Impact of silicon on decreasing of salinity stress in greenhouse cucumber (Cucumis sativus L.) in soilless culture

Abstract

Salinity is one of the environmental threats to agriculture. A study was carried out to investigate impact of silicon on decreasing of salinity stress in greenhouse cucumber (Cucumis sativus L.) in soilless culture. Seeds of cucumber were sown in polystyrene boxes with a substrate composed of 50% peat and 50% perlite. After 40 days (after germination), seedlings were transferred to plastic containers with 17 liter volumes. Five levels of silicon by sodium silicate (NaSiO3) were considered including 0, 25, 50, 75 and 100 mg.L-1 using sodium silicate in nutrient solution. Salinity levels in the final nutrient solution were considered including 2.5, 3.5 and 4.5 (dS.m-1) using sodium chloride. After five weeks, samples were taken for testing. Maximum plant height, wet weight, dry weight (cm) and total chlorophyll (mg/g fresh weight) equal to 82.6, 333.4, 44.7 and 14.700 were recorded in No. 3 (EC=2.5 dS.m-1 and Si= 50 mg.L-1), 1 (EC= 2.5 dS.m-1 and Si=0 mg.L-1), 5 (EC=2.5 dS.m-1 and Si= 100 mg.L-1) and 2 (EC=2.5 dS.m-1 and Si= 25 mg.L-1), respectively. Minimum plant height, wet weight, dry weight (cm) and total chlorophyll (mg/g fresh weight) equal to 62.3, 281.7, 26.2 and 8.22 were recorded in No. 7 (EC=3.5 dS.m-1 and Si= 25 mg.L-1), 8 (EC=3.5 dS.m-1 and Si= 50 mg.L-1), 12 (EC=4.5 dS.m-1 and Si= 25 mg.L-1) and 7, respectively. The evidences provided by this experiment indicated that silicate has increased resistance of plant against salinity. Silicate caused an increase of chlorophyll content but it caused a decrease of plant height.