Tropical & Subtropical Fruits

Biennial bearing in mango

Mango producing good crop one year and no crop or fewer crops in the next year is known as biennial bearing or alternate bearing.
This is genetic and inherent in mango varieties.
Major causes for this are supposed to be

1. Climatological factors: Rain, high humidity, low temperature making on to off year
2. Age and size of shoots: Shoots of 8-10 months maturity will be productive.
3. Carbon/Nitrogen ratio: High carbon/moderate N encourages flower bud formation (30-40)
4. Hormonal balance: Higher levels of auxin and inhibitor like substance and lower levels of gibberellins like substances were found to be vital for a flowering shoot.
Inspite of several studies, the biennial bearing is still an unsolved problem which is thought could be corrected by genetic engineering only.

Presently the suggested measures to overcome biennial bearing are:

1. Proper upkeep and maintenance of orchards
2. Deblossoming in one year (NAA)
3. Smudging and chemical regulation like application of paclobutrazol (10gm/tree), spraying 1-2% KNO3, 6-8% calcium nitrate, etc.
4. Pruning: Pruning the fruited shoots and opening tree top properly
5. Growing regular bearing cultivars: Bangalore, Rumani, Neelum and almost all hybrids.