Detailed Explanation of High-Yield and Efficient Cultivation Techniques for Sweet Cherry
Jinzhou District is located at the southern tip of the Liaodong Peninsula, with an average annual temperature of 10-12°C, annual sunshine of 2505.5h, annual precipitation of 500-700mm, and a frost-free period of about 180d. It is mostly hilly and gently sloping terrain, with loose soil and moderate permeability, suitable for the growth and development of sweet cherry, and has a long history of cultivation. However, before 1998, due to a single variety and backward technology...
Jinzhou District is located at the southern tip of the Liaodong Peninsula, with an average annual temperature of 10-12°C, annual sunshine of 2505.5h, annual precipitation of 500-700mm, and a frost-free period of about 180d. It is mostly hilly and gently sloping terrain, with loose soil and moderate permeability, suitable for the growth and development of sweet cherry, and has a long history of cultivation. However, before 1998, due to a single variety and backward technology, sweet cherry fruited late with poor benefits, was rarely planted, and did not form scale production. In order to change this backward situation, the Jinzhou District Fruit Tree Center Demonstration Farm undertook the national Science and Technology Commission's "Sweet Cherry Early Fruiting, Early High Yield and Efficient Cultivation Technology" Spark Project in 1998, and built a 2h sq m sweet cherry demonstration orchard in the demonstration farm. In 1995, a 20h sq m sweet cherry demonstration orchard was also established in Lianfeng Village, Daweijia Town, introducing excellent sweet cherry varieties and rootstocks from home and abroad. Through research and demonstration, early fruiting and early high yield cultivation techniques for sweet cherry were summarized and promoted on a large scale. At present, 500,000 sweet cherry trees have been planted in the whole district. The number of plants planted per 666.7 sq m has increased from 18-28 in the past to 56-83, with the highest yield reaching 2100kg. Among them, the Hongdeng variety began to bear fruit 3 years after planting, and the yields per 666.7 sq m for 4-7 year old trees were 78kg, 136kg, 464kg and 690kg respectively. Sweet cherry varieties have increased from 7 in the past to 34, and many varieties have single fruit weight over 10g (previously only 5-6g), with fruit skin colors of red, yellow and purple. The early fruiting, early high yield and efficient cultivation techniques for sweet cherry are summarized as follows.
1. Selection of Orchard Site
Based on the characteristics of sweet cherry such as drought tolerance, poor waterlogging resistance, poor cold resistance, intolerance to salinity and alkalinity, and shallow root system, the sweet cherry orchard site should be selected in areas with deep soil layers, loose loam or sandy loam soil, low groundwater level, no water accumulation, good drainage and irrigation conditions, and not prone to wind damage. Sweet cherry should not be planted in areas with high groundwater level, overly heavy and sticky soil, heavy summer rainfall that cannot be drained in a short time, or high pH value.
2. Main Cultivated Varieties and Pollinizer Varieties
At present, the varieties widely promoted in the Dalian area are Hongdeng, Hongmi, Hongyan, Jiahong and Juhong bred by the Dalian Academy of Agricultural Sciences. Varieties being promoted include Zuishangjin, Takasago, Sato Nishiki, Shamideou, etc. These varieties have excellent quality, beautiful appearance and high economic value. Generally, Hongdeng is used as the main cultivated variety. The proportion of pollinizer trees should generally not be less than 30%. If 3 main cultivated varieties can pollinate each other, each should account for 1/3. The pollinizer varieties that can be configured for different main cultivated varieties are shown in Table 1.
Table 1 Main Cultivated Varieties and Pollinizer Varieties of Sweet Cherry
Main Cultivated Variety
Pollinizer Variety
Hongdeng
Hongmi, Bingku, Dazi, Jiahong
Dazi
Yantai No.1, Shuijing, Hongfeng, Napoleon, Bingku
Napoleon
Dazi, Rainier, Xianfeng
Rainier
Napoleon, Bingku
Hongmi
Hongdeng, Hongyan, Zuishangjin
Hongyan
Hongdeng, Hongyan, Zuishangjin
Zuishangjin
Hongmi, Hongyan, Hongdeng
Nanyang
Shamideou, Sato Nishiki, Beiguang
Sato Nishiki
Nanyang, Shamideou, Zheng Guangjin
Shamideou
Nanyang, Sato Nishiki
Zheng Guangjin
Nanyang, Sato Nishiki
Dongxiangjin
Hongdeng, Zheng Guangjin
3. Planting
Generally planted in spring after the soil thaws and before the seedlings sprout. In the Dalian area, planting in late March gives a relatively high survival rate. Per 666.7 sq m, 83 plants can be planted (spacing 2m x 4m) or 56 plants (spacing 3m x 4m). Dig 0.5 sq m pits according to the plant and row spacing, apply 30kg of organic fertilizer per pit, and fill the pit level with soil. Seedlings should be selected from healthy, disease-free, robust 1-year-old seedlings with well-developed root systems that have been trimmed. Before planting, soak the roots in water for 12h, then dip the roots in ABT rooting powder solution. When planting, the graft union should be slightly above the ground. After watering and settling, the union should be level with the ground, then cover with plastic film. After trunk heading, cover with a plastic bag to enclose the shaping zone, tie the lower part closed, which can prevent insects and improve the survival rate.
4. Training and Pruning
The tree shapes generally chosen for sweet cherry are the improved spindle shape and the multi-axis extension shape.
