High-density plantation — Future of apple cultivation

Ambika Sharma

Increasing pressure on land and reduction in average land holdings, shifting from low-density planting systems to high-density planting systems has become the need of the hour, especially in horticulture. Trees in high density are more precocious, heavy yielders and produce better quality fruits. It can play a significant role in improving the apple economy of Himachal.

Over the past few years, scientists at Dr YS Parmar University of Horticulture and Forestry (UHF), Nauni, have been undertaking research on high-density apple plantation. This is being facilitated under the World Bank-funded Himachal Pradesh Horticulture Development Project (HPHDP). UHF’s Directorate of Research is the nodal agency for implementation of the project at the university for the development of packages of practices (POP) on high-density apple plantations, which will be shared with farmers in the state. For this purpose, research trials are being carried out at the plantations raised in experimental farms of the Department of Fruit Science and Department of Soil Science and Water Management (SS&WM) of the university.

High-density plantation refers to the planting of maximum possible number of plants per unit area to get maximum crop yield and profit per unit of tree volume without impairing the soil fertility status. A high-density apple orchard with 500 plants was established on the university campus in 2016 by planting eight varieties on dwarfing and semi-dwarfing clonal rootstocks to identify suitable varieties and rootstocks along with ideal plant spacing and canopy management techniques for high-density apple plantations.

Dr JN Sharma, nodal officer and director research of the university, said: “Trials on varietal evaluation, planting density, canopy management, irrigation and fertigation are being conducted at the main Nauni campus and other research stations of the university located in different agro-climatic zones. Various varieties being studied are Jeromine, Red Velox, Red Cap Valtod, Scarlet Spur-II, Super Chief, Gale Gala, Redlum Gala and Auvil Early Fuji grafted on M9 and MM106 rootstocks.”

The plant spacing i.e. 2.5 X 0.75 m (5333 plants/ha), 2.5 X 1.0 m (4000/plants/ha) and 2.5 X 1.5 m (2666 plants/ha) and training systems viz., vertical axis, slender spindle and tall spindle are being tested. The results of varietal evaluation trial reveal that among eight varieties planted in high density, Jeromine, Red Cap Valtod, Scarlet Spur-11 and Redlum Gala is performing very well at low elevation (1,225 m AMSL) of Nauni in terms of colour development, yield, quality and productivity.

Vice-Chancellor Dr HC Sharma said: “The experimental trials initiated during 2016 on the main campus show that ‘Jeromine’ grafted on M9 rootstock planted at a spacing of 2.5m X 1.0 m (4000 trees/ha), trained to tall spindle training system performed better in terms of yield and fruit quality with a productivity of 20 MT/ha after the third year of planting. After getting encouraging results, the department has established a new demonstration block of 450 plants this year to integrate rootstock, variety, planting density, irrigation, training system and fertigation level to develop a complete module for farmers.”

Similarly, the Department of Soil Science and Water Management has also established two blocks containing 1,000 plants of Super Chief and Red Velox on rootstock MM106 and M9 at a spacing of 2.5 x2 m and 2.5x 1 m. This was done under the HPHDP sub-component- ‘Improving nutrient and water productivity for sustainability and profitability of fruit production in HP’. The SS&WM Department has initiated work with prime objectives of investigating the effects of irrigation schedules and fertiliser doses on the growth and productivity and determining efficient irrigation schedules and optimum fertiliser doses for high-density apple.

Two field experiments being conducted

Two field experiments are being conducted simultaneously in the same orchard, wherein drip irrigation and fertigation treatments were tried in triplicate. From the ongoing research, a farmer would be advised on how much water is to be used through a drip on a weekly basis throughout the growing season.

The study will establish the irrigation and fertigation schedules for high-density farmers of the state and country, who will be raising 3,000-5,000 plants/ha in comparison to the current practice of having 200-300 plants/ha. The study will bring out the best management practice for efficient use of scarce irrigation water and nutrient stewardship and motivate farmers to adopt the concept of applying fertilisers at the right time and at the right rate. It will be a new stride in enhancing the productivity of apple in the state. The university will prepare the final recommendations after the completion of trials at various locations.

What is High-Density Plantation

Standard apple plants raised on seedling rootstocks are planted at a spacing of 7.5 X 7.5 m with a planting density of 178 trees/ha and spur varieties on seedling rootstocks are planted at a spacing of 5.0 X 5.0 m with a planting density of 400 plants/ha. The average productivity of these orchards is approximately 6 to 8 MT/ ha, which is much below the productivity obtained in high-density orchards (40-60 MT/ ha). In high-density planting, apple plants on clonal rootstocks up to 5,333 plants/ha can be planted to increase the production per unit area basis and improve the quality of the produce. High-density orcharding can be done on flat and fertile lands with assured irrigation using dwarf/semi-dwarf clonal rootstocks, which can be trained to modern methods of canopy management viz., vertical axis, slender spindle and tall spindle etc. The technology is helpful in the best utilisation of land and resources and ease in orchard inter-culture operations, plant protection as well as harvesting and to obtain export quality of the produce. Canopy management has paramount importance in high-density planting to control vigour of trees and harvest quality fruits. Training and pruning are two important horticultural practices of canopy architecture. Training aims at more penetration of sunlight, support to main branches for desired tree architecture to increase the planting density and finally increasing production. Training systems like tall spindle, vertical axes, slender-spindle, head and spread are recommended for high-density apple orchards. Under these, branches are trained to horizontal positions/ below horizontal, using cloth pins on 8-10 cm shoots and tying of branches during summer.