Protocol Optimization for In Vitro Propagation of Grapevine (Vitis vinifera L.) Using Axillary Bud Culture”

Abstract

The production of grapevine through conventional propagation methods requires mature mother vines. This takes four to five years to reach maturity for woody production besides the limited amount of planting material that can be produced. In vitro propagation has a potential to quickly provide relatively large amount of planting materials to grapevine growers. This is especially very important when planting materials are required in large quantities. In vitro propagation of grapevine can be carried out by the culture of intact or fragmented shoot apical meristems, axillary bud or through adventitious bud formation. The degree of response to certain culture is highly depends on the particular genotype and part of organ used as ex-plant. Therefore, this study was initiated to optimize a protocol for in vitro propagation of grapevine using axillary bud. The material used for the study was a cultivar named Black Corinth. Experiment one was laid out in Completely Randomized Design (CRD) with three replications and five ex-plants were use per jar. Different concentrations of BAP (0.2, 0.6, 1.0, 1.5 and 2.0 mg/l) in combination with 0.1mg/l NAA were used. Experiment two was also replicated three times with factorial arrangement in Completely Randomized Design (CRD) and three shoots per jar were used. BAP (1.0, 2.0, 2.5, 3.0 and 3.5 mg/l) in combination with NAA (0.1, 0.2 and 0.3 mg/l) were used as the treatments. Similarly, experiment three was also replicated three times with factorial arrangement in Completely Randomized Design (CRD).Three shoots per jar were used. IBA (0.0, 0.8, 1.2, 1.6 and 2.0 mg/l) in combination with NAA (0.0, 0.2, 0.5, 0.8 and 1.0 mg/l) treatments were used. For shoot initiation, sterilized explants were cultured on MS basal medium supplemented with 0.6 and 1.0mg/l BAP in 0.1mg/l NAA and resulted in highest (80.00±0.00) percentage of explants showing shoot initiation and maximum number of shoot/ex-plant (1.72±0.05) was obtained on 1.5mg/l BAP. The highest shoot height (3.22±0.26) was recorded at 1.0mg/l BAP with 0.1mg/l NAA. On shoot multiplication, the maximum (2.67±0.14) number of shoots/ex-plant was obtained on 3.0 mg/l and 0.2mg/l BAP and NAA concentration respectively. The highest value (3.23±0.25) for shoot height was obtained on MS medium containing BAP and NAA at 1.mg/l and 0.2mg/l respectively. The combination of IBA and NAA at 0.8 and 0.5 mg/l, 1.2 and 1.0 mg/l, 1.6 and 1.0mg/l, 2.0 and 0.5mg/l and 2.0 and 1.0mg/l resulted in the highest value (100%) for rooting percentage. Concentration of IBA and NAA at 2.0 and 0.2mg/l respectively resulted in the highest value (12.50±0.50) for number of roots/shoot and the maximum root length (5.39±0.19) was recorded on 1.6mg/l IBA and 0.5mg/l NAA. The concentration of 1.5mg/l BAP in 0.1mg/l NAA could be the best option for shoot initiation whiles the combination of 2.5mg/l BAP + 0.1mg/l NAA was the optimal concentration for shoot multiplications. For in vitro rooting, the combination of 1.2mg/l IBA and 1.0mg/l NAA could be taken as the best alternative. About 80% of plantlets transferred to the greenhouse were successfully acclimatized. As this protocol was tested on a single cultivar, further studies using other genotypes are required so as to have a reliable protocol for in vitro propagation of grapevine.