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In the midwestern United States, especially Missouri, winegrape (Vitis sp.) growers mostly plant interspecific hybrids, which are well adapted to the climate and pests of the region. ‘Chambourcin’ (an interspecific French-American hybrid) is one of the most widely planted winegrape cultivars in the area. It is usually grown as own-rooted (nongrafted) vines because the economic and horticultural benefits of grafting this cultivar to rootstocks have not been well developed. Further, few significant winegrape rootstock evaluations have been conducted in the midwestern United States, including evaluations of newer rootstocks developed and released by private and public breeding programs. The aim of this study was to assess the potential value of using rootstocks in ‘Chambourcin’ production in southern Missouri, with implications for the midwestern United States. Fruit yield, vine growth, and fruit composition metrics from ‘Chambourcin’ on 10 different root systems [own-rooted, and grafted to rootstocks ‘Couderc 3309’, ‘Couderc 1616’, ‘Paulsen 1103’, ‘Sélection Oppenheim 4’, ‘Millardet et de Grasset 420A’, ‘Millardet et de Grasset 101-14’, ‘Kingfisher’, ‘Matador’ (all Vitis sp.), and ‘Gloire de Montpellier’ riverbank grape (Vitis riparia)] in an experimental vineyard in southwest Missouri were compared. Following three establishment years (2008–10), data were collected across four growing and vintage seasons (2011–14). Yield components evaluated included total fruit production, clusters per vine, cluster weight, berry weight, weight of cane prunings, and crop load. Petiole mineral analysis was conducted in 2011, 2013, and 2014. Grape juice attributes measured were soluble solids concentration, juice pH, titratable acidity (TA), potassium (K), anthocyanins, tannins, phenolics, and organic acids. When simply comparing grafted vs. ungrafted vines, grafting generally induced higher plant vigor and a higher pH in the juice, whereas the other parameters did not differ. When the performances were compared among the 10 root systems, vines grafted to ‘Couderc 3309’ had higher yields compared with vines grafted to six other rootstocks and own-rooted vines. Grafting to ‘Millardet et de Grasset 101-14’ induced higher cluster weight compared with the other rootstocks. The ‘Millardet et de Grasset 420A’ rootstock promoted a higher pH and TA as well as a higher concentration of K in the juice, and ‘Paulsen 1103’ also promoted high pH, TA, and malic acid in the juice, and higher concentrations of phosphorous (P) and K in the petiole compared with most rootstocks. ‘Gloire de Montpellier’ induced a lower P content in the petiole and a higher tartaric/malic acid ratio. Rootstock use can strongly influence some vineyard production metrics as well as nutrient uptake and K levels in the juice (the latter further influencing juice pH). The results of this study provide insights into the complex viticultural and enological interactions resulting from the use of rootstocks in hybrid winegrape production in Missouri, USA.
We investigated sugar (solute) accumulation in watermelon [Citrullus lanatus (Thunb.) Matsum. et Nakai] fruits at the immature stage. Watermelon plants were grown hydroponically in a nutrient solution with an electric conductivity (EC) of 1.2 S⋅m−1 (EC 1.2 regime); then, fruits were harvested 21 days after anthesis. The flesh of each fruit was divided into seven different parts to measure the sugar concentration and water status. The results indicated that the sugar concentration was higher in the center of the fruit flesh than in the other parts, such as around the pericarp. Moreover, the lowest osmotic potential was observed in the center of the fruit flesh, indicating solute accumulation. Concurrently, when the transport of photosynthates in the fruit was investigated using the 13CO2 isotope, the active solute accumulation in the center of the fruit flesh was observed, supporting the observed sugar accumulation in this part. Consequently, this active solute accumulation and distribution occurred in the center of the watermelon fruit, as demonstrated by the data of osmotic pressure and sugar concentration and supported by the observed active photosynthate accumulation. Additionally, we investigated these measurements by increasing the nutrient solution concentration 14 days after anthesis. As a result, fruit growth was slightly inhibited using the EC 3.0 regime, and 13C translocation was also inhibited in the fruit, especially in its center. Even though the sugar concentration and osmotic pressure of the fruit flesh were not clearly affected by high nutrient solution concentrations, the cell turgor of the central flesh of the fruit grown using the EC 2.0 and 3.0 regimes was lower than that of the fruit grown using the EC 1.2 regime. Treatments with higher nutrient concentrations might have negative effects on immature watermelon fruits.
