Effects of Potassium and Phosphorous Fertilization on Quality of Sweet Potatoes1

Abstract

Potassium applications from 0 to 140 kg/ha at 4 locations had more influence on quality of sweet potatoes than P applications of 0 to 73.9 kg/ha as an average of years and locations. As the rate of K but not P applications increased, percent dry matter decreased. K and P applications reduced protein content and firmness of canned roots. K slightly increased the crude fiber content (dry wt basis) of the roots, whereas P applications had no affect on fiber content. K and P fertilization had no influence on carotenoid content (fresh or processed), percent splitting of canned roots, or crude fiber content (fresh weight basis). Year and location effects were noted for some of the quality variables studied. Most of the differences observed were of low magnitude, thus had little effect on the overall quality of sweet potatoes. The most outstanding effect was the reduction in dry matter content due to K applications.

Influence of Mineral Nutrition and Storage on Quality Factors of ‘Jewel’ Sweet Potatoes1

“…Dry matter content of some sweet potato cultivars was not influence by fertilizers (2). In other research, dry matter content decreased with an increase level of K (3,4). Potassium level did not influence weight loss in storage ( 4), but increased N has been associated with greater weight loss (13).…”

“…Modem high density plantings require careful management in order to control tree size and maintain productivity. Summer pruning is presently being promoted by some pomologists as an aid to control tree vigor (2,5,10,12,15), to increase fruit bud formation (5,10,11,12), and to improve fruit quality (3,4). Earlier research indicated summer pruning was too devitalizing and laborious to be of commercial value (1).…”

“…Leonard et al (12) observed that carbohydrate content of 'Triumph' sweet potatoes decreased with increased K-levels. Nutrient ratios and various soil amendment applications did not influence the carotene content of sweet pottoes (2,3,5,9,20). Constantin et al (1) found that the flesh color of sweet potatoes was decreased with an increased N ap plication.…”

Nitrogen, Potassium, Sulfur Fertilization, and Protein Content of Sweet Potato Roots1

“…When S was the limiting element in soil, uptake of N by com (13) and other grains (5,14) was controlled by amounts of available S. The effect of S on the N content of sweet potatoes has not been reported. Potassium has been observed to produce a linear yield response in sweet potatoes (3,6). Increased yield, 'Received for publication Dec. 20, 1980; paper no.…”

Effects of Late-season Nitrogen and Foliar Calcium Applications on Sweet Potatoes1,2

“…High rates of nitrogen increase root cracking (10,14), decay and weight loss during storage of the roots (10), and de crease flesh color with increases in pro tein and firmness of canned products (3). Phosphorus did not increase sweet potato yield on continuously cropped soils (13) or influence dry matter, carotenoids, crude fiber, and splits of canned products but did decrease firmness and protein lev el (2). Potassium has been reported to in crease yield and cracking (4) with a re duction of dry matter and firmness of the canned product (2,4) but not influence carotenoids or splitting (2).…”