Growth of early potatoes from different portions of seed tubers II. Yield

Several of the recently released early-potato (Solanum tuberosum L.) cultivars used in Ontario have produced uneven stands which have been shown to be a result of delayed emergence from basal end seed pieces. A study was conducted to evaluate the effects of seed portions on the yield of three early potato cultivars, Jemseg, Superior and Yukon Gold. Yield of plants from basal seed pieces was lower than that from apical seed pieces or whole tubers for Jemseg and Yukon Gold during several sequential harvests. With Superior, cut seed portions yielded less than whole seed. Number of stems per plant was lower for basal plants of Jemseg. Tubers with strong apical dominance or dormancy such as Jemseg and Yukon Gold are prone to differences in yield among seed portions.     

The concept and development of management profiles for potato cultivars and selections

Potato (Solanum tuberosum L.) growers in Ontario, Canada have funded research specifically to develop management profiles for potato cultivars. Such profiles have been developed for Atlantic, Conestoga, Jemseg, Monona, Norchip, Shepody, Superior and Yukon Gold grown under Ontario conditions. The development of management profiles to facilitate the optimum production and storage of different potato cultivars and selections is recognized as a valuable tool in aiding in the technology transfer of potato research and information to growers and processors. Unique differences among cultivars such as herbicide tolerance, time and duration of bulking, fertility requirements, processing quality and other variables may have significant impact on management of a particular cultivar. Some cultivar traits can be modified via management techniques while others cannot. A clarification of such information is critical to the industry.     

Red Gold: A yellow-fleshed,red-skinned potato cultivar with short dormancy and high tuber set

Red Gold is a midseason maturity potato with pink-red skin and a bright yellow flesh. It is characterized by having a high set per plant of medium-small sized tubers. Marketable yields in Ontario, Canada are similar to or slightly less than Conestoga, Yukon Gold, and Superior. Boiling, baking, and field chip quality are acceptable with medium specific gravities (1.070–1.080). Short tuber dormancy makes this variety well adapted for whole seed tuber production for fall export markets. Red Gold has performed well in trials in Uruguay. Red Gold is moderately resistant to scab, field resistant to virus Y and leafroll, and susceptible to mild mosaic.     

AC Sunbury: A new light yellow-fleshed medium early table potato cultivar with resistance to golden cyst nematode

AC Sunbury is an attractive, round /oval, medium early table potato with light yellow flesh and very good culinary quality, especially when baked. It produces yields comparable to Jemseg or Superior at 80 days and is resistant to the golden cyst nematode Rol and to infection by PVY°. It was bred at the Potato Research Centre, Agriculture and Agri-Food Canada, Fredericton, NB, and released in 2001.     

Changes in color and sugar content of yellow-fleshed potatoes stored at three different temperatures

Yellow-fleshed potatoes, Yukon Gold, Red Gold, Sag-maw Gold, Augsberg Gold, and AO82283.1 were compared to white-fleshed cultivars, Russet Burbank and Norchip, in relation to flesh color and sugar content during long-term storage. Yellow-fleshed cultivars had higher hue angles (h°) and chroma values (C*) compared to the white-fleshed potatoes. These values were consistently higher at all storage temperatures. Chroma values were maximum for most yellow-fleshed tubers when stored at 8.3 C for 84 days. As expected, lower concentrations of sucrose, glucose, and fructose were observed in tubers stored at 10 C compared to those stored at 3.3 and 8.3 C. After storage at either 3.3 or 8.3 C, Saginaw Gold, Augs-berg Gold, and AO82283.1 accumulated lower amounts of glucose or fructose compared to Norchip, Russet Burbank, Yukon Gold, and Red Gold. Although the yellow-fleshed clones accumulated up to 7.4 mg/g glucose or fructose when stored at 3.3 C, Saginaw Gold and Augsberg Gold responded well to reconditioning.     

