Yield, growth and element content of zucchini squash grown under saline-sodic conditions

'Isotta' zucchini squash plants (Cucurbita pepo L.) were grown in 157 1 containers and irrigated with water containing 0, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9 g 1(-1) of NaCl. Zucchini squash was moderately tolerant to salinity. The thresholds, expressed as electrical conductivity of irrigation water (ECi) and saturated soil extract (ECe), for marketable yield, were 2.8 and 5.1 dS m(-1) respectively. The slopes of marketable yield against EC were 12.8% and 11.65% per dS m(-1) for ECi and ECe respectively. The research examined especially the ion distribution in different plant tissues under controlled salinity conditions. Of all the tissues analysed, roots had the highest Na concentration which generally increased with increasing salinity and reached a highest value of 1400 mmol kg(-1) dry weight at 15.2 dS m(-1). Na concentration in leaves was very low. Cl concentration in mature leaves was about 3200 mmol kg(-1) dry weight at 11.4 dS m(-1) K and Ca uptake was less affected by salinity increase.