The influence of irrigation regime on yield and quality of potato tubers and nutritional status of plants

Abstract

Yield and quality (mealiness) of Russet Burbank potatoes are markedly increased by increasing the frequency and quantity of irrigation water. No advantage in yield or quality of tubers was observed for either sprinkle or furrow irrigation when soil moisture tensions in the root zone were comparable. The use of critical levels as a basis for appraising the nutrient status of potatoes under some conditions appears unsatisfactory. Conclusions favoring the use of a modification of Thomas’ “quantity factor” and “quality factors” over the use of “critical levels” are based on the following three assumptions: (1) that concentrations of macronutrients (N, P and K) below the “critical levels” should adversely affect yield and possibly quality of potato tubers, (2) that high yields of potato tubers are possible only when potato plants are well-nourished and (3) that proper balance of macro-nutrients in plant tissue (N, P and K) is more important in the production of high yields of tubers than is the total concentration of these nutrients in leaf blades individually or collectively. The application of a modification of Thomas’ quantity factor and quality factor to data on the chemical composition of potato leaf-blades and leaf-petioles indicates that the proper balance of the principal nutrient elements is a critical factor in the production of high yields of potatoes. It would seem wise to determine the range in quantity factor and quality factors suitable to the production of high yields of the important potato varieties under the climatic conditions where they are to be grown. Under conditions where phosphorus nutrition is not a controlling factor, the N:K ratio sensitively indicates nitrogen and potassium nutritional status. The principle of foliar diagnosis, when applied to soluble constituents extracted from potato leaf-petioles, promises to be a useful basis for appraising the nutrient status of potato plants.