CROP IRREGULARITY.   Grafted mango-trees bear fruits from the fourth or fifth year onwards and a full crop from the tenth or fifteenth year. The erratic bearing of mango is well known. It depends upon the variety , the weather and climatic conditions and cultural treatments. The selection of regular-bearing varieties, timely cultural practices and proper nutrition help to produce a regular crop. New growth in spring, on which flower-buds are produced during the next winter, can be encouraged by applying nitrogenous fertilizers (0.45 to 0.90 kg of N per tree). In the case of heavy late rains, an additional ploughing in winter helps to produce flower-buds in January-February. In the case of individual trees, ringing or girdling in August-September may also to help to force flower-buds the following winter. The application of Ethral (200 ppm) from September onwards has been found to induce flowering in mango in Karnataka by the Indian Institute of Horticultural Research.

IMPROVEMENT OF OLD AND SEEDLING-TREES.   Mango-trees of inferior varieties, so also those raised from seeddlings, can be converted into choice varieties by grafting them in situ either by crown or side-grafting. In crown-grafting, the trunk of the tree is cut down to about half a metre from the ground and one or more scions of the selected variety are inserted into it between the bark and the wood by splitting open the bark. The scion should be a dormant, terminal shoot, about 12.5 mm in diameter, with a whorl of plump swollen buds at the top. In side-grafting, the procedure is the same as in crown-grafting, except that the trunk of the stock tree above the grafting joint is cut down after the scions have sprouted and have established themselves properly. Old trees, having several branches, can be similarly improved (top-worked) by crown-grafting on each branch at a suitable height. Sometimes, the grafting is done by inarching, but the process is cumbersome, expensive and not very satisfactory.

HARVESTING AND MARKETING.   The fruit takes five to six months to mature. Depending upon the onset of flowering, the mature fruits are ready for harvesting from April to May in western India, from May to June in the Deccan, from February to March in Malabar, from April to July in the coastal Andhra Pradesh, from May to August in Mysore and Rayalaseema, and from June to August in northern India. The mature fruits are harvested by severing the stalks to which they are attached, when they are still green and hard. The signs of maturity vary with different varieties. As a mango tree usually bears flowers in three or four distinct flushes lasting over a month, it is preferable to harvest the fruits as they mature. The fruits, so harvested, can be transported after packing them in baskets or wooden crates, properly padded with straw, wood-shavings or wool, to long distances. For overseas markets, they are packed in a single layer in specially designed wooden crates.

For ripening, the fruits are spread out on rice straw in a single layer. Two or three such layers are built one above another in a well-ventilated room. The mangoes are ready for disposal after they change colour.

Yield varies considerably with the variety, vigour of growth, flowering, etc. A grafted tree yields about 300 to 500 fruits in the tenth year, about 1,000 in the 15th year and 2,000 to 5,000 from the 20th year onwards.

Citrus is grown in almost all the states of India. The total area covered is over 67,650 hectares, of which Madhya Pradesh, Madras and Maharashtra have the largest share. Citrus trees are grown in almost all kinds of soils, varying from heavy black soils to shallow open soils. Some of the varieties of citrus seem to adapt themselves to soil conditions better than others. They thrive in free-draining alluvial or medium black soil of loamy texture. A hard substratum or a sticky impervious layer is very injurious. Soils having a high water-table should be avoided. Though citrus trees on the whole do well in dry climate, with a rainfall between 75 and 125 cm, certain species, such as pummelo and certain mandarin oranges, thrive in heavy-rainfall areas of Konkan, Assam and Coorg.

Grapefruit.   The name grapefruit (Citrus paradisi Macf.) has been derived from the habit of bearing the fruit in clusters like grapes. In India, its introduction is comparatively recent, and its cultivation is confined mostly to Punjab, the western parts of Uttar Pradesh and to places around Poona in Maharashtra.

CLIMATE AND SOIL.   The climatic and soil requirements of the grapefruit are similar to those of the orange. High rainfall and humidity are harmful, as they encourage diseases.

VARIETIES.   The popular varieties, which are all imported, are 'Marsh Seedless', pink-fleshed 'Foster' and yellow-fleshed 'Duncan'.

PROPOGATION AND PLANTING.   Propogation is done by budding. However, owing to their polyembryonic nature, seedling trees have been frequently found to be quite satisfactory. The rootstock most successfully employed in the northern regions is kharna khatta (Citrus karna Raf.). In the south and Bombay-Deccan, 'Jamburi' is commonly employed, whereas in Assam grapefruit does well on Rabab tenga.

Planting, irrigation, manuring and interculture are the same as for the orange.

PRUNING.   Grapefruit trees require less pruning than orange-trees.

