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.
An investigation was undertaken to determine whether various light reduction and shoot banding treatments could increase rooting on stem cuttings of Lindera benzoin [(L.) Blume] (northern spicebush), a difficult-to-root woody plant. Stock plants were grown under one of three light conditions (light, shade, or etiolation). Emerging shoots received either no treatment or a banding treatment that involved adhering a hook-and-loop fastener coated with varying concentrations of indole-3-butyric acid (IBA) around the shoot base to create a localized etiolated zone before taking cuttings. Data on rooting percentage and number of roots per cutting were analyzed using logistic and Quasi-Poisson regression, respectively. Etiolated cuttings treated with a band without IBA had the highest rooting probability and number of roots; however, etiolated cuttings across all banding treatments had similarly successful results. Additionally, there were several significant differences in rooting probabilities and root numbers between banding treatments within the shade- and light-grown groups. This research evaluated asexual propagation approaches for use with northern spicebush and provides a framework for the adoption and development of this taxon as a nursery crop.
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.
Copper (Cu) is typically adequate at 0.5 μM (0.03 ppm) in hydroponics and at 2 μM (0.125 ppm) in soilless media, but elevated levels can be used to inhibit pathogenic fungal growth. We studied the effect of elevated Cu on the growth of lettuce and tomato in peat-based media and deep-flow hydroponics. Lettuce growth in hydroponics was not hindered until a concentration greater than 4 μM (0.25 ppm) Cu was used, which is eight times greater than the adequate level. Tomato was more tolerant of elevated Cu, with no growth suppression up to 8 μM (0.5 ppm) in hydroponics. Organic matter tightly binds Cu, and bioavailability is thus determined by organic components in soilless media. We confirmed an adsorption capacity of 19 mg Cu per g of peat, which explains why there was no inhibition of lettuce or tomato growth up to 1000 μM (64 ppm) Cu in peat-based media. When chelated with ethylenediaminetetraacetic acid, Cu binding to organic matter was reduced and growth was decreased in lettuce but not tomato. Both species tolerated a 100-fold greater concentration of Cu in peat-based media than in deep-flow hydroponics. Elevated Cu in solution increased concentrations 20 times greater in root tissue than in leaves. These solution and tissue concentrations are greater than identified toxicity thresholds of pathogenic fungal and fungal-like organisms, and could thus be used to suppress root-borne fungal and fungal-like diseases.