Citrus planting technology

Citrus fruits are rich in nutrition, excellent in color, flavor and taste. They can be eaten fresh and processed into various processed products mainly fruit juice. Citrus yield ranks first among all fruits, citrus juice accounts for 3/4 of juice, widely favored by consumers. Citrus is the most important fruit tree species in South China with long life, high and stable yield and high economic benefit. It plays an important role in poverty alleviation and rural economic development.

seedling technology

1. Rootstock seedling cultivation

The nursery land should be selected with convenient transportation, flat terrain, water source, gentle slope below 5° or irrigated paddy field, and the soil layer should be deep, good structure, soil quality on sandy soil or soil. The pH value should be in the range of 5.5~6.5. Avoid water and air pollution and stay away from old citrus gardens. Rootstocks are required to be varieties or types that adapt to local conditions, have strong affinity with the main varieties, grow normally, have developed roots, have strong resistance, can bear early, high yield, stable yield, high quality after grafting, and have no quarantine diseases and insect pests. Guangdong, Guangxi and Hainan sweet oranges, mandarin oranges and ponkan oranges are mostly based on sour oranges, red oranges (Jiangxi red oranges) and red oranges; in recent years, ponkan oranges and navel oranges are based on trifoliate orange. Fujian red tangerine for broad skin orange rootstock, but also useful orange for ponkan, banana orange and sweet orange rootstock. Taiwan's banana orange, ponkan more sour orange, red stick lemon for the rootstock. Guangdong, guangxi, fujian pomelo rootstock multi-acid pomelo. Rootstock seed is collected mature fruit, with a special fruit plate or knife, longitudinal cut 6-8 petals, squeeze out the seeds. Then put it into bamboo or coarse cloth bag, add a small amount of plant ash and rub it gently, then wash with water to remove the fruit residue and pectin on the seed coat. Spread the washed seeds in a cool and ventilated place, and sow them when the seed coat is white. Fresh seed is best, otherwise dry storage or sand storage should be used for preservation. Seed content and sowing quantity of rootstock fruit. Sowing land should be intensively cultivated, fully ploughed and harrowed, and evenly applied with sufficient base fertilizer. Generally, pig manure, cow dung, high-quality compost 3750-4500kg, calcium superphosphate 225-375kg, lime 375-450kg per hectare. Sowing methods are broadcast and drill two kinds. After sowing, the seedbed soil should be kept moist, the seedlings grow 3-4 true leaves, and the water and fertilizer should be applied thinly, and attention should be paid to the prevention and control of anthracnose, blight and leaf miner. Rootstock seedling transplantation is divided into two kinds: new seedlings and old seedlings. The newly planted seedlings are sown in spring in the first winter, transplanted in 20cm×12cm plant spacing from May to the middle of July of the next year, grafted in winter and spring, and planted in autumn. The whole seedling time is two years. This method should strengthen fertilizer and water management, so that rootstocks grow rapidly, in order to timely out of the nursery. The old seedlings were transplanted in the autumn and winter of the following year or in the spring of the third year according to the plant spacing of 25cm×12-15cm, and those sown in spring were transplanted in autumn and winter or in April and May of the following year after the spring shoots were mature. After 9-15 months of growth, winter and spring grafting is carried out, and the whole seedling time is two years.

2. Cultivation of grafted seedlings

Grafting can be done throughout the year, but it is best before the beginning of spring. Grafting can be done early when the branches are full in winter, and delayed otherwise. In order to raise seedlings quickly, summer grafting and autumn grafting can also be carried out in sunny and warm days. Rainy soil is too wet and strong north wind weather is not suitable for grafting. Summer and autumn grafting should be avoided in rainy days and strong sunshine at noon. Grafting methods Guangdong, Guangxi, Fujian, Hainan and other places with single bud cutting or single bud abdominal grafting, survival rate of more than 90%. Grafted seedlings should be shaped in nursery, mainly to determine the height of trunk and cultivate a certain number of backbone branches. Summer shoot pruning promotes autumn shoot initiation. Clipping in hot areas is generally carried out before and after the beginning of autumn. Cold dew wind comes early, drought prone places or nursery in late autumn and early winter can be appropriately advanced. In the middle and upper part of the first summer shoot, select the part with consistent internode density and complete leaves, and cut the top at 25-30cm from the ground. If the spring shoot exceeds this height, cut it off on the spring shoot. After cutting the top, pick off the sporadic autumn shoots in time. Most seedlings have 3-6 buds before they sprout, so as to keep the branch growth balanced. When the buds grow to about 3cm, select 3 - 5 strong and evenly distributed main sticks in all directions, and the rest are thinned out in time. The criteria of excellent grafted seedlings are: fine and pure varieties, no yellow shoot disease and quarantine diseases, strong branches, good healing of joint, height of new seedlings above 10cm (height of old seedlings above 50cm), stem diameter above 0.8 cm, 3~5 main branches evenly distributed, dark green and shiny leaves, main root length above 15cm, fibrous roots with uniform color at most, balanced growth of the whole plant above ground and underground, etc.

3. Virus-free seedling cultivation. Citrus diseases, especially dangerous diseases, are threatened greatly by high temperature and humidity in hot areas. Breeding virus-free seedlings is an important way to solve this problem. The main methods are:

① Heat treatment. Rootstock seeds were treated with hot water at 56℃ for 50min, scions with steam at 50℃ for 45min, and seedlings before spring flowering were treated with steam at 49℃ for 50 min.

② Antibiotic treatment. Scions were immersed in streptomycin 700u/ml solution for 1 h and tetracycline 1000u/ml solution for 2h. If tetracycline 1000u/ml solution was heated to 46℃, the immersion time could be shortened to 20 min.

③ shoot tip culture. After removing leaf primordia from the tip of scion variety, shoot tip (cone meristem without vascular bundle tissue) of scion variety about 0.1-0.2mm was taken and cultured into seedlings in appropriate medium.

④ Micrografting. The seedlings of non-toxic rootstock were cultured by heat treatment and in vitro seeding, and then the potted seedlings of scion varieties were placed in an artificial climate chamber (30~40℃) for 2-4 weeks to promote new shoots. When the new shoots grow to a few centimeters, take them.