Everything you need to know about apricot cultivation! Learn about: 1. Botany of Apricot 2. Climate and Soil for Apricot 3. Orchard Cultural Practices 4. Propagation and Rootstocks 5. Planting Operation 6. Flowering and Fruiting 7. Training and Pruning 8. Harvesting and Handling.
Botany of Apricot:
The cultivated apricot belongs to the family Rosaceae and species Prunus armeniaca. The other related species are either grown for fruits, rootstocks or ornamental purposes. These are P. ansu, P. brigantiaca, P. dasycarpa, P.davidiana, P. mand schurica, P.mume and P. sibirica.
The cultivated apricot (Prunus armeniaca) is a small tree, 6-9 metres in height, with reddish bark and glabrous twigs. Leaves ovate to round ovate, sometimes subcordate, abruptly short- pointed, mostly obtusely serrate, glabrous above, pubescent on veins beneath, petioles with conspicuous glands. Flowers pinkish or nearly white produced before the leaves. Fruit is velvety when young, peach like in colour and shape, flesh yellowish orange. Stone is smooth and flattened.
Apricot is drupe fruit and its edible portion is epicarp and mesocarp.
Climate and Soil Required for Apricot Cultivation:
Apricot is very much susceptible to frost due to early flowering. Flowers are liable to suffer from frosts or cold winds during the period early February or March. Temperature limit for flowering lies near about 27-31°F and for fruit setting is 30-32°F. The minimum temperature for fruit ripening varied from 15-19°C. The apricot is grown successfully at an altitude of 1200-1500 metres above sea level.
Its variety St. Ambroise fruits better at higher altitude upto 1829 metres. White-fleshed, sweet kernelled apricots require cool climate and are grown in dry temperate region upto 3000 MSL. Yellow-fleshed, bitter kernelled apricots do best under the warm climate of mid hills ranging 900 – 1500 MSL and long cool winter, frost free and warm spring. They require 300 – 900 chilling hours below 7°C.
The long cool winter and uninterrupted warm spring are favourable for apricot fruiting. If the temperatures are hot for a long period during the dormancy, the flower bud may drop which is a serious problem in warmer climate. High humid conditions in summer increase the possibility of brown rot attack. An annual rainfall of about 100 cm is sufficient for obtaining a good apricot crop.
Apricots are quite hardy to grow in most of the soils which are deep and well-drained. The soil should be about 3 metre deep. The pH of soil should range in between 6 to 7. In Kinnaur region of Himachal Pradesh where apricots grow in large wild stands, the soils are sandy, well-drained but not very fertile. If the drainage is good, high lime content of the soil does not depress the tree growth.
Orchard Cultural Practices for Cultivating Apricot:
i. Irrigation:
The apricot tree has shallow roots; therefore, good soil moisture is beneficial. The purpose of irrigation to apricot is to wet the entire area containing a major portion of the roots. Since apricot roots are mainly confined to about 2 metres from the surface, irrigation should aim at wetting the land up to a depth of 2 metres. Special attention to irrigating the apricot tree should be given during April-Mid June when the fruit is in developing and maturity stage.
The apricot field should be irrigated at 10 days interval during May and weekly interval during June. In Himachal Pradesh, 8 irrigations in a season are sufficient for better fruit growth and quality. In the rainfed conditions mulching and water harvesting techniques should be practised but the cultivation of drought resistant cultivars is more desirable. Black polythene mulch in apricot orchard help in moisture conservation.
ii. Weed Control:
The weeds in apricot field are cleared with frequent light hoeing. The use of chemical weedicides has been tried successfully. Simazine or diuron in each @ 4-6 kg per hectare as pre- emergence herbicides in 15 year old trees of cv New Castle gave good control of emerging weeds for 90 days.
The post-emergence herbicides glyphosate @ 800 ml/ha or gramoxone @ 2l/ha are also effective in checking the weed flora in apricot orchards. The cost of applying weedicides is much less than manual weeding.
iii. Manuring and Fertilization:
Nitrogen plays an important role in apricot nutrition as its deficiency adversely affects the leaf dry matter content, fruit set and number of mature fruits. The deficiency of phosphorus causes reduction in fruit set, fruit growth and calcium and magnesium contents of leaves. The potassium application increases the growth, flowering, fruit size and yield.
Highest yields were recorded on the trees receiving N at 100-200 kg, P at 80 kg and K at 100 kg per hectare with leaf NPK contents of 2.5-2.7, 0.17 – 0.18 and 3.3-3.5%, respectively. On poor sandy soils, application of organic manure along with inorganic fertilizers is necessary.
