Effects of Different Types of Phytohormone over Traditional Seed Pre-Treatments on Germination of Dryland Tree Species

The need for more energy, shelter and food has necessitated increased afforestation. However, the problem of seed dormancy has hindered the germination of the several trees species and therefore ways of breaking seed dormancy remains urgent. The main objective of study was therefore to determine the efficacy of different phyto-hormonal over traditional seed pre-treatments on germination of selected dryland tree species. Seeds of four tree species (Balanite aegyptiaca, Melia volkensii, Acacia tortilis and Adansonia digitata) were sterilized by soaking in 1 % potassium permanganate (KMnO4) for 10 minutes, rinsed with distilled water and air dried for 2 days before treatment. The four phytohormones were Naphthaleneacetic acid (IAA), 2, 4-Dichlorophenoxyacetic acid (2-4, D), Giberrelic acid (GA3) and N6 Benzyl adenine (BAP). The experimental setup was a Completely Randomized Design (CRD) constituting four hormones with a control (without any pretreatment). The hormonal pre-treatment were also compared with traditional seed pretreatment methods consisting of scarification, H2SO4 treatment, warm water at 30C and hot water at 100C. Seeds were then be monitored for germination. Mean differences in the germination percentages were analyzed using One-Way ANOVA following arc-sine transformation. Germination in control was always low ( 20 %) while taking up to 39 days to first germination. Among the traditional seed pre-treatment methods, the highest germination % occurred in H2SO4 and but rarely exceeded 45 % germination. Phytohormones mainly auxins gave better response over seeds without any pre-treatment and over other traditional pretreatment methods. Amongst all growth hormones, 2, 4-D, NAA and BPA gave best response for seed germination (70-90 %) and therefore managers of dryland agroforestry species should use phytohormones in enhancing seed germination. However, further studies on the effect different concentrations of hormones and combination of the traditional methods and hormonal treatments should also be conducted