A22/0074/2009 SUPERVISED BY; DR. R. NYANKANGA BY; KIPLAGAT SHADRACK EFFECT OF SEED TUBER SIZE AND SEED PIECES ON THE EMERGENCE, GROWTH VIGOUR AND YIELD OF IRISH POTATOES (SOLANUM TUBEROSUM L) BY; KIPLAGAT SHADRACK A22/0074/2009 SUPERVISED BY; DR. R. NYANKANGA

INTRODUCTION Potato is grown worldwide and ranks fourth in food production after wheat, maize and rice stem tuber crops and root crops followed by cassava, sweet potato and yam In Kenya potato ranks as the second most important food crop after maize (Guyton et al., 1994) and plays a major role in food security and income generation by providing employment opportunities (MOA, 2003).

Production constraints Lack of quality seed potatoes among growers Prices of potato fluctuate according to the seasonality potato crop is susceptible to more than 300 pests and diseases (Horton, 1902). e.g potato tuber moth, late blight and bacterial wilt.

Problem statement and justification The potato seed is bulk and one requires 4tons/ha. This is costly. Lack of good quality seeds among growers has been a problem. Lack of knowledge among the farmers in the right size of potato tubers to be planted has led to low yields in potato production. The use of other alternative propagules such as TPS, mini tubers and macro tubers has also been faced with challenges. This study therefore plans to investigate the effect of seed tuber size and the use of seed pieces on emergence, growth vigour and yield of potatoes. Lack ofgood quality seeds among growers is a major problem adversely affecting the expansion of potato production in many developing countries such as Kenya( Crissman et al., 1993; Maingi et al., 19940).

Objectives The broad objective of this study is to improve potato production by the use of quality potato seed tubers in terms of correct tuber size and correct handling of the seed pieces. Specific objective To determine the effect of seed tuber size on emergence, growth vigour and yield of Irish potato. To determine the effect of tuber seed pieces on emergence, growth vigour and yield on Irish potato.

Hypothesis Seed tuber size has no effect on emergence , growth vigour and yield of Irish potato Seed pieces have no effect on the emergence, growth vigour and yield of Irish potato.

Materials and methods The study will be carried out at Kabete campus field station, University of Nairobi. The research will be carried out using two potato varieties ( Asante and Tigoni varieties) . The experiment will be laid on a completely randomised design (CRD) with each treatments being replicated three times. The treatments are; Small tuber size (28-45 mm diameter),Medium tuber size (45-55 mm diameter) and Large tuber size (> 55 mm diameter) and the seed pieces. The seed pieces will be suberized by being stored on warm conditions for 10 days.

Data collection Data will be collected on infection during suberization and after planting on the following parameters. Emergence (%) Number of stems per hill Plant vigour Plant height Number of leaves per plant Number and weight of tubers Plant height

Data analysis Analysis of variance (ANOVA) will be performed by genstat package and the means will be separated using LSD at 5% level of significance. Comparison will be done on the whole seed verses the seed pieces.

Work plan Activity Stage February March April May Land preparation Primary   Secondary Procurement of inputs Planting Weeding Data collection Report writing Report submission

Budget item Units Unit cost Total cost Seed tubers 10 kg 60 600 DAP 150 Labour 4 410 1640 Report printing 2 copies 400 800 Pesticides 1 500 Total   4,140

Reference Ngugi, D.N., 1983. Potato production in Kenya, Potential and limitation in: Reserve for the potato in the year 2000. Edited by Hooker, W.W. Burton, w.g., 1989. The potato (3rd edition), Longman London 742 Allen EJ and RK Scoot. 1980. An analysis of growth of potato crop. Journal of Agriculture Science, Camb.94:583-608. Beukema HP and DE. Vander Zaag. 1990. Introduction to potato production. PudockWageningen. 208 Relationships of seed size, spacing, stem numbers to yieldsof Russet Burbank potatoes. American Potato Journal 40:463-479. Moorby J. 1967. Inter stem and inter tuber competition in potatoes. European Potato Journal 10:189-205. Wiersema SG and K Cabello. 1986. Comparative performance of different sized seed tubers derived from truepotato seed. American Potato Journal 63(3):241- 250. Wiersema SG. 1986. A method of producing seed tubers from true potato seed. Potato Research 29:225-237. Mosley, I Vales, J. McMorran, S. Yilma. 2000. CSS 322, Principles of potato production. Hooper R.W., Plaisted R.L. 1987. Potato (chapter 11) substracted from. the basic principles of cultivar Development volume 2. Stark, J.C and S.L. Love.editors, 2003. Potato production systems

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