An online survey of plant purchasers was conducted to ascertain the influence of plant benefits messaging on consumer behavior. Three plant attributes, including type of plant, price, and plant availability, were used to distinguish purchasing preferences. To assess plant purchasing behavior, participants viewed a list of 12 different plant types and selected those they had purchased in the past year. The 12 plant types included annuals, vegetables, herbs, perennials, flowering shrubs, evergreen shrubs, fruit trees, evergreen trees, shade trees, flowering plants, foliage plants, and succulents. The most common retail locations patronized for plant purchases were home improvement stores, closely followed by independent garden centers. Consumers were grouped according to eight different plant benefit messages that they were exposed to, including physical, emotional, cognitive, social, educational, environmental, financial, and aesthetic benefits. Although some of the groups (clusters) exhibited similar purchasing behaviors in terms of plant types purchased, price levels preferred, and their preference for rare, common, or moderately available plants, there were just enough differences among groups to be able to distinguish them from other groups. The plant benefits were obviously affecting purchasing behavior, but further study is needed to understand the underlying reasons more fully.
Bacterial, fungal, and viral diseases of tomato (Solanum lycopersicum) are responsible for widespread yield losses, especially in humid growing environments. Chromosome 11 of tomato contains genes that modulate resistance to several prominent tomato pathogens, including bacterial spot caused by Xanthomonas spp., gray leaf spot caused by Stemphylium spp., Fusarium wilt caused by race 2 of Fusarium oxysporum f. sp. lycopersici, and tomato yellow leaf curl virus (TYLCV) caused by begomoviruses. Major resistance loci are quantitative trait locus 11 (QTL-11) and Xv3/Rx4 for bacterial spot, Sm for gray leaf spot, I2 for Fusarium wilt, and Ty-2 for TYLCV. Marker-assisted selection was used to select for rare recombination events that combined these resistance loci into a linked cassette that can be inherited together in future crosses. A pedigree breeding strategy was used with marker-assisted selection and used to identify a novel coupling of Xv3/Rx4 and Ty-2. Recombination between the two genes was estimated as 0.056 cM, demonstrating that effective combinations of resistance can be established using publicly available germplasm. Progeny from the recombinant plants were screened using inoculated seedling trials to confirm resistance. The recombinants identified maintained resistance levels similar to the resistant controls. Trial results suggest that the trait markers on chromosome 11 are tightly linked to the respective resistance loci and are effective for selecting plants with resistance to the target diseases.
We compared the performance of Brussels sprout (Brassica oleracea var. gemmifera) cultivars in New Hampshire and evaluated the effects of topping (apical meristem removal) on marketable yields. A total of 23 cultivars were evaluated in the study, with 8 to 16 cultivars evaluated in any given year. We identified several cultivars that produced moderate to high yields of well-spaced, uniform sprouts that had few Alternaria blight (Alternaria sp.) symptoms, and identified many others, including all red cultivars evaluated, that produced very low yields consistently. In 2013, 2014, and 2015, we used a replicated split-plot experimental design with cultivar as the main plot and topping treatment as the subplot, to evaluate the effects of topping plants. Early and midseason cultivars showed increased yields in response to topping, unless topping was performed too early. Cultivars with sprouts that did not reach marketable size within our growing season generally produced low yields, and topping had no effect on yields. To explore the effects of topping at different dates, we evaluated three cultivars on seven different topping dates plus an untopped control in 2015 and 2017. In addition to reducing stalk height by limiting late-season growth, topping affected marketable yields by affecting the number of sprouts that were either undersized or oversized. The ideal topping date window for minimizing defects and maximizing yields varied slightly for each cultivar, ranging from early to late September.