MANGOES - PLANTING, GROWING AND VARIETIES

PROPAGATION

Mangoes are raised from seed or propagated vegetatively. Propagation from seed, though easy and cheap, is unable to perpetuate characters of the parent tree because most commercial varieties in India are cross-pollinated and monoembryonic. Plants also take more time to bear fruit. Accordingly, several methods of vegetative propagation have been tried with varying degree of success. However, it is essential to raise seedlings to be used as rootstocks. For this purpose, stones should be sown in June-July in beds mixed with well decomposed farm yard manure at the rate of 8-10 tonnes per hectare. Alternatively, 25 kg nitrogen (N) per ha may be applied in the form of urea, CAN or any other available inorganic source in two split doses at about two months interval after the leaves have become green. When the seedlings attain the age of 2-3 months, they should be transplanted well in prepared beds or pots one transplanting should be given in well prepared beds or pots. In this season, proper care should be exercised in irrigating the young transplanted seedlings. The seedlings should also be protected from frost by putting the pots under big trees or thatching the young seedlings in the field.
Plants are generally propagated using random seedling rootstocks. The polyembryonic rootstocks, however, have shown a promise in producing plants of uniform size and vigour. Moreover, these rootstocks have indicated possibility of inducing dwarfing and earlier bearing and are under test. Various methods employed in vegetative propagation of mango are described below :
a) Inarching : The method of inarching or approach grafting is quite cumbersome and time consuming, but it is still the leading method for commercial propagation of mango plants. The method consists of uniting the selected shoot (scion) of a desired parent tree (mother plant) with the potted or transplanted seedling (rootstock) by approach grafting. For this purpose, about one-year-old seedlings are most suitable when they attain a height of about 30-45 cm and thickness ranging from 0.75 to 1.5 cm. These seedlings are either grown in pots or under the mother plant from which the grafts are to be prepared, depending upon the availability of suitable branches. Generally, a one-year-old twig of the scion tree about 60 cm in length and nearly of the same thickness as that of the stock is chosen for grafting. Young and non-bearing trees should not be selected as mother plants.
Inarching should be done during the growing period when the tree is in active sap flow condition termed as active growth period. A hot and very dry period, as well as heavy rainfall during the inarching period is not suitable. The end of the monsoon in heavy rainfall areas and early monsoon in the light rainfall areas is the best period for inarching. In north India, July is the best month for inarching. In the more equitable climate of south India, the operation can be done any time between July and February.
A thin slice of bark and wood, about 5 cm in length, 7.5 mm width and 2 mm deep, is removed by means of a sharp grafting knife from the stem of the stock as well as from the scion branch. The dimensions can be proportionately increased or decreased according to the thickness of the stock and scion. The cuts thus made should be absolutely flat, clean, boat shaped, even and smooth. The ends of these cuts should be round and not angular. The cut surfaces of both, i.e., stock and scion are made to coincide facing each other so that there remains no hollow space between the two. These are then tightly tied by polythene / alkathene strips of about 1.5 cm in width and preferably of 200 gauge thickness, which has proved to be a good tying material.
After about one month of operation, the scion below the graft union and stock above the graft union should be given light ‘V’ shape cuts at weekly intervals such that grafts can finally be detached while giving the fourth cut. In the last stage, the top of the stock above graft union should also be removed completely.
b) Veneer grafting : This method of propagation possesses promise for mass scale commercial propagation. The method is simple and can be adopted with success. The rootstocks as mentioned, for inarching are suitable for this method also. For conducting this grafting operation, a downward and inward 30-40 mm long cut is made in the smooth area of the stock at a height of about 20 cm. At the base of cut, a small shorter cut is given to intersect the first so as to remove the piece of wood and bark. The scion stick is given a long slanting cut on one side and a small short cut on the other so as to match the cuts of the stock. The scion is inserted in the stock so that the cambium layers come on the longer side. The graft union is then tied with polythene strip as recommended for inarching. After the scion takes and remains green for more than 10 days the rootstock should be clipped in stages.
