Effects of potassium silicate on some morphological and physiological traits of dichondra (Dichondra repens) cover plant grown under water deficit

Dichondra repens is a low growing, creeping perennial that spreads by underground runners. This plant is usually planted instead of lawn in warm areas and is also suitable as a cover to fill the gap between the pavements and for planting in rock gardens. Soil drought is one of the major abiotic factors that limit crop growth and productivity worldwide. Drought stress triggers production of reactive oxygen species (ROS) that cause oxidative damage to proteins, membrane lipids and other cellular components. Silicon (Si) is the second most prevalent element after oxygen in the soil. The beneficial effect of the silicon is well documented for several agricultural crops.

The present study was conducted to assess the effect of potassium silicate on growth characteristics of Dichondra repens under water deficit as factorial in a completely randomized design in 2018. Water deficit was applied in three levels (100%, 66% and 33% Field capacity) and potassium silicate in four levels (0, 50, 100 and 200 mg/l). Data analysis was performed with SAS software. Mean data were compared with Duncan test at 5% level. Plant height was measured from the collar to the tip of the plant with a caliper. To measure the fresh weight of the shoot, the plant was weighed after harvesting with a digital scale. To measure the roots, the roots were gently removed from the soil and weighed with a digital scale. Leaf chlorophyll was measured by Arnon (1949) method at 480, 663 and 645 nm with a spectrophotometer. Catalase activity was measured by Eising and Gerhardt (1989) method. Measurement of superoxide dismutase activity by Dhindsa et al. (1982) was performed. Potassium concentration was measured by flame photometry. Elliott and Snyder (1991) method was used to measure leaf silicon concentration.

Plant height decreased by 38% in 33% field capacity and non-use of potassium silicate interaction in comparison of 100% field capacity and 200 mg/l potassium silicate interaction. Potassium silicate 200 and 100 mg/l increased chlorophyll content in 100 and 66% of field capacity. Catalase and superoxide dismutase enzymes showed the highest activity in 33% field capacity and 200 mg/l potassium silicate interaction and 33% field capacity and no potassium silicate interaction, respectively. The lowest relative leaf water content was observed in 33% field capacity and no potassium silicate interaction and there is no significant difference between it and potassium silicate at 50 mg/l. The highest amount of potassium was observed in the treatment of 66% of field capacity and 50 mg/l of potassium silicate, which was not significantly different from the interaction of 100% of field capacity and 100 mg/l of potassium silicate. The highest amount of silicon was observed in treatment of 100% of field capacity and 200 mg/l of potassium silicate, which was significantly different from other treatments.

Treatment of 100% field capacity and potassium silicate at 200 mg/l was identified as the most efficient treatment in improving the growth characteristics of dichondra. So with proper management 66% field capacity and 100 mg potassium silicate treatment can be replaced with 100% field capacity potassium silicate at 200 mg/l.