Performance of Top-Grafted Hongnanguo Pear Introduction and Key Cultivation Techniques

Hongnanguo pear is a bud sport of Nanguo pear identified in 1996 at Shenyang Agricultural University. In 2003, Luan County introduced 5000 scions from the Fushun Special Products Research Institute for top-grafting trial planting. It performed well in Luan County. In the second year after top-grafting, the yield was 300 kg per 667 sq m with an income of 4200 yuan; in 2005, the yield was 800 kg per 667 sq m with an income of 8000 yuan; in 2006, it reached 1500 kg with an income of 12000 yuan, showing significant economic benefits. 1 Basic Information of the Top-Grafting Trial Orchard The introduction site was set up in Xishaijiatuo Village, Xiaomazhuang Town, the production demonstration base of the Luan County Pear Research Institute in Hebei, with an area of 6.67 hm2. The local average annual temperature is 10.5°C, the average annual precipitation is 680 mm, the average annual sunshine duration is 2651 hours, and the frost-free period is 175 days. The soil is flat sandy loam, with soil organic matter content of 0.6% and a pH value of 6.8. The top-grafted trees are 7-year-old Jinfeng and Yali pear; the average trunk circumference of the top-grafted trees is 10 cm, and the spacing between plants and rows is 3 m x 4 m. 2 Characteristics of the Hongnanguo Pear Variety 2.1 Botanical Characteristics This variety has moderate vigor, an upright tree posture, relatively sparse lenticels on branches, and thick, firm branches that are relatively densely distributed; mature trees have an open tree posture. The leaves are long ovate, with pointed tips, medium to large; the leaf margins have bristle-like serrations and are relatively regular; the leaf color is dark green and glossy. The veins of mature leaves are red or dark red. The flower buds are mixed flower buds and belong to corymbose inflorescences. 2.2 Growth and Fruiting Habits Hongnanguo has relatively strong vigor. In the year of top-grafting, branches can reach 1 m in length, branch easily, and can form a small number of medium and short branches in the same year, some of which can form terminal flower buds. A small number of long branches can form some axillary flower buds. The more scions there are, the easier it is to form flowers. In the second year, fruiting is mainly from terminal flower buds on medium and short fruiting branches and from axillary flower buds, and the habit of fruiting from axillary flower buds is relatively strong. The branch germination rate is high, branching ability is strong, and apical dominance is strong; branches are not easily produced from the middle and lower parts. Fruiting branches have a strong ability to bear fruit continuously; if management is poor, alternate bearing is likely to occur. It is self-unfruitful, so pollinizer trees should be configured, with Pingxiang and Daci pear being preferable. 2.3 Economic Characteristics of the Fruit The fruit of Hongnanguo is nearly round, with a fruit shape index of 0.9. The fruit is medium to large, with an average single fruit weight of 100 g and a maximum fruit weight of 145 g. The sunny side of the fruit has a red blush, the fruit surface is smooth and glossy, the fruit dots are large and dense, the stem cavity is relatively shallow and nearly flat, with groove lines; the calyx cavity is relatively deep and relatively neat, and the calyx is deciduous or persistent. The fruit stalk is short and thin, the core is relatively small, and the flesh is milky white. After harvest, the flesh is relatively firm and can be eaten crisp and sweet; after one week of ripening, the flesh becomes yellowish white, the texture is fine, soft and juicy, with few stone cells. The soluble solids can reach 16%, the Vc content is 135 ug/100 g, the aroma is rich, and it is sweet and sour and palatable, with superior quality. The shelf life at room temperature is 20 days, and it can be stored for 3 months under refrigeration. 2.4 Phenological Period In Luan County, Hebei, Hongnanguo sprouts in early to mid-April, blooms in late April, with a flowering period of about one week, the fruit ripens in late September, and leaves fall in early November. This variety has wide adaptability and strong resistance to diseases and pests. 3 Key Cultivation Techniques 3.1 Training and Pruning The pruning principle in the first 1-2 years after top-grafting is light pruning and delayed shooting, generally not thinning or heading back, so as to rapidly restore the canopy and achieve early high yield. In the second year after top-grafting, Hongnanguo can form a few medium and short branches, with a few terminal flower buds and some axillary flower buds. Pruning is mainly carried out during the growing season, with winter pruning as a supplement. In the third year, the focus is on thinning out overly dense branches, competing branches, and overlapping branches, transitioning toward a free spindle shape, and promptly retracting branches on small main branches after fruiting to cultivate small and medium-sized fruiting branch groups. 3.2 Scientific Fertilization After harvesting Hongnanguo, more organic fertilizer should be applied. The organic fertilizer must be mixed with trace elements, with more B and Zn added. Generally, about 6000 kg of organic fertilizer is applied per 667 sq m. During the growing season, foliar fertilizer should be sprayed, mainly urea, borax, and monopotassium phosphate, to promote leaf growth and flower bud differentiation and to prevent deficiency symptoms and early defoliation. 3.3 Flower and Fruit Management Hongnanguo fruits late and does not form flowers easily. In the early stage, attention should be paid to bud notching and ringing, combined with branch bending and branch pulling, and PBO should be applied to achieve early high yield. Hongnanguo is self-unfruitful, so artificial pollination is best. After fruit set, leave 1 fruit every 25 cm, with a leaf-to-fruit ratio of 40:1, and control the yield per 667 sq m within 2000 kg. 3.4 Pest and Disease Control Pests and diseases of Hongnanguo are relatively mild. The main diseases include pear scab and trunk diseases. The main control agents are diniconazole, triadimefon, Daconil M-45, and thiophanate-methyl; the main insect pests include pear stem sawfly, pear psylla, fruit borers, and slug moths. Fenpropathrin, imidacloprid, abamectin, and diflubenzuron can be used in combination. Pay attention to pesticide mixing, use concentration, and the interval between two applications to avoid phytotoxicity and achieve the goal of pollution-free control.