Integration of Irrigation Water and Mineral Nutrient Supply Effects on Firmness and Total Soluble Solids Content of Seed Potato (Solanum Tuberosum L.)

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Gathungu, G. K.
Aguyo, J. N.
Isutsa, D. K.
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Potato (Solanum tuberosum L.) is of significant economic and nutritional importance in many countries. Establishment of good fertility, proper nitrogen, and phosphorus and potassium fertilisation together with adequate water supply is critical in improvement of seed potato quality. Trials were conducted from August 2011 on a Fann at Egerton University to detennine the effects of irrigation water, nitrogen (N) and phosphorus (P) on quality of seed potatoes. The three factors were tested in a split-split plot design with irrigation water assigned to main plots, N to subplots and P to sub-subplots. The treatments were replicated three times and repeated once. The treatments consisted of three irrigation rates (40%, 65% and 100% field capacity), applied throughout the potato growth period in drip tube lines. Water was supplied to root zones only, leaving the inter-row spaces dry. Nitrogen was supplied as urea (46% N) at four rates (0, 75, 112.5 and 150 kg N/ha), each in two splits, with the first half at planting and the second at 5 weeks after planting. Phosphorus was supplied at planting time as triple superphosphate (46% P205) at four rates (0, 115, 172.5 and 230 kg P205lha), translating to 0, 50.6, 75.9, 101.2 kg P/ha. Analysis of variance revealed significant differences in firmness and total soluble solids (TSS) as affected by irrigation water, N and P supply. High irrigation water resulted in relatively low firmness (9.23 and 10.17), compared to low irrigation water, which had high firmness (l0.43 and 11.44) in both trials. The low N supply improved firmness (9.51 and 10.31), while the low P rate reduced firmness of the seed potatoes (9.07 and 9.98). While high irrigation water supply reduced TSS, high supply of both P and N increased TSS. The 100% irrigation water (5.48 and 5.52) and both low N by P supply (5.33 and 5.49) resulted in relatively low TSS, compared to 40% irrigation water (6.00 and 6.06) and high N by P supply (5.66 and 5.93) in both trials. It is recommended to apply low irrigation water and N but high P to increase firmness that reduces susceptibility of seed potatoes to mechanical injury and decay in storage, leading to low detenoration. In addition, low irrigation Potato (Solanum tuberosum L.) is of significant water plus high N and P should be supplied to increase economic and nutritional importance in many countries. TSS content that enhances seed potato tuber physiology Establishment of good fertility, proper nitrogen, and growth of resulting potato plants.
East African Agricultural And Forestry Journal, 79 (1), p. 17-21