Application of 450 g N, 150 g P2O5 and 750 g K2O per tree is recommended for 10 years old plants in Kashmir. Half dose of nitrogen and total quantity of phosphorus and potash should be applied two weeks before normal bloom. The second half of nitrogen should be applied three weeks after fruit set. In another study, for full grown tree of 7 years old, 40 kg FYM, 500 g nitrogen, 250 g phosphorus and 200 g potash in suggested. The phosphorus and potash along with FYM is applied in December. Half nitrogen is given a fortnight before flowering and half about one month after fruit-set.
Propagation and Rootstocks of Apricot:
Apricots are commercially raised by vegetative methods of propagation like budding and grafting.
Seed Propagation:
Apricot seeds require stratification for a period of 72 days at 4°C. The stratification medium should have proper moisture retaining capacity and good aeration. The germination of seeds can be hastened by removal of kernel from shell, scarification and gibberellic acid or kinetin treatment. The seeds are soaked for 24 hours in 500 ppm GA3 or 5 ppm kinetin solution before planting. Both the growth regulators also increase the seedling growth.
The seeds should be sown carefully in 30 cm apart in rows. Sufficient moisture in the nursery beds ensures good germination and seedling growth. Frequent watering and mulches helps in better germination. Application of terbacil at 2-3 kg/ha before weed emergence helps in weed control in the nursery. To make better growth of seedlings, small quantity of urea may be applied.
Rootstocks:
Apricots are generally propagated on wild apricot (Zardalu), wild peach seedlings and plum. Apricot seedlings are the best rootstock as the graft union on this is good and the trees are more vigorous than on plum. Peach is also a satisfactory rootstock for apricot, but sometimes the graft union is enlarged or rough. In rainfed orchards, where drought conditions prevail, apricot on peach makes better growth than on apricot seedlings.
Peach rootstock therefore, should be used in dry and light soils. Many apricot cultivars are not compatible with Myrobalan plum, but this rootstock is used when the trees are to be planted in heavy soils or under excessive soil moisture conditions. Marianna plum is also suitable under such conditions.
Vegetative Propagation:
T-budding, chip-budding and tongue grafting are generally adopted for apricot multiplication. The seedlings which attain pencil thickness in the month of May-June are budded and the other seedlings are utilized for fall budding in September. The rootstock should be more than 0.6 cm in diameter with a bark separating readily from the wood. The stock may be budded at a height of about 10-25 cm above the ground level in a smooth bark surface.
Some of the May-June budded plants become ready for planting in the dormant season while fall budded plants can only be utilized in the next dormant season. The seedlings which do not make enough growth for budding are usually grafted in the following dormant season January to mid-February by tongue grafting. A high percentage of success is obtained in apricot both in budding and grafting.
Planting Operation of Apricot:
The pits of 1 x 1 x 1 m dimension are dug in winter season i.e. December-January and properly filled with a mixture of soil and well rotten farmyard manure. On the plain land planting is done according to the square or rectangular or triangle system but on hill slopes contour system is generally practiced. The spacing of plants varies with the soil, climate and vigour of the cultivar to be grown. The plants are generally planted at the distance of 6 x 6 m in square system, thus, accommodates 275 plants per hectare.
To determine the minimum limit of planting density of 1110 to 8880 trees per hectare was followed in a trial adopting free spindle, Tatura and open centre training system. The highest cumulative 4-year yield was obtained with 2500-3333 trees per hectare.
Well grown plants of about one meter height should be planted. Water should be given immediately after planting to establish close contact between roots and soil.
Flowering and Fruiting of Apricot:
In apricot, usually three flower buds develop in the axil of a leaf at each node on a shoot and spur. The central one is vegetative bud and the two side ones are floral buds. In Himachal Pradesh, the flowering in apricot cultivars mostly occurs in the month of March.
The duration of flowering varies with the cultivar and prevailing weather conditions. High temperature, low humidity and wind shorten the flowering duration by increasing the transpiration. The apricot suffers more due to spring frost because of earlier blooming than other temperate tree fruits. A delay in its flowering is, therefore, very much desired to reduce the frost damage.
The pattern of growth is expressed by developing fruit of apricot cv. New Castle in respect of increase in length, diameter, weight and volume depicted double sigmoidal growth curve. The specific gravity of the young fruits, first showed an upward trend followed by a slight decline and thereafter, maintained more or less uniform trend, remaining slightly below unity. The approximate period of fruit development is 73, 82, 85, 88 and 96 days in case of Shipley, New Castle, Kaisha, Royal and Shakarpara cultivars.
