High Density Planting of Mangoes

Introduction

  • Mango is the most important fruit crop of India and comes next to banana, apple and oranges on the basis of global acreage and production.
  • India contributes about 60% (9.5 million t) in the world mango production (15.7 million t).
  • Mango contributes 40% to national fruit production (22.168 million t) and occupies 42% of the total fruit area (24.87 million ha) of the country.
  • Uttar Pradesh (U.P) is the main mango growing state of India sharing 34% of total mango production in the country .
  • However, its productivity is 5.83 t/ha in U.P. as compared to 8.67 t/ha of the country.
  • Because of its low productivity, mango is slowly getting out of reach of the common man.
  • Indian mangoes are world famous and have great potential for export as compared to other fruits of the country.
  • Therefore, the question before us today is how to increase productivity and quality of our mangoes.
  • The reasons for low productivity of our mangoes are many.
  • Most of the commercial cultivars are location specific with long gestation period and alternate bearing habit viz., Deshehari, Langra, Chausa, Bombay Green, Alphonso, Banganpalli, Pairi, Himsagar, Kesar, Mulgoa etc of northern, southern, western and eastern India.
  • The normal planting distance in these cultivars has been 10-12m.
  • The orchard takes 10-15 years to provide economic returns depending upon the cultivar, planting distance and other cultural practices.
  • Due to poor early returns and clash between the cultural requirements of the inter crop with main crop, mango orcharding so far is done by large farmers who can manage tall trees and are capable of sustaining failure of inter crops particularly in the early stages of orchard life (10-20 years,) when the tree is full of vigour and dominance of vegetative phase prevails over reproductive phase adversely affecting flowering, fruit set and fruit growth, besides fruit drop due to high competition for photosynthates between vegetative and reproductive phases of the tree.
  • In mango, vegetative and reproductive phases are antagonistic to each other.
  • The tall trees of normal density at high productive stage require heavy machinery and equipment for spraying of pesticides and crop harvest because outer tree canopy is the major fruiting area extending outwardly with the enlargement of the tree.
  • These problems can be tackled by large farmers only.
  • Thus, small farmers are unable to take up mango orcharding.
  • High density orcharding appears to be the most appropriate answer to overcome low productivity and long gestation period for early returns and export of mangoes.
  • The high density orcharding is already successful in many fruits.
  • Perhaps, the high density orcharding has been the area of most intense focus in the last decade.
  • To meet the challenge of high productivity, one has to optimize the parameters of growth and minimise the unproductive components of plants without sacrificing the overall health of the tree and quality of the product.
  • This control of excessive vegetative growth in the tree for increased productivity is the major principle of high density orcharding.
  • In modern fruit production, a tree, which has not received proper growth management is inefficient with low productivity.
  • Therefore, controlling tree size by dwarfing rootstocks in high density orchards has been one of the methods of increasing production.
  • In high density system, yields are improved in early years of orchard life.
  • Once the trees have filled their allotted spaces crowding may occur and canopies of an adjacent trees begin to overlap.
  • This may lead to excessive shading and reduction in photosynthesis by layered leaves within the tree canopy resulting in poor yields.
  • In fact, at some point of time most fruit trees require vegetative growth control particularly in high density orcharding.
  • The horticultural methods most commonly known to control tree growth are training, pruning, use of dwarfing rootstock and growth regulators.
  • The training begins when the tree is first planted and continues through out its productive life.
  • Proper tree forms, branch angle and limb spacing in themselves aid in growth control.
  • Once the tree is mature, excessive growth can be regularly removed by pruning to provide a short term or immediate benefit.

Planting Density and Method

  • The veneer grafted Dashehari plants prepared on seedling rootstock in July 1975 were planted in August, 1976 at two densities: 12m x 12m (69 plants/ha-normal density) and 2.5m x 3.0 (1333 plants/ha-high density).
  • Eight grafts were planted in normal density and 216 grafts were planted in high density employing about 0.162 ha area for each density.
  • Grafts in normal density were planted at marked points prepared by pit digging (1x1x1m) and then by filling the pits with dug soil mixed with 100g N, 75 g P2O5 and 75 g K2O fertilizer mixture, whereas grafts in high density were planted directly in soil mixed with fertilizers containing 100g N, 75 g P2O5 and 75 g K2O fertilizer mixture.

