By Qamar Shahzad Anjum, Institute of Horticultural Sciences, University of Agriculture Faisalabad Pakistan.
Pakistan is blessed with four seasons, having ideal environmental conditions for diversified agriculture production systems. Total geographical area of Pakistan is 79.6 million hectares ranging from great Himalayas to fertile Indus basin and deserted areas in Sindh and Baluchistan. Presently out of this total area, only 24.6 million hectares is under cultivation including 4.2 million hectares covered with forests. Remaining area accounts for deserted, mountainous and barren lands. Area classified as irrigated is about 18 million hectares while 6.6 million hectares is subjected to natural arid environmental conditions, completely depending upon natural precipitation to meet the crop irrigation requirements.
Agriculture sector plays the role of backbone for the country pertaining to its socio-economic matters. Contribution of this sector to National Gross Domestic Production is 21.62% and involves about 44.7% of the total employment of the country. There is no blinking the fact that agriculture is the sector which has great potential to be explored for amelioration of economically strained circumstances, in which our country is entangled. Substantial growth of agriculture sector will not only tackle the menace of food security but will also resolve the severe issue of unemployment to great extent. Agronomic as well as horticultural crops are of great importance for feeding the 200 million people of the country. Major horticultural produce of the country are vegetable and fruit crops. Among the vegetables potato ranks higher position regarding area under cultivation and total yield.
Globally potato is fourth largest food crop after rice, wheat and maize. China is the top country on global scale for potato production where 74.79 million tonnes were harvested in 2010. India produced 36.57 million tonnes of potato in 2010. In 2010-2011 potato was cultivated over an area of 159.4 thousand hectares (0.159 million hectares) and 3726.5 thousand tonnes (3.73 million tonnes) of potato were harvested in Pakistan. Surplus potato produced locally is exported to Dubai, Malaysia, Sri Lanka, Indonesia, Singapore and Iran. In 2009-2010, 245.329 million kg potato was exported to above mentioned countries and about Rs. 15 Billion export revenue is generated by potato yearly. Russia is another big market where demand of Pakistani potato is on rise.
Domestication of potato is reported to be between 8000 BC-5000 BC in the regions of modern Peru and Bolivia. Present cultivated species of potato (Solanum tuberosum) is considered to be originated from Solanum brevicaule found in Peru. International Potato Center (Peru) holds the position of ISO-Accredited Collection Authority for potato germplasm. Potato plants are herbaceous perennials and require 25 0C temperature for germination, 20 0C for vegetative and 16-19°C for tuber formation. It is an entomophilic cross pollinated crop. Protein and energy production of potato crop is 1.4 kg/ha/day and 216 MJ/ha/day, respectively while for wheat crop protein production is 1.3 kg/ha/day and energy production is 135 MJ/ha/day. These figures make potato superior to wheat crop.
Freshly harvested potato tubers contain about 79% moisture contents and 21% dry matter. Of total dry matter about 60-80% is starch in the form of amylose and amylopectin. Its nutritional value can be revealed by the presence of vitamins (B1, B2 and B6), minerals (potassium, phosphorus and magnesium), falate, pantothenic acid and riboflavin. In addition to this research activities explored its medicinal value. Presence of soluble and insoluble fibers help in preventing constipation, protect from colon cancer and decrease absorption of dietary cholesterol which leads to lower plasma LDL cholesterol. Recent studies suggest that flavonoids, antioxidants and querceton present in potato tubers have anticancer and cardio-protective properties and also protect our human body from infectious agents and scavenge harmful, pro-inflammatory free radicals.
Starch from potato tubers is extensively used in paper, wood, textile and pharmaceutical industry where it is used as binder, texture, adhesive and filler agent. Oil drilling firms make use of potato starch for washing the boreholes. Tubers may contain toxic alkaloids as solanine and chaconine. Formation of solanine in tubers is indicated by greenish discoloration with sprouts on potato skin.
