Breeding of a new late-maturing and yellow-green apple variety Yanxiangcui

Abstract：Yanxiangcui is a new late- ripening and yellowish green apple variety, formerly named as HL105. It was the seed of Hongro introduced from Korean in the autumn of 2003. In the spring of 2005, strong seedlings were selected and planted. HL105 was selected as an excellent individual after fruiting of the seedlings in 2009. In the next year, it was selected into the selection nursery. In 2014, a large number of fruits were produced and the fruit properties were stable. The tree vigor of this variety is medium-strong, the tree posture is open, the annual branches are brown with a few hairs, the average length and thickness are 87.00 cm and 0.53 cm respectively, and the internode length is 3.2 cm. It is easy to initiate flower buds. The leaf is oval, with an average length of 9.5 cm and a width of 5.8 cm. The petiole is 3.0 cm long. The leaf surface is wavy and the leaf margin is sharp-serrated. The bud is pink, the corolla diameter is about 4.8 cm, the petals are oblong and the edges of the petals are separated. The fruit of Yanxiangcui is nearly round and the weight of single fruit is 118.3 g. The fruit surface is smooth and waxy without rust, fruit edges and powder, the fruit spot is medium-large and dense, the sepals are persistent and retrorse, the fruit top is flat, and the fruit surface is yellow green at maturity. The flesh is light yellow, crisp and sweet in taste, delicate in meat quality, and the fresh quality is excellent. The fruit hardness with peel is 10.00 kg·cm^-2 , the soluble solidis content is 17.50%, the soluble sugar content is 13.85%, the titratable acid content is 0.28% and the vitamin C content is 23.50 mg·kg^-1 . It was registered by the Ministry of Agriculture and Rural Affairs in 2022 and officially named Yanxiang-cui. In Yantai, Yanxiangcui sprouts flower buds in mid March, leaves sprout in mid April, blooms start in late April, and fruit development period lasts about 165 days. The fruit matures in early October and belongs to the late maturing variety. The leaves fall in the first ten days of November, and the entire growing period is about 210 days. Through SSR molecular marker analysis, it was found that Yanxiangcui was different from existing green apple germplasm, and was indeed a new yellow-green apple germplasm. The combination of resistance identification and field experiment observation showed that the tobacco- fragrant-jade variety has high resistance to branch ring rot, rot and rust, moderate sensitivity to anthracnose leaf blight, good winter cold resistance, and moderate frost resistance during flowering, making it suitable for spring planting in Shandong, Xinjiang, Yunnan and other places. The yield per hectare during the full fruit period can reach 2.28 tons. In newly planted orchards, we can choose suitable rootstocks based on the depth of the soil layer, with tree shapes of high spindle or free spindle system. In terms of pest management, as this variety is suitable for bagging- free cultivation, the physical and biological pest control measures should also be combined to achieve the goal of producing good fruit besides conventional chemical control.