Effect of Organic and Industrial Fertilizers on Reducing Sugar, Specific Gravity, Dry Matter and Starch Composition of Fresh Harvested Irish Potato Varieties in Musanze District Rwanda

Potatoes for use in industrial processing must have a low reducing sugar concentration. This study investigates the impact of organic and synthetic fertilizers on the composition of Irish potato cultivars’ reducing sugar, specific gravity, dry matter, and starch. The research was conducted at Busogo Farm in Rwanda, using randomized complete block designs in seasons 2021 B and 2022 A with rate of ten tones per hectare under the doses of 100%, 50%, and 0% and three hundred kilograms per hector under the dose of 100%, 50% and 0% respectively for farmyard manure and NPK 17.17.17. Results showed significant effects of season and treatment on reducing sugar levels in potatoes. Twihaze and Kirundo varieties recorded high glucose (0.09%), while Gisubizo variety in control, recorded low glucose (0.01%). Additionally, the analysis of variance showed that Irish potato varieties with low to moderate and moderate to high glucose contents, respectively, experienced extremely significant (p 0.001) effects of farmyard manure and NPK on glucose content for the seasons 2021 B and 2022 A. The application of inorganic and organic fertilizers had a significant impact (p 0.05) on dry matter in seasons B and A, according to the analysis of variance. Additionally, the results demonstrated extremely significant (p<0.01) differences in specific gravity and starch in both seasons, with Kinigi variety having higher values of dry matter, specific gravity, and starch content in season B and A, respectively, of 24.58, 1.10, and 18.59%. Season 2022 A’s high decreasing sugar levels were caused by meteorological conditions brought on by the soil’s high moisture content as well as the maturity of the tubers. Due to its low level of reducing sugar, Gikungu, Kirundo, and Kinigi are excellent for chips whereas Twihaze variety is advised for boiling cooking methods.