Physiological disorders affect both the appearance and nutritional quality of processing tomatoes intended for whole-peel and diced products. The cause of color disorders, such as yellow shoulder disorder (YSD), involves an interaction between plant genotype and the environment. Soil factors that correlate with the incidence of YSD are soil K, K:Mg ratios, organic matter, and phosphorus. Fields with an organic matter above 3.5% have a lower incidence of YSD. Progress in developing an integrated crop management system that growers and processors can use to profitably improve quality and nutritional value while reducing color disorders of tomato has been made. Decision tools for managing color disorders have been developed. Varieties of tomato differ in their susceptibility to color disorders; thus, variety use may offer growers a strategy to manage fields with low potassium, phosphorus, or low organic matter. Soil K application through drip irrigation was effective when applied at full bloom when the plants were most actively growing. Trials conducted in Indiana and Ohio during the 2003 and 2004 growing seasons demonstrated that weekly K application as a batch injection or solid application improved fruit color and reduced internal whitening. The effect of K addition is toward improved hue and L (lower values), but that trend is not always statistically significant and variety-specific responses are observed. Environmental factors for this response are explored. Managing this complex color disorder will entail minimizing risk of incidence, rather than preventative or curative applications.
The lack of resistance to bacterial diseases increases both the financial cost and environmental impact of tomato (Lycopersicon esculentum Mill.) production while reducing yield and quality. Because several bacterial diseases can be present in the same field, developing varieties with resistance to multiple diseases is a desirable goal. Bacterial spot (caused by four Xanthomonas Dowson species) and bacterial speck (caused by Pseudomonas syringae pv. tomato Young, Dye and Wilkie) are two economically important diseases of tomato with a worldwide distribution. The resistance gene Pto confers a hypersensitive response (HR) to race 0 strains of the bacterial speck pathogen. The locus Rx3 explains up to 41% of the variation for resistance to bacterial spot race T1 in field trials, and is associated with HR following infiltration. Both Pto and Rx3 are linked in repulsion phase on chromosome 5. We made a cross between two elite breeding lines, Ohio 981205 carrying Pto and Ohio 9834 carrying Rx3, to develop an F2 population and subsequent inbred generations. Marker-assisted selection (MAS) was applied to the F2 progeny and to F2:3 families in order to select for coupling-phase resistance. Thirteen homozygous progeny from 419 F2 plants and 20 homozygous families from 3716 F3 plants were obtained. Resistance was confirmed in all selected families based on HR in greenhouse screens using bacterial speck race 0 and bacterial spot race T1 isolates. Resistance to bacterial spot race T1 was confirmed in the field for 33 of the selected families. All selected families were also resistant to bacterial speck in the field. MAS was an efficient tool to select for desirable recombination events and pyramid resistance.
The genetic and environmental variation for flesh color of tomato (Lycopersicon esculentum Mill.) fruit was quantified using 41 red-fruited breeding lines, open-pollinated cultivars, and hybrids that are representative of the diversity of tomatoes grown for whole-peel processing in the midwestern and eastern United States and Ontario, Canada. Objective color measurements were made for 2 years from replicated experiments with 2 to 4 blocks per year. Genotypes differed significantly in lightness value (L*), saturation (chroma), and hue angle. Variation within fruit and among fruit in plots accounted for more than 75% of the environmental variation for the color traits. The crimson locus (ogc) accounted for less than one-third of the variation in fruit color among genotypic means, and explained 18% to 27% of the genotypic variation for L*, chroma, and hue. Estimates of variance components were used to develop sampling strategies for improving selection efficiency. Genotypes were identified that may be useful for studying genetic differences that lead to quantitative variation for fruit color in red-fruited populations of tomato.
Yellow shoulder disorder (YSD) is a physiological disorder of processing tomato that affects both the appearance and nutritional quality of the fruit. This disorder reduces the suitability of fruit intended for the whole-peeled and diced product markets. The YSD involves an interaction between plant genotype and the environment. A number of soil factors have been related to the incidence of YSD, including organic matter, phosphorous, K/Mg ratios, and soil K. Varieties of tomatoes differ in their susceptibility to color disorders, thus variety selection offers growers one strategy to manage this color disorder. The use of supplemental K application at a time when plants are blooming and actively growing offers a second strategy for management of YSD. To this end, a field study was conducted at the Southwest Purdue Agricultural Program in southwestern Indiana to study the effects of different sources of K on the color and quality of tomato fruit. Potassium chloride, potassium nitrate, and potassium sulfate were applied at first flowering in a solid, broadcast application. Appropriate controls were used to balance the nutrients supplied in addition to K. Supplemental K, regardless of source, improved fruit hue, though the trend was not always statistically significant between treatments. Variety specific effects were observed. This is a complex disorder and its management will entail minimizing risk of incidence through careful selection of variety and field location.
