Crop Regulatory Practices in Horticultural Crops.pdf

Crop regulatory practices in horticultural crops involve techniques to optimize plant growth, enhance yield, and improve quality. These practices include pruning, thinning, and training to manage canopy structure, ensuring better light penetration and air circulation. Growth regulators, such as auxins, gibberellins, and ethylene, are often used to control flowering, fruit setting, and ripening. Proper irrigation scheduling, nutrient management, and pest control are also critical for maintaining plant health and productivity. These practices help achieve uniform growth, improve marketability, and reduce losses in crops like fruits, vegetables, and ornamental plants.

1. Crop Regulatory Practices
22CHOR11 - Fundamentals of Horticulture 2(1+1)
Dr. M. Kumaresan (Hort.)
Department of Horticulture
Vels Institute of Science, Technology & Advanced
Studies (VISTAS)
Pallavaram, Chennai, Tamil Nadu -600117

2. CROP REGULATORY PRACTICES
Crop regulatory practices mean developing a desired shape of the tree with particular
objectives by controlling habit of growth.
Its is start from nursery stage of plant.
Some fruit crops like grape Vines, Ber, Fig, Guava etc., require training

3. Terms
•Trunk: The main stem of the plant.
•Head: The point on the trunk from which first branches arise.
•Scaffold branches: The main branches arising from the head are known as scaffold
branches. Trees in which scaffold branches arise within 60-70cm height from the ground
level are called low head trees and those in which they come out from the trunk above 120cm
are called high head trees.
•Crotch: The angle made by the scaffold limb to the trunk or the secondary branch to the
scaffold limb is called crotch.
•Leader: The main stem growing from ground level up to the tip dominating all other
branches is called leader.
•Water shoot: A vigorous growing unbranched shoot arising on any branch or leader is called
water shoot.

6. Objectives of Training
•Maximize light penetration: By training plants into desired shapes, growers ensure that the
canopy receives adequate sunlight, which is essential for photosynthesis and fruit production.
•Improve air circulation: Proper training helps in reducing the risk of fungal diseases and
pests by promoting better airflow between plant parts.
•Optimize space utilization: For crops grown in limited space, training helps direct plant
growth vertically or along specific structures (e.g., trellises), thus maximizing the area
available for planting.
•Enhance fruit quality and yield: Properly trained plants tend to produce more uniform
fruit, improve fruit size, and reduce overcrowding, leading to better yields.
•Facilitate harvesting: Training plants can make it easier to access fruits, reducing labor time
and improving the quality of the harvest.
•Support plant structure: Especially for tall or vining crops, training can prevent plant
breakage or lodging, supporting the weight of fruits or flowers

7. DETAILS OF TRAINING
Height of head
•The distance from the ground level at which the main of scaffold limbs branch from the trunk is
known as the “height of the head” and this has to be decided before training
•Low head: 0.7–0.9 meters, which is common in windy areas
•Medium head: 0.9–1.2 meters, which is the most common height and can withstand wind while still
being easy to manage
•High head: More than 1.2 meters, which is common in wind-free tropical areas
•High headed trees help in easy orchard cultivation but in tropical climate, high headed trees are
unsuitable as their exposed trunks are subjected to sunscald injuries.
•Low headed trees come into bearing comparatively much earlier and are able to resist stormy
winds more effectively and permit easy cultural operations like pruning, spraying, thinning and
picking.

8. DETAILS OF TRAINING
Number of scaffold limbs
•Number of main branches or scaffold limbs to be allowed while training varies from
2 to 15 or even more.
•If there are only two or three main scaffold limbs, they are almost certain to form
‘crotches’, that they are likely to split and allow one or two branches to break down.
•These weak crotches may be avoided by training more and better spaced scaffold
limbs.
•A fruit tree with 5 to 8 numbers of scaffold branches makes it mechanically strong and
at the same time open enough to facilitate necessary orchard operations.

