Influence of different ratios of nitrate and ammonium and silicon on growth, nitrate reductase activity and fatty acid composition of sunflower under salt stress

Sunflower is a major oil seed crop worldwide and it is also an important crop in Mediterranean areas where salinity is an increasing problem. Although seed oil of standard cultivated sunflower is considered to be of good quality for edible purposes, the development of cultivars with oil high in oleic acid is an important breeding objective for this crop. In this paper, the effect of the salinity, silicium and different nitrate and ammonium ratios were evaluated on growth, sodium and potassium content, nitrate reductase activity and fatty acid composition. Sunflower plants were grown in a pot hydroponical system. The results revealed that salinity significantly decreased plant growth, potassium accumulation, K/Na ratio and linolenic acid percentage while increased sodium content and oleic acid percentage. Also, silicium increased plant growth, oleic acid and linolenic acid percentage, potassium content, K/Na ratio and silicium content. Silicium prevented sodium accumulation in plants. Among different nitrate and ammonium ratios 25:75 ratio was the best treatment in respect of plant growth.