Breeding report of a new excellent jackfruit variety Qiongyin No.8

Abstract: Qiongyin No.8 jackfruit is a superior variety bred from the native offspring in Thailand. Due to its high yield, good quality and early maturity, it was introduced into Hainan in 2012. In 2014, it began to blossom and bear fruit, and the buds were grafted and propagated. From 2015 to 2020, the main economic traits, biological characteristics, fruit quality and yield of the sample trees were observed for 5 consecutive years to evaluate their stability. On June 2, 2022, it obtained the certification of Hainan nonmajor crop varieties. This variety is dwarf and up to 3.54 m tall. The canopy of the tree is multi-umbrella or pyramid-shaped, and tree-posture is upright. Branches are glabrous, grayish-brown, medium density and whorled. Leaves are elliptic, leaf apex is blunt pointed, and the leaf base is cuneate, 14.01 cm long and 7.89 cm wide, adaxial smooth and glabrous, The opposite side of the leaf is rough, with the leaf margin being neat and unwavy, and unisecious. The male inflorescence is rod shaped, generally located at the end of the branches, and the female inflorescence is elliptic, located on the central leader and fruiting branches. The fruit is oval, with yellow green peel and golden yellow to orange yellow fruit bract, thick-fleshed, strong sweetness and crisp. The flesh fiber content is low, with less pectin content. The average weight per fruit is 13.70 kg, the maximum weight per fruit is 20.59 kg, and the fruit shape index is 1.65. The edible rate is 38.6%. The average number of seeds per fruit is 231.67. The soluble solids content is 25.53% with high quality. In Changjiang area of Hainan province (longitude 109.055 59°and latitude 19.298 28°) , this variety has three peak ripening periods, which are from mid-February to late March, mid- June to early July, and late September to mid- October. The fruit growth period is about 120 d to 125 d, 105 d to 110 d and 105 d to 110 d, respectively. Usually, each plant bears 16 to 18 fruits, flowering and fruit-setting rates are more than 85.0%, the yield per plant is 232.9 kg, the yield per 666.7 m2 is 5356.7 kg, and the maximum yield per plant can reach 350 kg. It has strong drought and heat resistance, but it is not resistant to waterlogged, and it is resistance to anthracnose, leaf spot mildew, large stem spot brown spot, needle leaf spot disease, stem rot disease, gummosis and other diseases. The storage period of the fruit is not long, the shelf life is 4 to 7 days, and the refrigerated period is about 1 month. The fruit has a strong aroma during storage. It is suitable for planting this jackfruit variety in Changjiang, Dongfang, Ledong, Sanya and other southwestern cities and counties of Hainan province, and the variety can blossom and bear fruit in 1.5 years with good yield. The orchard should be established on loam or sandy loam lands with deep soil layer, rich organic matter, pH value of about 5.0 or above, and good air permeability. Vigorous seedlings in 30-45 cm height should be selected for planting. The planting spacing is 5.0 m×(5.0-6.0) m. Young jackfruit plantations are suitable for intercropping. The soil should be kept moist during flowering and fruit development to reduce fruit cracking and fruit falling. If the growth direction and angle of branches are not reasonable, they should be pulled, pressed, bent, hung cut back or treated with other adjusting techniques, whose purpose is to maintain the tree shape and make the tree canopy to possess a good ventilation.