Improved spindle shape: head the trunk at a height of 40cm. From early June to early August, keep one upward upright growing new shoot as the central leader, and cut all other new shoots back to about 30cm. The next spring, cut the central leader back to 60cm, and cut the main and lateral branch leaders back to 30-40cm. From early June to early August, keep one upward upright growing new shoot as the central leader, and cut other new shoots back to 30cm. Repeat 2-3 times, and in autumn pull the new shoots to a horizontal position. In the 3rd year, do the same as in the 2nd year. The tree shape can be formed in 3 years, with a trunk height of about 40cm, tree height of 2.5-3.2m, 8-10 main branches on the whole tree, and each main branch directly bearing 10-15 large fruiting branch groups. This tree shape can rapidly increase the number of branches in the tree body, has strong capacity for three-dimensional fruiting, and high population benefit. The branch number per 666.7 sq m of 4-year-old trees can reach about 60,000, very suitable for varieties such as Hongmi and Zuishangjin with high bud germination rate, strong branching ability and moderate tree vigor. The yields per 666.7 sq m in the 4th year were 257.3kg and 229.9kg respectively, and in the 7th year were 1950.5kg and 1625.8kg.
Multi-axis extension shape: head the trunk at about 45cm. In mid-June of the current year, keep one upright upward new shoot as the central leader, and when the others grow to more than 30cm, cut them back to 20-30cm. The next spring, cut the central leader back to 50-60cm and the main branches back to 20-30cm. In June-July, cut the vigorous new branches of the first layer back to 20-30cm. For the second layer of new shoots, except for keeping one central leader uncut, cut the rest back to 20-30cm. In August-September, bend the branches. For vigorous varieties such as Hongdeng, the bending angle should be large (90 degrees or downward slanting), while for moderately vigorous varieties such as Hongmi and Zuishangjin, the angle should be slightly smaller (70-80 degrees). Pruning in the 3rd year is the same as in the 2nd year. The tree shape can be formed in 3 years, with tree height of 2-2.5m, 12-15 main branches on the whole tree, 2-3 lateral branches on each main branch, and fruiting branches directly borne on the main and lateral branches. The tree body is short and suitable for close planting. For upright varieties with strong vigor such as Hongdeng, using this tree shape can quickly enter the full fruiting period. The yield per 666.7 sq m in the 4th year was 121.18kg, and in the 7th year was 888.1kg. For varieties with moderate vigor such as Hongmi and Zuishangjin, although they enter the fruiting period early, the yield declines in the later stage and the tree body prematurely senesces, so this shape is not suitable.
5. Water and Fertilizer Management
In the Dalian area, sweet cherry needs 4 irrigation periods per year. After flower drop, when the fruit is the size of a soybean (mid to late May), irrigate the "hard pit water". At this time, the sweet cherry tree has the most vigorous growth and development and is most sensitive to water. Irrigation can greatly reduce fruit drop (the fruit drop rates with and without irrigation are 11% and 31% respectively), and improve yield and quality, so irrigate frequently and sufficiently. Around early June is the rapid fruit enlargement period, and timely irrigation can increase yield by 30%-40%. After fruit harvest, flower bud differentiation mainly occurs. To restore the tree body and ensure normal flower bud differentiation, fertilizer and water should be applied immediately after harvest, but the irrigation amount should be just enough to wet the surface of the soil. Short-term drought after irrigation is beneficial to flower bud differentiation. During the growing season of sweet cherry, irrigation should not be excessive, generally keeping soil moisture at about 70% of field capacity. In early November, irrigate "freezing water" with sufficient amount. Also apply 3 good fertilizer applications. Spraying 0.3% urea + 0.1%-0.3% borax + potassium dihydrogen phosphate 600 times solution during the flowering period can increase the fruit setting rate by 13.1%, and the fruit setting rate of Zuishangjin cherry can be increased by 39.7%. About 10d after fruit harvest of sweet cherry, apply 200kg per 666.7 sq m for fruiting trees, and 100kg compound fertilizer and about 2000kg decomposed human manure for young trees. In autumn, during the second peak growth period of roots, apply 5000kg organic fertilizer per 666.7 sq m, which can increase the stored nutrients of the tree body.
6. Supplementary Pollination
Sweet cherry is a fruit tree with low self-fruitfulness. On the premise of configuring enough pollinizer trees, supplementary pollination must be carried out, which can generally increase the flower fruit setting rate by 43.2%, and releasing bees during the flowering period can increase it by 39.7%.
7. Application of Growth Regulators
The vegetative growth of 3-4 year old sweet cherry young trees is generally excessive. For varieties such as Hongmi, Zheng Guangjin and Shamideou, summer pruning can effectively control their vegetative growth, make reproductive growth and vegetative growth develop in a balanced way, and achieve the goal of early fruiting and early high yield. However, for varieties with upright tree posture such as Hongdeng, although measures such as branch bending, delayed pruning, shoot tip cutting and repeated pinching were taken, their growth still could not be controlled, and the proportion of long branches still accounted for more than 30%, affecting the formation of flower buds on medium and short fruiting branches. In mid-August each year, 15% PP333 can be applied to the soil within the crown projection area of Hongdeng trees at 5g per tree (5 sq m). On average, this can make each lateral branch form 9.6 more medium and short branches and 12.7 more flower buds, advancing entry into the fruiting period.
8. Overwintering Protection
Sweet cherry is a fruit tree that prefers warmth and is not cold-resistant. It is prone to freezing damage at low winter temperatures, and after freezing is very prone to shoot shriveling. Using the protective antifreeze wax produced by the Jinzhou Paraffin Factory can solve this problem. From late November to early December, after the tree body has undergone cold hardening, spray the whole tree with a concentration of warm water 5 to stock solution 1. For 2-year-old Hongdeng trees, the shoot shriveling rate of one-year-old branches decreased from the original 34.4% to 1.6% (average of 5 trees).