The effectiveness of gamma radiation as an enhancer of anthocyanin and flavonol pigment synthesis in cranberries was determined. Three different maturities of cranberries, based on their degree of coloration, and radiation levels of 150 and 300 krad were employed. The changes in the anthocyanin and flavonol pigments were measured quantitatively at regular intervals during storage. Radiation had a beneficial effect on the pigmentation of full-red cranberries and resulted in a significant increase in the anthocyanin and flavonol pigment contents. Effects on the less colored berries were not as great and in some cases flavonoid synthesis was reduced. The radiation induced changes were strictly quantitative in nature and there were no qualitative changes in the anthocyanins and flavonols. The visual effects of radiation on cranberries were minor softening and a stimulation of pigment production in the endocarp area of the fruit, resulting in internal coloration of the fruit. It was concluded that gamma radiation has an effect on the biosynthesis of the pigments involved and that the maturity stage of the cranberries was the controlling factor in determining the degree of response to radiation treatment. A possible mode of action of radiation on flavonoid synthesis was postulated.
An inbred backcross (IBC) population derived from Lycopersicon hirsutum LA407 and L. esculentum was evaluated in replicated field trials to assess its potential for the improvement of red-fruited tomatoes. Significant phenotypic variation among genotypes was detected for the hue (tint), L (darkness), and chroma (saturation) of color. Significant effects due to environment and genotype × environment interactions also were observed. One superior inbred backcross line from this population, IBL 2349, was used to develop an F2 population and to explore the genetic basis of color. Two independent L. esculentum quantitative trait loci (QTL) associated with improved color were identified based on linkage to markers mapping to chromosome 4 and chromosome 11. Epistatic interactions were identified between the two L. esculentum loci. Unexpected epistatic interactions also were identified between L. esculentum loci and an LA407 introgression on chromosome 7 present within IBL 2349. The two L. esculentum QTL and the epistatic interactions were confirmed in replicated trials with F3 and F4 families. The loci identified in this study and their epistatic interactions may provide additional tools for the improvement of red-fruited tomatoes in breeding programs.
‘Andover’ parsnip (Pastinaca sativa L.) is being released for commercial fresh-market and home garden production as a cultivar with desirable root type and resistance to field and storage attack by Itersonilia perplexans Derx. (1-4), which causes a foliar leaf spot, and, in storage, a root canker followed by root deterioration. The disease is commonly known as parsnip canker. A need for resistance to deterioration in storage gave rise to the breeding program. It was found that canker was a major reason for this deterioration, although other organisms are known to be involved.
Successful organic farming requires synchronizing soil-based processes affecting nutrient supply with crop demand, variable among and within crops. We report here on two studies conducted in transitional- (TO) and certified-organic (CO) systems containing subplots that, annually, were either amended with compost or not amended prior to vegetable crop planting. Dairy-manure compost was added at rates providing the portion of a crop's anticipated nitrogen requirement not provided by a leguminous rotation crop and/or carryover from previous compost application. In the TO study, potato (2003), squash (2004), green bean (2005), and tomato (2006) were planted in main-season plots in open fields and high tunnels, and beet, lettuce, radish, spinach, and swiss chard were planted in high tunnels in early spring and late fall. Long-term CO open-field plots (±compost) were planted to multiple varieties of lettuce, potato, popcorn, and processing tomato in 2004–2006. Drip irrigation was used in all TO plots and CO lettuce and processing tomato plots. Treatment effects on crop physical and biochemical variables, some related to buyer perceptions of crop quality, were emphasized in each study. Yield in TO, compost-amended plots exceeded yield in unamended plots by 1.3 to 4 times, with the greatest increases observed in high-tunnel-grown mesclun lettuce and the smallest response observed in potato. Similar results were found in CO plots, although compost effects differed by crop and variety. The data suggest that: 1) compost application and the use of specific varieties are needed to maximize yield in organic vegetable systems in temperate zones, regardless of age; and 2) production phase management may influence buyer-oriented aspects of crop quality.