Relative differences in sugar content of basal and apical portions of Russet Burbank potatoes

Basal and apical portions of mature and immature Russet Burbank tubers stored at 42 F (5.6 C), 45 F (7.2 C), and 48 F (8.0 C) were analyzed for sucrose and reducing sugars at seven monthly intervals for three seasons. Percent relative difference of reducing sugars (between mature and immature tubers) was greater in the apical than the basal portion. On the other hand, seasonal differences in percent reducing sugars were reflected more in the basal portion by greater relative differences among seasons than in the apical portion. Statistical analysis showed no trend or influence of maturity or storage temperature in affecting the relativeratio of reducing sugars between the basal and apical portions. Differences among growing seasons appeared to affect this ratio. Tubers from the 1970–71 season had more equal relative amounts of sugars in the two portions than did the tubers from 1968–69 or 1969–70 seasons. Ratio ofsucrose between the basal and apical portions was not affected appreciably by maturity, storage temperature or season, although immaturity and lower storage temperatures caused slightly greater overall sucrose accumulation. Sucrose and reducing sugar contents were poorly correlated regardless of maturity, storage temperature or different seasons.     

Michigold: A yellow-fleshed potato cultivar for fresh market

Michigold (MS704-10Y) is a round, blocky, yellow-fleshed cultivar with medium netting selected at Michigan State University for the fresh market. It could also be used for chip processing out of field or from short-term storage at 10 C. Under Michigan conditions, Michigold matures in 110–120 days with marketable yields of 122% of Yukon Gold and 95% of Atlantic. Plant growth is vigorous and Michigold appears to have moderate resistance to early blight. Internal defects have been minimal. An electrophoretic fingerprint based upon 13 isozyme loci is presented to facilitate cultivar identification during seed certification processes.     

TX1523-1Ru/Y a.k.a Sierra Gold™: An early maturing, yellow-fleshed ruseet cultivar for the specialty/gourmet market

TX1523-1Ru/Y, a unique specialty cultivar with deep-yellow flesh color and an attractive russet skin, was released in 2003 by the Texas Agricultural Experiment Station. The smaller, immature tubers are round, but take on an oval shape as they mature. Eyes are shallow and the tuber surface is smooth. Tuber size tends to be medium (113.4–283.5 g; 4–10 oz). Total and marketable yield varies with year and location, but tends to be comparable to ‘Yukon Gold’, with percent marketable yield slightly higher. Vines are semi-prostrate, with medium vigor and size, and relatively early maturity. Specific gravity is about the same or slightly less than Yukon Gold, but generally greater than ‘Russet Norkotah’. TX1523-1Ru/Y has good culinary qualities, with resistance to after-cooking-darkening, and can be chipped, boiled, baked, or microwaved. It has been reported to be excellent to superior as a microwave product. Unlike Yukon Gold, TX1523-1Ru/Y is resistant to hollow heart, brown centers, and internal discoloration. It tends to be less susceptible to tuber infection by late blight (Phytopthora infestans) than Yukon Gold, has greater resistance to common scab (Streptomyces scabies), and is less susceptible to black scurf (Rhizoctonia solani). TX1523-1Ru/Y is believed to be the first yellow-fleshed resset-skin cultivar released in the United States.     

Manipulating Stem Number, Tuber Set and Size Distribution in Specialty Potato Cultivars

Manipulating seed physiological age is an effective method to alter tuber set and size distribution for many cultivars. However, cultivars Cal White, Red La Soda, Chieftain, Yukon Gold, and Satina were largely insensitive to high temperature-induced age-priming treatments. Gibberellins (GA) also have potential for altering tuber set and size development. When applied to cut seed of the five cultivars, GA hastened plant emergence, increased stem and tuber numbers per plant, and decreased average tuber size. The optimum concentration of GA for shifting tuber size distribution to maximize crop value without decreasing total yield depended on cultivar. Total yields decreased substantially in all cultivars with 10 mg L^?1 GA but lower concentrations (0.5–4 mg L^?1) either increased yields of Red La Soda, Yukon Gold, Chieftain and Satina by 11, 13, 15, and 24 %, respectively, or had no effect (Cal White). GA-induced increases in tubers per hectare ranged from zero (Cal White, Satina) to 36 % (Chieftain) and associated increases in yields of premium priced creamer size potatoes (C size; 10–66 g, 28–51 mm diameter) ranged from 0 to 140 %, depending on cultivar and length of the growing season. Increases in total crop values ranged from 7 to 30 % (Chieftain) with the optimum concentrations of GA, which also varied by cultivar. Effective use of GA to alter tuber size distribution for increased value depends on cultivar, concentration, and harvest timing.     

