Nitrogen fertilizer promoting salt tolerance of two sorghum varieties under different salt compositions

Soil salinization is more aggravating than ever before and techniques are needed to mitigate this problem; understanding salinity-fertilizer relationship is of considerable economic importance for promoting crop growth and productivity in saline soil. A pot experiment was done in a greenhouse to determine whether the N could alleviate the negative effect of different salts compositions on the growth, and physiological attributes of the two most used Sudan sorghum (Sorghum bicolor (L.) Moench) cultivars (Wadahmed and Tabat). The plant was subjected to the salt stress at 0, 0.3419 M NaCl, and 0.1408 M [Na.sub.2]S[O.sub.4], and four levels of N application 0, 4, 8, and 12 g N [kg.sup.-1] soil, designated as N0, N1, N2, and N3, respectively. Results showed that [Na.sub.2]S[O.sub.4] was reduced plant height, leaf area index, number of leaves, dry weight (DW), chlorophyll a, total chlorophyll content, and increased soluble protein content, activities of peroxidase (POD) and catalase (CAT) activities by 16.4%, 29.7%, 61.5%, 28.7%, 39.6%, 12.7%, 99.7%, 34.3%, 51.8%, respectively, when compared with the non-saline treatment. The [Na.sub.2]S[O.sub.4] salt had a more harmful effect than NaCl. This study revealed that N fertilizer was successful for alleviating the adverse impacts of both types of salt. In this study, 12 g N [kg.sup.-1] soil was most effective on most of the measured parameters of two sorghum cultivars. These findings demonstrated that the N soil amendment application could alleviate the harmful impact of salinity. 'Wadahmed' was more tolerant to salinity stress than 'Tabat' during the boot stage of sorghum plant. Key words: Boot stage, nitrogen application, NaCl, [Na.sub.2]S[O.sub.4], Sorghum bicolor.