Effect of N Fertilization on Sugarbeet Crown Tissue Production and Processing Quality1

Abstract

AbstractOver the past 4 decades, sucrose content of sugarbeets (Beta vulgaris L.) has decreased while root yield has increased. Reasons reported include processing of more crown material, because mechanical harvesting removes less crown tissue than hand‐topping methods, and incre ased use of N fertilizer. Our objective was to determine the relationship between N application rate and sugarbeet crown tissue production, and its effects on processing quality of sugarbeets. Reported are the results of two studies conducted in 1975 and one in 1976, each using a different sugarbeet cultivar and seven N rates. Green petiole material was removed before each sugarbeet was sectioned into root and crown tissues for yield and quality analyses. Crown tissue increased linearly as rates of N application increased. Root tissue and recoverable sucrose yields were near maximum when spring soil NO3‐N or soil NO3‐N plus added N reached 200 to 225 kg/ha. At higher N levels, crown tissue yield increased and sucrose content in both root and crown tissues decreased, offsetting any potential benefits from increased whole beet yield. When N was adequate for maximmn sucrose production, crown tissue contributed approximately 20% of the total recoverable sucrose per ha. As N rate increased, sucrose concentration, extractable sucrose per metric ton, and purity decreased whereas Na, K, amino‐N, invert sugar, and imaturity index values increased for both root and crown tissues. Root tissue always had higher levels than crown tissue of extractable sucrose and purity and lower levels of Na, amino‐N, invert sugar, and impurity index. Crown tissue production can be minimized, and processing quality of sngarbeets can be improved by conservative use of N fertilizer.