‘LZ106’，a new apomixis and semi-dwarfing rootstock for apple

Abstract: ‘LZ106’is a new semi-dwarfing rootstock for apple with the habit of apomixist could be propa⁃gated by seeds was derived from the cross of Malus hupehensis var. pingyiensis and‘M27’in 1999 at Liaon⁃ing Institute of Pomology experimental field. Through artificial hybridization pollination, 3 260 seedlingswas got from 4 190 seeds. 197 crossed hybrids were initially selected by leaf’s figure in 2000, and primaryselections though botanical in dwarf and weak growth in 2003.‘LZ106’became further selection afteridentification of apomixis, ploidy, and resistance of tolerance of cold in 2004. After identification of graftcompatibility, early fruit, high yield,‘LZ106’became strain in 2006. After regional adaptability testing atseven sites (including Changchun, Yantai, Baoding, Zhaotong, Yining, Shenyang and Dashiqiao. etc) overeight years from 2008 to 2015. It was finally registered by Liaoning committee of seed in 2016 with the No:2016-4-7. The plant is a mid-high tree, attaining a height of 4.5 m, and semi-vigorous growth with ra⁃mose crown and half-open gesture. Young branches are glabrous, yellow-brown in color which is 66cmlong in average, 4.3 cm thick, and internode length is 3.2 cm in average. Leaves is ovate, sharply serrated.Flower is white, 3.5-3.8 cm across. Fruit position and fruit uniformity is oblate. Chromosome of tree’sbody is tetraploid and apomoxis ratio is 93.5% which is identified by bagging flowers and sowing seeds.Fruit is oblate, which has yellowish-red peel and light ware surface. Its flesh is yellow-white, crisp, richjuice, fine texture. The average fruit weight is 5.6 g, and fruit shape index is 0.91. The content of solublesolid is 22.6%, the content of total acid is 2.12%, soluble sugar content is 13.3%, and vitamin C is 10.3mg·g-1 et al. The fruit development period is 150 d and it matures at the end October in Xiongyue area.There are 5-6 flowers of each inflorescence, 6-8 seeds per fruit, and 14.6 g weight for 1 000 seeds. Germi⁃nation ability is medium, and branching ability is strong. Rate of sprout, and seedlings uniform are 90.3%and 93.2%, respectively. Good combination between stock of‘LZ106’and scion of‘Fuji’‘Gala’‘GoldenDelicious’and‘Hanfu’, etc. The graft survival ratio reaches 93.4% in average. The average yield of 4-6years plant tree is 1 730 kg to 3 050 kg per 666.7 m² similar with M26. Tree’s size belongs to a semi-dwarfing rootstock which is similar with M7 and a strong resistance of ring spot. Well developed root system andstrongly hold the soil. It could endure -32 ℃ low temperature including Shenyang and with the north, orthe region with similar climate. Capable of early fruits in the third year after planted with a high yield po⁃tential. With the utilization of seeds propagating based on it’s strong habit of apomixis. There 45-55 daysfor stratification after seeds collecting, and as a mount of 160-200 wet-seeds used for sowing per m2. 2years old of stock used for graft with scions to foster young plant tree with 7-12 branches, height of 1.8-2.0m in the current autumn, which are suitable for orchard construction to be kept upright free of a pole tohold the tree. Orchard should choose neutral sandy soil which is flat and has ability of moisture and fertiliz⁃er retention. Spacing in the rows and spacing between rows are 2 m×4 m. Pruning includes pinching, bend⁃ing and back spune, aiming at controlling tree size and maintaining tree vigor.