The yellow passion fruits are in high demand both locally and globally. Some of the biggest markets for yellow passion fruits are the EU and the Middle East. However, in spite of the high current demand, production of yellow passion fruits still remains low and this is usually due to the limited access that many farmers have to high quality passion fruit planting materials. The yellow passion fruit orchards also have a shorter lifespan compared to the purple passion fruit varieties as a result of the woodiness viral disease and poor agronomic practices by passion fruit farmers.
In locations with good rainy seasons, it is generally advisable to plant the yellow passion fruit varieties. The varieties to be planted generally vary from country to country. In Uganda, the best yellow passion fruit varieties to plant include the KPF4, KPF11, KPF11 and the KPF12 yellow passion fruit varieties. The KPF4 variety of yellow passion fruits generally has light green leaves and vines as well as oval fruits and a pulp that is deep yellow in colour. On the other hand, the KPF12 variety has darker green leaves and vines, rounder fruits and heavy flowering and fruiting. The KPF12 yellow passion fruit variety grown in Uganda also produces round fruits.
The purple passion fruit is subtropical. It grows and produces well between altitudes of 2,000 and 4,000 ft (650-1,300 m) in India.
In Java, it grows well in lowlands but will flower and fruit only above 3,200 ft (1,000 m).
In west-central Florida, at 28º N latitude and slightly above sea-level, 3-year-old vines have survived freezing temperatures with the lower 3 ft (.9 m) of the stems wrapped in fiberglass 4 in (10 cm) thick. The upper parts suffered cold injury, were cut back, the vines were heavily fertilized, recovered rapidly and fruited heavily the second summer thereafter.
The yellow passion fruit is tropical or near-tropical. In Western Samoa, it is grown from near sea-level up to an elevation of 2,000 ft (600 m).
Yellow passion fruits do really well in the lowlands and mid-altitude locations. They are also growing increasingly popular due to their delicious juices and flavor.
Both forms need protection from wind. Generally, annual rainfall should be at least 35 in (90 cm), but in the Northern Transvaal, in South Africa, there is reduced transpiration because of high atmospheric humidity and commercial culture is carried on with precipitation of only 24 in (60 cm). It is reported that annual rainfall in passion fruit-growing areas of India ranges between 40 and 100 in (100-250 cm).
Characteristics of Yellow passion
- Has a large fruit with a yellow rind
- Has a more acid flavor
- It’s resistant to Fusarium wilt and nematodes
- It has brown seeds
- It has a more vigorous vine and more tolerant to frost
- The flowers are self-sterile with heavy and sticky pollen and hence wind pollination is ineffective. Since their pollen is sticky and the flowers have to be pollinated, bees are the most effective pollinators.
Characteristics of purple passion
- Has a smaller fruit with a purple rind
- Has a less acidic flavor, a sweet pulp, and a higher juice proportion
- It has black seeds
- Has a less vigorous vine
- It can self-pollinate and has light pollen. Pollination is, however, best under humid conditions.
When crossing purple and yellow passion, it is important to use the purple parent as the seed parent since the flowers of yellow passion are not receptive to pollen from the purple passion variety. Crossing the yellow and purple passion enables the plant to withstand the woodiness virus.
Yellow passionfruit flowers are perfect but self-sterile. In controlled pollination studies at the College of Agriculture of Jaboticabal, Sao Paulo, Brazil, it was found that the yellow passionfruit has three types of flowers according to the curvature of the style: TC (totally curved), PC (partially curved), and SC (upright-styled). TC flowers are most prevalent. Carpenter bees (Xylocopa megaxylocopa frontalis and X. neoxylocopa) efficiently pollinated TC and PC flowers. Honey bees (Apis mellifera adansonii) were much less efficient. Wind is ineffective because of the heaviness and stickiness of the pollen. SC flowers have fertile pollen but do not set fruit. To assure the presence of carpenter bees, it is wise to have decaying logs among the vines to provide nesting places. Carpenter bees will not work the flowers if the nectary is wet. If rain occurs in 1 1/2 hrs after pollination, there will be no fruit set, but if 2 hrs pass before rain falls, it will have no detrimental effect. In the absence of carpenter bees in Fiji, farmers cross-pollinate by hand, treating 600 flowers an hour, with 70% fruit set and 60% of fruit reaching maturity.
