Herman Timm

Sprouting, plant growth, and tuber production as affected by chemical treatment of white potato seed pieces

SummaryA curtailment of the rest period, resulting from treatment with gibberellic acid (GA), of newly dug White Rose, Kennebec, and Russet Burbank potatoes was indicated by a 2-to 3-week acceleration of sprouting. Five- and 90-minute dip treatments were equally effective. Concentrations of 50, 500, or 2000 μg/ml of GA produced comparable stimulation. Differences among varieties in the percentage of sprouting and in sprout elongation were observed following GA treatment. Preliminary results indicated that GA failed to overcome “chemical dormancy” of tubers from plants which had been sprayed three months earlier with 6000 μg/ml of maleic hydrazide.

Parenchyma cell growth in potato tubers I. Different tuber regions

Enlargement rates of starch-storage parenchyma cells during growth of Kennebec and Russet Burbank potato cultivars were determined for cortical, perimedullary, and pith tissuues of bud ends, midsections, and stem ends of tubers. Average volumetric size of parenchyma cells increased 7 to 18x during growth of Russet Burbank tubers, with the greatest increases occurring in cortical and perimedullary cells of bud ends and midsections, and the least in stem ends and pith tissues. In Kennebec tubers parenchyma cells in both stem end and midsection increased only 5 to 8 x, whereas increases in bud ends ranged from 8 to 20 times.Cell enlargement to tuber enlargement ratios appproached unity early in growth of Russet Burbank tubers. As tubers increased beyond the 45 g size, cell enlargement and tuber enlargement rates were essentially equal. Calculations of cells per unit tissue volume agreed with ratio determinations. The timing of such unity appeared to be delayed in Kennebec tubers, and was not quite as pronounced as in Russet Burbank tubers. This may have been due to differences in growth rates of individual tubers in response to cultural conditions. In general, cells of harvestmature Kennebec tubers were about 60% as large as similar cells of Russet Burbank tubers.

Differential ozone susceptibility of Centennial Russet and White Rose potato as demonstrated by fumigation and antioxidant treatments

Because quantitative field estimates of potato (Solarium tuberosum L.) yield losses attributable to ozone (O3) air pollution damage in California need to be assessed, the antioxidant compound N-[-2-(2-oxo-l-imidazolidiny l)ethyl]-N′-phenylurea (EDU or DPX-4891) was evaluated for suitability in estimating these yield losses and in differentiating O3-susceptible from O3-resistant cultivars.Differential susceptibility of two cultivars, ‘Centennial Russet’ (O3sensitive) and ‘White Rose’ (O3-resistant), to O3 was confirmed in greenhouse experiments. Five weekly 5-hour treatments with 25 parts per hundred million O3 reduced tuber yield of Centennial Russet by 32% but did not reduce the yield of White Rose.In the absence of O3 under greenhouse conditions, EDU had no observable effect on shoot dry weight, tuber number, or tuber yield of either cultivar, suggesting that EDU does not materially affect plant growth in the absence of O3 at the treatment levels used and under the conditions herein. In field experiments conducted at the University of California at Riverside (UCR) and in commercial fields of Kern County (KC), untreated Centennial Russet and White Rose plants produced total tuber yields of 174 and 512 q/ha, respectively at UCR and 268 and 498 q/ha, respectively, at KC. At UCR, EDU applied at the highest rate—17.8 kg/ha—increased marketable and total tuber yields of Centennial Russet by 208 and 188 q/ha, respectively, and increased specific gravity by 0.013. White Rose was not affected by EDU. Averaged over four KC experiments, EDU application at 8.9 kg/ha increased Centennial Russet marketable and total tuber yields by 40 (from 214) and 45 (from 268) q/ha, respectively, whereas White Rose was not affected and averaged 398 (marketable) and 491 (total) q/ha.ResumenPara determinar cuantitativamente las pérdidas de campo en rendimiento de la papa (Solarium tuberosum L.) que pueden ser atribuidos al daño causado por la contaminatión del aire con ozono (02) en California, se hizo una evaluación del compuesto antioxidante N-(-2-2(2-oxo-l-imidazolidinil) etilo) -N′-fenilúrea (EDU o DPX-4891) para ver si era factible o no utilizarlo para estimar dichas pérdidas de rendimiento y para diferenciar las variedades cultivadas susceptibles a 03 de las resistentes a 03.En experimentos de invernadero se confirmé la susceptibilidad diferencial a 03 de dos variedades cultivadas, “Centennial Russet (sensible a 03) y “White Rose” (resistente a 03). Cinco tratamientos semanales de cinco horas cada uno con 25 partes por cien millones (0, 25 partes por millón) de 03 redujeron en 32% el rendimiento de tubérculos de Centennial Russet, pero no redujeron el rendimiento de White Rose.En ausencia de 03 en condiciones de invernadero, el EDU no tuvo efecto observable en el peso seco de las yemas, en el número de tubérculos o en el rendimiento de cualquiera de las dos variedades, lo cual sugiere que el EDU no afecta substancialmente el crecimiento de la planta en ausencia de 03 en los niveles aplicados y bajo las condiciones mencionadas.En experimentos de campo efectuados en la Universidad de California en Riverside (UCR) y en los campos de cultivo comercial de Kern County (KC), las plantas sin tratar de Centennial Russet y White Rose dieron rendimientos de tubérculos de 8 004 kg/ha y 23 552 kg/ha respectivamente en UCR y de 12 328 kg/ha y 22 908 kg/ha respectivamente en KC. En Riverside (UCR) al aplicar EDU en la dosis más alta 17,8 kg/ha, aumentaron los rendimientos de tubérculos comerciables y los totales de Centennial Russet en 9 568 kg/ha y 8 648 ka/ha respectivamente, y aumentó la gravedad específica en 0,013. White Rose no resultó afectada por EDU. Sacando el promedio de cuatro experimentos en KC, una aplicación de EDU de 8,9 kg/ha aumentó el rendimiento de Centennial Russet tanto en tubérculos comerciables como totales en 1 840 kg/ha (adicionales a 9 844 kg/ha) y 2 070 ka/ha (adicionales a 12 328 kg/ha) respectivamente, mientras que White Rose no fue afectada y dió un promedio de 18 308 kg/ha de tubérculos comerciables y de 22 586 kg/ha en rendimiento total.