In our country potato cultivation is categorized in three growing seasons as spring, summer and autumn crop with different geographical locations. In spring season it is grown in plains and lower hills of Balochistan and KPK province in January-February with harvesting in April-May. Summer crop is sown in northern hilly areas and Azad Jammu and Kashmir in March-May with harvesting in August-September. Autumn sowing is done in plains and
southern Punjab, Sindh and plains of Balochistan in September-October and harvesting is done January-February. In total annual production, share of spring, summer and autumn crop is 7-10%, 15-20% and 70-75% respectively. For total area under cultivation for potato, share of Punjab is 83%, Sindh is 1%, KPK is 10% and Baluchistan is 6%. Punjab has highest share for production and area which is contributed by autumn and spring crop. Major potato producing districts in Punjab are Okara, Sahiwal, kasur, Sialkot, Sheikhupura, Narowal, Lahore, Pakpattan, Jhang, Tobe Tek Singh and Gujranwala, in KPK are Nowshera, Dir and Mansehra, in Baluchistan are Pishin, Kila Saaifulla and Kalat. Although, Pakistan is a large potato producing country yet per hectare yield is only 19.34 tonnes which is about 45.66 tones lower than that of developed countries as USA and Holland where average per hectare yield is 65 and 45.5 tonnes respectively.
About 5000 varieties of potato exist worldwide. In Pakistan both white and red skin varieties are cultivated but red skinned are mostly liked by consumers. Red skin varieties include desiree, asterix, lady roseta, krouda, rodeo, cardinal, ultimas, lal-e-faisal, and simphonia while diamant, santana, ajax, patrones, multa and sante are white skin varieties being cultivated commercially.
Sowing of virus contaminated uncertified seed, imbalanced use of NPK fertilizers, low level use of potassium, occurrence of copious diseases and insect pests are factors responsible for low yield. More than 18 potato diseases have been reported in Pakistan and 13 of which are of common occurrence including early blight, late blight, powdery mildew, common scab, stem rot, soft rot, and wilt caused by Alternaria solani, Phytophthora infestans, Erysiphe cichoracearum, Streptomyces scabies, Erwinia carotovora spp. carotovora, Fussarium spp and Verticillium dahlia, respectively. Potato viruses damaging the crop above threshhold level include potato virus X, potato virus Y, potato leaf roll virus and potato mop top virus. Major insect pests attacking crop include green peach aphids (Myzus persicae), cutworms (Agrotis spp.), colorado potato beetle, white grubs (Phyllorphaga spp.), wire worms (Elateridae spp.), potato leaf hoppers (Empoasca Fabae) and field cricket (Gryllus bimaculatus). Besides that potato cyst nematode (Heterodera rostochiensis) and root knot nematodes (Meloidogyne incognita) hamper root and tuber formation.
Seed involves about 35-40% of total cost of production so virus free seed gains attention. White fly is the major vector of potato viral diseases. Although, certified seed production in country is limited due to lack of technical, economical and managerial skills and is unable to meet total seed requirement, yet Punjab Seed Corporation is a milestone from public research sector which started sale of virus free seed by using modern tissue culture technology. Limited quantities of caroda, santee, burna, easterx, desiree, cardinal and diamente produced by tissue culture are supplied to farmers. Major importers and distributers of potato seed are PEPSICO, AGRICO and Bari Seeds. National public sector organizations working in potato seed production are Agricultural Biotechnology NARC Islamabad, Plant Virology AARI Faisalabad, Hazara Agriculture Research Station Abbottabad, Potato Seed Unit Deptt. of Agri. Gilgit and Punjab Seed Corporation Sahiwal. While Syko International Company Lahore, Bari traders Lahore, Okara Potato, Vegetable & Fruit Growers Co-operative Society, Bhatti Brothers Lahore, Hammad & Company Sahiwal, Haji Sons Lahore, Stamex International Lahore, AGB Seed Company Lahore, Trade Channels Lahore and Punjab Agri. Farms Lahore are private sector organizations working in potato seed production locally.
Biotechnological tools are also in application for developing genetically modified potato varieties. By the application of genetic engineering techniques Rpi-Vnt1.1 gene from Solanum venturrii has been introduced in commercial variety “Desiree” as this gene confers resistance to Phytophthora infestans (late blight).
In conclusion, by following crop advisory recommendations for sowing time, plant population, balanced use of fertilizers, increased use of potassium, integrated disease and insect pests management, we will not only step forward to sustainable agriculture but will also reap economic benefit by increasing per acre yield to fetch foreign exchange by exporting the surplus produce.
*Pictures source: Google
About author: Qamar Shahzad Anjum is a PhD scholar at Institute of Horticultural Sciences, University of Agriculture Faisalabad Pakistan. Email: email@example.com
Copyright Hortist, 2013