Effect of Saline Water on Seed Germination and Seedling Growth of Some Citrus Rootstocks

Abstract

The experiment was carried out during the spring season 2021 at the research station the Faculty of Agriculture, University of Tripoli, to study the effect of treatment with different concentrations of salinity (control - 1500 - 3000 - 4500 ppm) on the germination of seeds and growth of seedlings of three citrus rootstocks, namely bitter orange (Citrus aurantium L.), Cleopatra mandarin (Citrus reshni L.) and sugar orange (Citrus sinensis L.). The experiment was designed according to the completely randomized design (CRD) method, including 12 treatments (3 citrus rootstocks and 4 concentrations of saline water, each treatment included 3 replicates, each replicate containing 30 seeds. The results of the experiment were analyzed using the SPSS statistical program, and the significant differences between treatments were calculated according to Duncan's multiple range test at a confidence level of 95%. The results of the statistical analysis showed a decrease in the percentage of seed germination with increasing salinity of irrigation water, where the germination percentage was recorded in the bitter orange rootstock (63.20%) at a concentration of 1500 ppm of saline water, while the lowest germination percentage was in the sugar orange rootstock (4.20%) at a concentration of 4500 ppm, It was also noted that the highest average seedling length (18.5 cm) was for the bitter orange rootstock at a concentration of 1500 ppm and for the Cleopatra mandarin rootstock at a concentration of 3000 ppm, and the lowest average seedling length (8.25 cm) was for the Cleopatra mandarin rootstock at a concentration of 4500 ppm. The highest average vitamin C content in leaves (14.4 mg/100 g fresh weight) was recorded for the Cleopatra mandarin rootstock at a concentration of 1500 ppm, and the lowest average vitamin C content in leaves (5.85 mg/100 g fresh weight) was for the orange rootstock at a concentration of 3000 ppm. When studying the chlorophyll content in leaves, the results showed a decrease in the relative content of this pigment in leaves with increasing salinity. The highest average of chlorophyll content in leaves (10.72 mg/100 g fresh weight) was for the sugar orange rootstock at a concentration of 1500 ppm, and the lowest average was (2.00 mg/100 g fresh weight) for the Cleopatra mandarin rootstock at a concentration of 3000 ppm. When studying the sodium content in the roots, it was found that the roots of the orange rootstock contained a higher percentage of sodium (3.31%) compared to the two rootstocks; The Cleopatra Mandarin rootstock had the lowest sodium content (0.76%) in its roots. However, no significant differences were found in the sodium content of the leaves and stems among the three studied rootstocks. Therefore, it is evident that the bitter orange rootstock is the most tolerant to salinity compared to the other studied rootstocks.