B.N.- Solanum tuberosum Famliy- Solanaceae
Nutritive value- The potato is rich source of carbohydrates (22.6g) while other nutrients like protein (1.6g) and vitamin C (17 mg) are also present in the edible part of the potato.
Uses- Potato is the king of the vegetables. It is mainly used as curry. Preserve potatoes are very popular in market as allu chips, allu bhujiya. It is highly consumed as allu chop, katlet, aalu dam etc.
Varities- Kufri jyoti, Kufri siduri, Dijire, Janak dev, Khumal rato-2, Khumal seto-1, Cardinal, NPI 106, Kufri badshah etc.
Climatic and soil requirement- Potato is a cool season crop and requires low temperature, low humidity and bright sunny days. The temperature for germination of tubers and satisfactory tuber growth is 25oC and 17-19oC respectively. A temperature above 30oC completely stops the tuber formation.
Potato can be grown on a variety of soil but well drained sandy loam to clay loam soils rich in organic matter having pH 5.5-7.5 are found best.
Manuring- Potato is heavy feeder and thus, needs a high doses of nutrients. Well rotten FYM @ 200-250 q/ha in the soil 3-4 weeks before planting is incorporated. Besides 100 kg N, 100 kg P, 60 kg K depending upon type of soil and fertility status should be supplied. 2/3 quantity of N and whole quantities of P and K should be applied at the time of planting. Apply the remaining dose of N at 30-35 days after planting i.e. at the time of first earthing up.
Time of planting- The planting time of potato varies considerably from region to region. The main time of planting in high hills is falgun to chaitra, poush to magh for mid hills and asoj to mangsir for terai.
Method of planting- The commonly used methods of potato planting are as follows:
Flat bed method- It is commonly adopted in areas having light sandy soils. The tubers are planted in flat beds in very shallow furrows. The method requires two earthing up. First at 30-35 DAS and second 25-30 days after first earthing up.
Furrow planting- In this method tubers are planted in furrows (5-7 cm deep) and adopted in irrigated areas having light sandy soils. It needs ridging to 10-15 cm height soon after planting and then at 30-35 DAP.
Planting on ridges- The ridges of 30 cm height are made at 70 cm spacing and tubers are planted opposite in these ridges.
Seed size, spacing and seed rate- Tuber having 25g weight and 2.5-3.0 cm diameter are considered ideal for main crop planting. Seed rate depends upon the size of seed tubers and spacing. A medium size of tuber can be planted at a distance of 75 cm from row to row and 25 cm from plant to plant. Generally 15-20 q seed tubers are required for one hectare area.
Cutting of seed- Cut the large sized tubers in small pieces with the help of disinfected knife. The main objective of cutting the seeds are to lower down the cost of seed. During cutting keep 2-3 healthy eyes on the cut pieces. The average weight of the cut seed piece should be 30-40g.
Irrigation- Being a shallow rooted crop, potato requires light irrigation frequently. In general light soils should be irrigated at an interval of 8-10 days whereas heavy soils at 12-15 days. Light irrigation should be given when frost is expected. The critical stages for irrigation are germination, tuber formation followed by earthing up and tuber bulking appears at 10-12, 30-35 and 55-60 DAP respectively.
Weeding- Two manual weeding first at 15-20 DAP and second weeding-cum-hoeing at 30-35 DAP. The first weeding may be replaced by use of herbicide but second weeding and hoeing at earthing is a must. The most common herbicide used to control weeds in potato are Fluchloralin (1.0 kg/ha) and Pendimethalin (0.5 kg/ha) used as pre-planting while Simazine (0.5 Kg/ha), Alchlor (1.0-1.5 kg/ha) applied as early pre-emergence and Paraquat (0.5 kg/ha) applied at early post emergence i.e. when more than 5% potato plants have just emerged from the soil.
Earthing- If potato tubers are exposed to sunlight, they will start to synthesize anthocyanin and chlorophyll. The chlorophyll formation in tubers check the accumulation of starch which resulted in small sized tubers with bitter in taste due to presence of Solanin. Generally two earthing is sufficient in flat bed planting. First at 30-35 DAP and second at 25-30 days after first earthing up. Irrigate the field lightly just after earthing.
Harvesting- The time of harvesting of potato depends on number of factors viz. variety, market price, weather condition, purpose for which crop is grown etc. Early varieties mature in 80 days, medium in 90-100 days and late in 100-120 days. Sometimes, the crop is harvested early to fetch high market price and to facilitate the sowing of succeeding crop. Potatoes harvested at full maturity stage will have better shelf life. Withholding of irrigation about 15 days before the harvesting will harden the skin of tubers. The harvested tubers are allowed to dry in open under shade.
Insect pests-
Aphids (Aphis gossypii and Myzus persicae)- The nymph and adults suck the sap from tender parts of the plant. They also act as vector for several viral diseases like potato mosaic, leaf roll virus etc.
Management-
Incorporate Phorate 10 g @15 kg/ha in the soil at planting in the furrows.
Spray the crop with Dimethoate (Rogor) 0.05% .
Potato tuber moth (Gnorimoschema opercullela)- It is a serious pest of potato both in the field and storage. After hatching, the caterpillar bores and makes tunnels into the tubers.
Management-
Select healthy and insect free tubers for planting.
Proper earthing should be done so that tubers are not exposed to ovipositing female moth.
Spray the crop with carbaryl (0.2%).
Treat the gunny bags used for storage with Neem karnel extract at 10%.