Tree Growth and Canopy Management

  • The tree growth was similar in both the densities upto eight years.
  • The trees of high density orchard showed slightly higher growth in terms of height from 8th year onwards than those of normal density.
  • .A reverse trend occurred in the growth of crown circumference and main stem girth and the differences in the growth of trees in both densities widened after 10th year.
  • The tree height, circumference and main stem girth in high density was reduced by dehorning of branches after crop harvest in 11th and 15th years, besides light pruning of fruited shoots (5-10 cm top) in other years.
  • In general, 3m tree height and 10m circumference was maintained in high density by dehorning and pruning of branches and shoots, whereas unpruned shoots and branches of normal density trees grew upto 6m height and 20m circumference in 19 years.
  • As a result of pruning, the main stem girth of high density trees also remained low.
  • No pruning was practised in normal density orchard, except removal of low spreading branches in first year.
  • However, in high density planting, the first training treatment was given after one growing season in February 1977.
  • Each plant was allowed to maintain single stem (main stem) in February 1977 having upward growth and the top of the main stem was removed by cutting out at 60cm height from the soil surface.
  • In February, 1978, 4-5 primary branches were retained on each main stem.
  • Thereafter, shoots arising from secondary and tertiary branches were given 5-10 deep pruning in July soon after fruit harvest.
  • No pruning was done in non-flowering and fruiting years.
  • Spray of 1% urea combined with 0.2% Blitox-50 or any other copper fungicide was done soon after pruning in July.
  • Shoot pruning and spray of fungicide was not done in normal density orchard.
  • Pruning induced new shoot production in July-August within one month.
  • In general, every pruned shoot produced one new shoot but occasionally more than one shoot was also produced.
  • In July 1987, about 75% branches of the tree canopy were dethroned in high density orchard and the remaining 25% branches were dethroned in July 1988 after crop harvest.
  • Dethroning was done to avoid overlapping of trees in the high-density orchard.
  • Results of paclobutrazol applications also indicated dwarfing effect on tree growth and vigour.

Nutrition

  • In normal density each tree was given 100g N, 75g P2Oand 75g K2O for one year of age.
  • The N,P,K doses were increased upto 10 years and then stabilized.
  • From the 10th year onwards, each tree of normal density was given 1000g N, 750g P2O5 and 750g K2O.
  • Full doses of P and K fertilizers (Single superphosphate and muriate of potash) were given in December, whereas N (urea) was given in the two split doses in December and July.
  • High density orchard was given 100kg N, 75kg P2O5 and 75 kg K2O per ha every year.
  • Soil application of full doses of P and K we done in December, Whereas N was given in two equal doses in December and after crop harvest in July, besides spray of 1% urea (5 kg/ha).
  • Leaf litter was allowed to decompose in the orchard soil.

Irrigation

  • High density orchard was irrigated soon after paclobutrazol treatment.
  • Thereafter, the orchards of both the densities were irrigated from panicle emergence to crop harvest at 15-20 days interval from March to June.
  • However, no irrigation was applied first shower of the rains in June to February-end.

Interculture

  • Only clean cultivation was practised.
  • Tillage operations were done in October-November to keep the orchard free from weeds and also to mix fertilizers and leaf litter into the orchard soil.

Control of Pests and Diseases

  • To control the pests and disease in the orchard, the recommended practices and chemicals were used in both the densities at the same time uniformly except that no insecticide was required to control shoot gall maker in high density orchard.
  • Mango hopper, Rhynchoenus, powdery mildew and anthracnose were the main pests and diseases in the high density planting similar to that in normal density.
  • The spray schedule followed for control of pests and diseases were as given below:
  1. Ist week January-Spray of Agromonark or nuvacron @ 1.25 ml/1 water.
  2. Ist week of February–Spray of Agromonark or Nuvacron @ 1.25 ml/1 water.
  3. Ist week of March–Spray of mixture of 15 ml Agromonark or Nuvacron and 6 ml Karathane for each 10 litre water.
  4. Ist week of April–Spray of mixture of 2 g Carbaryl (5%) and 2 g Blitox-50 for each litre water.
  5. June-July–Spray of 0.2% Blitox-50 or any other fungicide with 1% urea soon after crop harvest and shoot pruning in high density orchard only.
  6. August-September–Spray of Roger @ 3 ml/litre in first or second week of August followed by nuvacron spray (2 ml/l) in III or IV week of August and then Roger spray again after 10d, if required and
  7. December–Follicle dusting in soil under the tree @ 3 kg and 6 kg/year/ha in normal and high density orchards, respectively, from 5th year of tree age.

 Fruit Yield

 Similar to that of growth, trees in both the densities started fruiting in fifth year of their planting and a similar rise and fall occurred in the annual yields of trees in both the densities without any significant change in two densities upto nine years.

  • However trees of normal density started producing more fruits per tree than high density from 10th year onwards because tree size in high density was reduced by dehorning and pruning to avoid overlapping of branches and also to induce growth after crop harvest in fruited shoots.
  • Annual fruit yield per hectare, however, was much higher from high density Dashehari orchard starting from fifth year itself due to higher number of trees per hectare (1333 tree/ha) than that of normal density (69 trees/ha).
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