The scion wood to be used for veneer grafting requires proper preparation. The desired shoots should be defoliated at least one week prior to grafting so that the dormant buds in the axis of leaves become swollen. The best time for this method is the same for different regions as for inarching.
c) Budding : Although success of budding in mango was reported in the beginning of this century, budding still continues to remain in experimental stage as far as commercial mango propagation is concerned.
d) Stone Epicotyl grafting : Mango is generally propagated by inarchig and veneer grafting. These methods are time consuming. Stone epicotyl grafting is a new technique of mango propagation. This method is simple, cheap and quick. Fresh mango stones are sown in the nursery beds. After germination, seedlings with tender stems having coppery leaves are lifted with stones still attached. The roots and stones are dipped in 0.1 per cent Bavistin solution for 5 minutes after washing the soil. The seedling stems are headed back leaving 6-8 cm long stem. A 4-6 cm longitudinal cut is made running down through the middle of the stem. A wedge shaped cut starting on both sides is made on the lower part of scion stick. The scion stick should be 4-6 months old and 10-15 cm long containing plumpy terminal buds. The scion stick is then inserted in the cleft of the seedlings and tied with polythene strips. The grafts are then planted in polyethylene bags containing potting mixture. The bags are then kept in the shade protecting from heavy rain. When the scion sprouts and the leaves become green, the grafted plants should be planted in nursery beds. July is the most suitable month for stone grafting.
e) Soft-wood grafting : The technique of soft-wood grafting is similar to that of cleft or wedge grafting. In this case, grafting is done on newly emerged flush having bronze coloured leaves and stem. This method is useful in in-situ grafting. The scion wood to be used should be defoliated 10 days prior to the frafting and having same thickness as that of terminal shoot. The graft should be secured firmly using 1.5 cm wide and 4.5 cm long, 200 gauge polythene strip. July and August are the best months for soft-wood grafting.
f) Air layering : Air layering can be done successfully in mango using IBA or NAA 10,000 ppm in lanolin paste. Success up to 50 per cent has also been obtained by using Seradix-B as root promoter. The air-layers can be used for permanent planting or for raising uniform rootstocks.
PLANTING
Prior to planting, field should be deeply ploughed, harrowed and leveled. Pits of proper size should be dug at appropriate distances and filled by adding sufficient quantity of farm yard manure. The grafts to be planted should be procured from reliable nurseries few days before actual transplanting.
a) Time of planting : The best time for planting all over India is during the monsoon when there is sufficient moisture in the atmosphere. In the area, of heavy rainfall, the best time of planting mango is the end of the rainy season. In tracts where the rainfall is less, the planting can be done in the early part of the monsoon for better establishment. The planting should be done in the evening, otherwise if the day turns out to be unusually hot or dry, the plants may wither due to excessive loss of water. If the sky is overcast, planting can be done during day time also.
b) Planting distance : The planting distance varies according to variety, the fertility level of the soil and general growth conditions in the area. Where the growth is excessive, the distance should be 12 x 12 m, but in the dry zones where the growth is less, it can be regulated to about 10 x 10 m. For high density planting, the distance can be 5 x 3 or 5 x 2.5 or 3 x 2.5 or 2.5 x 2.5 meter.
c) Size of pits : In locations where the soil is loamy and deep, pits of 0.5 x 0.5 x 0.5 m be dug at desired distances. However, in shallow and hill soils, the pits should at last be of 1 x 1 x 1 m size.
d) Filling of pits : The pits should be filled with the original soil mixed with 50 kg well rotten farm yard manure. In the top two-third portion, the proportion of the manure and soil may be kept as 1:3. If the soil is having infestation of white ants, 200-250 g of aldrex or BHC dust may also be mixed.
