Morphological characters and Flowering:
- Apple plant is deciduous without spiny branches.
- Buds are ovoid with imbricate scales, leaves are serrate or lobed, folded in bud and stipulate.
- Floral buds are mixed buds borne terminally on spurs and terminally or laterally on long shoot, depending upon the cultivar, age and vigour of tree.
- The initiation of flower primordia starts about 3-6 weeks after full bloom (June).
- The inflorescence is determinate having five flowers. Flowers white or pink or carmine in cymes.
- Flower of most cultivars are epigynous and hermaphrodite.
- Flower consists of five petals, five sepals,15-20 stamens and a pistil which is divided into five carpals each containing two ovules.
- Ovary is inferior.
Pollination and Pollinizers:
- Most of apple varieties are self unfruitful and can not produce fruit if fertilized by their own pollen and thus require some compatible cutivars for cross pollination and good fruit set.
- Apple tree produce abundant bloom but fail to set fruit especially under adverse climatic conditions due to lack of pollination Inadequate fruit set often results from a failure during the pollination period, which is associated with pollen production, transfer and germination, pollen tube development or fertility of the ovule.
- Sterility and incompatibility are two main causes of unfruitfulness in apple. Self incompatibility is most common, although cases of cross incompatibility are also known. The commercial cutivars Red Delicious, Royal Delicious, Top Red, Vance Delicious, Red Chief and Oregon Spur are self incompatible.
- Various climatic and edaphic factors are also responsible for poor pollination and fruit set.
- Low temperature, rainfall and cloudy weather at flowering time adversely affect the bee activity, transfer of pollen to stigma, pollen germination, and ultimately result in poor fruit set.
Plate 2. Non synchronization of flowering of main and pollinizer cultivars due to insufficient winter chilling
- The cross pollination and fruit set in apple can be improved by planting atleast 25 to 33 per cent of pollinizers,
- placement of 5 to 6 honey bees colonies per hectare,
- top working of 2-4 shoots of commercial varieties with pollinizers.
- placement of bouquets.
Insufficient winter chilling
- The cross pollination and fruit set in apple can be improved by planting atleast 25 to 33 per cent of pollinizers,
- placement of 5 to 6 honey bees colonies per hectare,
- top working of 2-4 shoots of commercial varieties with pollinizers.
- placement of bouquets.
NUTRITIONAL REQUIREMENTS
- Apple requires all the essential nutrients for proper growth and fruit production.
- The nutrient requirement is mainly met through the application of manures and fertilizers, which should be applied annually.
Manure and fertilizers
- The manure and fertilizer requirement depend upon the soil fertility, age of tree, cultural practices and crop load.
- To judge the actual nutrient requirement, the leaf and soil analysis should be done to know the status of nutrients in the tree and soil.
- The manure and fertilizer schedule for any fruit crop is suggested after long term fertilizers trial.
- In the orchard of optimal fertility, nitrogen, phosphorus and potassium is applied in the ratio of 70:35:70 g per year age of apple tree and doses of these NPK fertilizers are stabilized at the age of 10 years .
- For ten or more than ten year- apple tree, 100 kg FYM, 700 g N, 350 g P2O5 and 700 g K2O should be given annually.
- The N, P and K are applied in the form of calcium ammonium nitrate, single super phosphate and muriate of potash fertilizers, respectively.
Time and method of application
- FYM along with full dose of P2O5 and K2O is applied during December-January.
- Nitrogen is applied in two split doses. Half dose of N is applied one month before flowering (March) and remaining half dose one month after fruit set.
- These fertilizers should be applied when there is enough moisture in the soil.
- The fertilizers should be broadcasted in tree basins 30 cm away from the trunk..
- However, in very steep slopes and heavy rainfall areas band application of fertilizers is recommended to avoid leaching and run off losses of fertilizers.
- For higher fertilizer use efficiency, soluble fertilizers can also be applied through drip irrigation.
Foliar application of nutrients
- The micro-nutrients particularly boron, zinc, iron and manganese are essential for normal growth of plant and their deficiency is frequently observed in apple.
- It can be corrected by two foliar sprays of ZnSO4 (0.5%) and boric acid (0.01%) before flowering and in May-June.
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