Detailed Explanation of Key Cultivation Techniques for Xinshengxi No. 3 Ponkan
Cultivation Points for Xinshengxi No. 3 Ponkan
1. Suitable rootstock and strong seedlings, rational close planting
Trifoliate orange is suitable as the rootstock, giving early fruiting, high yield, and a small, compact canopy; in Guangdong and Guangxi, sour orange is used as the rootstock, showing early fruiting and early high yield.
The Xinshengxi No. 3 Ponkan tree grows upright, especially when young. To make full use of land resources, it may be planted somewhat densely or under a planned dense-planting system. Usually, 74-89 trees per mu, that is, a row spacing of 3 m x 3 m to 3 m x 2.5 m, is appropriate; for planned dense planting, a row spacing of 3 m x 2 m, that is, 112 trees per mu, is suitable, and after 5-6 years of fruiting, thinning or moving out is carried out between trees, changing the density to 56 trees per mu.
2. Scientific fertilization, timely irrigation
(1) Fertilization
For fertilizing non-fruiting young trees, adhere to the principle of small amounts applied frequently. Usually, apply once before the spring, summer, and autumn shoots sprout and once after they sprout but before the leaves turn green. The fertilizer should be mainly quick-acting nitrogen and potassium, with an appropriate addition of phosphate fertilizer; in late autumn or winter, apply an overwintering fertilizer, mainly organic fertilizer (livestock pen manure, compost, green manure, etc.). In acidic red-yellow soil, lime should also be mixed in to reduce soil acidity. Fertilization rates: for one-year-old trees, apply 30 g of urea (or potassium sulfate) per tree each time; for two-year-old trees, 50 g; for three-year-old trees, 75-100 g. A compound fertilizer with N, P2O5, and K2O each at more than 15% may also be used, with the same application rates as above for one-, two-, and three-year-old trees. To promote the rapid formation of a canopy and early production, foliar spraying of 0.3%-0.5% urea or 0.3% monopotassium phosphate may also be combined with pest and disease control, 3-4 times a year, with good results when sprayed before the leaves of each flush turn green.
For fruiting mature trees, fertilize 4-5 times a year. In February, apply spring shoot fertilizer, mainly quick-acting nitrogen fertilizer, to promote spring shoot growth; in May, apply fruit-setting fertilizer, mainly organic and chemical fertilizers complete in nitrogen, phosphorus, and potassium. For weaker trees, in combination with pest and disease control, increase foliar spraying of 0.3%-0.5% urea or 0.3% monopotassium phosphate to improve the fruit-setting rate; in July, in combination with drought resistance, apply fruit-swelling fertilizer, mainly increasing organic fertilizer, to promote fruit enlargement and vigorous growth and the sprouting of early autumn shoots, preparing excellent fruiting mother branches for the next year; in September, apply flower bud fertilizer, mainly phosphorus and potassium, to promote flower bud differentiation, root growth, and fruit quality; in November, apply winter fertilizer, mainly organic fertilizer, to help the tree overwinter. Fertilization varies with yield per unit area. For example, for 8-year-old trees planted at 74 trees per mu with a yield of 3000 kg per mu, apply 1.5 kg pure nitrogen, 1.0 kg pure phosphorus, and 1.2 kg pure potassium per tree per year.
(2) Irrigation and drainage
Irrigating in drought and draining in waterlogging are important conditions for obtaining yield and high yield in ponkan. Usually, irrigation is carried out in the following 4 periods. First, the sprouting to young fruit stage (April to June): irrigate promptly when drought occurs; second, the fruit enlargement stage (July to August): this is the fruit enlargement period, and irrigation during drought is extremely important; third, the late fruit enlargement to maturity stage (late August to November): irrigate appropriately according to drought conditions. However, before maturity, pay attention to water control and avoid excessive irrigation; fourth, the growth cessation stage (after harvest to March of the next year): generally no irrigation is carried out, but when excessive drought causes leaf drop, a moderate amount of irrigation should be applied.