Parenchyma cell growth in potato tubers II. Cell divisions vs. cell enlargement

Initial swelling and early tuber enlargement are the result of cell enlargement at a rate surpassing addition of new storage cells. New phloem strands are added by procambial activity. New storage cells are formed marginal to the phloem strands. Frequency of divisions in these new cells rapidly decreases.Tubers in which mitotic processes are compapratively restricted in early stages of development are slow growers; i.e., cell enlargement proceeds with fewer cells present. Tubers in which more phloem strands and associated cells have been added in early growth are rapid growers and contain more enlarging cells.Reduction in mitotic rate concurrently with increased cell enlargement progresses radially from each phloem strand in young tubers. Cell divisions are rare in all young storage tissues by the time a tuber has attained a size of 30 to 40 g, except in the immediate sites of “eye” buds. Some cell divisions are nececssary for phloem strands to keep pace with tuber enlargement, and also for formation of phellogen. Volumetric increase in these highly localized areas accounts for a small percentage of the increase in tuber volume resulting from enlargement of cells.

Potato composition: II. Tissue selection and its effects on total sugar, total reducing sugar, glucose, fructose and sucrose contents

Total sugar, reducing sugar, glucose, fructose, and sucrose were determined in three parts (bud-end, stem-end, and core) of tubers of White Rose, Red La Soda, Kennebec, Russet Burbank, Norchip and Lenape. Tubers were sampled at harvest, after storage for 2 and 4 mo at 7 C, and after reconditioning for 3 wk at 20 C after each storage period. The quantity of different sugar fractions varied with cultivar and changed with storage treatments. Only sucrose was uniformly distributed among the different parts of the tuber. Except for fructose and sucrose the relationships among different parts of the tuber for distribution of all other sugar fractions varied significantly with cultivar, and these relationships among parts were not significantly changed by temperature, or duration of storage.ResumenAzúcares totales, azúcares reductores, glucosa, fructosa y sucrosa se determinaron en tres partes (ápice, base y centro) de tubérculos de White Rose, Red La Soda, Kennebec, Russet Burbank, Norchip y Lenape. Los tubérculos fueron muestreados a la cosecha, después de almacenamiento de 2 y 4 meses a 7° C, y después de re-acondicionar por 3 semanas a 20° C después de cada periodo de almacenamiento. La cantidad de las diferentes fracciones de azúcares variaron con el cultivar y cambiaron con los tratamientos de almacenamiento. Solo la sucrosa estuvo distribuída uniformemente entre las diferentes partes del tubérculo. Con la excepción de fructosa y sucrosa las relaciones de distribución entre las diferentes partes del tubérculo de todas las fracciones de azúcares variaron significativamente con el cultivar y esas relaciones entre partes no fueron cambiadas significativamente con la temperatura o con la duraci⤵ del almacenamiento.