Huckleberry Gold: A Specialty Market Potato Cultivar with Purple-Skin,Yellow-Flesh,High Tuber Antioxidants,and Resistance to Potato Cyst Nematode (H1) and Potato virus X (Nb and Rx1)

Huckleberry Gold is a purple-skin, yellow-flesh fresh market cultivar with similar culinary qualities to the market standard Yukon Gold. It has lower specific gravity, sucrose and vitamin C content, but a significantly higher level of tuber antioxidants than Yukon Gold. Notable disease resistant characteristics are Potato virus X resistance based on the presence of molecular markers for the PVX resistance genes, Nb and Rx1. In addition it also has the H1 gene present which confers resistance to the potato cyst nematode, Globodera rostochiensis, which has been confirmed by bioassay to pathotype Ro1. The size profile of Huckleberry Gold is smaller than Yukon Gold, allowing a better fit into specialty markets that are geared to smaller size for fresh use. Huckleberry Gold represents the first purple-skin, yellow-flesh cultivar to come from the Northwest (Tri-State) Potato Variety Development program.     

Effect of seed piece removal on yield and agronomic characteristics of Russet Burbank potatoes

There is inadequate information available to ascertain the length of time seed pieces contribute to the yield and agronomic characteristics of potatoes (Solanum tuberosum L.) under field conditions. Previous studies have not accounted for root system disturbance during seed piece removal. In 1994, 1995, and 1997 a field study was conducted using Russet Burbank to determine whether seed piece removal at each of three growth stages affects yield and agronomic characteristics. A trowel was used to tunnel into the side of potato hills to remove seed pieces by hand either at emergence, at 20- cm plant height, or at first bloom. Control plots consisted of plants with root systems disturbed on the same date as seed removal (disturbed control) or not treated (non-disturbed control). Seed pieces were analyzed for solids, sucrose, and reducing sugars before planting and after removal at each growth stage in 1997. Removing seed pieces or disturbing roots at all growth stages significantly decreased total and U.S. No. 1 yields compared with non- disturbed control. Total yield from plots disturbed at emergence was 37.8 Mg ha^-1 compared to 22.1 Mg ha^-1 when the seed pieces were removed. Disturbing seed pieces at emergence resulted in U.S. No. 1 yield of 21.2 Mg ha^-1 compared with 10.6 Mg ha^-1 when seed pieces were removed at the same growth stage. For U.S. No. 1 yield, a difference between removing the seed pieces and disturbing the root systems was still evident at the 20-cm plant height growth stage (15.4 Mg ha^-1 vs 20.3 Mg ha^-1, respectively). Disturbing plants at emergence or at 20-cm plant height growth stage reduced the number of tubers per plant to 8.8 for both treatments compared to 9.7 for the non-disturbed control. Removing seed pieces at these same growth stages further reduced tubers per plant to 6.9 and 7.6, respectively. Vines of plants with seed pieces removed at emergence were shorter and remained green later into the season compared with disturbed and non-disturbed control treatments. Percent solids in seed pieces decreased from 20.68 at planting to 5.03 at first bloom. Seed piece percent sucrose remained constant from planting through the 20-cm plant height growth stage and then fell to nearly zero at first bloom. Reducing sugar in the seed pieces atplanting and emergence was 0.67%, rose to 1.08% at the 20-cm plant height growth stage, and then decreased to 0.89% at first bloom.     

Field infection of potato by the Solanum apical leaf curling virus (SALCV)

Potato plants grown from true seed were naturally infected with the Solanum apical leaf curling virus (SALCV) at the high jungle site near San Ramon, Peru. Tubers from these plants were greenhouse indexed. Symptoms of SALCV infected potato plants include apical rolling, stunting, delayed emergence, weak plants, hair sprouts, and tuber dormancy. These symptoms superficially resemble certain aspects of unusually severe current season potato leafroll virus (4) infection or those of the aster yellows and stolbur mycoplasma diseases (5). Up to 12 percent of the indexed plants were naturally infected with SALCV and SALCV was demonstrated in approximately half of the tubers that produced hair sprouts.     

