Effect of Hormones and Leaf Retention on Rooting and Growth of Coffee (Coffea arabica L.) Hybrid Cuttings

Abstract

Ethiopia is the primary center of origin for Arabica coffee (Coffea arabica L.) which is the single most important cash crop that has been contributing a lion’s share to economy. Despite the significant role that coffee plays in the economy of the country, the crop suffers from many production constraints that affect both quantity and quality. This shows that much is expected to increase the production both in quantity and quality. To do this, availability of adequate high quality planting materials that maintain high and sustainable production of good quality crop is needed. The three hybrid coffee varieties (Aba-buna, MelkoCH2 and Gawe) which were released by EIAR can be used for this purpose. However; their multiplication by seed gets difficulty to reach the farmers, Coffee State Farms and the private investors because of the varieties exposure to segregation. On the other hand, hand pollination has also limitations like low fruit set, labor shortage and unfavorable weather conditions which resulted in insufficient planting material. Some methods, such as grafting, budding and tissue culture, need skilled personnel to follow. However, propagation by cutting is one means of reproduction which ensures genetic purity of planting materials especially for those varieties which are exposed to segregation such as F1 hybrids. The success of rooting in previous work done in Ethiopia did not exceed 89 % under mist propagator and the study did not include other high yielder recently released Ethiopian arabica coffee hybrids, cutting types; and synthetic plant rooting hormones. An experiment was initiated to determine the best rooting hormones (IBA and NAA) which help in establishing a simple and reliable vegetative propagation method using semi hard wood cuttings, without mist propagator in lath house condition by evaluating the rooting ability of hybrid coffee, and to recommend the best practice to the users at, Jimma University College of Agriculture and Veterinary Medicine. Factorial experiment with RCBD was laid down and there were three factors of hybrid, cutting type and hormone of three, two and three levels respectively. Hybrids evaluated were Aba-buna, Gawe and Melko-CH2. Two types of cuttings, six month aged full node with single leaf retention and full node with a pair of leaves retention treated or not treated with indole butyric acid (IBA) and 1-naphthaleneacetic acid (NAA) each with concentration of 400-ppm were also investigated, giving eighteen treatment combinations and replicated three times. Results obtained from the experiment revealed significant difference (P≤0.05) between treatments for number of cutting sprouted, percent of rooting , number of roots per cutting , root volume, root length, root girth , leaf area, leaf number, shoot number, shoot height, shoot girth, shoot and root fresh weight and shoot, and root dry weight, root to shoot ratio and total dry weight. Percentage of rooting for Gawe hybrid coffee variety treated with both IBA (94.44 %) and NAA (89.81%), and Aba-buna treated with IBA (92.59%) were promising. The results obtained from this study have therefore shown that vegetative production of hybrid coffee(Aba-buna & Gawe) could be attained by application of rooting hormones (IBA and NAA) on semi hard wood single nodal cuttings having a pair of leaf retention and inserting directly in the polybags for successful establishment of cuttings. Further, investigations for different concentrations of hormones, high concentrations for Melko-CH2, cost benefit analysis and use of alternatives for media and hormones, and evaluations of field performance of the cuttings could be suggested as future line of work.