The latest course of Citrus planting techniques and methods

Citrus fruits are rich in nutrition, excellent in color, aroma and taste, which can not only be eaten fresh, but also be processed into various processed products dominated by fruit juices. The output of citrus ranks first among all fruits, and citrus juice accounts for 3x4 of fruit juice, which is widely favored by consumers. Citrus is the most important fruit tree species in southern China because of its longevity, high and stable yield and high economic benefits. it plays an important role in getting rid of poverty and rural economic development.

Seedling raising technique

1. Cultivation of rootstock seedlings.

The nursery land should choose the gentle slope land with convenient transportation, flat terrain, water source and slope below 5 °or irrigation and treatment paddy field, which requires deep soil layer, good structure and soil quality on sandy soil or on soil. the soil whose pH value is in the range of 5.5-6.5. Avoid water and air pollution and stay away from the old orange orchard. Rootstocks are required to use varieties or types adapted to local soil conditions, strong affinity with main varieties, normal growth, developed root system, strong stress resistance, early fruiting, high yield, stable yield, high quality and no quarantine STD pests after grafting. Guangdong, Guangxi, Hainan sweet oranges, banana oranges, banana oranges, mandarins (Jiangxi red tangerines) and red lemons are mostly used as rootstocks; in recent years, Ponkan and navel orange are used as rootstocks to show early and high yield. Fujian red oranges are used as rootstocks for wide-skinned oranges, and citrus is also used as rootstocks for mandarins, banana oranges and sweet oranges. Most of Taiwan's banana oranges and mandarins use sour oranges and red lemons as rootstocks. Guangdong, Guangxi and Fujian grapefruit rootstocks are often used as sour pomelo. Rootstock seeds are collected mature fruit, with a special cutting board or knife, cut 6-8 pieces longitudinally, squeeze out the seeds. Put it in a bamboo or coarse cloth bag, gently rub with a small amount of plant ash, then rinse with water to remove fruit dregs and pectin from the seed coat. Spread the cleaned seeds in a cool and ventilated place and sow the seed coat with white hair. Fresh sowing is the best, otherwise dry storage or sand storage should be used to preserve the seeds. Seed content and sowing rate of rootstock fruit. The sowing land should be cultivated carefully, fully plough and rake the soil, and evenly apply sufficient base fertilizer. Generally per hectare, pig manure, cow manure, high-quality compost 3750-4500kg, calcium superphosphate 225-375kg, lime 375-450kg. There are two sowing methods: sowing and strip sowing. After sowing, the soil of the seedling bed should be kept moist, 3-4 true leaves of seedlings should be thinly applied with water and fertilizer, and attention should be paid to the control of diseases and insect pests such as anthracnose, blight and leaf moth. Rootstock seedlings can be divided into two types: new seedlings and old seedlings. The new seedlings were sown in the first winter and then sown in spring, then transplanted with 20cm × 12cm plants in the middle of May and July next year, grafted in winter and spring, and left the nursery in autumn. The whole seedling raising time was two years. In this method, the management of fertilizer and water should be strengthened to make the rootstock grow rapidly before it can get out of the nursery in time. The old seedlings were transplanted according to the row spacing of 25cm × 12-15cm in the autumn and winter of the following year or the spring of the third year, and the spring shoots were transplanted in autumn and winter or April-May of the following year. After growing for 9-15 months, the seedlings were grafted in winter and spring, and the whole seedling raising time was two years.

2. Cultivation of grafted seedlings.

It can be grafted all the year round, but it is best before the Beginning of Spring. If the branches are warm in winter, they can be grafted earlier, otherwise they will be delayed. In order to grow seedlings quickly, summer and autumn grafting should be carried out in sunny and warm days, but not in rainy days when the soil is too wet and strong north wind. Summer and autumn grafting should be avoided in windy and rainy days and when the sun is strong at noon. Grafting methods Guangdong, Guangxi, Fujian, Hainan and other places mostly use single bud cutting or single bud ventral grafting, the survival rate is more than 90%. The grafted seedlings should be reshaped in the nursery, mainly to determine the height of the trunk and cultivate a certain number of backbone branches. And promote the autumn shoot by cutting the top of the summer shoot. Hot area clipping is generally carried out before and after the Beginning of Autumn, Cold Dew wind comes early, easy to dry places or late autumn and early winter out of the nursery can be in advance. In the middle and upper part of the shoot in the first summer, the internodes are dense and uniform, and the complete part of the leaf is cut at 25-30cm from the ground. If the spring shoot exceeds this height, it will be cut off on the spring shoot. The sporadic autumn shoots with early vomiting were removed in time after topping, and most of the seedlings had 3-6 buds germinated before they were released to maintain a balanced branch growth. When the buds grew to about 3cm, 5 sturdy and uniformly distributed main sticks in all directions were selected, and the rest were thinned in time. The criteria of excellent grafted seedlings are as follows: excellent and pure varieties, no Huanglong disease and its quarantine diseases, strong branches, good healing of joints, height of newly planted seedlings above 10cm (above 50cm of old seedlings), stem diameter above 0.8cm, and 3-5 main branches evenly distributed, leaves are dark green and glossy, main roots are longer than 15cm, there are most fibrous roots with uniform thickness and bright yellow, and the growth of the aboveground and underground parts of the whole plant is balanced.

3. Cultivation of virus-free seedlings. Hot areas are hot and humid, and citrus diseases, especially dangerous diseases, pose a great threat. Raising virus-free seedlings is an important way to solve this problem. The main methods are:

① heat treatment. The rootstock seeds were treated with 56 ℃ hot water for 50min, the scions for 45min were treated with 50 ℃ steam, and the seedlings before spring were treated with 49 ℃ steam for 50min.

② antibiotic treatment. The scion was impregnated with lh; tetracycline 700u/ml solution for 2 hours, and if tetracycline 1000u/ml solution was heated to 46 ℃, the impregnation time could be shortened to 20min.

③ shoot tip culture. After the leaf primordium was removed from the tip of the scion variety, the stem tip of about 0.1-0.2mm (cone meristem without vascular bundle tissue) was cultured in proper medium by tissue culture technique.

④ micrografting. The rootstock seedlings were cultivated by heat treatment and test tube sowing, and then the potted seedlings of scion varieties were placed in the artificial climate chamber (3040 ℃) for 2-4 weeks to promote new shoots. When the new tip is several centimeters long, take it.