Comparative Effects of NaCl and CaCl2 Salinity on Cucumber Grown in a Closed Hydroponic System

Abstract

<jats:p>The objective of this study was to discriminate among Na, Cl, and Ca salinity effects on cucumber (<jats:italic>Cucumis sativus</jats:italic> L.). Cucumber plants grown in perlite were exposed for 134 days to low and moderate levels of salinity induced by the addition of either NaCl or CaCl<jats:sub>2</jats:sub> at equal rates (on a chemical equivalent basis) to a standard nutrient solution for cucumber up to two target electrical conductivity (EC) levels (3.0 and 5.0 dS·m<jats:sup>–1</jats:sup>). The experimental treatments included also a control, which was irrigated with the standard nutrient solution without additional salt. The mean EC values in the drainage solution were 2.35, 3.94, 4.2, 6.31, and 6.35 dS·m<jats:sup>–1</jats:sup> for the control, low NaCl, low CaCl<jats:sub>2</jats:sub>, high NaCl, and high CaCl<jats:sub>2</jats:sub> treatments, respectively. The fresh and dry weights of stems and leaves were reduced only under conditions of high NaCl salinity, whereas root mass was not affected. Fruit yield decreased in proportion to the increase in NaCl salinity, while CaCl<jats:sub>2</jats:sub> salinity reduced yield only at the high EC, to a level that corresponded to the low NaCl salinity. The suppression of yield with increasing salinity resulted mainly from a decrease in fruit size, while the number of fruit per plant was reduced to a lesser extent. These changes caused a reduction in the number of Class I fruit and an increase in nonmarketable produce. Both salinity sources enhanced the total soluble solids and the fruit chlorophyll concentration. NaCl salinity appreciably raised the concentrations of Na and Cl in young and old leaves, and suppressed the K concentration. CaCl<jats:sub>2</jats:sub> salinity increased leaf Cl and Ca levels and diminished Mg and K. It is concluded that cucumber is more susceptible to NaCl salinity than to equal EC levels of CaCl<jats:sub>2</jats:sub> salinity.</jats:p>

Effect of salt stress on cucumber: Na+–K+ ratio, osmolyte concentration, phenols and chlorophyll content

“…The reports on reduction in fruit yield under salt stress conditions by Shaterian et al (2005) in Solanum tuberosum, Bustan et al (2005) in melon, and Trajkava et al (2006) in cucumber also supported the present findings. High salt stress not only imposes osmotic and ionic stress on plant, it also influences the uptake and transport of essential nutrients such as K ?…”

Improving cucumber photosynthetic capacity under NaCl stress by grafting onto two salt-tolerant pumpkin rootstocks

“…Rather than Cl -, Na + has been reported as the primary cause of salt damage in cucumber. This appears to be the reason for the accumulation of a large amount of Cl -in Chaojiquanwang, while showing a lower degree of growth inhibition (Trajkova et al 2006). The present study demonstrated the importance of osmotic components, while taking into consideration the salt tolerance mechanism of grafted plants.…”

Attenuating the negative effects of irrigation with saline water on cucumber ( Cucumis sativus L.) by application of straw biological-reactor

“…6). This result was not in agreement with results from several previous studies (Trajkova et al, 2006;Huang et al, 2009). Different environmental conditions between these studies may explain the discrepancy.…”

“…Different environmental conditions between these studies may explain the discrepancy. Trajkova et al (2006) investigated effects of NaCl salinity on the fruit quality of cucumber grown in a closed hydroponic system, while Huang et al (2009) studied effects of NaCl stress on the fruit quality of cucumber grown in a substrate medium (a mix of peat, vermiculite and perlite). In this study, cucumber plants were grown in field soils, which showed different physicochemical and biological properties compared to soilless cultivation conditions used by Trajkova et al (2006) and Huang et al (2009).…”

“…Trajkova et al (2006) investigated effects of NaCl salinity on the fruit quality of cucumber grown in a closed hydroponic system, while Huang et al (2009) studied effects of NaCl stress on the fruit quality of cucumber grown in a substrate medium (a mix of peat, vermiculite and perlite). In this study, cucumber plants were grown in field soils, which showed different physicochemical and biological properties compared to soilless cultivation conditions used by Trajkova et al (2006) and Huang et al (2009). It has been demonstrated that fruits often show different quality in soil cultivation compared to soilless cultivation (Rouphael et al, 2004;Tagliavini et al, 2005).…”