Published online by Cambridge University Press: 04 October 2010
Introduction. Cashew production has been on a decline due to poor yield resulting from poor quality traits of open-pollinated seedling populations that were used to establish plantations. Clones established from outstanding individuals through air-layering root poorly and are not likely to survive transplanting, thus clonal propagation by air-layering has been of little value for cashew propagation. Materials and method. To improve the rooting percentages of air-layering, three auxins (IBA, NAA and IAA) were applied at six concentrations [(0, 1, 2, 3, 4 and 5)%] on four cashew genotypes. Results and discussion. Significant improvement was recorded in terms of layer take, number of roots per layer, number of days to rooting, length of roots and percentage of surviving clones after transplanting. Improvement varied between the different auxins, concentrations and genotypes. We observed that degree of rooting was genotype-specific and influenced by auxin type and specific concentration. Our data showed that, among the auxins tested, IBA was most effective, with optimum performance at the 2% concentration. Conclusion. Using auxins made it possible to significantly improve the rooting and survival of cashew propagules; however, to achieve sufficient rooting and better establishment after transplanting, auxin treatment should not exceed 3% concentration. This intervention would help alleviate the problem of clonal establishment in cashew.