Nitrogen and potassium fertilization of potatoes: Sugars and starch

Abstract

Considerable evidence exists that both N and K influence potato (Solanum tuberosum L.) yields and quality. The impact of nutrients on tuber quality parameters under field conditions should be identified so optimum management practices can be utilized. We evaluated the N and K fertilization by Ksources effects on concentrations of nutrients, reducing sugars, sucrose and starch in the stem and apical tuber ends from two irrigated field experiments with the Russet Burbank cultivar. Nitrogen rates of 0, 112, 224 or 336 kg ha-' were combined with selected K rates of 0, 112, 224 or 448 kg ha-' as either KCI or K2SQ4 arranged as an incomplete factorial. A multiple linear regression model was fit to the data and used to predict the response surface for a complete factorial for each K-source. Nitrogen applications increased or decreased reducing sugars in the apical and stem ends, respectively. Potassium decreased reducing sugars in both tuber ends. Sucrose was higher in the apical end than in the stem end but was not appreciably affected by fertilizer treatment. Nitrogen and potassium applications reduced dry matter and starch concentrations in both tuber ends. Potassium had a smaller effect on the apical end when starch was expressed on a dry weight basis, indicating that increased water content was a factor in the K effect. Both N and K concentrations in the tuber ends were negatively related to starch concentrations, but the relationship was different for the apical and stem ends. Tuber Cl concentration indirectly affected starch concentrations in the stem end when KCL was applied. The K fertilization effect on specific gravity depended upon the K concentration in the harvested tuber and was independent of K fertilizer source. These data illustrate the effects of preplant N and K fertilization rates on final tuber quality parameters. Additional studies are needed to further define the effects of nutrient concentrations at different plant growth stages. CompendioExiste considerable evidencia que tanto el N coma el K influencian los rendimientos y calidad de la papa (Solanum tuberosum L. campo, debe ser identificado de modo que pueden utilizarse practicas Optimas de manejo. Se evaluO la fertilizaciOn con N y K por los efectos de las fuentes de K sobre la concentraciem de nutrientes, los aplcares reductores, sucrosa y almidem en los extremos apical y terminal de tuberculos de dos experimentos de campo bajo irrigaciem, con el cultivar Russet Burbank. Se combinaron dosis de 0, 112, 224, o 336 kg ha' de N, con dosis seleccionadas de K de 0,112, 224 o 448 kg ha'', sea comb KC1 o como K2SO4, dispuestas como un factorial incompleto. Se dispuso la information convenientemente en un modelo de regresiOn linear multiple y se le utilizO para pronosticar la superficie de respuesta para un factorial completo para cada fuente de K. Las aplicaciones de N incrementaron o disminuyeron los azikares reductores en los extremos apical y terminal, respectivamente. El K redujo los azficares reductores en ambos extremos del tuberculo....

Nitrogen and potassium fertilization of potatoes: Yield and specific gravity

“…Both petiole NO 3-N and K concentrations were both related to yields and SG but complex interactions appeared to obscure their relationships. Other papers have addressed the N and K rates, and K-source effects on petiole and tuber chemistries (7,25).…”

Some unique benefits with sudangrass for improved U.S. #1 yields and size of Russet Burbank potato

“…In general, cultural practices were as recommended by the University of Idaho for potato production (Anonymous 1986;Bishop et al 1982;Kleinkopf et al 1981;Ohms 1962;Westermann et al 1994). Foliar sprays of either mancozeb at 1.8 kg ha-' or chlorothalonil at 1.25 kg ha-' were applied at weekly intervals between mid-July and 1 September to protect against foliar diseases (early blight and black dot) that can reduce yield (Anonymous 1986;Mohan et al 1992).…”

Effect of Fertilizers on Growth and Productivity of Potato-A Review

“…However, the potato gave optimum tuber yield when N fertilizer was applied at the rate of 204 kg/ha and yield reduction was noted when applied above this rate [26]. There was also decrease in the dry matter beyond 200 kg N/ha, which might be due to difference in relative maturity of tubers [27]. The results of the experiment conducted by Georgakis et al during the year 1997 showed that increase in nitrogen rates up to favorite point led to increase in tuber yield per unit area beyond which the rate decrease [28].…”