The effect of fertilizer and growing season on tuber dry matter and nitrate content in potato
¹Estonian Crop Research Institute, Department of Plant Biotechnology, Aamisepa 1, EE48309 Jõgeva, Estonia
²Estonian Research Institute of Agriculture, Department of Plant Sciences, Teaduse 13, 75501 Saku, Estonia
³Estonian University of Life Sciences, Department of Field Crop and Grassland Husbandry, Kreutzwaldi 1, EE51014 Tartu, Estonia
Field trials with two potato varieties were undertaken at the Estonian Research Institute of Agriculture in 2005 and 2006. Year 2005 was generally optimal for potato growth but year 2006 was dry and very warm, hence, it was adverse for growth. The effect of fertilizing on two main traits of potato, i. e. tuber dry matter (DM) and nitrate content was examined. Five rates of compound fertilizer were applied, N50P20K85, N70P28K119, N90P36K153, N110P44K187 and N130P52K221. Results indicated that DM content was largely determined by variety but it also depended on fertilizer amounts and particular environmental conditions of a year. Nitrate content of tubers was quite clearly dependent upon variety, but growing season had significant effect on final nitrate content in tubers. Water stress during early and main bulking periods resulted in high tuber nitrate levels. In order to gain tuber yield fit for intended use, it is necessary to manage nutrient acquisition based on expected yield and nutrient supply from soils.