9. DETAILS OF TRAINING
Distribution of scaffold limbs
•Distribution is more important than the number.
•If the scaffold branches arise at closer interval i.e. 20 to 25 cm distances, they form
bad crotches much sooner than when distributed at 45 to 60 cm distances of the
trunk.
•Crotch angle should be also considered in selecting scaffold branches.
•Cambium divides continuously forming new layers, therefore, branches which grow
upright should be removed as the angle is ‘y’ shaped.
•Layers of cambium are not continuous and the branches may be easily broken.
•On the other hand, branches arising from the trunk at angles ranging from 45 to 90°
are the strongest because the cambium is continuous without phloem inclusion

10. METHODS OF LEADER TRAINING
•Open centre (Vase-shaped system): Main stem is allowed to grow only upto a certain
height and the leader stem is pruned to encourage scaffold branches production.
•Central leader (closed centered) : In this system a tree is trained to form a trunk which
extends from the surface of the soil to the top of the tree.
• Modified leader: It is intermediate between the open centre and central leader. This
is developed by first training the trees to the leader type by allowing the central axis to
grow unhampered for the first four or five years. The central stem is then headed
back and lateral branches are allowed to grow as in the open centre system.

11. METHODS OF LEADER TRAINING

12. Bower system
•Bower system is also called as ‘Pandal’ or ‘Arbour’ or ‘Pergola’ system.
•Practiced in grapes and other cucurbitaceous vegetables
•Vines are spread over a crise cross network of wires, usually at 2.1 to 2.4 m above
ground, supported by concrete or stone pillars or live support like Commiphera sp.
•Vine is allowed to grow single shoot till it reaches the wire net and is usually
supported, by bamboo sticks tied with jute thread.
•Vine reaches the wires, its growing point is pinched off to facilitate the production of
side shoots.
•Main advantage of this system is that it is capable of giving higher yield.
•Main drawbacks are (i) most expensive system (ii) pruning; training and spraying
operations are generally difficult.

13. Bower systems

14. Bower system

15. Bower system

16. Bower system

17. Bower system

18. Espalier system
•Plants are trained to grow flat on trellis or on horizontal wires by training the branches
perpendicularly to the main stem on both the sides and trained horizontally on to
wires.
•Plants trained in this system are called ‘espaliers’.
•Espalier with one shoot or two shoots growing are called as ‘cordon’

19. Kniffin system
•Two trellis of wire are strung supported by vertical posts.
•Vines such as grape when trained in this system has four canes one along each wire
and the bearing shoot hangs freely with no tying being necessary

20. Telephone system
•Overhead trellis system
•Consists of 3 or 4 wires usually kept at 45-60 cm apart fixed to the cross-angle arms
supported by vertical pillars or posts

21. Tatura trellis
•Trees are trained to a multi-layered wire trellis.
•Trellis is V-shaped, supported by two long, stout poles embedded into the soil at
angles of 60° from the horizontal.
•Five wires at 60 cm intervals are fastened to these poles.
•Followed for pome fruits, nut fruits and grapes.
•Trees are grown as double leader.
•Tree with each leader is inclined at an angle of 60° from the horizontal.

22. Pruning
Pruning involves the removal of certain parts of the plant, such as dead or diseased branches,
to improve growth, yield, and overall health of the plant. Pruning is done at specific times of the
year, depending on the plant species and the goals of the grower

23. Objectives of Pruning
•Remove dead, damaged, or diseased wood: Pruning helps in eliminating unhealthy growth,
which can prevent the spread of diseases and pests.
•Promote new growth: By cutting back older wood or unproductive branches, pruning
encourages the development of new, healthy shoots and branches.
•Enhance fruit production: In fruiting crops, pruning can help direct energy into the
formation of fruit-bearing buds, leading to higher yields and improved fruit quality.
•Shape the plant: Pruning is used to control the size and shape of a plant, ensuring it stays
within the desired space and is aesthetically appealing.
•Improve air circulation and light penetration: Removing excess branches and foliage
opens up the canopy, reducing the risk of diseases and improving photosynthesis, which
contributes to healthier growth.
•Maintain plant health: Pruning ensures that the plant's energy is directed toward the
strongest branches, promoting overall plant health and longevity.

24. Methods of Pruning
•Thinning out: A few shoots or branches that are considered undesirable are removed
entirely without leaving any stub.
•Heading back: Removal of terminal portion of the shoots, branches or limb, leaving its
basal portion intact
•Thinning: Removing entire branches or stems from the base to open up the plant and reduce
overcrowding. This helps improve air circulation and light exposure.
•Cleaning: Removing dead, diseased, or broken wood from the plant. This is usually done
early in the growing season to maintain plant health.
•Renewal Pruning: Cutting back old or unproductive growth to encourage the development
of new, more vigorous growth. This is common in fruit crops like apples or raspberries.

