CULTIVATION PRACTICES OF SAPOTA

Cultivation

Planting

      Since sapota is a crop of warm and humid tropics, it can be planted in any season provided irrigation facilities are available. But it is beneficial to plant the grafts in beginning of the rainy season. In areas having heavy rainfall, it can be planted in September. In light soils, pits of 60cm × 60cm × 60cm size, whereas in heavy and gravely soils pits of 100cm × 100cm × 100cm size are made in April–May and exposed to sun for 15 days. Top 30cm soil is mixed with equal quantity of well-rotten compost or farmyard manure, 3kg superphosphate and 1.5kg muriate of potash are used for pit filling. To begin with all sides and bottom of the pit are dusted with 5% BHC dust and pits mixture is added to fill the pit and remaining vacant space is filled with remaining soil to a height of 15cm above soil surface. Such pits are left to monsoon rains for settling and then planting is done at appropriate time. At the time of planting, a small hole sufficient to accommodate the ball of soil and roots of grafts is made in the centre of the pit and planted with scion in the direction of heavy wind to avoid damage to joint. After planting, soil around the plant is gently and firmly pressed and stakes are provided to avoid wind damage. Planting should preferably be done in the evening to avoid sun heat. The plants are then lightly watered. Young plants should also be protected against sun scold by providing dry grass thatch on top and three sides excepting the south-east for sunlight. Such well-cared plants establish fast.

        Since sapota tree makes uniform all-round growth, square system of planting is recommended. However, in land with 5–15% slope, contour planting is recommended. Depending on growth habit, sapota orchards are planted at 10m × 10m but being slower in growth, it takes longer period to occupy allotted space. Therefore, high-density plantations having 5m × 5m spacing up to the age of 13 years are very remunerative. Thereafter yields begin to decline.

Training and pruning

        A seedling tree grows excellently giving a shape of an umbrella. However, plants raised through inarching require training for appropriate shape and framework development. No definite system of training has been developed for sapota. Most trees are trained in central leader system.

Sapota being an evergreen tree requires no regular pruning but regulation of vegetative growth to improve productivity and quality of fruits is necessary. At times thinning of branches is affected in old plantation. Pruning in sapota is confined to open the tree to light, and removal of dead and diseased branches.

Manuring and fertilization

       Owing to evergreen nature of the plant, any inadequacy in its nutrition leads to sub-optimal yield. Deficiency of N leads to yellowing of leaves from margin to mid-rib. The P-deficient plants have purplish flecks on lamina with rusty pigmentation all over and inadequacy of K is marked by development of chlorotic symptoms along leaf margins which become dark grey in advanced stage. Zinc deficiency is marked by small and erect leaves, short internodes and defoliation of terminals, whereas in calcareous soils Fe deficiency causes general yellowing of leaves with premature shedding.

     

       A dose of 50kg farmyard manure, 1,000g N, 500g P₂O₅ and 500g K₂O/tree/year is optimum. This quantity can be regulated on the basis of age of tree and status of nutrients in soil especially of P and K. Under rainfed conditions, dose of N should be raised to 1.5kg/tree. Castor cake is beneficial for high-quality fruits. The nutrient doses prevalent in the country are given in Table 2.

Table 2. Fertilizer doses for sapota (per tree)

State	Farmyard manure	N (g)	P2O5 (g)	K2O (g)
Andhra Pradesh	50.00	400	160	450
Assam	1.25kg bone-meal + 8kg caster cake
Gujarat	50.00	900	450	450
Karnataka	50.00	400	160	450
Kerala	55.00	500	360	750
Madhya Pradesh	50.00	500	250	125
Maharashtra	30.00	500	-	-
Orissa	15.00+200g stera meal	45	150	-
Tamil Nadu	50.00	750	640	1,200

        Under rainfed condition, fertilizers should be applied before the onset of monsoon. However, under irrigated conditions it should be applied in 2 splits. Total quantity of organic manure and half of chemical fertilizers should be applied at the beginning of monsoon and remaining half in the post-monsoon period (September–October). Since 90% of active roots are distributed within drip up to a depth of 30cm, nutrients should be applied under tree canopy and mixed thoroughly in soil up to a depth of 15cm. In Zn and Fe deficiency, the requirement should be met through application of organic manures and spraying of ZnSO₄ and FeSO₄ (0.5%).

Aftercare

       Depending on growth habit of sapota tree a planting distance of 10m × 10m is ideal. Being a slow-grower, it takes longer to occupy allotted space. Therefore, intercropping is imperative. Intercropping banana, papaya, pineapple and cocoa; French bean, tomato, brinjal, cabbage, cauliflower and cucurbits is recommended depending on climate and water resources. In established orchards, pre-monsoon and post-monsoon intercultivation is recommended for better aeration and effective weed control. In young orchards, weed hazard is common. Use of 2kg Bromacil + 2kg Diuron/ha as pre-emergence spray is effective for a period of 10–12 months. Mixed plantation with mango and guava should be avoided to reduce the problem of fruitfly.

Irrigation

        Habit of tree and its vegetative growth demand continuous supply of water. But sapota is grown both under irrigated and non-irrigated conditions. Sapota requires irrigation at 30 days interval in winter and 15 days in summer. Adoption of drip irrigation system is also beneficial, saving 40% water with 70–75% higher net income. This system should be laid out with 2 drippers spaced 50cm from tree during initial 2 years and 4 drippers at 1m from tree until 5 years of age. With dripper discharge rate of 4litres/hr, the system should be operated for 4 hr during winter and 7 hr during summer on alternate days. Under short supply of water, timing could be 3hr and 30minutes in winter and 5hr and 40minutes in summer.

Harvesting and Postharvest management

         Sapota takes about 7–10½ months from anthesis to maturity of fruits depending on variety and climate. Fruits follow double sigmoid pattern of growth. Properly developed fruits have high TSS and sugar, and reduced acidity, astringency, latex and vitamin C. Maturity is decided on the basis of ease with which brown scruff gets off the fruit surface and development of yellowish tinge intermixed with corky-brown colour on the surface of the fruit. At this stage, practically no green tissue and milky latex are seen on fruits when scratched with nails. The fruits are hand picked or harvested with special harvester which has a round ring with a net bag fixed onto a long bamboo. Depending on management level, 15–20 tonnes fruits are harvested from a hectare.

         Since sapota is a climacteric fruit, it has to be ripen artificially. Fruits are highly perishable and they undergo rapid ripening changes within 5–7 days during which the fruits become soft, sweet and develop excellent aroma with decline in tannins, latex sapotin, aldehydes and acidity. These changes are associated with increase in production of ethylene, rate of respiration, catalase, peroxidase and PME activities. These changes can be regulated through chemicals, temperature and storage gas composition.

        Harvested fruits should be cleaned of latex and scurf by washing in clean water to make them look attractive. Such fruits should be graded into big, medium and small sizes. Fruits should be tightly packed in cardboard boxes of 10kg capacity with rice straw as padding material and with ethylene absorbents and transported quickly to wholesale markets. For extending shelf-life and to avoid storage rots, fruits can be dipped in GA 300ppm + Bavistin 1,000ppm solution at prepacking stage. For uniform and rapid ripening Ethephon (1,000ppm) can be utilized at 20°–25°C. Modified storage with 5–10% (c/c) CO₂ can be employed for long storage (21–25 days). Refrigerated vans (12–13°C) should be utilized for long distance and export markets.