Avocado (Persea armenican)
Fruits are out favorite to eat just to sustain life, fulfill required nutrition to body & maintain the sound health of our body. Avocado is called Ghiufal in Nepali which is especially known as fruit of rich people. It becomes more sweeter on having more which contain more fibers with sweet flavor. This fruit contains low amount of sugar with high caloric value which makes it perfect for diabetic patient. Ripen avocado is used as table fruit while its pulp is used in preparing bread, ice-cream & milk shake.
Avocado is believed to be originated from Central America.
Climate & Soil:
Avocado prefers tropical & sub-tropical mild cool climatic condition. Frost & severe cold cause injury to avocado. At freezing temperature, yield of avocado is tentatively zero. It can be cultivated from 600m to 1300m altitude above sea level. West Indian cultivars perform better in tropical whereas Mexican & Guatemalan cultivars perform well in sub-tropical zone. It is susceptible to drought & requires average annual rainfall of 66-146 cm throughout the year. Optimum temperature for this fruit is 14-28 degree Celsius with soil of pH 4-7, deep fertile soil with better drainage facility.
Species & Cultivars:
- Mexican race: Hash, Ethinger, Urtaj
- Guatemalan race: Green, Red
- West Indian race: Purple
- Hybrid: Furte (cross between Guatemalan & Mexican species)
Normally, plant to plant distance is 10m with pit size of 1m3 dug 1 month before transplanting. Pit is filled with 20-25 kg FYM & top soil in ratio 4:1 in the month of Baisakh raising pit 1ft above the ground surface. Mark the center if the filled pit with stake. Saplings are transplanted during rainy season month Jestha or Ashad at the center of pit.
Seed is main propagation material in Nepal. Germination ability of seed is very less only 2-3 weeks. So, it is stored in dry pit or at 5degree Celsius temperature for extending its longevity. Germination percentage will be higher when it is sown removing outer covering of seed. Seed is sown 2cm deep in polythene bags which can be transplanted in main field after a year.
Irrigation for avocado plant is provided at 21 days interval during winter, 10-15 days during autumn following ring method. Irrigation through pipes at basin is not good as it causes root rot in avocado.
It is heavy feeding fruit plant. Every year 20-25 kg well decomposed FYM & nitrogen, phosphorus & potassium fertilizer in ratio of 1: 1:1 for plants with age below 10 while 2: 1: 2 for plants above 10 years. When soil pH is greater than 7, iron deficiency is prominent in avocado so, iron chelate @ 35gram/plant is applied.
Calculate the required amount of fertilizer here.
Training pruning & inter-culture:
In avocado, light pruning is carried out. Upright growing varieties are cut back to promote lateral branching. In varieties where branches growth is dominant, pruning is done to maintain scanty branches with shorter length. Diseased, pest affected & small crutch angled branches are pruned from time to time.
Shallow root crops or leguminous vegetable crops are planted as inter-culture crop in avocado orchard. Tillage is restricted not to distract the surfacial roots. Mulching is necessary around the base of truck of tree.
Flowering & Fruiting:
Male & female flowers mature at different time known as dichogamy. So, self-pollination is not possible in avocado. 2-3 cultivars of avocado is planted in the same orchard to maintain sound pollination for fruiting in avocado tree. Mexican cultivars are early maturing type. A group & B group variety are present in avocado according to flowering pattern & time. Temperature plays role in flower opening in avocado plant. Beep hives are necessary in the orchard @ 1 hive per ropani. A-type & B-type varieties must be planted in ratio 1:1 or 2:1 in avocado orchard.
A type: Hash, Gyun, Pinkartan, Female stimulated pollen turn red, Anahem, Lab dash Mexico etc.
B type: Tray, Jutaune, Bacon, Hobbitsell, Surprise, Ethinjar etc.
Effect of Temperature in Flowering:
- when temperature falls below 60 degree Fahrenheit there will be no fruiting at all.
- Research carried out in California with varieties under A group & B group in hayash avocado fruit rating has been good with 40-150% increase in yield.
- In A group varieties, during initial days they flower in the morning and stops during daytime whereas it starts only in the next day afternoon.
- In B group varieties, during first day, they flower in the noon whereas they flower in the morning in the next day.
- According to this flowering pattern, the female A type variety is pollinated by pollen of B type variety everyday. They receive each others pollen at different period of time.
Harvesting & yield:
Avocado is climacteric fruit which is harvested after it reaches maturity & artificially ripen after harvesting. For dark green fruit variety when fruit turns into light green or in type with seed slight intact, on hitting the fruit producing hollow sound is indication for harvesting. Fruiting starts from 5-6 years of age. According to type of avocado, 100-500 fruits yield in a single tree.
Immediately after harvest, grading according to type or size of fruit is done shipping in suitable package. It is ripened artificially due to its climacteric nature at suitable temperature in suitable room. It takes 6-12 days at 20 degree Celsius temperature for mature fruit to fully ripen. Cold resistant varieties can be stored at 4 degree Celsius in cold storage while other cold susceptible varieties are stored at 10-13 degree Celsius.