Stress at the Early Growth Stages

Abstract

Drought is an important abiotic stress that limits the plant growth and productivity. This experiment was done at two successive seasons of 2018/2019 and 2019/2020 to investigate the effect of seaweeds extract (algae) on the growth and quality at the early growth stages of Acokanthera oblongifolia under drought conditions. Four irrigation levels, i.e. 100% (control), 75%, 50% and 25% of field capacity were maintained throughout the experiment and four different concentrations of seaweeds extract (algae) [0.0 (control), 1.0, 2.0 and 3.0 mg/l] were applied as a foliar spray at 15 days intervals. The results showed that most vegetative and root growth parameters were significantly improved by increasing the natural extract concentrations up to 2mg/l which caused the highest significant increase in vegetative growth parameters plant height, number of leaves, and branches/plant, fresh weight, dry weight, leaf area and stem diameter). The same trend was also found for the root characters. The treatment 2mg/l resulted in the highest significant root fresh weight, volume and dry weight. For the chemical characters (chlorophyll a, b and carbohydrate content) ,3mg/l, was the best concentration, but they were significantly decreased with decreasing water field capacity. Moreover, the percentage of proline content was reduced with increasing algae extract concentration. According to these results, it could be concluded that 6-month-old transplants of Acokanthera oblongifolia could be irrigated under four levels of water field capacity, it has been sprayed with algae extract at 2.00 or 3.00 mg/l improved growth and chemical constituents under water stress.