Potato composition: I. Tissue selection and its effects on solids content and amylose/amylopectin ratios

Solids content and amylose/amylopectin ratios were determined in different parts of tubers of White Rose, Red La Soda, Kennebec, Russet Burbank, Norchip and Lenape at harvest, after storage at 7 C for 2 and 4 mo, and after reconditioning at 20 C for 3 wk following each storage period. In all cultivars, solids content was greatest in stem-end, lower in bud-end and lowest in core tissue. The relationships for distribution of solids among the different parts of the tubers was not changed by storage treatments in any of the cultivars. Amylose/amylopectin ratios were similar in all parts of the tuber. Both the solids content and amylose/amylopectin ratio were changed by storage, but not uniformly in all cultivars.ResumenEl contenido de sólidos y las proporciones de amilosa/amilopectina fueron determinados en diferentes partes de tubérculos de White Rose, Red La Soda, Kennebec, Russet Burbank, Norchip y Lenape a la cosecha, después de almacenamiento a 7°C por 2 y 4 meses, y después de reacondicionamiento a 20° C por 3 semanas después de cada periodo de almacenamiento. En todos los cultivares el contenido de soolidos fue mayor en la base, menor en el apice y mucho menor en el centro. Las relaciones de distributión de sólidos entre las diferentes partes del tubérculo no fué cambiada por el almacenamiento aninguno de los cultivares. Las proporciones de amilosa/amilopectina fueron similares en todas las partes del tuberculo. El contenido de sólidos y la proportión amilosa/amilopectina fueron cambiados por el almacenamiento, pero no uniformemente todos los cultivares.

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.

POTATO COMPOSITION: III. TISSUE SELECTION AND ITS EFFECTS ON TOTAL NITROGEN, FREE AMINO ACID NITROGEN AND ENZYME ACTIVITY (POLYPHENOLASE, MONOPHENOLASE, PEROXIDASE AND CATALASE)

Russet Burbank, Norchip, Kennebec, White Rose, Red La Soda and Lenape tubers were sampled at harvest, after storage for 2 and 4 mo at 7 C, and after 3 wk at 20 C following each storage treatment. Freeze-dried tissue from the bud-end, stem-end and core was analyzed for total, and free amino acid nitrogen, and for monophenolase, polyphenolase, peroxidase, and catalase activities. Significant differences among cultivars and among different parts of the tuber were found for all nitrogen fractions and all enzyme activities. Storage treatments significantly changed the total and free amino acid nitrogen contents and polyphenolase, peroxidase, and catalase activities. When compared for total nitrogen content and catalase activity, differences among different parts of the tuber which were statistically significant were similar in all cultivars. However, when compared for free amino acid content, and monophenolase, polyphenolase and peroxidase activities, differences among different parts of the tuber which were statistically significant were dependent upon which cultivar was examined. The differences among cultivars which were statistically significant for all nitrogen fractions and all enzyme activities, except peroxidase, were not significantly changed by storage treatment. The differences among different parts of the tuber which were statistically significant for quantity of both nitrogen fractions and for all enzyme activities were not significantly changed by storage.ResumenSe muestrearon tubérculos de Russet Burbank, Norchip, Kennebec, White Rose, Red La Soda y Lenape al momento de la cosecha, después de almacenamiento por 2 y 4 meses a 7° C, y después de tres semanas a 20° C, a continuación de cada tratamiento de almecenamiento.Tejido liofilizado de la parte apical, basal y central fue analizado para determinar N Total y N de aminoácidos libres y las actividades de monofenolasa, polifenolasa, peroxidasa y catalasa. Se encontraron diferencias significantes entre cultivares y entre las diferentes partes del tubérculo para todas las fracciones de N y para todas las enzimas. Los tratamientos de almacenamiento cambiaron significativamente el contenido de N Total y el N de aminoácidos libres y las actividades de polifenolasa, peroxidasa y catalasa. Cuando se comparé el contenido total de N y la actividad de catalasa, las diferencias entre las diferentes partes del tubérculo, las cuales fueron estadísticamente significantes, fueron similares en todos los cultivares. Sin embargo, cuando se comparé el contenido de aminoácidos libres y las actividades de menofenolasa, polifenolasa y peroxidasa, las diferencias entre las diferentes partes del tubérculo, las cuales fueron estadísticamente significantes, fueron dependientes del cultivar. Las diferencias entre cultivares, las cuales fueron estadísticamente significantes para todas las fracciones de N y para todas las actividades enzimáticas, excepto peroxidasa, no fueron estadísticamente cambiadas por el tratamiento de almacenamiento. Las diferencias entre las diferentes partes del tubérculo, las cuales fueron estadísticamente significantes para la cantidad de ambas fracciones de N y para todas las actividades enzimáticas, no fueron cambiadas significativamente por el almacenamiento.