25. On the basis of bearing habit
Six categories
•Fruit buds borne terminally and giving rise to inflorescence without leaves. e.g. Mango, Cherry, etc.
•Fruit buds borne terminally and unfolding to produce leafy shoots which terminate in flower clusters.
e.g. Apple
•Fruit buds borne terminally and unfolding to produce leafy shoots with flower or flower clusters
e.g Guava
•Fruit bud borne laterally containing flower parts only and giving rise to inflorescence without leaves
or leaves present, they are reduced in size., e.g. Citrus
•Fruit bud borne laterally and unfolding to produce leafy shoots terminally in flower clusters this type
of flowering is noticed in grapes and cashewnut.
•Fruit buds borne laterally and unfolding to produce leafy shoots with flower clusters in leafy axils.,
eg. Fig.

26. 1. Fruit buds borne terminally and giving rise to inflorescence
without leaves

27. 2. Fruit buds borne terminally and unfolding to produce leafy
shoots which terminate in flower clusters

28. 3. Fruit buds borne terminally and unfolding to produce leafy shoots with
flower or flower clusters

29. 4. Fruit bud borne laterally containing flower parts only and giving rise to
inflorescence without leaves or leaves present, they are reduced in size

30. 5. Fruit bud borne laterally and unfolding to produce leafy shoots terminally
in flower clusters

31. 6. Fruit buds borne laterally and unfolding to produce leafy shoots with
flower clusters in leafy axils

32. SPECIAL PRUNING TECHNIQUES
Root pruning
•A circular trench of 45 cm away from the stem is dug out annually and the roots are cut-off
every year with a sharp knife.
•After pruning, the trench is filled with manures
•As a result of this the circular mass of fibrous roots increases very slowly from year to
year and the tree makes short but stocky and well ripened shoots.
•Diameter of the circular trenches may be extended slowly as years roll on.
•Each year 4 to 5 cm of the stumps of the previous year growth are pruned.
•This helps to increase the production of mass fibrous roots, dwarf the trees and bears
abundantly.
•In Deccan Virdharba area of North India, root pruning is practiced to induce flowering of
oranges in required season.

33. SPECIAL PRUNING TECHNIQUES
Ringing
•It is one of the known practices to increase fruit bud formation in certain fruit crops.
•Operation consists of removal of a complete ring of bark from a branch or the trunk.
•Ringing interrupts the downward passage of carbohydrates through the phloem and thus
causes them to accumulate in the part of the tree above the ring.
•Ringing is practiced on mango to force flowering in over vegetative trees which do not
normally bear a satisfactory crop.
•This practice cannot be recommended for all fruit crops and it is found beneficial in
promoting fruit set in certain vigorously growing grape varieties and they often result in
large size fruits.

34. SPECIAL PRUNING TECHNIQUES
Notching
•Notching is a partial ringing of a branch above a dormant lateral bud.
•The operation consists of removing a small narrow strip of bark just above and close to a
dormant bud.
•Notching above a bud increases the yield of fig trees in Pune.
•In apple, notching helps to produce strong shoot.
•Notching a bud prevents the inhibitory influence of certain compounds on the bud, the supply of
carbohydrates coming through the phloem from above and increase the supply of water and
nitrogen from below through the xylem.
•The practice of notching below a bud (otherwise known as ‘nicking’) is effective in starting a
floral shoot.
•It causes a greater concentration of carbohydrates in the bud and reduces the supply of water and
nitrogen from below.
•Nicking helps to produce spurs from buds in apple

35. SPECIAL PRUNING TECHNIQUES
Notching

36. SPECIAL PRUNING TECHNIQUES
Smudging
•It refers to the practice of smoking the trees like mango, commonly employed in
Philippines to produce off-season crop.
•Smoke is produced by burning branches and fallen leaves on the ground and the smoke is
allowed to pass through the centre of the crown of the trees.
•Tree is smoked heavily and continuously for a week.
•Smoking can be discontinued as soon as the terminal buds in the past season should begin to
swell.
•Smudging of mango trees, not followed in India

