Growth Inhibition and Changes in Nutrient Accumulation in Cucumber Plants under Salinity Conditions

Soil salinity affects plant growth, including germination, reproductive development and yield. The most common soil salt, sodium chloride (NaCl) produces ionic toxicity, osmotic stress and nutrient deficiencies in plants, mainly of N, Ca, K, P, Fe and Zn. In this research we evaluated the response of two cultivars of cucumber (AF-1661 and Slice Max) to five NaCl concentrations (0, 50, 100, 150 and 200 mM) in the nutrient solution. Plants were grown under greenhouse using red tezontle (inert red volcanic gravel) as substrate and the nutrient solution of Steiner at 100%. The different levels of NaCl were applied during 60 days after transplanting. Height of plant, weight of fresh and dry matter of shoot and roots as well as concentration and accumulation of Ca, K, Mg, P, Na and N in shoot and roots were determined. The nutrient accumulation was estimated using the nutrient concentration and the weight of dry matter of shoot and roots. The cultivar 'AF1661' had significant reductions in plant height with the addition of 150 mM NaCl. Salinity reduced the accumulation (mg/organ) of P, K, Ca, Mg and N, as well as the K/Na ratio both in shoot and in roots in both cultivars, because of antagonism between these macronutrients with the Na. At 200 mM NaCl, the cultivar 'Slice Max' showed higher sensibility to salinity than 'AF-1661', as this cultivar was unable of blocking the Na transport to shoots and therefore a higher accumulation of Na in shoots that caused leaf necrosis was observed.