A new red pulp dragon fruit cultivar 'Dalong '

Abstract：‘Dalong'is a new red pulp dragon fruit cultivar which was selected from dozens of dragon fruit germplasm resources collected from domestic and abroad by Hainan Academy of Agricultural Sciences. The branches of‘Dalong'are three or four rhombus cylindrical and the former take the majority.The young branches are pale green, and the matured branches are blackish green and succulent, on which dozens of yellowish brown or gray aerial roots are obviously observed. The perimeter of stem is 17.68 cm, and the matured branch segment is 55.80 cm in length with a perimeter of 17.42 cm. There are 14.8 short areoles on each ridge of the branch segment, where 2-5 yellowish brown to blackish brown thorns (mostly 3-4) attached and the tissue around the areole is suberification which is yellow brown to gray. The bud is creamy yellow and rapidly turns light red after 2-4 d, and will turn yellow green gradually as the bud progressively expanded. In the initial blossom period, the flower is funnelshaped hermaphroditic and 29.40 cm in length. The stamen is long and thin, the anther is creamy and the pistil stigma is yellowish green. The petal is pure white, erect, slender and ensiform. There are 21.40 calyxes per flower which is fleshy, liguliform, and yellowish green, with a purple red margin. The young fruit is green and will ripen about 30 d after flowering. The fruit is oval to long oval, with the fruit shape index of 1.34, whose surface is located by 18-30 red soft obtuse triangle-to-ensiform squamas. The average weight of single fruit is 510.38 g and the maximum fruit weight is 825 g. The soft purple-red fruit pericarp has been measured as 2.60 mm in thickness, which is nearly equal to the red pulpcontrol cultivar‘Zilong' (2.68 mm) , but thinner than the white pulp control which is mainly cultivated in Hainan (3.26 mm) at a significant level (p < 0.05) . The edible rate of fruit is 76.48%, The pulp is brightcoloured, purple to red, and has a total soluble solids content of 15.18% (entire pulp) and 20.29% (in middle portion) , a total soluble sugar of 10.42%, total acid of 0.25%, vitamin C content of 86.70 mg·kg-1 and water content of 90.20%. The pulp is soft, tender, juicy and full-flavored, in which there are hundreds of edible soft black sesame-like seeds and sweet juice. This cultivar has the characteristics of an early production, a high self-fruitful rate (higher than 90%) without artificial pollination, moderately large fruit, brightly colored soft pulp with good taste, which exhibits a superior cultivation adaptability and strong resistance to stress and pests in the production process. This cultivar begins to fruit in the 1 st year after planting, and reaches stable yield 3 years later in Hainan island, with a yield of 37 500 kg · hm-2 at least under the condition of normal management. This cultivar exhibits obvious overlapping of flowering and fruiting period, and can harvest 14-17 batches per year with a 26-43 d (32 d on average) flowering-fruiting cycle. In our experiments, cultivar‘Dalong'shows great adaptive capacity and behaves well in comprehensive aspects. It is suitable to be cultivated in Hainan and potential to the other suitable planting areas of China, and the orchards located on gentle-slope with sandy loam are most appropriate.