Planting of fruit trees rather at a close spacing then the recommended one using special techniques with solo objective of maximum production per unit area without sacrificing quality is often refers to high density planting or HDP. 

HDP is first established in apple in Europe during sixties and now praticed in Europe, America, Australia and New Zealand.

Four planting density is reconized for apple low HDP( less than 250 trees/ha), moderate HDP( 500-1250 trees/ha) and Ultra HDP( more than 1250 trees/ha). Super HDP planting system has been also established in Apple Orchards with a plant population of 20,000 trees/ha.

In some orchards more closer planting of apple trees is followed(70,000 trees/ha) which is often referred as 'Meadow orchards'.

High density planting

Advantages of HDP

  • Early cropping and higher yield for long time.For example the average yield in Apple is 50 tonnes/ha and in HDP 140 tonnes/ha.
  • Reduce labour cost.
  • Improve fruit quality.

Characters of HDP

  • The trees of HDP should have maximum number of fruiting branches and minimum number of structural branches.
  • The trees are generally trained with a central leader surrounded by nearly Horizontal fruiting branches.
  • That branch should be arranged and pruned in such a way that each branch cast minimum amount of shade on other branches.
  • The height should be one and half in diameter at the base.
  • A key to successful HDP depends upon the control of tree size.This is achieved by

  1. Use of size controlling root stocks. In apple an intermediate stock like MM106, MM109 and MM111 are used to control the size of the plant.
  2. Use of spur type Scion in temperate fruit crops like apple, litchi etc.
  3. Training and Pruning methods to induce dwarfness.
  4. Mechanical device and use of chemicals to control size. Growth regulators such as deminozide, ethpkon reduce shoot growth.

Planting system for HDP

The success of HDP depends up on the right choice of planning system. Generally rectangular planting with the single, double and three row planting are followed.

  • In single row planting, the distance within the row is close, where is the distance between the Row is wide (4x2m).
  • In double row planting, a wider spacing is given after each two rows (4+2x2m).
  • In three row planting, a wider spacing given after every three rows (4+2x2x2m).
  • In Meadow orchard system a bed of 10 to 15 rows is closely planted (30x45cm) and separated by alleys of 2.5 m width between beds. This system is also called as bed system.



Reference 
Introduction to Horticulture by N.kumar