Flowering Phenology and Mating System of a Red Skin Pitaya (Hylocereus spp.) Germplasm Collection in Taiwan

Aims: To Investigate flowering phenology and mating systems of 30 red skin pitaya genotypes

Study Design: Around ten-years-old pitaya genotypes were used in this study. The pitaya plants were grown on concrete posts/pillars with 1.5 m height and spacing of 2 m between plants and 3 m between rows. One-two plants were used for intercropping with each other.

Place and Duration of Study: At the NPUST’s Orchard between May and December 2014.

Methodology: From 1 to 2 plants for each genotype was verified for flowering characteristics, fruit set and fruit weight. Hand self-pollination and hand cross-pollination method was applied. Fruit weights were compared using Duncan’s multiple range test at a significance level of P ≤ 0.05.

Results: The natural flowering season of the pitayas occur from June to October with early comings in higher temperatures. Mostly red or magenta pulp pitayas have genotypes for a longer flowering season than white flesh ones. A number of flowering flushes and flowers/season/plant highly varies with 3 – 6 waves and 9 - 40 flowers. The floral and fruit stages spend 14 – 18 days and 27 – 33 days, respectively. Full self-compatibility (F-SC) in 3 white flesh and 3 magenta flesh, partial self-compatibility in 2 magenta flesh, and complete self-incompatibility (C-SI) in 22 red or magenta flesh was found. Hand cross-pollination gave high fruit set percentages (72.7 ‒ 100%) in all and larger fruits than hand self-pollination in almost all genotypes except for VN-White producing smaller fruits that performed strong SC mechanism.

Conclusion: A diversity in reproductive biology was found in the pitaya collection. VN-White, Chuchi Luu, D4, Chaozhou large, Chaozhou 5 and F4 that exhibited good reproductive characteristics could be further multiplicated for commercial cultivation and the one which have extended flowering season should be induced for off-season fruits. The breeding system types of cultivars help to design desired planting system orchards that achieve the most effective fruit production.