Coastal Chip: A chipping potato variety resistant to heat stress

Coastal Chip is a medium-late maturing potato chipping variety suitable for production in locations along the east coast of the United States where heat stress reduces internal quality of tubers. It yields as well as the variety Atlantic but is not as susceptible to heat necrosis. The specific gravity of Coastal Chip averages approximately 0.010 less than Atlantic at locations subject to heat stress. In the seed producing areas of Maine it’s specific gravity averages approximately 0.005 less than that of Atlantic. Tubers are round, netted-skinned, and have moderately deep stem and bud ends. Chips from Coastal Chip are slightly lighter in color than those produced by Atlantic. In mid-Atlantic states where heat stress adversely affects chip color Coastal Chip processes into chips for a slightly longer period of time after harvest than does Atlantic. Glycoalkaloid content of Coastal Chip averaged 7.9 mg/100 g fresh tissue. Sunburned (green) tubers of Coastal Chip develop purple streaks that remain following processing. Hills must be properly covered to reduce losses. Coastal Chip is resistant to race A of the golden nematode (Globodera rostochiensis) and potato virus A. It is tolerant to Verticillium wilt, more susceptible to common scab and Rhizoctonia than Atlantic and susceptible to potato virus X.     

Influence of landscape structure on reef fish assemblages

Management of tropical marine environments calls for interdisciplinary studies and innovative methodologies that consider processes occurring over broad spatial scales. We investigated relationships between landscape structure and reef fish assemblage structure in the US Virgin Islands. Measures of landscape structure were transformed into a reduced set of composite indices using principal component analyses (PCA) to synthesize data on the spatial patterning of the landscape structure of the study reefs. However, composite indices (e.g., habitat diversity) were not particularly informative for predicting reef fish assemblage structure. Rather, relationships were interpreted more easily when functional groups of fishes were related to individual habitat features. In particular, multiple reef fish parameters were strongly associated with reef context. Fishes responded to benthic habitat structure at multiple spatial scales, with various groups of fishes each correlated to a unique suite of variables. Accordingly, future experiments should be designed to test functional relationships based on the ecology of the organisms of interest. Our study demonstrates that landscape-scale habitat features influence reef fish communities, illustrating promise in applying a landscape ecology approach to better understand factors that structure coral reef ecosystems. Furthermore, our findings may prove useful in design of spatially-based conservation approaches such as marine protected areas (MPAs), because landscape-scale metrics may serve as proxies for areas with high species diversity and abundance within the coral reef landscape.

     

Influence of calcium on internal heat necrosis of Atlantic potato

While Atlantic is the cultivar of choice of potato chip processors for the mid-Atlantic region, susceptibility to internal heat necrosis (IHN) greatly increases grower risk of economic loss from unsalable tubers. Yield, tuber calcium levels, and percentage of tubers with IHN of several cultivars from a common seed source were examined at two locations. The percentage of tubers with IHN were significantly higher for Atlantic while the tuber Ca concentration was lower than those of Superior. Both the percentage of tubers with IHN and tuber Ca concentration was higher in New Jersey than Virginia. Lower Ca levels were found in tubers with necrotic medullary tissue than in those without. Studies were completed in Virginia and New Jersey to evaluate the influence of Ca source, Ca rate and location within the hill as well as nitrogen rate on the onset and progression of IHN of Atlantic potato. Tuber yield was not significantly influenced by either Ca source (calcium carbonate (CaCO₃) or calcium sulfate (CaSO₄)) or Ca rate (0-1800 kg Ca/ha). Calcium rate had no influence on size distribution. As expected, a significantly greater percentage of large tubers were noted with delayed harvest. In a short growing season (<110 days) yield was not influenced by nitrogen rates ranging from 84 to 252 kg/ha. However, with delayed harvest, yield was increased and IHN slightly reduced with 168 or 252 kg N/ha when compared to 84 kg/ha. The influence of applied Ca on IHN varied between years, but the addition of Ca or N did not reduce IHN sufficiently to avoid out-of-grade because of internal defects. Location of applied Ca within the hill had no effect on yield, specific gravity, IHN, or tissue Ca concentrations. Slightly higher leaf Ca was found when using CaCO₃ than CaSo₄. The influence of Ca rate in 1987 and 1988 on leaf, periderm, or medullary Ca concentrations was not consistent. Nitrogen had no significant influence on tissue Ca levels.     

A heat-sum model to determine yield and onset of internal heat necrosis for atlantic potato

The influence of temperature on tuber yield and development of internal heat necrosis (IHN) in Atlantic (Solanum tuberosum L.) was examined in field trials in two locations over three years (seven plantings). Under simulated commercial production, yield and development of IHN varied significantly between Virginia (VA) and New Jersey (NJ) in 1986, 1987, and 1988. Marketable yield ranged from 49.8 mt.ha^?1 for the early planting in 1986 in New Jersey (NJ86E) to 17.9 for VA87. Tubers developing IHN to a level which potato chip processors would rate unacceptable (off-grade) varied with year and location. Significant correlations were found between the number of days to off-grade and the mean maximum temperature for 0–30 (r = ?.83), 30–60 (r = ?.86) and 60–90 DAP (r = ?.81) as well as the mean minimum temperature for the same periods (r = ?.91,, ?.80 and ?.91, respectively). The relationship between yield or IHN and temperature was examined using heat-sum models with a penalty for maximum daily temperature > 25C but with or without a penalty for minimum temperature > 21C. The multiple coefficients of determination for yield were similar using either variables generated from the heat-sum model with maximum and minimum temperature penalties or from the model with maximum temperature penalty only (R² = 0.83 and R² = 0.82). The prediction of the time from first symptom of necrosis to off-grade (interval) was improved by including variables generated by the heat-sum model that included both the minimum and maximum temperature penalty (R² = 0.50 vs. R² = 0.27), respectively. High minimum temperatures as reflected in the days to maximum heat-sum were found to significantly affect tuber yield and the expression and development of IHN.     

Detection of papillomaviral-like DNA sequences in premalignant and malignant perineal lesions of sheep.

Small hyperkeratotic and ulcerated lesions and clinical cancers were isolated from the perineal region of sheep and examined for evidence of papillomavirus infection by various criteria including gross morphology, histology, immunohistochemistry and DNA hybridisation. No specific diagnostic features of papillomaviral infection by immunohistochemistry were found, although some lesions showed gross morphological and histological features similar to papillomaviral effect in other species. DNA hybridisation analysis, using human papillomaviral type 11, 13, 16 and 18 DNA probes under conditions of reduced stringency (Tm-40 degrees C), detected homologous sequences in two thirds of the biopsies examined. These homologous sequences occurred in benign hyperkeratosis as well as invasive squamous cell carcinomas but were much more frequently isolated from carcinomas. This finding suggests that a papillomavirus is associated with the development of squamous cell carcinomas of the perineum of sheep.