PRINCIPLES AND METHODS OF TRAINING IN FRUIT CROPS

Training is the process of shaping the growth of fruit trees to achieve a desired form. It ensures the development of a strong structural framework for the tree, which supports healthy growth, fruit production, and ease of management over its lifetime. Proper training makes trees easier to prune, improves light penetration, and helps in performing orchard operations efficiently.

Objectives of Training

Control Tree Shape Regulates the growth of trees into a specific form, making cultural practices like pruning, spraying, and harvesting easier.

Sunlight and Air Penetration Ensures adequate sunlight and air reach the center of the tree, improving photosynthesis and reducing disease incidences.

Development of Strong Framework Builds a robust structure with well-spaced scaffold branches that can bear the weight of fruit without damage.

Improve Crotch Angles Promotes better crotch angles between scaffold branches, reducing the risk of branch splitting and providing stronger support.

Height Management Ensures that the tree grows to an optimal height, reducing exposure to sunscald, wind damage, and making operations more manageable.

Balance Vegetative and Reproductive Growth Maintains a balance between vegetative growth (leaves and branches) and reproductive growth (flowers and fruits) for better yield.

Control Spread of Tree Limits the tree’s spread to make orchard operations like spraying, thinning, and harvesting more efficient and cost-effective.

Systems of Training in Fruit Crops

Different training systems are used to suit the growth habits of specific fruit crops. These systems focus on developing a tree structure that optimizes light penetration, productivity, and ease of maintenance.

1. Central Leader System

• Description:
  • This system is suitable for fruit trees with strong apical dominance, where the central trunk grows uninterrupted.
  • The tree develops a tall, closed canopy resembling a “Christmas tree.”

• Structure:
  • The main trunk, or “leader,” grows upright, forming the backbone of the tree.
  • Branching begins 75–100 cm above the soil surface, allowing movement underneath the tree.
  • Scaffold branches form in whorls, spaced 50–60 cm apart along the trunk. The lowest branches are the longest, with upper branches progressively shorter to allow sunlight to reach the lower canopy.

• Advantages:
  • Strong trunk supports the tree structure.
  • Facilitates better light distribution throughout the canopy.
  • Increases the tree’s height, maximizing vertical space utilization.

• Disadvantages: Limited accessibility for pruning and harvesting in tall trees.
• Example Crops: Pear, Walnut.

2. Open Center System

• Description:
  • The main trunk is headed back within the first year of planting, encouraging lateral branch development and creating an open center.
  • This system results in a low-headed tree with the majority of the crop closer to the ground.

• Structure:
  • The central stem is pruned to a certain height, allowing lateral branches to dominate.
  • The open center ensures sunlight and air reach all parts of the tree equally.

• Advantages:
  • Simplifies operations like spraying, thinning, and harvesting.
  • Promotes fruitfulness by allowing sunlight to reach all branches.

• Disadvantages:
  • Branches form weak crotches due to close spacing at the base.
  • Risk of branch splitting under heavy fruit loads.
  • Trees in high-light areas may suffer sunscald injuries.

• Example Crops: Peach, Apple.

3. Modified Leader System

• Description:
  • This system combines the advantages of both the central leader and open center systems.
  • The tree is initially trained as a central leader for 2–5 years, after which the leader is pruned, allowing lateral branches to form the main structure.

• Structure:
  • The central trunk is allowed to grow unpruned for the first few years, forming a strong base.
  • Lateral branches arise at reasonable intervals along the trunk.
  • Once the desired number of branches is established, the central leader is cut, and the top laterals take over as the primary branches.

• Advantages:
  • Results in a moderately spreading tree with strong branches.
  • Combines the strength of a central leader with the accessibility of an open center.
  • Facilitates better light penetration and air circulation.

• Disadvantages: Requires careful monitoring and timely pruning to avoid structural issues.
• Example Crops: Pear, Apple, Walnut.

