DRAGON FRUIT QUALITY AND STORAGE LIFE: EFFECT OF HARVESTING TIME, USE OF PLANT GROWTH REGULATORS AND MODIFIED ATMOSPHERE PACKAGING

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.

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Plant Growth Regulators Modify Fruit Set, Fruit Quality, and Return Bloom in Sweet Cherry

HortScience ◽

10.21273/hortsci15835-21 ◽

2021 ◽

pp. 1-10

Author(s):

Irfan Ali Sabir ◽

Xunju Liu ◽

Songtao Jiu ◽

Matthew Whiting ◽

Caixi Zhang

Keyword(s):

Plant Growth ◽

Plant Growth Regulators ◽

Growth Regulators ◽

Fruit Quality ◽

Sweet Cherry ◽

Prunus Avium ◽

Fruit Set ◽

Foliar Application ◽

Negative Effects ◽

Return Bloom

Sweet cherry (Prunus avium L.) is a valuable fruit crop worldwide. Farmers’ incomes are closely related to fruit quantity and quality, yet these can be highly variable across years. As part of a broader project for optimizing fruit set and fruit quality in sweet cherries, this study was conducted to evaluate the potential of various plant growth regulators (PGRs) for improving fruit set and fruit quality. Cytokinins, gibberellins, auxin, and polyamines were used as treatments. Treatments were applied as foliar sprays at full bloom to ‘Bing’ and three low-productivity genotypes, ‘Regina’, ‘Tieton’, and ‘PC8011-3’. We assessed the fruit set, fruit quality, and return bloom from each treatment. 4-chlorophenoxyacetic acid (4-CPA) increased fruit set by 53% and 36% in ‘Bing’ and ‘Tieton’, respectively. The combination of gibberellin (GA)3 + GA4/7 was more effective for improving fruit set than other isomers of gibberellin alone. Cytokinin treatments had slight adverse effects or no effect on fruit set except for CPPU. In ‘PC8011-3’, both N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) and 4-CPA enhanced fruit set by ≈81% and 100% compared with untreated control. The response of cherry trees to polyamine sprays depended on the properties of the cultivars and the treatment concentration. Foliar application of GA3, GA4/7, or N-phenyl-N'-(1, 2, 3-thiadiazol-5-yl) urea (TDZ) in ‘Bing’ trees has negative effects on return bloom, whereas GA1 can increase the yield and flower buds. These results suggest that PGRs may have varied effects on sweet cherry fruit set and that more work is needed to develop practical programs for improving yield security.

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