alternate bearing character in mango and apple and reasons behind this behavior was discussed

2.  Alternate Bearing: Alternate Bearing (AB) refers to an
alternating cropping pattern that is internally regulated by
the plant.
(OR)
The tendency for wide cyclical swings in yield (‘On’
and ‘Off’ years).
Effects of alternate bearing:
 AB is a significant economic problem
 Low quality of on year crop
Net return to the grower is low during off-years crop
The limited supply of fruit in the off-crop

3. Nuts Temperate
Fruits
Sub-Tropical
Fruits
Tropical
Fruits
Most effected with AB
Formula 1: Alternate bearing index (I) = (year 1 yield) - (year 2 yield) / (year 1 yield + year 2
yield), where I = 0 is no alternate bearing and I = 1.0 is complete alternate bearing; and
Formula 2: Alternate bearing = (current year's yield) - (5-year running average yield)/5-year
running average yield; when the current yield is 20% greater than the 5-year average yield, it is
an on-crop and when the current yield is 20% less than the 5-year average, it is an off-crop.
( Monselise and Goldschmidt, 1982)
ABI:

4. Theories of alternate bearing
Starch depletion theory
Inhibition of flowering by hormones

5. S.no Endogenous factors
1 Genotypic differences 10 Effects of leaves
2 Competition between vegetative
and reproductive sinks
11 Crop over load
3 Carbohydrate reserves (C:N) 12 Tree age and vigour
4 Hormonal imbalance (auxin, GAs,
CK, ABA and Poly amines)
13 Natural abscission of buds,
flowers and fruits
5. Flower inhibition by growing fruits 14 Nutrient status
6 Pollination 15 Age and size of shoot
7 Effects of seeds on fruit drop 16 Fruiting habit
8 Root stocks 17 Growth pattern
9 Branch anatomy 18 Others

6. Exogenous factors
I. Environmental factors
Temperature
Light
Relative humidity
Rains
Snow
Spring frost
Hails
Water stress
II. Edaphic factors
III. Biotic factors

7. Measures to overcome biennial bearing
 Proper orchard management
 Regulation of flowering (use of chemicals, Smudging,
girdling and application of paclobutrazol)
 Tipping growing shoots
 Proper nutrition
 Deblossoming
 Fruit thinning
 Selective pruning
 Early harvesting
 Growing regular bearing cultivars
 Dwarfing root stocks
 Gibberellins as anti flowering agents (“on” crop year)

8. Conclusion:
 Alternate bearing is a serious economic problem for growers and the
industry
 It is difficult to find a hypothesis that explains all aspects involved in
alternate bearing
 Horticulturally the key is to attempt the maintenance of the ideal
vegetative and reproductive balance as determined for particular
environmental conditions
 Research in specific areas is needed in order to fine tune orchard
management practices that growers can use to eliminate alternate
bearing