Noteworthy specific germplasm of wild apricot (Prunus sibirica) in Chaoyang, Liaoning
Abstract: We surveyed apricot germplasm resources in Chaoyang City, Liaoning Province, and identified 11 specific germplasms, including 3 kernel-use germplasms, 4 landscaping germplasms, and 4 germplasms pending further identification. These new germplasms not only enrich the apricot germplasm resources of Liaoning Province, but also lay a material foundation for breeding new cultivars.
Keywords: apricot germplasm, kernel use, landscaping
Chaoyang City, Liaoning Province is one of the main apricot production areas in China, with a long history of apricot cultivation. In the past, local wild apricots were mostly propagated by seed, and the genetic differences of wild apricot at the three levels of individual, stand and provenance were fully differentiated and accumulated. Wild apricot germplasm resources are abundant and there are many variant types, which laid the foundation for the discovery of new germplasms and the selection of variant types. In order to clarify the general situation of wild apricot germplasm resources in Chaoyang City, we surveyed the apricot germplasm resources of the city and selected specific germplasms or variant types of value for production and scientific research.
1 Survey methods
We surveyed wild apricot germplasm in Chaoyang City by combining interviews with fruit growers and route surveys. Interviews with fruit growers involved asking contractors of wild apricot forests to provide information on local wild apricot germplasm resources. Route surveys were based on ecological factor gradients and resource distribution, visually assessing wild apricot trees and their variant types within the field of view, and preliminarily determining plants as new germplasms or variant types. The focus of the survey was tree shape, tree age, crown width, tree height, trunk diameter, basal angle of main branches, growth vigor and color of 1-year-old branches; corolla diameter, petal color, petal number, sepal color and percentage of complete flowers; leaf shape, color, leaf tip, leaf base, leaf margin shape and serration size; and traits such as fruit shape, fruit weight, color, pit, kernel, flesh and kernel flavor. The survey sample size for flowers, leaves, fruits, pits and kernels was 50. While investigating tree growth, fruit traits, leaf traits and flower traits, we also recorded the place name and habitat overview of the wild apricot germplasm. We calculated average single fruit weight, single pit weight, single kernel weight, pit rate and kernel rate.
2 Specific germplasm of wild apricot in Chaoyang
2.1 Kernel-use germplasm
(1) 100% complete-flower wild apricot was found in Wujiazi Village, Dachengzi Town, Kazuo County, Liaoning Province and Magou Village, Dachengzi Town, Kazuo County, with a total of 2 trees, 15 years old. Small tree, basal angle of main branches 25°, natural open-center shape, 1-year-old branches grayish white. Leaf tip acute, leaf margin finely serrate, leaf base rounded. Corolla diameter 2.26 cm, petals white, complete flowers 100%, and pistil 5-6 mm higher than stamens. Fruit oblate, average single fruit weight 5.4 g, fruit longitudinal × transverse × lateral diameter 3.12 cm × 2.89 cm × 1.60 cm; yellow-brown, with a red blush on the sunny side, flesh bitter; average single pit weight 1.81 g, apricot pit longitudinal × transverse × lateral diameter 2.24 cm × 2.14 cm × 1.10 cm; average single kernel weight 0.60 g, kernel longitudinal × transverse × lateral diameter 1.40 cm × 1.24 cm × 0.48 cm, kernel bitter. Fruit ripening period mid-to-late June, average apricot pit yield per square meter of crown 164.68 g.
(2) Bitter-flesh sweet-kernel wild apricot was found in Guozhangzi Village, Taizi Township, Chaoyang County, Liaoning Province, 19 years old. Small tree, basal angle of main branches 45°, 1-year-old branches reddish brown. Leaves round, apex acute, margin sharply serrate. Corolla diameter 2.40 cm, petals pinkish white, complete flowers 80%. Fruit oblate, average single fruit weight 6.2 g, fruit longitudinal × transverse × lateral diameter 2.42 cm × 2.23 cm × 1.99 cm; yellow-brown, with a red blush on the sunny side, pericarp relatively thick; flesh bitter, average single pit weight 0.98 g, apricot pit longitudinal × transverse × lateral diameter 2.05 cm × 1.71 cm × 0.91 cm; kernel flavor sweet, average single kernel weight 0.36 g, kernel longitudinal × transverse × lateral diameter 1.49 cm × 1.12 cm × 0.72 cm. The kernels can be processed into almond milk, refined into almond oil, and developed into almond medicinal materials, etc. Fruit ripening period mid-to-late June, average apricot pit yield per square meter of crown 431.92 g.
