La pomme de terre (Solanum tuberosum L.) est une culture annuelle et dicotylédone appartenant à la famille des solanacées qui comprend 26 genres et 2800 variétés. Les pommes de terre cultivées sont les S. tuberosum qui englobent 180 variétés, toutes productrices de tubercules. La plupart des variétés commerciales de S. tuberosum sont tétraploïdes. Il existe deux sous-variétés : le tuberosum et l’andigenum, la distribution mondiale du tuberosum étant épuisée. Le système racinaire de S. tuberosum est fasciculé et il se développe facilement dans un sol léger à texture sableuse et argileuse. Les pommes de terre sont multipliées soit par multiplication asexuée, ou l’enterrement de tubercules, soit par multiplication sexuée, ou l’enterrement de semences.
Importance of Potato
The potato is one of the main staple foods and the world’s most important non-grain food crop. This crop is cultivated worldwide, and it is the fourth main food crop in the world after corn, rice and wheat in terms of total global production.
Botanical Features
The leaves are compound pinnate. The main petiole is herbaceous and has light green color with 7-9 leaflets. The leaflets are ovate, irregular, entire margin and little lobed with dark green color. The veins of leaflets are clear with light green color. The leaflets have trichomes on both the sides with very short petiole (Figure 1). The flowers of S. tuberosum are two types: actinomorph and zygomorph. There are five sepals, soft or corky and with green, red, or purple color and different length. The petioles are also different in length size. The corolla is star shape, rectangular, or circular. In case of color, most of them are white, but they are clear in red, purple, blue, yellow, and pink type. The stamens are 5, and most of them have long and column anther with yellow or orange color. They show related groups which are individual or divergent (Figure 2). The pollen grains are expended from the top of anther. The fruit is in form of burry epigenous with two carpels and 5-8 mm thickness. Tiny seeds are spread in berry fruit. The modified stem or tuber is the main reserving organ in potato.
The size of tuber varies according to the kind of variety, soil properties, and also climatic conditions. The potato is commonly circular – elliptical and or oval. The skin of tuber is soft, hard or nettled. The color of the tuber skin is white, and, purple and also pink or yellow (Figure 3). The tuber contains 75 or 80% water, 12% starch, 1.5 and or 2% protein, 2 or 3% fiber, salts and also vitamin C. Some lateral stems are horizontally grown on buds of underground stems. Their lengths are varied and are also the main factor to recognize varieties. S. tuberosum can be produced in different ecological areas: in tropical, subtropical, desert, mountainous, and temperate areas. S. tuberosum is used for feeding herd and humans. They contain vitamin C, potassium, calcium, family of vitamin B and a little sodium.
Common Varieties
The most popular available seed varieties are Agria, Banba, Marfona, Jelly, Cosima, Desiree, Diamond, Ramos, Picasso, Sante and Arinda (Figures 4-7).
The most important diseases of potato include Rhizoctonia canker (Rhizoctonia solani), Early blight (Alternaria solani), Late blight (Phytophtora infestans), Fusarium wilt (Fusarium solani), Bacterial scab (Streptomyces scabies), Blackleg (Pectobacterium atrosepticum) and Cyst nematode (Globodera sp.). Major pests of potato include Turnip moth (Agrotis segetum), Wire worm (Agriotes lineatus), Colorado beetle (Leptinotarsa decemlineata), Armiworm (Spodoptera exigua), Tuber moth (Phtorimaea operculella) and Thrips (Thrips tabaci) (Figures 8-17).
References
- Abebe, G.K., Bijman, J., Pascucci, S., & Omta,O. (2013). Adoption of improved potato varieties: The role of agricultural knowledge and innovation system and smallholder farmers’quality assessment. Agricultural Systems, 122, 22–32.
- Vreugdenhil, D., Bradshaw, J., Gebhardt, C., Govers, F., MacKerron, D. K. L., Taylor, M. A., & Ross, H. (2007). Potato biology and biotechnology (advances and perspectives). The Boulevard, Langford Lane, Kidlington, Oxford, Amsterdam, the Netherlands, Elsevier, 823 p.
- S. B. Jones and A. E. Luchsinger, “Plant Systematic,” 2nd Edition, McGraw-Hill Book Company, New York, 1987, p. 512.