Cutworms (Agrotis ipsilon)- Among the different spices of cutworm the Agrotis ipsilon is the most common and devasting one. The caterpillars cut the young seedlings at the base near the soil.
Management-
Apply phorate 10 g @ 15 kg/ha in the soil before sowing.
Drench the soil around the plants with cholofevninphos @ 0.05%.
White grub (Holotrichia insularis)- The grub feed on the roots and developing tubers and make large holes. The adults feed on the foliage of trees and lay eggs in the soil.
Management-
Follow clean cultivation.
Apply phorate 10 g @ 15 kg/ha in the soil before sowing.
Spray the neighbouring trees with endosulphan @ 0.03%.
Diseases- (Fungal diseases)
Early Blight (c.o.- Alternaria solani)- The disease is characterized by the appearance of dead spots with concentric rings on the leaves. The fungus is soil borne and warm moist weather is favourable for the development and spread of disease.
Control-
Grow resistant varieties like kufri sinduri, kufri jeevan etc
Follow crop rotation
Adopt phytosanitary measures
Spray dithane M-45(Mancozeb), Dimethomorph etc. @ 0.25% at 10 days interval.
Late blight (c.o.- Phytophthora infestans)- Circular or irregular water soaked spots appear on the leaves which soon turn to brownish black lesions. The lesions enlarge and coalesce killing the entire leaves. Decayed leaves emit offensive odour. Cool moist environment is favourable.
Control-
Use healthy, disese free and certified seed tubers for planting.
Locate resistant varieties like- Kufri jeevan, kufri alankar etc.
Make four prophylactic sprays of Blitox-50 or dithane M-45 at 7 days interval.
Spray the crop with dithane M-45 @ 0.25% at 15 days interval starting from the appearance of disease.
Wart (Synchytrium endobioticum)- It is a serious soil disease but restricted to only Darjelling hills and surrounding areas. The disease attacks all under ground part except roots. Affected parts exhibit warty outgrowth. The wart is a distorted, proliferated branched structure grown together into a mass.
Control-
Follow quarantine measures
Avoid potato cultivation on wart affected soil.
Grow wart resistant varieties like Kufri jyoti, kufri jeevan.
Soil sterilization should be done by copper sulphate or formaline before planting.
Bacterial diseases-
Bacterial wilt (Pseodomonas solanacearum)- It is characterized by the appearance of wilting, stunting and yellowing of foliage followed by collapse of the plant. Browning of the xylem in the vascular bundles occurs. The infected tubers are discoloured. The pathogen is soil borne.
Control-
Use healthy, disese free and certified seed tubers for planting.
Follow at least 3 years crop rotation with maize, cowpea, French bean etc.
Treat the seed tubers with streptocycline solution @ 0.02% for 30 minutes before planting.
Soft rot (Erwinia carotovora spp. atroseptica)- The infected plants remain dwarf and stunted. Leaves turned yellow and curled. Brown black rotten areas develop on the base of the stem called black leg. The affected tubers become dark both inside and outside. The internal tissues become soft resulting in disintegration of whole tuber. The pathogen is also prevalent in storage.
Control-
Select disease free seed tubers for planting.
Follow long term crop rotation.
Uproot affected plants and destroy them.
Treat the seed tubers in streptocyclin solution @ 0.01% before planting.
Viral diseases
Leaf roll- It is affected by leaf roll virus. The leaves of affected plant roll upward turn light green in colour and become leathery in texture. It is transmited through several species of aphids (Myzus persicae).
Mosaic- The causal organism is potato mosaic virus. mild mottling or light green colours of the infected plants occur. It is transmitted mechanically by the contact of disease plants and other farm implements.
Control-
Select disease free seed tubers for planting.
Uproot affected plants and destroy them.
Before the use of tools implements wash them with 3% solution of trisodium phosphate.
Post-harvest, handling and storage- Nearly one fifth of the total potato production in the country is used as planting material in the following season. Therefore, post-harvest handling particularly seed stocks become very important. After harvesting potatoes are kept in heaps in cool places for another 10-15 days for drying and curing of skin. Heaps 3-4 meter long, wide at the base and 1 meter in the central height are the best. In hills the harvested potatoes are spread in well ventilated rooms for drying. Before grading all the cut, damaged and rotted tubers are removed. The tubers are then graded and packed in gunny bags according to sizes preferably in 4 sizes, e.g. small (below 25g), medium (25-50g), large (50-75g) and extra large (above 75g). After grading potatoes meant for use as seed next year are treated with 3% boric acid solution for 30 minutes for protecting against soil-pathogens, e.g. black scurf, common scab etc. before storing in the bags.
In plains the seed potatoes after drying, curing and grading are stored in cold stores where temperature is maintained at 2-4oC with high relative humidity. The low temperature checks sprouting and rottage and high relative humidity reduces weight loss in tubers.
Value added products of potato- Potatoes can be easily processed into dehydrated and canned products like- chips, french fries, finger chips, granules, disc, cubes, flour etc.
Marketing- Potatoes are semi-perishable and bulky therefore their transport to long distance is problem. Often potatoes rot during transit because of high temperatures at the time of transportation. The problem is compounded further due to shortage of transporting wagons. The total cold storage capacity in the country is very low. The markets in potato producing belts in plains are also not properly integrated. Because of these factors marketing of potato is a complicated process and potato price are prone to high fluctuations and often glut situations. www.narc.gov.np