(3) Sweet-flesh sweet-kernel wild apricot was found in Xinan Gou Village, Liuguanyingzi Township, Kazuo County, Liaoning Province, 21 years old. Small tree, basal angle of main branches 20°, natural open-center shape, 1-year-old branches reddish brown. Leaf apex obtuse-acute, margin finely serrate, base cordate or truncate. Corolla diameter 2.30 cm, petals pinkish white, complete flowers 85%. Fruit oblong, average single fruit weight 3.6 g, fruit longitudinal × transverse × lateral diameter 3.08 cm × 2.55 cm × 2.29 cm; yellow-brown, with a red blush on the sunny side, with short pubescence; apricot flesh flavor sweet, suitable for fresh eating; pit surface smooth, dorsal base truncate, wing small, ventral suture wing small, average single pit weight 0.93 g, apricot pit longitudinal × transverse × lateral diameter 2.20 cm × 1.60 cm × 0.90 cm; average single kernel weight 0.27 g, kernel longitudinal × transverse × lateral diameter 1.12 cm × 1.02 cm × 0.51 cm, kernel flavor sweet. Flowering period 2-3 days later than common wild apricot cultivars, fruit ripening period early July, average apricot pit yield per square meter of crown 380.9290
2.2 Germplasm suitable for landscaping
(1) Weeping wild apricot was found in Toudaowa Village, Dachengzi Town, Kazuo County, Liaoning Province, 18 years old. Tree, basal angle of main branches 30-55°, tree shape graceful, branches pendulous, branches grayish white. Leaf tip acute, leaf margin finely serrate, leaf base rounded. Corolla diameter 2.30 cm, petals white, complete flowers 35%. Fruit oblate, average single fruit weight 3.3 g, fruit longitudinal × transverse × lateral diameter 1.85 cm × 1.96 cm × 1.58 cm; yellow-brown, with a red blush on the sunny side, flesh bitter; average single pit weight 1.00 g, apricot pit longitudinal × transverse × lateral diameter 1.61 cm × 1.46 cm × 0.90 cm; average single kernel weight 0.31 g, kernel longitudinal × transverse × lateral diameter 1.22 cm × 1.00 cm × 0.53 cm; yield not high, average apricot pit yield per square meter of crown 20.97 g. Flowering period 7 days, can be used for landscaping.
(2) Double-flowered wild apricot was found, one tree each, at the Forest Tree Improved Variety Breeding Center of Beipiao City, Liaoning Province and Malian Gou, Dachengzi Town, Kazuo County, aged 4 years and 5 years respectively. Small tree, basal angle of main branches 30-45°, 1-year-old branches reddish brown, leaf apex acute, leaf base rounded, leaf margin coarsely serrate. Corolla diameter is 1.34-1.50 times the corolla diameter of common wild apricot cultivars, petals 6-9, arranged in 2 layers, being double-flowered wild apricot (Plates 4-5), complete flower proportion 35%, flowering period 3-4 days longer than common wild apricot, being 9-10 days. Fruit oblate, average single fruit weight 4.3 g, fruit longitudinal × transverse × lateral diameter 2.58 cm × 2.66 cm × 1.86 cm; yellow-brown, flesh bitter; average single pit weight 1.40 g, apricot pit longitudinal × transverse × lateral diameter 2.13 cm × 1.94 cm × 1.01 cm; average single kernel weight 0.41 g, kernel longitudinal × transverse × lateral diameter 1.61 cm × 1.33 cm × 0.72 cm. Double-flowered wild apricot has relatively high ornamental value and can be used for landscaping and as a parent for breeding crosses.