Varietal Differences in Minituber Production Costs

Minitubers have become important components of seed potato production systems. Minituber production methods and yields affect costs. We used data from the University of Wisconsin seed potato program to estimate minituber production costs by variety in 2009, 2010, and 2011. Labor is identified as the most significant operating cost, while salaries represent the greatest fixed cost. The 3 year average total cost per minituber across all varieties was estimated at $0.47. Of the varieties grown in all 3 years of analysis Langlade had the highest average yield and lowest cost. Yukon Gold and Pike had the lowest yields and highest costs.     

Ac belmont: a new early-maturing potato cultivar with short dormancy

AC Belmont is adapted as a second early cultivar in Eastern Canada. It has a short dormancy. The white-skinned round oval tubers size and bulk early, but more similar to Superior than to Jemseg. The specific gravity of AC Belmont is lower than Superior. When boiled, the tubers of AC Belmont have a good, somewhat moist texture; when baked the texture of AC Belmont is relatively dry. AC Belmont is highly resistant toVerticillium albo-atrum, moderately resistant to PVY,Fusarium coeruleum, F. sambucinum f.6. andRhizoctonia solani.     

Efficacy of Seed Aging and Gibberellin Treatments for Manipulating Apical Dominance,Tuber Set and Size Distribution of cv. Shepody

The cultivar Shepody has excellent early processing qualities and produces above average tuber yields but sets relatively few tubers that often become excessively large relative to market demand. Optimizing tuber set and size of Shepody for seed and frozen processing markets currently entails adjusting in-row spacing and vine kill date. However, arresting tuber growth by vine killing for size control sacrifices yield potential. Aging seed by storing at 12, 22, and 32°C for 80-, 450-, and 900-degree days, or gibberellin (GA) treatments, were evaluated as more direct approaches for modulating stem number (apical dominance), tuber set, and size distribution relationships. Shepody proved to be inherently resistant to high temperature-induced age-priming treatments. In contrast to other cultivars studied previously, age-priming Shepody seed during storage had no effect on plant emergence and the resulting increases in stem number, tuber set, and associated decreases in average tuber weight were marginal. By contrast, GA applied as seed dip or spray effectively hastened plant emergence, reduced apical dominance, increased tuber set, and decreased average tuber size. The magnitude of these GA-induced effects depended on concentration and application technique (seed dip versus spray). For frozen processing, GA applied as a seed dip at 1 mg L^-1 added an additional tuber per plant and decreased average tuber size by 15% without affecting U.S. No. 1 tuber yields and gross returns; however, 2 and 3 mg L^-1 GA decreased U.S. No. 1 tuber yields and crop value by an average of 16 and 14%, respectively. Spray applications of 2–6 mg L^-1 GA also reduced U.S. No. 1 tuber yield and frozen processing value. Conversely, the increase in tuber set (1.5 tubers plant^-1) and associated 25% reduction in average tuber weight induced by 2 mg L^-1 GA applied as either dip or spray increased gross crop values on a seed contract by 25 and 38%, respectively. The differential efficacies of dip versus spray applications of GA on tuber set and size distribution were likely attributable to differences in GA deposition on the seed. Applying low concentrations of GA to cut seed of Shepody as either a dip (1–2 mg L^-1) or spray (2 mg L^-1) effectively modulated tuber set and size to significantly increase gross returns for seed, and to better satisfy the needs of processors for more moderate size tubers.     

Rose Gold: A yellow fleshed,pink-red skinned,tablestock cultivar with short dormancy and full season maturity

Rose Gold is a pink-red skinned, bright yellow fleshed, tablestock potato cultivar. In Ontario trials, Rose Gold is later maturing than its half sibling Red Gold and is characterized by producing larger and fewer tubers per plant than Red Gold. Rose Gold rarely develops symptoms of virus diseases when grown for repeated generations under high virus disease pressure (PVY, PLRV, PVX). Tubers have a very short dormancy. Yields are similar to Yukon Gold on mineral soil and generally higher than Red Gold. Rose Gold has produced high marketable yields on muck soil.     