In case of stony soils, it is better to remove all the stones from the excavated material and remaining soils should be mixed with soil scrapped from the left over area and FYM. The pits should invariably be filled before the rainy season, so that there is maximum settling down before the advent of heavy rainfall and much before planting.
e) Planting of grafts : The plant with its ball of earth intact should be taken out of the soil or pot. The plant can then be placed with the help of a planting board in the centre of the pit by excavating as much soil as necessary to accommodate the root-ball. The moist soil of the pit is then pressed all around the root ball to complete the the planting process. A small basin is then made and the plant is properly watered. The planting should not be done so deep as to bury the graft-union in the soil or so high as to expose the upper roots. It is always better to adjust it at the same height/depth at which it was in the pot or the nursery bed.
f) Training and pruning : Normally, mango trees require very less or no pruning. However, the training of the plants in the initial stages is very essential to give them proper shape. Specially when the graft has branched too low, the process of training becomes very important. At least 75 cm of the main stem should be kept free from branching and the first leader / main branch may be allowed after that. The main branches should be spaced in such a way that they grow in different directions and are at least 20-25 cm apart, otherwise there are chances of breakage due to smaller crotch angles and heavy top.
The branches which exhibit tendency of crossing and rubbing each other should be removed in the pencil thickness stage, otherwise they break by rubbing each other at a later stage and create complications. Secondly, if the centre is closed the fruits produced are of poor quality having less colouration in the absence of sufficient sunlight.
By following the above practice and after giving proper shape to the trees, there will be very less scope for future pruning except removal of diseased, pest infested or dried shoots / wood.
FERTILIZER REQUIREMENTS
Nutrient uptake in mango is from large volume of soils. Therefore, it is able to sustain growth even in low fertility soils. But, its efficient management involves the replenishment of the nutrients used-up by the tree for its growth and maintenance, harvested produce and natural losses from soils through leaching and run of. Even the under-nourished trees can be revived by suitable supplementation of nutrients through fertilizers. The idea of manuring bearing trees is also to secure regular fruiting. Recommendations based on very limited research and also on experience gained by the orchardists are given below.
a) Quantity of fertilizer : Manuring mango plant starts right from planting operation in the orchard. First application is made at the time of filling of the pits (refer item 6 d). Fertilizer application during the first year of planting may be given as 100 g N, 50 g P2O5 and 100 g K2O per plant.
Above dose should be increased every year up to 10 years in the multiple of first year’s dose. Accordingly, a 10-year-old tree should receive 1 kg N, 500 g P2O5 and 1 kg K2O. This dose should be continued to be applied in subsequent years also. Application of 50 kg well-decomposed organic manure should be given four yearly to create proper soil physical environment. For trench application of fertilizers, 400 g each of N and K2O and 200 g of P2O5 per plant should be given.
The application of micronutrients is not recommended as a routine. Need based supplimentations are essential when these become limiting factor for production. It is advisable to apply micronutrients through foliar sprays.
b) Time of fertilizer application : Fertilizers may be applied in two split doses, one half immediately after the harvesting of fruits in June / July and the other half in October, in both young and old orchards, followed by irrigation if there are no rains. Foliar application of 3 per cent urea in sandy soils is recommended before flowering.
c) Method of fertilizer application : First of all, the weeds should be removed from basins. The mixture of recommended dose of fertilizers should be broadcast under the canopy of plant leaving about 50 cm from tree trunk in old trees. The applied fertilizer should be amalgamated well up to the dept of 15 cm soil.
To increase fertilizer use efficiency, fertilizers should be applied in 25 cm wide and 25-30 cm deep trenches dug around the tree 2 m away from trunk.
IRRIGATION
Amount and frequency of irrigation depends upon the type of soil, prevailing climatic conditions, especially rainfall to be given, and its distribution and age of trees. No irrigation is required during the monsoon months unless there are long spells of drought. During the first year when the plants are very young with shallow root system