Regulating leaf number:
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Sufficient number of green leaves is necessary for growth, development, and yield. Insufficient number of leaves results in low quality fruits and lesser inflorescence . About 75-100 leaves are in Khadarawy, Zahidi, Barhee, and one to every 8-9 leaves in Halway, Deglet Noor and Dayri. Further, 12 leaves/ bunch is optimum leaf-bunch ratio in Barhee dates. Optimum yield and good quality fruits could be obtained with 8 active leaves /bunch when 5-8 bunches/ plant are retained. The old and senescing leaves should be pruned. Time of leaf pruning is June. To facilitate pollination and subsequent handling of bunches, the spines from the leaves around bunches are also removed in the late winter to early spring.
Pollination:
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• Date palm is highly cross pollinated due to its dioecious nature.
• In commercial plantation, mechanical or hand pollination is done. For this, 2-3 male trees are enough to pollinate 100 female palms.
• About 2-3 strands of male flowers are inserted between the strands of female flowers. Since metaxenia is common in date palm, selection of a good pollenizer is important. The quality of date fruits, particularly fruit size and time of ripening are influenced by pollen. Under Indian conditions, early ripening is desired to avoid losses due to rains. If the male spathes open earlier than female, the pollen is dried and stored for use at a later date. Dried pollen containing about 10% moisture can be stored satisfactorily with calcium chloride at room temperature for 2-3 weeks.
Fruit thinning:
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Fruit thinning is necessary to ensure adequate flowering in the following year, to improve fruit quality, prevent delayed ripening and reduce compactness and increase ventilation of the bunches. Thinning can be done manually of by chemical sprays. Manual method is common which involves removal of some bunches or strands from each bunch or shortening the length of strands. The number of fruit that a palm can sustain depends on variety, age, vigour and number of green leaves. Three to four bunches/palm is recommended from fifth year onwards. In India 8-10 bunches are left on each palm. The best results are obtained by removing one third strands from the centre of the bunch. Plant growth regulator ethephon is an effective fruit thinning agent. It provides additional benefit in inducing early ripening of berries. This is of great significance in India, as harvesting of fruits before the onset of rains is advantageous. Ethrel at 500-1,000ppm encourages early ripening.
