Breeding of a fine apricot cultivar, 'Xiajin', for protected cultivation

‘Xiajin’ is an early maturing apricot cultivar suitable for protected cultivation. It was selected from seedlings of ‘Jintaiyang’ with desirable traits. Under greenhouse conditions, ‘Xiajin’ flowered 3-5 days later than ‘Jintaiyang’. However, ‘Xiajin’ has a short fruit development period (58 days). The fruits matured approximately 7 days earlier than those of ‘Jintaiyang’. The average fruit weight of ‘Xiajin’ was 90.42 g, which is 22 g greater than that of ‘Jintaiyang’, and the weight of its biggest fruit was 114.7 g. The dormant period of ‘Xiajin’ is very short, with a very limited chilling requirement. A low temperature treatment at ≤7°C for 400 h terminated dormancy and initiated blooming and normal fruit bearing. The percentage of full flowers, with pistils either longer than or equal in length to that of the stamens, was over 90%, whereas those with pistils shorter than stamens or degraded stamens was lower than 10%. After planting, the fruit yield of individual trees in the fifth year was 5.6 kg, equivalent to 940.8 kg mu^‑1. In the sixth year, the density of trees was adjusted to 168 trees mu^‑1. From the sixth to the eighth year, the fruit yield of individual trees stabilized at 8.99 kg, corresponding to 1510 kg mu^‑1 and 30,200 RMB yuan output value. Grown in greenhouses in Yuncheng district of Shanxi Province, the cultivar can completely avoid the effects of late frost and other natural disasters and realize stable and efficient production and, therefore, it is a promising greenhouse-grown apricot cultivar.