Fertilizer and varietal effects on growth and yield of potato (solanum tuberosum L.) under medium altitude tropical conditions
Sigunga, D O
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Potato (Solanum tuberosum L.) production in Kenya is still restricted to the highlands, and yet its consumption has spread to almost allover the country including medium and low altitude areas. An attempt was made to introduce potato growing in medium altitude areas. The experimental o site, Bukura Institute of Agricultur~ is located at 0 13 o I North and 34 37 East, and is 1463M above sea level. Two experiments were conducted durinf the,short rains of 1979 and the long rains o£ 1980 to investigate the production potential as well as fertilizer requirements of the potatoes under Bukura conditions. Three potato varieties namely Anett, Roslin Eburu (B53) and Kenya Baraka representing early, medium-late and late maturing commercial cultivars in Kenya were used. Five levels of diammonium phosnhate were applied at equally spaced intervals starting from 0 to 600 kg/ha. The 15 treatment combinations were randomly distributed in each of the three replicates. The plants were sampled fortnightly for analysis starting from three weeks after the beginning of emergence. In terms of tuber yields Anett significantly outy~ elded both B5) and Kenya Baraka during the short rains. The difference between B53 and Kenya Baraka was not significant. However, the performance of the crop during this season was poor mainly due to low rainfall. During the long rainy season Kenya Baraka was significantly the best yielder. Anett also significantly outyielded B53 in this season as well. The fertilizer level, 300 kg/ha, gave rise to significantly the highest tuber yield during the short rains, while the level, 450 kg/ha, resulted in significantly the highest yield during the long rains. The tuber dry matter percent of the total fresh tuber yield was not responsive to the fertilizer treatments in experiment II, but showed slight decrease with increasing fertilizer levels in experiment I. The performance of the crop'in terms of leaf area developed, total and ware tuber yields was far better in experiment II than in experiment I. The interaction between variety and fertilizer in both expetiments was not sicnificant. This was thought to be so because the fertilizer was applied once at the time of planting thus providing no advantage for the late maturing variety, Kenya Baraka, to significantly benefit over the early maturing variety, Anett. 'The results of these experiments showed that potato production can be extended to medium altitude tropical areas provided water and fertilizer supplies are adequate.