The purple form blooms in spring and early summer (July-November) in Queensland and again for a shorter period in fall and early winter (February-April). In Florida, blooming occurs from mid-March through April. The flowers open early in the morning (about dawn) and close before noon, and are self-compatible. The yellow form has one flowering season in Queensland (October-June). In Florida, blooming has occurred from mid-April to mid-November. The flowers open around noon and close about 9 to 10 PM and are self-incompatible.
In crossing the yellow and purple forms, it is necessary to use the purple as the seed parent because the flowers of the yellow are not receptive to the pollen of the purple, and an early-blooming yellow must be utilized in order to have a sufficient overlapping period for pollen transfer. Dr. R.J. Knight has suggested lengthening the overlap by exposing the yellow to artificial light for 6 weeks before the normal flowering season. However, despite the seasonal and hourly differences, natural hybrids between the two forms occur in South Africa, Queensland and in Hawaii. Growers of purple passion fruit in South Africa are warned not to take seed from any vine in proximity to a planting of yellow passion fruit, otherwise the seedlings are apt to produce hybrid fruit of inferior quality.
In some areas, trellis-grown vines of the yellow passion fruit require hand-pollination to assist fruit set. In the home garden, at least two vines of different parentage should be planted and allowed to intertwine for cross-pollination.
Passion fruit vines are usually grown from seeds. With the yellow form, seedling variation provides cross-pollination and helps overcome the problem of self-sterility. Some say that the fruits should be stored for a week or two to allow them to shrivel and become perfectly ripe before seeds are extracted. If planted soon after removal from the fruit, seeds will germinate in 2 to 3 weeks. Cleaned and stored seeds have a lower and slower rate of germination. Sprouting may be hastened by allowing the pulp to ferment for a few days before separating the seeds, or by chipping the seeds or rubbing them with fine sandpaper. Soaking, often recommended, has not proved helpful. Seeds are planted 1/2 in (1.25 cm) deep in beds, and seedlings may be transplanted when 10 in (25 cm) high. If taller–up to 3 ft (.9 in)–the tops should be cut back and the plants heavily watered.
Some growers prefer layers or cuttings of matured wood with 3 to 4 nodes. Cuttings should be well rooted and ready for setting out in 90 days. Rooting may be hastened by hormone treatment. Grafting is an important means of perpetuating hybrids and reducing nematode damage and diseases by utilizing the resistant yellow passion fruit rootstock. If seeds are available in the early spring, seedlings for rootstocks can be raised 4 in (10 cm) apart in rows 24 in (60 cm) apart and the grafted plants will be ready to set out in late summer. If seeds cannot be obtained until late summer, the seedlings are raised and grafted in pots and set out in the spring. Scions from healthy young vines are preferred to those from mature plants. The diameter of the selected scion should match that of the rootstock. Either a cleft graft, whip graft, or side-wedge graft may be made.
If approach-grafting is to be done, a row of potted scions must be placed close alongside the row of rootstocks so that the union can be made at about 3/4 of the height of the plant
Yellow passion fruit contains riboflavin and niacin and is rich in amino acids. They also are higher in citric acid and carotene than the Purple passion fruit though they have a lower content of ascorbic acid.
The traditional Purple passion fruit originated in the Amazon region of Brazil, Yellow passion fruit as well is thought to have possibly originated there as a hybrid of P. edulis (Purple passion fruit) and P. ligularis (Sweet Granadilla) or potentially as a chance mutant in Australia. A tropical fruit, the Yellow passion fruit thrives in areas that receive adequate rainfall and sunshine. Its vines do well if sheltered from the wind and will be less susceptible to pests if allowed to grow climbing up a tree or trellis. Today it is grown commercially predominately in Australia, New Zealand, Hawaii, India, Columbia, Brazil and Venezuela.