J. C. Bishop

Effect of sources of nitrogen on yield and nitrogen absorption of potatoes

In tests with sources of N, (NH4)2SO4, when banded in the soil, usually resulted in highest tuber yield. Yields with Nitroform and sulfur-coated urea were similar to each other, and somewhat less than those from urea. Application of Aqua Humus, a humic acid derivative, in addition to several sources of N, had no significant effect on yields.Nitrogen absorption was highest from (NH4)2SO4, as measured by NO3 content of the petioles or total N absorption by the entire plant. There was little difference in N absorption from Nitroform and sulfurcoated urea. These materials did not result in increased N absorption by plants during late growth.In Kern County experiments, about 80% of the N from (NH4)2SO4 and urea had nitrified and leached from the fertilizer band by 40 days after application. At 80 days after application, half of the N from Nitroform was still in place. In an experiment at Davis on a heavier soil, Nitroform had a slower rate of N release than sulfur-coated urea, followed in order by (NH4)2SO4 and urea.

Influence of high-temperature exposure on sugar content and chipping quality of potatoes.

SummaryKennebec and White Rose potatoes harvested at different dates were exposed for 2 or 4 days to temperatures above 25 C, then transferred to 20 C. Increase in concentration of total sugars was stimulated by exposure to high temperature, but diminished during holding at lower temperature. Reducing sugars were not affected similarly. High total sugar concentration enhanced darkening of chips. Light-colored chips were obtained from tubers transferred to 20 C after exposure to high temperature, provided tubers had a low reducing sugar concentration.ResumenPapas Kennebec y White Rose cosechadas en fechas diferentes fueron expuestas durante 2 0 4 días a temperaturas mayores de 25 C y después transferidas a 20 C. Incremento en concentración de azúcares totales fué estimulado a causa de la alta temperatura pero disminuyó durante la preservación a la temperatura más baja. Azúcares reductores no fueron afectados de una manera similar. Una total alta concentración de azúcares dió papas fritas más obscuras. Papas fritas de color más ligero fueron obtenidas de tubérculos transferidos a 20 C después de haber sido expuestos a temperaturas más altas, cuando estos tubérculos contenían una baja concentración de azúcares reductores.

The effect of size and spacing of seed pieces on the yield and grade of white rose potatoes in Kern County, California

SummaryBoth total yield and, to a somewhat lesser degree, yield of U. S. No. 1 tubers were increased by increasing the quantity of seed potatoes planted per acre—through closer spacing and/or larger seed pieces. The rate of yield increase declined with each increment of seed potatoes. Planting more than approximately 16 sacks of seed potatoes per acre did not increase the yield sufficiently to justify the greater expense.Large seed pieces spaced at 71/2-inch intervals produced the highest proportion of small tubers. Potato size was determined more by spacing than by seed piece size.The yield of “rough” tubers (misshapen, growth-cracked, and second-growth tubers) was slightly and inconsistently affected by size or spacing of seed pieces.

Sprouting, plant growth, and tuber production as affected by chemical treatment of white potato seed pieces: IV. Responses of dormant and sprouted seed potatoes to gibberellic acid

SummaryWhole, dormant or sprouted seed potatoes were treated with various concentrations of gibberellic acid, cut, and planted at three locations. Emergence of plants from treated seed was more rapid than from untreated seed. However, vigorously sprouting seed is less affected by GA than dormant seed. Concentrations of GA as high as 5 ppm had no material effect upon total yield of tubers, but concentrations higher than 5 ppm caused marked reduction of yield and changes in tuber shape. A more uniform size of U.S. No. 1 tubers resulted in some instances with GA treatment; specific gravity was not affected by GA treatment. With the possible exception of its use in producing small potatoes for seed, GA is not recommended as a seed treatment for dormant or sprouting potatoes.

Investigations with maleic hydrazide on potatoes I. Effect of time of application and concentration upon potato performance

SummaryMaleic hydrazide was applied to the foliage of five varieties of potatoes grown at two California locations, Shafter and Tulelake. Plants were sprayed two and three weeks before harvest, and harvested tubers were held for six months at 45°–55° and 68° F.No significant differences in yield or specific gravity of tubers due to MH-40 spray treatments were found.Increasing concentrations of MH-40 spray resulted in a reduction in sprout development and loss of tuber weight in stored potatoes. Application three weeks before harvest was more effective in reducing losses in storage than application two weeks before harvest.A greater loss in tuber weight and more sprouting occurred at 68° F. than at 45°–55° F.Applications of MH-40 caused no change in chipping or cooking quality of tubers.

Abstracts of papers presented at the Fifty-Second Annual Meeting of The Potato Association of America

F I F T Y S E C O N D A N N U A L M E E T I N G

Sprout inhibition of fall-grown potatoes by airplane applications of maleic hydrazide

SummaryIn Tulare County, California, airplane application of maleic hydrazide as MH-30 on fall grown potatoes retarded sprouting in field storage and in subsequent common storage. Weight loss in common storage was significantly reduced. Total yield was not significantly affected. Three pounds of maleic hydrazide per acre were generally as effective as were 6 pounds.There was a wide range in the amount of maleic hydrazide residue found in the tubers at harvest. On the average, about twice as much maleic hydrazide was found in the tubers from plants treated with 6 pounds of maleic hydrazide per acre than was found in those from the 3-pound plots.Specific gravity of tubers harvested on February 26, 1959 and on March 23, 1960, was not affected by treatment.Preliminary results in 1957–58 showed that hand-sprayed maleic hydrazide prevented a reduction in specific gravity of soil-stored potatoes when harvest was delayed.

Comparative influence of gibberellic acid and of plant population on distribution of potato tuber size

SummaryThe comparative influence of GA and of plant population on distributión of tuber size was evaluated for 3 years. Both closer seed spacing and treating seed with GA resulted in a reduction in tuber size without marked changes in total yield. However, with a growing season of 97 days, yield of U. S. No. 1 tubers from GA-treated seed was lower than from nontreated seed. Cost of seed required to achieve a denser plant population compared to cost of treating seed with GA was approximately

Growth, yield, and quality of White Rose potatoes as affected by plant population and levels of nitrogen1

69 versus

Abstracts 60th annual PAA meeting (Part II)

1 per acre.ResumenLa influencia comparativa de ácido jiberélico y de la populatión de plantas sobre la distributión del tamaño de tubérculos fué evaluada durante 3 años. Ya sembrando la semilla a distancias menores como tratando la semilla con ácido jiberélico tuvo como resultado la reduction en tamaño de tubérculos sin cambios mercados en el rendimiento total de tubérculos. Sinembargo, con una estación de crecimiento de 97 días, el rendimiento de tubérculos de U.S. No. 1, obtenidos de semilla tratada con ácido jiberélico, fué menor que el rendimiento obtenido de semilla no tratada. El costo de semilla requerida para obtener una populatión más densa, comparado al costo de tratar la semilla con ácido jiberélico fué