Sweet Potato

INTRODUCTION Botanical name: Ipomoea batatus Family: Convolvulaceae Chromosome no.: 2n=90 Origin: South America It is an important starchy food crop throughout the

tropical and subtropical countries. Popularly known as Sakarkand in India

AREA AND PRODUCTION Area = 111 thousand hectare Production = 1338 thousand tones per hectare The leading states in terms of area and production are

Bihar, Orissa and U.P. Sweet potato is grown in almost all the states of India

except Jammu and Kashmir.

USES Eaten usually after boiling, baking and frying and may

be candied with or used as a puree. Tubers are utilized for canning, dehydrating and flour

manufacture. Important source of starch, glucose, pectin, sugar syrup

and industrial alcohol. Sweet potato is the cheapest source of calories. Also contains appreciable amount of vitamin A, B, and

C.

VARIETIES Sweet potato cultivars grown in India are mostly

popular local cultivars. They are usually grouped either as white or red type. Few cultivars are currently used for commercial

production are: Pusa Safed and Pusa Red (Bihar and U.P.) Rajendra Sakarkand-5 (Bihar) H-268 (Maharashtra) Kanhangad Local (Kerela) H-41,H-42,H-268 and S-30(Andhra Pradesh)

POPULAR VARIETIES Co 3, Co CIP 1 Sree Kanaka( high carotene sweet potato) Sree Nandini Sree Vardhini Kiran Sree Bhadra Sree Rathna Gouri Sankar Others are:

OP-1,H-260,Cross-4,V-35,Kalmegh

Red type Sweet Potato White type Sweet Potato

SOIL The best soil is sandy loam and clay subsoil. It can be grown in loamy to clay loam soil also. Soil should be well drained and soil pH varies from 5.2

to 6.7. Heavy clay soil and highly sandy soil are undesirable.

CLIMATE It requires moderately warm weather. Temperature ranges between 21.1-26.7 ̊C Temperature less than 20̊C was found critical for

tuberisation. Requires plenty of sunshine and moderate rainfall i.e. 75

to 150 cm. High rainfall and long photoperiod promote vine growth

and reduces tuber yield.

PROPAGATION Sweet potatoes are propagated from sprouts or from slips (vine

cuttings); sprouts are preferred. Sprouts are grown from plant stock selected for its appearance, freedom from disease and off-types.

Approximately 75-100 kg of planting stock sweet potatoes are needed to produce enough sprouts to plant one hectare. Selected tubers are planted at a spacing of 45 x 30 cm & 5-6 cm deep.

The sprouts are cut after 40-45 days and planted in secondary nursery. The cuttings 20-30 cm in length are planted in this nursery at a distance of 60 x 30 cm.

For 1 ha, primary nursery of 100m² and a secondary nursery of

500 m² are required.

SWEET POTATO CUTTINGS

Planting Season: June-July and September are highly suitable for

planting. Manures and Fertilizers:

Farmyard manure :100-150 q/ha. 90: 60: 90 kg N, P₂O₅ and K₂O per ha. Half of dose nitrogenous fertilizer is applied as basal and half dose 40 days after planting.

Irrigation: The critical stage of moisture supply is 40 days after

planting and earthing up (35DAP) may be followed by irrigation.

Interculture and Weed control:In early stages of crop growth i.e. up to two months

after planting, weeds are a problem to sweet potato. Two manual weedings at 20 and 45 days after planting are sufficient to keep the weeds under control. Earthing up is done at second weeding to prevent exposure of roots (particularly during rainy season). Fluchloralin @ 1.0 kg/ha in the soil as pre-planting to control the weeds is effective. Also, application of chloramben @ 3.0 kg/ha at post planting stage control the weeds.

EFFECT OF GROWTH SUBSTANCES

Foliar application of CCC at 250,500 and 1000 ppm increased the yield.

Application of ethephon at 250 ppm results in larger number of tubers and higher yield.

Foliar application of kinetin at 50 and 100 ppm caused higher tuber yield of (number, fresh and dry weight)

HARVESTING Sweet potato is usually harvested when the leaves turn

yellow begin to shed. Maturity can be ascertained by cutting tuber and the

latex from mature tuber dries up without turning black. The time of harvesting differs with cultivar which may

extend from 120-180 days. Avoid mechanical injuries while digging out tubers.

YIELD AND STORAGE Yield:

Under irrigated conditions= 35-40 t/haUnder rainfed conditions= 8-10t/ha

Storage:Highly perishable nature of tubers of sweet

potato does not permit it to be stored for a long period in the tropics.

Sweet potato were successfully cured at RH 80-90% and temperature 29-40̊C for 5-7 days.

Stem Rot or Wilt (Fusarium oxysporum f. batatus)

Symptoms: Leaves become yellow along with discoloration of vascular bundles. The fungus infects tuber and causes circular shrunken spots.

Management: Use clean, healthy

planting material Crop rotation Resistant varieties

Diseases

Black rot (Certocytis fimbriata)

Symptoms: Yellow sickly appearance of foliage and black spot on tubers.

Management: Use clean healthy planting

material Dip cutting in 0.2%

solution of Aretan or Agallol before planting.

Cercospora leaf spot ( Cercospora bataticola) Symptoms: Dark brown leaf spots with a light shade

at the centre. Management: Three spraying of 0.25% Dithane M-45 at fortnightly

interval is effective. Soil rot (Streptomyces ipomoea) Symptoms: On tubers infection starts as a spot and

the skin collapses leaving cavities with irregular margins.

Management: Maintain Soil pH (5.2 or less)

Scurf (Monilochaetes infuscans)

Symptoms: Produces black spot of varying sizes and shapes on the tubers.

Management: Good drainage Application of sulphur @

300-400 lb/acre to neutral soils.

Soft rot (Rhizopus nigricans) Symptoms: Soft watery rot on tuber and fleshy tissue

becomes soft and water exudes from affected skin Tissue becomes brownish.

Management: Proper temperature and a RH of 85-90% should be

maintained.

PESTS Sweet Potato Weevil(Cylas formicarius)

Management Clean Cultivation Crop rotation Treatment of planting material with 0.05% Monocrotophos,

spraying at tri-weekly interval from one month after planting. Other pests are

Stem borerLeaf feeding caterpillarsLeaf feeding beetles

ATTACK OF STEM BORER

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