Drainage to prevent waterlogging should be carried out promptly. Especially in orchards with a high water table that drain poorly, deep furrows and high beds should be used for planting to lower the water table and promptly remove standing water, so as to favor root growth.
3. Training and pruning, promoting and thinning fruit
The Xinshengxi No. 3 Ponkan tree grows upright with obvious apical dominance. To promote early fruiting and early high yield, attention should be paid to training young trees and cultivating a low-trunk, high-yielding canopy. Later, as the tree ages, the branches and shoots show an obvious trend of differentiation into strong and weak, with the middle and upper shoots strong and the lower branches weak. Pruning should be strengthened to maintain a high-yielding canopy for a longer period.
By increasing branch angles and pruning for a low trunk, flower bud differentiation and fruiting of young trees are promoted. After entering the fruiting stage, especially after the full fruiting stage, in order to prevent or reduce alternate bearing and improve fruit appearance and internal quality, branch thinning, flower thinning, and fruit thinning should be carried out to make the yield moderate and stable and to increase the rate of marketable fruit and first-grade fruit.
4. Integrated control of pests and diseases
Xinshengxi No. 3 Ponkan has quite a few pests and diseases, but they differ by region. In epidemic areas, control huanglongbing, canker, and the large fruit fly well; in non-epidemic areas, strictly implement quarantine and strictly prohibit the introduction of quarantine pests and diseases. Apart from quarantine pests and diseases, the main pests and diseases of Xinshengxi No. 3 Ponkan include exocortis, anthracnose, scab, sooty mold, and blue-green mold, etc.; the main insect pests include red spider mite, yellow spider mite, leafminer, tortrix moth, swallowtail butterfly, aphid, scale insect, and longhorn beetle, etc. Attention should be paid to their control.
For the control of pests and diseases, pesticide use must be accurate, timely, and thorough. Use chemical pesticides as little as possible, prohibit highly toxic pesticides, and adopt biological pesticides and integrated control, so as to produce high-quality, safe ponkan.
Trifoliate orange is suitable as the rootstock, giving early fruiting, high yield, and a small, compact canopy; in Guangdong and Guangxi, sour orange is used as the rootstock, showing early fruiting and early high yield.
The Xinshengxi No. 3 Ponkan tree grows upright, especially when young. To make full use of land resources, it may be planted somewhat densely or under a planned dense-planting system. Usually, 74-89 trees per mu, that is, a row spacing of 3 m x 3 m to 3 m x 2.5 m, is appropriate; for planned dense planting, a row spacing of 3 m x 2 m, that is, 112 trees per mu, is suitable, and after 5-6 years of fruiting, thinning or moving out is carried out between trees, changing the density to 56 trees per mu.
2. Scientific fertilization, timely irrigation
(1) Fertilization
For fertilizing non-fruiting young trees, adhere to the principle of small amounts applied frequently. Usually, apply once before the spring, summer, and autumn shoots sprout and once after they sprout but before the leaves turn green. The fertilizer should be mainly quick-acting nitrogen and potassium, with an appropriate addition of phosphate fertilizer; in late autumn or winter, apply an overwintering fertilizer, mainly organic fertilizer (livestock pen manure, compost, green manure, etc.). In acidic red-yellow soil, lime should also be mixed in to reduce soil acidity. Fertilization rates: for one-year-old trees, apply 30 g of urea (or potassium sulfate) per tree each time; for two-year-old trees, 50 g; for three-year-old trees, 75-100 g. A compound fertilizer with N, P2O5, and K2O each at more than 15% may also be used, with the same application rates as above for one-, two-, and three-year-old trees. To promote the rapid formation of a canopy and early production, foliar spraying of 0.3%-0.5% urea or 0.3% monopotassium phosphate may also be combined with pest and disease control, 3-4 times a year, with good results when sprayed before the leaves of each flush turn green.