Seed longevity and seedling emergence rate of Urochloa decumbens as influenced by sowing depth in a Cerrado soil

Urochloa decumbens (Signal grass) is an African grass species that is widely used in Brazil for pasture formation, and it has a high potential for invading natural areas. This study evaluated the longevity of U. decumbens seeds in the soil seed bank and the emergence rates of seedlings from different depths. In the greenhouse (natural light; ~25°C), seeds were sown at depths of 0, 1, 2 or 3 cm, in trays filled with sterile soil, to assess seedling emergence. Seeds sowed on the soil surface began to germinate 3 days after sowing. Seeds sowed at depths of 2 and 3 cm germinated 5 days after sowing. No seedlings emerged after 15 days. The seedling emergence rate was 74 ± 7% with no significant difference between sowing depths. In the field, seed longevity was evaluated by burying 60 replicates of 100 seeds at a soil depth of 2–3 cm, in a Cerrado area in the IBGE Ecological Reserve, Brasília. From September 2016 to April 2017, five samples were retrieved monthly to assess seed viability. In September, the viability was 68%, declining to 3% in October; by February, viable seeds were no longer recorded. As U. decumbens flowers in several episodes throughout the year, a soil survey may result in a misleading interpretation of the formation of a permanent soil seed bank.     

红小豆、大豆以及菜豆的形态特征和出苗日数的相关性

对红小豆、大豆以及菜豆3种豆类品种的种子形态特性进行了调查。3种豆类品种种子的粒重和粒长、粒宽以及粒厚之间有很高的正相关关系。把各种豆类的粒长、粒宽以及粒厚之间的关系用直线回归系数来表示,并使粒形的形态特征数值化。另外,大豆和菜豆种子的粒重和种子所占子叶比率之间成正相关关系,种子的粒重和种子所占胚芽比率之间成负相关关系,但红小豆没有相关关系。通过两年试验,从播种到出苗日数,3种豆类中红小豆最晚（15～20d）。在降雨量多的年份红小豆的出苗日数和种子的大小没有相关性,但是大豆和菜豆的粒重和出苗日数之间成负相关关系。播种时期土壤水分充足时,大豆和菜豆粒重轻的种子比粒重重的种子先出苗,但是红小豆没有看到这种关系。这可能与种子的吸水速度有关。     

Nutrient composition of groundnut cultures (Arachis hypogaea L.) in relation to their kernel size

Seven varieties of groundnuts of varying kernel size were selected to study the relation between kernel size and nutritional quality. Results indicated that no significant (r=0.22) difference was found in oil contents among the various varieties which ranged from 46–52 percent. Protein contents ranged from 17–25.2 percent. Protein content of small seed varieties was high compared to bold seeded varieties, whereas sugar content of bold seeded varieties was higher. No significant differences in amino acid and fatty acid compositions were observed among the varieties tested. In vitro digestibility of protein tended to be slightly less but not significantly so in bold seeded varieties compared to small and medium size varieties. Niacin content of bold seeded varieties was slightly higher compared to other varieties.     

Some factors influencing the pH of apical and basal portions of Russet Burbank and Norgold Russet potatoes

Studies were made of pH changes of apical and basal portions of Russet Burbank and Norgold Russet potatoes during growth and in storage. Russet Burbank had a higher pH of the apical portion during the later stages of growth as compared to the basal portion. No significant differences between the two portions were found during growth with Norgold Russet. After a period of moisture stress the pH of the basal portion of Russet Burbank dropped significantly. The basal portion of both varieties at higher specific gravities had higher pH after storage than the apical portion. A highly significant negative correlation was obtained after storage between reducing sugar levels of tubers of different specific gravities and pH levels in both varieties. There were no significant differences in pH among storage temperatures of 34, 38, 42 and 45 F. However, the pH level at 48 F storage was significantly higher than at the other temperatures. The pH level of tubers from seedlings and varieties were poorly correlated with their reducing sugar contents after storage. It appears that pH can be an indicator of potential chip color only within the confined limits of a specific lot.