HARVESTING AND MARKETING.   The harvesting season is from January to March in the north and from September to November in the south. Picking, packing and other operations are the same as for the orange. Quality and flavour of the fruit is improved if it is stored before transporting.

Lemon (Citrus limon (L.) Burm.f) is not cultivation to any great extent in India, as it requires a comparitively cool climate for regular bearing. Its fruit is not so highly flavoured as that of sour lime.

Lime. The lime(Citrus aurantiifolia Swingle), both sour and sweet, known as kaghzi nimboo and mitha respectively, are more orized in India than lemon. Sour lime is propagated mainly from seed. Budding on rough lemon rootstock, layering and morcotting are also practiced to some extent. The tree is susceptible to frost. It flowers twice a year in February-March and again in August. The main crop is obtained in August from the first flowering. The second crop is ready in the following February.

The propagation of sweet lime is done from mature wood cuttings which root readily. It can also be propagated from seeds and the seedlings, usually come true to type. Planting of limes and their pruning, manuring, etc. are the same as for the sweet orange.

Mandarin orange.

CLIMATE AND SOIL.   Santra or mandarin orange Citrus reticulata Balanco) grows successfully in all tropical and subtropical parts of the country. It tolerates more humidity in summer and winter than the sweer orange. It is grown under rain-fed conditions in Coorg, Wynad tract, Palni Hills and the Nilgiris in the south between elevations of 600 and 1,500 metres. In Assam, the main centres of production are the Khasi, Jaintia and Lushai Hills. The region around Nagpur (elevation about 370 metres) produces a superior quality of mandarins. It is mainly grown under irrigation. In Punjab, its cultivation is confined mainly to the submontane districts up to about 600 metres. It can be grown successfully on a wide range of soils, but the ideal soil is medium or light loam with a slightly heavier subsoil. Heavy black soil, underlain with murram and having good drainage, is also suitable. In the Khasi Hills of Assam, oranges are grown on sandy or gravelly soils.

VARIETIES.   The important varieties cultivated on a commercial scale are the 'Nagpur' orange, the 'Khasi' orange, the 'Coorg' orange, 'Desi Emperor' and the 'Sikkim' orange.

PROPOGATION.   The propagation of mandarin orange is largely through seed, except the 'Nagpur' and 'Emperor' varieties which are propagated by budding. Like other citrus species, the seed is polyembryonic. Therefore, while propagating by seed, the sexual seedlings which are usually stunted and poor are rogued out and the rest that are produced from the cells of the nucellus are allowed to grow. The seedlings, thus selected, are more or less uniform in growth and production. They are, however, late in bearing and remain tall and slender. Budded plants do not suffer from these defects. The santra orange is usually budded on rough lemon (jambhiri, Soh-myndong or jatti khatti rootstock. The variety 'Emperor' is budded on the kharna khatta rootstock. Studies at the Citrus Experiment Station, Coorg, of the Indian Institute of Horticultural research, has shown that trifoliate, Rangpur lime, Kodakthuli and Troyer citrage are good rootstocks for mandarin.

PLANTING.   In the hills and humid regions, where plantings are generally done on steep slopes, the land is properly terraced. In the plains, where the trees have to be irrigated, the land should be levelled. The trees are usually transplanted during the monsoon. In heavy-rainfall areas, the plantings is generally done at the end of the heavy rains. They are planted 4.5 to 6 metres apart.

PRUNING.   Prune young trees to build up a strong framework, as recommended for sweet orange. The bearing trees require little or no pruning. Undesirable growths, like water-shoots and crossing branches, should be removed once or twice a year.

In Bombay-Deccan, root exposure or resting treatment is given to santra trees to make them flower to order. The treatment is the same as for the sweet orange.

MANURING.   Farmyard manure, 20 to 25 kg per tree, is applied at planting, together with about half a kilo of ammonium sulphate. A mixture supplying 0.09 kg each of N, P and K per tree may be applied in the first year after planting, and the dose is gradually increased to 0.45 kg of each N and P and to 0.90 kg of K per tree in the seventh year and kept constant thereafter. The dose of farmyard manure is increased to 50 kg per tree. It may be replaced by green manuring.

In northern India, manuring is generally done in winter, whereas in Bombay-Deccan it is done before the advent of the monsoon or at the time of root exposure.

IRRIGATION.   When grown under irrigation, the method and frequency of application of water are the same as described under sweet orange.

HARVESTING.   Seedling trees bear their first crop in the eighth year and the full crop from the tenth year onwards. Budded trees start bearing from the fourth year and full crop is had from the seventh year onwards. The harvesting periods differ in different parts of the country.

While picking the fruit, the stem-end should be cut close to the fruit without damaging rind. Packing is done by putting the fruits of different size grades in separate wooden crates.