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This study has investigated, over two seasons, salinity stress, and two mineral nitrogen fertilizer effects on Acacia gerrardii (Benth.) and Vachellia origena (Hunde.) growth. Photosynthesis and growth characteristics both responded positively to fertilization. Vachellia origena growth improved and become more tolerant to salinity stress by aid of fertilization. Calcium nitrate fertilization has induced the highest seedling height, diameter, and dry weight. The salt concentrations negatively affected growth, particularly 5000 ppm. Calcium nitrate or ammonium sulfate can improve the growth and the biomass of the tree seedlings and increase tolerance to high salinities either in nursery or in the field. [ABSTRACT FROM AUTHOR]

Chemical mutagenesis is one of techniques used to induce mutations and increase the genetic variability in breeding programs of economically important plants. This study aimed to evaluate the effect of different concentrations of two mutagens, sodium azide (SA) and diethyl sulphate (DES), on the growth of Leucaena leucocephala (Lam.) trees. Six concentrations of SA and DES (zero (control), 1000, 2000, 3000, 4000 and 5000 ppm) were used to soak the L. leucocephala seeds, which were planted and kept in open field at the experimental station of the Faculty of Agriculture, King Saud University, for four years. This study demonstrates that inducing SA and DES mutagens by soaking the seeds significantly affects the vegetative growth of L. leucocephala. The mutagen DES more strongly affected plant development than did SA. The concentration of 1000 ppm SA had the greatest effect on the number of branches and leaves, the stem diameter and the pod length compared to treatment with DES. In contrast, DES had the greatest effect on the plant height and the number of flowers per plant. The concentration of 5000 ppm SA had a lethal effect on seed germination and did not permit growth. The total chlorophyll content was significantly decreased under all of the studied concentrations compared with control seedlings. [ABSTRACT FROM AUTHOR]