For fruiting mature trees, fertilize 4-5 times a year. In February, apply spring shoot fertilizer, mainly quick-acting nitrogen fertilizer, to promote spring shoot growth; in May, apply fruit-setting fertilizer, mainly organic and chemical fertilizers complete in nitrogen, phosphorus, and potassium. For weaker trees, in combination with pest and disease control, increase foliar spraying of 0.3%-0.5% urea or 0.3% monopotassium phosphate to improve the fruit-setting rate; in July, in combination with drought resistance, apply fruit-swelling fertilizer, mainly increasing organic fertilizer, to promote fruit enlargement and vigorous growth and the sprouting of early autumn shoots, preparing excellent fruiting mother branches for the next year; in September, apply flower bud fertilizer, mainly phosphorus and potassium, to promote flower bud differentiation, root growth, and fruit quality; in November, apply winter fertilizer, mainly organic fertilizer, to help the tree overwinter. Fertilization varies with yield per unit area. For example, for 8-year-old trees planted at 74 trees per mu with a yield of 3000 kg per mu, apply 1.5 kg pure nitrogen, 1.0 kg pure phosphorus, and 1.2 kg pure potassium per tree per year.
(2) Irrigation and drainage
Irrigating in drought and draining in waterlogging are important conditions for obtaining yield and high yield in ponkan. Usually, irrigation is carried out in the following 4 periods. First, the sprouting to young fruit stage (April to June): irrigate promptly when drought occurs; second, the fruit enlargement stage (July to August): this is the fruit enlargement period, and irrigation during drought is extremely important; third, the late fruit enlargement to maturity stage (late August to November): irrigate appropriately according to drought conditions. However, before maturity, pay attention to water control and avoid excessive irrigation; fourth, the growth cessation stage (after harvest to March of the next year): generally no irrigation is carried out, but when excessive drought causes leaf drop, a moderate amount of irrigation should be applied.
Drainage to prevent waterlogging should be carried out promptly. Especially in orchards with a high water table that drain poorly, deep furrows and high beds should be used for planting to lower the water table and promptly remove standing water, so as to favor root growth.
3. Training and pruning, promoting and thinning fruit
The Xinshengxi No. 3 Ponkan tree grows upright with obvious apical dominance. To promote early fruiting and early high yield, attention should be paid to training young trees and cultivating a low-trunk, high-yielding canopy. Later, as the tree ages, the branches and shoots show an obvious trend of differentiation into strong and weak, with the middle and upper shoots strong and the lower branches weak. Pruning should be strengthened to maintain a high-yielding canopy for a longer period.
By increasing branch angles and pruning for a low trunk, flower bud differentiation and fruiting of young trees are promoted. After entering the fruiting stage, especially after the full fruiting stage, in order to prevent or reduce alternate bearing and improve fruit appearance and internal quality, branch thinning, flower thinning, and fruit thinning should be carried out to make the yield moderate and stable and to increase the rate of marketable fruit and first-grade fruit.
4. Integrated control of pests and diseases
Xinshengxi No. 3 Ponkan has quite a few pests and diseases, but they differ by region. In epidemic areas, control huanglongbing, canker, and the large fruit fly well; in non-epidemic areas, strictly implement quarantine and strictly prohibit the introduction of quarantine pests and diseases. Apart from quarantine pests and diseases, the main pests and diseases of Xinshengxi No. 3 Ponkan include exocortis, anthracnose, scab, sooty mold, and blue-green mold, etc.; the main insect pests include red spider mite, yellow spider mite, leafminer, tortrix moth, swallowtail butterfly, aphid, scale insect, and longhorn beetle, etc. Attention should be paid to their control.
For the control of pests and diseases, pesticide use must be accurate, timely, and thorough. Use chemical pesticides as little as possible, prohibit highly toxic pesticides, and adopt biological pesticides and integrated control, so as to produce high-quality, safe ponkan.