AGRONOMY PRACTICE PLUM

• It is self-fruitful, high yielding indigenous variety with vigorous tree. Fruits are medium sized, round oblate depressed at both ends, on ripening turn dark purple. Flesh is yellowish with moderately juicy pulp. Fruits are somewhat acidic with 15% TSS and 1.2 per cent acidity. It ripens in the second week of May. Average yield is 45 kg /tree. Fruits are excellent for jam making.

• Kala Amritsari is propagated by hard wood cuttings while Satluj Purple by simultaneous grafting and rooting of rootstock cuttings. The time of preparation of cuttings and grafting is from end of December to end of January. Hardwood cuttings of Kala Amritsari should be 15-20 cm in length with 4-5 buds on them and should be of pencil thickness . To increase the rooting success their basal parts (4-5 cm) are dipped in 100ppm IBA solution for 24 hours. For making this solution, dissolve 100 mg IBA in 10-15 ml of alcohol and make up the volume to one litre.
• Satluj Purple is multiplied through stenting technique simultaneous grafting and rooting of rootstock cuttings. The cuttings of Kabul Green Gaze are used as rootstock. Rootstock cuttings about 20 cm in length are tongue grafted with scion wood in the first fortnight of January. The basal parts of the grafts are given 24 hours soaking treatment with 100 ppm (100 mg/litre of water) IBA solution. The cuttings/ grafts are transplanted in well prepared nursery plots at a distance of 15-20 cm in rows spaced 30 cm apart. The plants from the cutting/grafts are available for planting after one year in the month of January.

Manures and fertilizers to the plum trees are applied according to their age.

Apply farm yard manure, super phosphate and muriate of potash in December. Split the N fertilizer in two halves. Apply half of N fertilizer in spring before flowering and second half one month later after fruit set.

• Plum trees growing on light textured soils generally show zinc deficiency symptoms on the current season growth in the summer months. The affected leaves on the terminal parts of branches are narrow, small with interveinal chlorosis. On the growing tips, the affected leaves appear in whorls rossette form. If the deficiency persists, it may cause die back of the twigs and the fruits become hard and undersized. Zinc deficiency can be corrected by foliar spray (0.6% Zinc sulphate solution) containing 3 kg zinc sulphate and 1.5 kg unslaked lime in 500 litres of water as and when the deficiency symptoms are observed on plants.

• The young plum plants upto the age of 3-4 years need irrigation at 4-5 days interval during summer months starting from April to June. Being deciduous, the plums do not require frequent irrigation during winter. Apply irrigation only when the drought period is prolonged. The bearing trees should be given regular irrigation from fruit set to maturity. In summer, irrigation should be given at an interval of 4-5 days.

• Weeds can be checked by manual ploughing in the soil. Application of paddy straw mulch (10 cm layer) @ 4.5 per acre effectively check the weeds. Mulching should be done during first week of March after application of second split doses of inorganic fertilizers.

• Two sprays of NAA 10 ppm (Dissolve 1 gram NAA in 10-15 ml alchohal and then make 100 litre solution with water) in 2nd and 4th week of April or one spray of Ethrel 100 ppm (25 ml Ethrel in 100 litres of water) in 4th week of March (after pit hardening) reduced the pre-harvest fruit drop in plum cv. Satluj Purple.

• There should not be any water stress in the orchard at the time of spray of growth regulators.
• Ethrel 100 ppm should be sprayed just after pit hardening and neither before nor later than this. Otherwise, it may increase fruit drop.
• As the fruit growth is rapid during April, trees should be irrigated frequently.

• The maturity of plum fruits is indicated when these have attained normal size and colour. The peak season for plum harvest in Punjab starts from first week of May. The first sign of fruit maturity is the change of green colour to purple, red or yellow according to the variety. For local consumption fruit should be picked at ripe but firm stage. For distant market, fruits are picked when these have developed 50% colour on the skin and should be firm.
• Plum fruits are harvested with stem intact avoiding any skin injury. Fruits being perishable in nature should be handled with care. The basket used for picking should be padded with soft dry grass at the bottom and on the sides. Immediately after harvest, transfer the fruit to some shady area under the trees/shed. For local market, fruit should be picked in the early hours of the day and immediately shifted to the shed/tent for sorting, grading and packaging. For distant market the fruits are picked in the evening hours and kept in the orchard shed to cool them overnight for sorting, grading and packaging.

Post-harvest Handling

• The fruits which are over ripe, soft, bruised or immature should be discarded. Fruits are graded according to their size, colour and appearance. Different grades of fruits are packed in separate boxes and labeled. Three standard sizes recommended under “Ag-Mark” system of grading of plum along with the box size are as follows:

  Grade	Fruit size (diameter in cm)	Inner size of box (cm)	Number of layers	Number of fruits/layer
  Special	4.2 & above	36´16´16	3	28-32
  Grade-I	3.6-4.2	-do-	4	38-42
  Grade-II	Below 3.6	-do-	4	50-56

• In general, the fruits should be packed in 5 kg wooden boxes instead of bamboo baskets. To prevent the fruits from injury, interior of wooden box should be lined with newspaper sheets on all sides and paper strips as padding at the bottom. The fruits are placed in layers. After each layer make a partition of paper strips over lined with newspaper sheet. Top layer of the fruit is covered with a cushion of paper strips and newspaper sheet and finally the lid of the box is nailed.

• Plum is a perishable fruit and its shelf-life is short. Low temperature storage prolongs the effective life of fruit. For best results fruit should be picked at the correct maturity and placed immediately in commercial cold stores where temperature is 00-30C with relative humidity 85-90%. The fruit remains in good condition for 25 days. To facilitate better marketing of plum, refrigerated vans are desirable for transportation.

• The Satluj Purple plum fruits, harvested at colour break stage, followed by post-harvest treatment of calcium nitrate (2%) solution for five minutes, can be stored for four weeks in cold storage (0-10C and 90-95% RH) with post storage shelf-life of 2 days at ambient temperature.
• Non alcoholic naturally carbonated beverage can be prepared from fruits of Satluj Purple and Kala Amritsari plum at small and large scale. It has three months shelf life and retains its original nutrients.