Comparative Overview of Training Systems

Pruning

Pruning refers to the deliberate and judicious removal of specific parts of a plant, such as branches, shoots, roots, or other undesirable growth, to improve its productivity, quality, and health. It plays a critical role in maintaining a tree’s structure, promoting optimal fruit production, and ensuring longevity. Effective pruning allows for maximum light interception, better air circulation, and overall improved fruit size, firmness, soluble solids, and other quality attributes.

The intensity and frequency of pruning depend on the growth habits of the plant, its age, fruit-bearing patterns, and the season. By understanding and applying the principles and methods of pruning, farmers can maximize yield and maintain the health of their orchards.

Objectives of Pruning

Balance Between Vegetative and Reproductive Growth Pruning helps distribute fruiting wood evenly across the canopy, ensuring that the plant maintains a balance between leaf growth and fruit production.

Enhance Light Penetration and Air Circulation Thinning the branches improves sunlight and air penetration, allowing the interior parts of the tree to become more productive and reducing the risk of disease.

Improve Fruit Quality Pruning enhances the shape, size, color, and overall quality of fruits by concentrating the plant’s energy on fewer, healthier fruit-bearing branches.

Promote Regular Bearing By removing excess flowers and thinning fruiting branches, pruning helps avoid alternate bearing and encourages consistent annual production.

Disease and Pest Management Diseased, damaged, or insect-infested branches are removed during pruning, reducing the risk of spreading infections.

Optimize Fruit Size and Yield By diverting the tree’s energy from weak or non-fruiting parts, pruning enhances the quality and size of the fruits.

Maintain Tree Shape and Structure Pruning ensures the development of a strong framework that can support fruit load and withstand environmental stresses like wind or snow.

Methods of Pruning

There are three main methods of pruning used in fruit crops:

1. Thinning Out

• Definition: The complete removal of unwanted branches or shoots from their point of origin.
• Purpose: To reduce overcrowding and allow light to penetrate the canopy.
• Application:
  • Removal of water sprouts (vigorous upright shoots).
  • Elimination of crossing branches that cause shading.
  • Removal of weak or non-productive shoots.
• Result: Once a branch is removed through thinning, no new shoot arises from the same location.
• Example Crops: Used for citrus, apple, and guava trees to improve airflow and light distribution.

2. Heading Back

• Definition: Partial removal of the terminal portions of branches while keeping the basal part intact.
• Purpose:
  • To control the height of vigorous branches.
  • To stimulate lateral bud development by removing apical dominance.
• Process:
  • One-third to one-half of the terminal portions of branches are cut back.
  • This encourages the growth of shoots from the buds near the cut.
• Uses:
  • Filling gaps in the canopy.
  • Promoting spur-bearing or flower-bearing shoots.
  • Enhancing the structural balance of the tree.
• Example Crops: Common in pome fruits like apple and pear to develop a balanced canopy.

3. De-Blossoming

• Definition: The deliberate removal of excess flowers to regulate fruit production and ensure consistent yields annually.
• Purpose:
  • To prevent alternate bearing (fruiting heavily one year and minimally the next).
  • To balance the plant’s energy for better fruit quality.
• Application:
  • De-blossoming is often performed in crops like mango, apple, and guava, where excess flowering can lead to poor-quality fruit or uneven fruiting cycles.

Advantages of Pruning

Light and Air Penetration Improves light exposure to inner parts of the tree, enhancing photosynthesis and reducing disease.

Strengthens Tree Structure Helps develop a sturdy framework capable of supporting heavy fruit loads.

Improves Fruit Quality Enhances the size, color, flavor, and overall market value of the produce.

Encourages New Growth Stimulates the growth of productive shoots or spurs for future crops.

Regulates Crop Yield Ensures consistent production year after year by managing alternate bearing tendencies.

Disease Management Prevents the spread of fungal infections, bacterial diseases, and pest infestations by removing affected parts.