Evaluation of growth and physiological reactions of Kochia plant to simultaneous stress of salinity and cadmium

Nowadayes, due to the increasing use of phosphorus fertilizers in agricultural lands, the salinity of the soil along with contamination with heavy elements such as cadmium has increased sharply. Plants' response to a particular stress is different from when they experience multiple stresses simultaneously. The aim of this experiment was to investigate the simultaneous effect of salinity and cadmium stresses on morphological and physiological characteristics of Kochia.

For this purpose, a factorial greenhouse experiment based on a randomized complete block design with four replications was conducted in the educational-research greenhouse of the Faculty of Agriculture, Valiasr University of Rafsanjan in 1397. Experimental factors included four different levels of salinity stress (0, 6, 12 and 18 dS/m) and cadmium concentration in soil (0, 1, 5 and 10 mg/kg soil). The studied traits included dry weight of branches, stems and leaves, RWC, concentration of chlorophyll a, b and a + b, enzymes activity of superoxide dismutase, peroxidase, catalase, the concentration of cadmium, iron, zinc, manganese, calcium and magnesium.

The results showed that due to increasing salinity to 18 dS/m the dry weight of branches, leaf and stem dry weight and leaf area, RWC, concentration of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids decreased by 56.8, 48.01, 50, 46.09, 21, 53.76, 56.91, 53.75 and 51.21 percent, respectively. By increasing the cadmium concentration to 10 mg/L, the dry weight of lateral branches, leaves, stems and leaf area decreased by 24.32, 31.89, 28.45 and 41.24%, respectively, but the concentration of leaf cadmium compared to the control treatment1.7 times was increased. The activity of superoxide dismutase, peroxidase and catalase enzymes in treatment of 18 dS/m salinity alongside with 10 mg/L cadmium were 1.83, 1.4 and 4.7 times higher than the control treatment, respectively. Leaf iron, zinc, calcium and magnesium concentrations decreased by 73.07%, 51.51, 51.8%, 0.17 and 0.26% with increasing salinity stress to 18 dS/m, respectively, and with increasing cadmium concentration to 10 mg/L increased iron concentration by 37.32% and zinc and magnesium concentrations decreased by 28.70 and 0.12%, respectively.

The highest dry matter of Koshia in salinity and cadmium stress treatments belonged to the control treatment and the lowest dry matter were obtained from 18 dS / m salinity and 10 mg / kg cadmium in soil.