EFFECT OF SITE, VARIETY AND STORAGE ENVIRONMNET ON YIELD AND QUALITY OF SEED POTATO IN THE NORTH RIFT REGION OF KENYA

Abstract

Potato is the second most important food and nutrition crop in Kenya. It is grown largely by small scale farmers using recycled seed often diseased leading to low yields. Availability of certified seed is highly limited by land subdivision and change of use in traditional seed production areas which took place from mid 1980s. Consequently, there is urgent need to explore other suitable areas where potato has not been widely grown as in the North Rift. However, current varieties were not evaluated for their performance in the region and hence it is incumbent to identify suitable varieties with preferred quality characteristics for the region. Three experiments were conducted using local varieties to evaluate the seed yield potential, their field performance in different altitudes and pre- harvest handling characteristics. In the first experiment, eight potato varieties were grown in Kitale to assess stand establishment, number of stems/plant and foliage, tuber yield and yield distribution. Seed grade tubers were stored at ambient conditions to physiologically sprouted stage. In the second experiment, these tubers were planted at Kitale, Kapcherop and Kibigos and similar parameters as was in the first experiment were undertaken other than weight of foliage. In the third experiment ten kg seed size graded tubers of each variety from second experiment were stored in situ in the dark, diffuse and open environments replicated twice in a CRD. Tuber weight was taken at specific days for 117 days in storage. Data was subjected to Sheffe‟s test using SAS 9.3 Version and presented in ANOVA and C.V %. Means were separated by Sheffe‟s critical mean differences. At 27 days after planting (DAP), plant emergences was statistically similar (p = <0.05) for all varieties other than Pimpernel and Kenya Baraka. However, at 42 DAP all had passed 89 % plant emergence while Pimpernel had reached 9 %. In terms of ground cover Asante, Dutch Robjin, Tigoni1and Kenya Karibu were statistically similar 42 DAP but differed from the rest at 56 DAP and remained so even at 65 DAP. Asante had the highest number of tubers per plant at Kitale site. Plant emergence was slowest at Kibigos and fastest at Kitale. Dutch Robjin had the highest stem density per unit area and number of tubers per plant in seed size category across the sites. Most of varieties had tubers in seed grade at Kitale compared to the other sites. Tuber weight loss took place in the first 30 days irrespective of variety, site or store environment. Dutch Robjin had the highest dry matter at all the sites while Asante had the lowest. Introduction of potato in the region should be preceded by evaluation to identify suitable varieties