Unfruitfullness

A. External Factors:

• The environmental conditions govern the life cycle of a fruit plant
• These conditions greatly influence the flowering and fruit setting in the fruit plant
• Factors like nutrition, pruning, water supply, rootstock used, temperature, insect pests and diseases affect the fruiting in fruit trees

1. . Climate:

I. Temperature:

• This is one of the most important factors, which governs the flowering, fruiting and fruit development
• Temperature requirements are species specific
• Variation in day and night temperature or extreme fluctuations, or continuously hot temperature adversely affects the pollination and fruit set in most of the fruits
• For example, cloudy weather at full-bloom stage affects the pollination and fruit set in soft pears and plum
• Poor setting in Sapota fruit is due to drying of flowers
• Temperature affects the bee activity in an orchard
• Bees help in the pollination and fruit setting

II. Rainfall:

• Rainfall is very important to maintain the underground level of water
• It also helps in improving the quality of fruits particularly in peaches and mango
• Rain at full bloom washes away the pollen, stigmatic fluid and keeps the pollinizers away, hence affecting the fruit set

III. Winds:

• There are many fruits which get pollinated through wind (Anemophily)

• For these plants movement of air at the time of flowering is necessary to affect pollination
• Most of the fruit plants are insect-pollinated (entomophilous)
• In such plants, wind hinders rather than helping in pollination

IV. Frost/Freeze:

• It is the most important factor for deciding the fruitfulness in an orchard
• Frost injury can convert a regular bearing cultivar into an irregular bearing
• Even orchards may not produce any fruit for two to three years continuously due to killing of branches caused by severe frost

V. Hail Storm:

• Hail storm has been found to be very harmful in hilly areas
• Most of the apple crop was damaged by hails at fruit set, Hails kill flower buds and blossoms
• There are areas which are prone to hails and freezes every year
• Some areas are almost free from these hazards in the same zone

VI. Cloudy Weather:

• Cloudy weather is more dangerous than hails. The humidity makes the conditions most favorable to spread fungal diseases
• Powdery mildew in mango usually appears in cloudy weather

2. Disturbed Moisture in Soil:

• Soil moisture is one of the key factors to production of fruits

• The excess soil moisture as well as low soil moisture conditions at the time of flowering and fruit set encourage abscission layer formation, leading flower and fruit drop
• Growing cover crops or mulching the basins can overcome the low soil moisture
• Flooding of the orchards at flowering time should be avoided

3. Nutrition:

• When balanced nutrition is not given the plant’s growth and development is affected
• The practice of application of fertilizers at the time of flowering/fruit set should be avoided
• The manures and fertilizers need to be applied one to two months before flowering and in split doses after fruit setting
• Imbalance in the nutrients certainly cause unfruitfulness or flower drop
• Higher doses of fertilizers render many kinds of fruit plants more vegetative and without flowers or produce abnormalities in the flowers
• Excess of nitrogenous fertilization induces barrenness in plants

B. Internal Factors:

• Some fruit species produce abundant flowers arid set little fruit
• Sometimes there may not be any fruit on a tree.
• Pollination failure, sterility or deficiency of nutrients may be the major cause of unfruitfulness

The internal factors are:

(1) Impotency, (2) Incompatibility, and (3) embryo abortion

• Some other factors are related to flower structure and form