37. SPECIAL PRUNING TECHNIQUES
Coppicing
•Complete removal of the trunk in trees like Eucalyptus and Cinchona.
•Coppiced stump starts producing many vigorous shoots in about 6 months’ time.
•Only 2-3 shoots are retained per stump and the rest ones are completely thinned out.
•These left out shoots attain coppicing stage in about 10 years depending upon the locations
and other factors.
Pollarding
•This refers to the practice of removing the growing point in shade trees especially in silver
oak in order to encourage side branches

38. SPECIAL PRUNING TECHNIQUES
Lopping
•This refers to the practice of reducing the canopy cover in shade trees in order to permit
more light.
Pinching
•It usually refers to the removal of terminal growing point in herbaceous plant so as to
induce more laterals or side shoots production.
•Pinching is normally practiced in flower crops like carnation, chrysanthemum to reduce
the plant height and to promote axiliary branching.
Disbudding
•The practice of removing unwanted flower buds in a cluster so as to encourage the
remaining buds to develop into a large, showy, quality bloom is called disbudding.
•This practice is commonly done in cut flowers like carnation, chrysanthemum, dahlia,
marigold and zinnia etc.

39. SPECIAL PRUNING TECHNIQUES
Bahar treatment
•This practice is followed with fruit trees like mosambi, santra, grape fruit, guava,
pomegranate ber, lime etc. in the state of Maharashtra, M.P. and Gujarat etc.
•As there is no distinct winter (very cold winter) these fruit trees are usually continuous
vegetative growth resulting in indistinct flowering season.
•This practice is useful in encouraging flowering as well as regulating the time.
•About 1 to 1½ months prior to the expected flowering irrigation is withholding.
•There are three flowering seasons namely Mrig bahar, Hasta bahar and Ambe bahar.
•Mrig bahar: Flowering in June-July
•Hasta bahar: Flowering in October-November
•Ambe bahar: flowering in December-February

40. SPECIAL PRUNING TECHNIQUES
Thinning
•Fruiting is an exhaustive process to the tree especially if the crop is heavy.
•Permit the tree to mature as large a crop as possible and yet conserve sufficient nutrients and
carbohydrates for good shoot and spur growth, leaf development and flower bud formation
for the next year crop.
•In order to ensure proper balance between the amount of new shoot growth and flower
bud formation, thinning is practiced in certain fruit crops.
•Thinning is the removal of a part of flower buds, flowers or fruits (before it matures on
the tree) with the object of increasing the marketability of the remaining fruit and reducing
the alternate bearing tendency.

41. SPECIAL PRUNING TECHNIQUES
Time of thinning is also important
•In certain fruit crops, thinning is done at blossom timing (blossom thinning) to prevent
exhaustion.
•In other fruit trees, to prevent the overcrowding of the fruits, thinning is done at marble
stage.
•In few other fruit crops, thinning should be done soon after the natural fruit drop of
young fruits has started i.e. little before they have grown one-fourth of their normal size.
•The amount of thinning of fruits depends upon crop set, response of the variety to
thinning, nature of pruning given, age of the tree and the value of the increased size of
fruit in the market.

42. SPECIAL PRUNING TECHNIQUES
METHODS OF THINNING
Hand thinning
•The method is costly and advisable if diseases are present.
•20% hand thinning of pea size berries is beneficial to certain varieties of grapes.
•Thinned inflorescence produces better quality fruits.
•Manual thinning is common in date palm in which removal of some branches or removal
of some strands from each bunch or shortening the length of the strands is done.

43. SPECIAL PRUNING TECHNIQUES
METHODS OF THINNING
Chemical thinning
•Thinning of blossoms may be effectively and cheaply done by spraying certain chemical
substances.
•Naphthalene acetic acid (NAA) is effective in thinning the crop when applied two or
four weeks after petal fall stage in grapes.
•NAA at 100 ppm reduces the fruit setting from 67% to 50% in Anab-e-Shahi variety of
grapes.
•In mandarin, NAA 600 ppm on marble sized stage is recommended to thin overbearing
fruits so as to increase the size and quality of fruit.