EFFECT OF GIBBERELLIC ACID ON SEED GERMINATION PERCENTAGE AND GROWTH PERFORMANCE OF TWO CASSIA SPECIES

Abstract

The experiment was conducted in the plastic-house of the Department of Horticulture and Landscape at the College of Agriculture and Forestry, University of Mosul, Iraq during the period of 10/4/2018 and 31/1/2019 on two species of Cassia. Seeds were planted each seed depth twice the length of the seed in a plastic bowl (8 cm height, 6 cm diameter) full with a medium consisting of perlite, peat moss and sand with 1:1:1 (v/v/v) ratio. The developing seedling were then transferred to plastic pots with a diameter of 15 cm and a height of 12 cm in the same agricultural medium and transplanted into the plastic house after germination. The experiment was carried out by using two factors in split-plot design within randomized complete block design (RCBD). The first factor was two species of Cassia: Cassia surattenesis and Cassia siamea, while the second factor was soaking seeds in gibberellic acid at three levels of (0, 500 and 1000 mg L-1) for 48 hrs. The results showed that C. surattensis was superior in all seedling traits except for the leaf area, which was higher than C. siamea. Gibberellic acid had an important role in improving seedling properties and when used at (1000 mg L-1) on C. siamea the seedling height and leaf area were increased. There were no significant differences in both species of Cassia in some traits including seedling height. C. surattensis was characterized by its ability to flower in November after the appearance of flower buds at the beginning of the same month. Species differed in their tolerance to environmental conditions C. surattensis survived under cold waves, however, C. siamea was unable to survive under the same conditions in January.