ROLE OF BORON (B) IN APPLES
Micronutrients play a vital role in apple production. Boron is the key nutrient, important for flowering, fruiting, pollination and fruit quality. Boron is required in very small amounts but if it is deficient several disorders can occur. It is important in normal tissue development and cell wall structure. Adequate boron will help in increased pollination and fruit set, as it is responsible for pollen germination and pollen tube formation. It will help in lessening the bitter pit disorders. So if there is a poor supply of boron, there will be poor flowering, low fruit set and hence low yield.
Key role of boron
- It develops the cell wall structure.
- It increases flowering, pollination and fruit set.
- It helps in lessening the bitter pit spots.
- It helps in moving the nutrients from the leaves to the fruits.
- It is required for the reproductive growth in plants.
- It plays a crucial role in pollen tube growth.
- It helps in pollen tube elongation.
- It helps in pollen germination.
Boron Effect on Pollination and Fruit-Set
Boron is very important in pollen germination and pollen tube growth which helps in fruit setting. Application of boron can result in good fruit set hence higher yields. It has been observed that pre-bloom application of boron increases fruit set as well as yields. Soil application of boron also increases yield but to lesser extent. It has also been observed that foliar boron application after bloom increased fruit yield in apples.
Stages for Foliar Application of Boron
- Green tip —- pink bud
- fruit set—-pea stage
- post harvest—20 days before leaf fall
The boron can be applied as foliar spray @250gms/200lts of water. The boron can be applied single or can also be mixed with other pesticides. Over dosage of boron can result in many disorders.
Symptoms of Boron Deficiency
- Dieback of shoot tips
- Boron is important for flower formation and fruit set so its deficiency can result in decreased yields.
- B-deficiency can also result in “CORK PIT” (cork pit, darkening of internal tissue).
- Another symptom is bitter pit.
- Apples picked from boron deficient plant may be deformed, corked and can be more susceptible for russeting.