Most of the commercial apricot cultivars have been found self-fruitful in pollination and set fruits without pollenizers but open-pollination has always given better fruit set. The cultivars Charmagz and Perfection are self-incompatible. The failure of fruit set is mainly due to persistent rains. The pollination by honey bees prove superior over wind pollination.
There is generally a good fruit set in apricot cultivars growing in appropriate climatic conditions. It was noted 45.6% in New Castle, Royal, Shipley Early and Kaisha cultivars of apricot. The highest fruit drop occurs in the second and third week after fruit set and ranges from 78.3 per cent in Kaisha to 61.4 per cent in New Castle. A spray of 10 ppm NAA or 50 ppm 2, 4, 5 T at the beginning of pit hardening reduced the pre-harvest drop.
Training and Pruning of Apricot:
The apricot is trained according to modified leader system. The young plants are more branched. Thinning out and selection of 4-6 well spaced branches is very important aspect of training in the first year of growth.
Pruning of Young Trees:
One year old trees of apricot usually have numerous lateral branches.
The main central axis is cut off 50-75 cm above the ground and all laterals are cut off if these are not properly spaced along the central axis. Pruning at the end of first growing season in winter consists in selection of 5-6 well placed laterals around the trunk. The lowest branch should be about 40-45 cm and all other laterals should be completely thinned out. All the selected laterals should be headed back to get the secondary branches on them.
During the second year growth only 5-7 secondary scaffolds about breast height are retained and others are removed. At the end of third year, the pruning is confined to the thinning of branches which are either crossing or crowding each other for proper development of the framework and to admit sunlight in the tree center to promote growth of spurs. The leader of the tree is modified after fourth year of its age by cutting it back to very close to a lateral branch.
Pruning of Bearing Trees:
Most of the crop is borne on spurs which live for 4-5 years. A small portion of the crop is also borne on one year old shoots. To produce new spurs annually and to replace the older and unproductive ones, light to moderate thinning of branches and heading back of new laterals is essential annually.
In old trees when the growth becomes less the heavier pruning is done by way of cutting back of main primary limbs and thinning of undesirable secondary laterals.
Harvesting and Handling of Fruits of Apricot:
The fruits of apricot develop maximum flavour and are very delicious when ripen on the tree but such fruits cannot be transported to distant markets because of their perishable nature. Fruits harvested well in advance of ripening do not attain full taste. Therefore, the standardization of maturity and harvesting is essential for obtaining good return from the marketing of fresh fruits.
The fruit colour, flesh colour, size, firmness, TSS, titratable acidity, dry matter content, days from bloom and accumulated heat units above 10°C are the main maturity indices. The best harvesting date of apricot is around 9th May i.e. 64 days after full bloom for the cultivar of New Castle under mid hill conditions. At this time, the fruit attained good size, barium yellow skin colour, amber yellow flesh colour, 10.03% TSS and 5.48% total sugars.
The apricot fruits are best harvested on the basis of days taken from full bloom to maturity. Charmagaz takes 70 – 75 days, Kaisha 72 – 77 days, Frogmore Early 80 – 87 days, Gilgati Sweet 120 – 124 days, Amba 127 – 130 days and Quetta 128 – 132 days from full bloom to maturity.
Early ripened better coloured fruits get a premium in the market. Ethrel @ 25-150 ppm two weeks before the expected harvest advance ripening by 2-5 days in the fruits of Kaisha cultivar.
Normally the fruits are picked when they changed colour from green to yellow and lose flesh firmness. Fully ripe fruits are harvested for freezing, canning and drying. The apricot plant starts bearing at the age of 4-5 years but attain full bearing age at about 8-10 years. The full grown apricot tree yields about 50-80 kg fruit. The productive life of a apricot tree is about 30-40 years.
Grading of Fruits:
The fruits should be packed in 5 kg wooden box or CFB box (36 x 16 x 16 cm). Special grade fruits are packed in 3 layers and Grade-1 and Grade-2 in 4 layers in the box.
Storage of Fruits:
The apricot fruits harvested at optimum maturity can be stored for 7 days at 5°C temperature and 85 per cent relative humidity. The fruits kept at 0°C and 85 – 95 per cent RH can be stored for 1 – 2 weeks. Black mould rot can be effectively checked by treating the fruits with 1000 ppm Benlate.