Optimization of Propagation Methods For The Production of Queens Flower (Lagerstroemia Speciosa)

Abstract

This study consisted of two experiments that evaluated the effect of Indole-3-butyric acid (IBA) treatments on the rooting of Lagerstroemia speciosa stem cuttings and the effect of seed germination pre-treatments (sodium hydroxide, hydrogen peroxide and sulphuric acid) on the germination of Lagerstroemia speciosa seeds. In the rooting experiment, 15 cm long stem cuttings from softwood, semi-hardwood and hardwood were used. The treatments comprised six IBA concentrations namely, 0 ppm (control), 500 ppm, 1000 ppm, 1500 ppm, 3000 ppm and 4500 ppm for 10 seconds. The semi-hardwood and hardwood were subjected to the 0 ppm (control), 1500 ppm, 3000 ppm and 4500 ppm treatments while the softwood cuttings received 0 ppm (control), 500 ppm, 1000 ppm, 1500 ppm and 3000 ppm. There were 20 cuttings per treatment. Each treatment was replicated three times. The 1500 ppm IBA treatment outperformed the other IBA treatments in all the different stem cuttings producing 14.8 % rooting in softwood cuttings, 14.8 % in semi-hardwood cuttings and 16.6 % in the hardwood cuttings. Hardwood stem cuttings generally produced better response to rooting than the semi-hardwood and hardwood cuttings. Percent rooting, number of roots per cutting as well as length of longest roots improved with age of cuttings for the best IBA concentration as well as the control. Hence the combination of hardwood cuttings at 1500 ppm IBA rooting hormone produced the best rooting in Lagerstroemia speciosa. Mature seeds (820) from healthy looking trees were used in the germination experiment. Freshly harvested seeds (20 each) were treated with hydrogen peroxide (5% and 10%), 3.5% sodium hypochlorite (50% and 75%) and 90% sulphuric acid (5 min., 10 min., 15 min., and 20 min). The treatments consisting of a control and the pre-treatments mentioned were replicated five times. The evaluations performed for 34 days starting from seed sowing, showed that sulphuric acid had the highest germination percentage (3.7 %) than those treated with hydrogen peroxide (2.6 %) and sodium hydroxide (Clorox) 0.0 %. The most effective sulphuric acid treatments were for 10 min. and 20 min. Strategies for further improvement of germination as well as rooting of cuttings of Lagerstroemia speciosa are suggested