Nitrogen and potassium fertilization of potatoes: Sugars and starch

Westermann, D.T. and James, D.W. and Tindall, T.A. and Hurst, R.L. (1994) Nitrogen and potassium fertilization of potatoes: Sugars and starch. American Potato Journal. 71:433-453.

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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 K-sources
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-1
were combined with selected K rates of 0, 112, 224 or 448 kg ha-1 as either
KCl or K2SO4 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.

Item Type:	Article
NWISRL Publication Number:	0845
Subjects:	Irrigated crops > Potato Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:54
Last Modified:	28 Nov 2016 18:53
Item ID:	623
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/623