Significance of the fructose/glucose ratio in screening potato breeding lines with processing potential

Low sugar accumulation during low temperature holding is a most sought after characteristic in a potato cultivar utilized for processing. Although this property is largely inherited, the lack of a reliable biochemical test capable of screening large numbers of new breeding lines with low sugar accumulating ability has hampered present selection procedures of plant breeders. This study examined the concentration of individual sugar components and the ratios of sugar components from 80 to 110 day-old plants of three commercial potato cultivars, White Rose, Russet Burbank and Norchip, each with different inherent capacity to accumulate sugars under low temperature holding. By determining the fructose and glucose concentration of potatoes from 110-day old plants and calculating the fructose/ glucose ratio, it was possible at harvest to separate cultivars that accumulate high concentrations of sugars during cold storage from those that accumulate low concentration of sugarsResumenLa baja acumulación de azúcar durante el almacenamiento a temperatura baja, es una característica muy deseada en cultivares para procesamiento. Aunque esta propiedad es altamente hereditaria, la falta de una prueba bioquímica segura, capaz de tamizar un gran número de líneas en mejoramiento para una baja acumulación de azúcar, ha tratado los actuales procedimientos de selección de los mejoradores. Este estudio examinó la concentración individual de azúcares componentes y la proporción de azúcares componentes de plantas de 80 a 110 días de edad de los cultivares comerciales White Rose, Russet Burbank y Norchip, cada uno con una diferente capacidad inherente para acumular azúcares cuando son mantenidos a temperaturas bajas. Mediante la determinación de la concentración de fructosa y glucosa de papas proveniente de plantas de 110 días de edad y calculando la proporción fructosa/glucosa, fue posible separar a la cosecha cultivares que acumulan altas concentraciones de azúcar de aquellos cuya concentración es baja durante el almacenamiento frío

Cell size in Russet Burbank potato tubers with various levels of nitrogen and soil moisture tensions

Russet Burbank potatoes were grown at levels of added nitrogen of 0, 135, and 270 kg/ha and soil moisture tensions (SMT) of 0.5 and 1.0 atm. With all combinations, there was a consistent gradient of larger to smaller starch-storage parenchyma cells from stem end to bud end of mature tubers.Stem and bud ends of tubers grown at a SMT of 0.5 atm with N had smaller cortical and pith (innermost medullary or water-core) cells than did ends of tubers grown without N. Perimedullary tissues of bud ends of tubers receiving N likewise contained smaller cells than did corresponding tissues of tubers grown without N. No pronounced differences in cell size were found in tissues from the midsections.In bud-end tissue of tubers grown at a SMT of 1.0 atm, there were no consistent differences in cell size with respect to N levels. However, pith, perimedullary, and cortical tissues of the midsections and stem ends of tubers receiving N had smaller cells than did corresponding tissues from tubers without N. The different patterns of cell size in tubers grown at different SMT indicate that the effects of N may be influenced by soil moisure.