Effects of Salinity Stress on Germination, Growth and Some Physiological Characteristics of Kochia (Kochia scoparia L.) Plants

Kochia is a promising salt tolerant forage crop that could be cultivated under saline conditions. Germination cabinet and greenhouse pot experiments were conducted to study germination, growth and some physiological characteristics of Kochia scoparia under different levels of salinity. In the germination cabinet experiments, six salt treatments: 0, 25, 50, 100, 200 and 300 mM using three salt types: CaCl2, Na2SO4 and NaCl, were applied, and seed germination was monitored at 25°C for two weeks. Furthermore, greenhouse experiments were conducted using NaCl-CaCl2 solutions imposed by irrigation with half-strength Hoagland solution containing 0, 25, 50, 100, 200 and 300 mM at emergence, 2 weeks and 4 weeks after emergence. The results showed that germination percentage and rate were reduced with increasing the salinity level. The impact of CaCl2 on germination was greater than that of Na2SO4 and NaCl with values ranging from 33.2% to 47.0%. Shoot growth and root growth were significantly affected by salinity level at concentrations higher than 100 mM. 50% shoot and root growth reduction occurred at 200 mM and 300 mM, respectively. Increased salinity has also resulted in accumulation of proline and glycinebetaine to levels of 2.5 to 3 times that of the control treatment. Reductions in chlorophyll a and b and carotenoids to levels of 87% to 90% were also observed under high salinity levels. Results indicated that regardless of the reduction in growth parameters, kochia is a valuable candidate crop to be used under high salinity, where other traditional crops can not grow or produce under high levels of salinity