Effect of commercial plant growth regulator on the growth of dragon fruit (Hyolocereus sp) cuttings under greenhouse condition

Abstract

Information is limited on the effects of commercial plant growth regulators (PGRs) on dragon fruit. Most studies on rooting effects on dragon fruit cuttings employed very high doses of plant growth regulators (PGRs), which are not deemed practical for greenhouse and field applications. This study was initiated to evaluate the responses of four genotypes of dragon fruit (‘Royal Red’, ‘Moroccan Red’, ‘Mexican White’, and ‘Hawaiian White’) during greenhouse acclimatization to diluted concentrations of commercial PGRs that are readily available in the market. A single factorial experiment on genotype effects on root and shoot responses, without PGR, was conducted. A second experiment with a 4x3x2 completely randomized design, with four genotypes, three diluted commercial PGR formulations and two exposure times as factors was also done. Root length, number of roots, number of days to first shoot emergence and number of new shoots were measured after 50 days of acclimatization in the greenhouse. In the single factorial experiment, only ‘genotype’ had an effect on number of new shoots (P<0.05). In the multifactorial experiment, all factors tested did not have significant interaction effects. However, the main effect of ‘genotype’ on number of new shoots and number of days to first shoot emergence was also significant (P<0.05). The lack of significant effect of other factors and their interactions on most growth responses suggest that it is difficult to resolve differences among the four genotypes using highly diluted commercial PGR formulations after a 50-day observation period. However, our data still suggest that the ‘Red’ genotypes are more superior than the ‘White’ genotypes in terms of shoot growth.