Experiment Station Record, Volume 92, January-June, 1945 Page: 47

1945] 3 FIELD CROPS 47
Nitrates decreased rapidly as the plants matured. During the most rapid growth
period soluble P was less than 70 p. p. m. in plants on no-P plats. Soluble potash
(KaO) never ranged less than 10,000 p. p. m., about three times the minimum of
2,200 at the beginning and 4,500 p. p. m. at the end of the season. Starch content
decreased from 17.0 percent for tubers produced without N to less than 13 percent
for tubers grown on plats receiving N 210 lb per acre. N was lower in all parts
of plants grown on no-N plats than in plants on N plats. P was lower both in
plants on no-N and no-P plats. Omission of fertilizer N greatly reduced P absorption
by all plant parts analyzed. K was high in all samples, not being affected by
fertilizer treatments. Ca was highest in plants grown without N and lowest in
those grown without P. Mature tubers from liberally fertilized plats contained
(expressed as percentage of fresh weight) dry matter 21.0, N 0.037, P 0.067,
K 0.489, Ca 0.008, Mg 0.029, and ash 0.939 percent.
Studies on potato nutrition.-II, Nutrition uptake at various stages of growth
by Kern County potatoes, 0. A. LORENZ. (Univ. Calif.). (Amer. Soc. Hort.
Sci. Proc., 44 (1944), pp. 389-394).-Determination of seasonal nutrient uptake of
potatoes grown at three nutrient levels revealed that total absorption of ash varied
from 480 to 892 lb. per acre, N 65 to 189 lb., P 14 to 31, K 169 to 272, Ca 35 to 55,
and Mg from 13 to 33 lb. Tubers alone accounted for removal of from 245 to 377
lb. of ash per acre, N 50 to 149, P 1,3 to 27, K 113 to, 197, Mg 7 to 12, and about
3 lb. of Ca. Nearly all of the tuber growth occurred between 60 to 100 days after
planting or from 30 to 60 days after plant emergence.
Suitability for dehydration in white potatoes as determined by the factors of
variety and place of production, I, J. S. CALDWELL, C. W. CULPEPPER, and P. M.
LOMBARD. (U. S. D. A.). (Amer. Potato Jour., 21 (1944), No. 8, pp. 211216).-Each
of the 19 varieties of late or main-crop potatoes from nine stations in
seven Northern States was found in tests capable of producing a dehydrated product
of high quality when grown under suitable conditions. If the variety was grown
under each series of conditions to which it was progressively less adapted, quality
of the dried product became progressively poorer. A consistent correlation was
noted between specific gravity of the fresh entire tubers and quality of the dried
product. Raw stock of high specific gravity gave larger yields of dry product
with a more desirable texture or consistency (dryness or mealiness) when refreshed
and cooked than stock of lower specific gravity. Since color and flavor
varied independently of specific gravity, high specific gravity did not always
determine high quality of product, but very few lots of potatoes of low specific
gravity yielded products of the. highest quality. These results are in general
accordance with the work of Clark, Lombard, and Whiteman (E. S. R., 83, p. 768),
who found a high positive correlation between specific gravity and the dryness and
mealiness considered desirable in potatoes.
Suitability for dehydration in white potatoes as determined by the factors of
variety, place of production, and stage of maturity, II, J. S. CALDWELL, C. W.
CULPEPPER, and F. J. STEVENSON. (U. S. D. A.). (Amer. Potato Jour., 21 (1944),
No. 8, pp. 217-229).-The merits for dehydration of early or spring potatoes
from important southern districts and from California -were studied with nine
varieties. As a whole, dehydrated products made from early-crop potatoes
ranked significantly lower in quality than those made by identical methods from
late-crop potatoes of the same varieties. This result appeared due to some extent
:to the custom in the South of harvesting when plants are still green and vigorous
and tubers immature, and in part to imperfect adaptation of existing varieties to
climatic conditions under which the early crop is grown. Low yields and absence
of highest quality in dehydrated products made from immature potatoes indicate
that tubers intended for dehydration should be allowed to mature before digging.