Variegation is a common trait in plants that characteristically displays white or off-colored plant tissue. In grapevine, leaf variegation is expressed as white and pale green leaf tissue resulting in plants that are stunted in growth and hindered in development. In this study, several experiments were performed to investigate the impact of this mutation has on the anatomy of grape leaves and physiology of the plant. Histological staining of variegated and nonvariegated leaf tissue transections showed alterations to the leaf palisade mesophyll structure that affected leaf tissue width. An assay quantifying leaf pigments was performed to compare chlorophyll and carotenoid concentrations in leaves between variegated and wild-type seedlings, which showed that variegated leaf samples had reduced chlorophyll and carotenoid concentration. Through fluorescence imaging, we determined that photochemical efficiency of photosystem II (PSII) is reduced in variegated seedlings. By growing variegated and wild-type plants under high, medium, and low light intensities that variegated plants exposed to higher light intensity reduces the phenotypic expression of the variegation trait. Also, we found variegated plants to have significant reductions in growth traits such as plant height, leaf number, branch number, and dry weight compared with wild-type phenotype plants. Overall, our experiments revealed the variegation mutation altered normal leaf development causing significant effects to grapevine physiology.
Jack Olson and Matthew Clark
Ice encasement of perennial cool-season turfgrasses is a common problem in many northern regions of the world, and the incidence of ice encasement may increase with climate change. The objective of this review was to discuss recent advances in knowledge of how ice encasement affects turfgrass systems, current knowledge gaps, and current and potential future management strategies that can be used by turfgrass managers to mitigate ice encasement damage to turfgrass species that are sensitive to this stress. Ice encasement is a complex and severe stress, which if prolonged can include low temperatures, anoxia, toxic gases, toxic metabolic by-products, and other complications associated with the stress. Thus, research is needed to specifically identify responses of different turfgrasses to this stress. Species such as annual bluegrass (Poa annua) are widespread in the turfgrass industry but do not have adequate tolerance of ice encasement and extensive plant necrosis can occur. Repairs or renovations of large areas damaged by ice encasement is costly. Research on ice encasement of turfgrass species is needed to provide efficient recommendations and management strategies to the turfgrass industry.
Erin M.R. Clark, John M. Dole, and Jennifer Kalinowski
Six experiments were conducted using three cultivars to investigate the impact of water electrical conductivity (EC) and the addition of nutrients to vase solutions on postharvest quality of cut rose (Rosa hybrids) stems. Postharvest quality of cut ‘Freedom’ rose stems was evaluated using solutions containing either distilled water with sodium chloride (DW+NaCl) or DW+NaCl with the addition of a commercial floral preservative (holding solution containing carbohydrates and biocide) to generate a range of EC values (Expts. 1 and 2). The third experiment compared the effect of different EC levels from the salts NaCl, sodium sulfate (Na2SO4), and calcium chloride (CaCl2). The fourth experiment investigated EC’s impact on rose stems with the addition of two rose cultivars (Charlotte and Classy). When ‘Freedom’ stems were subjected to DW+NaCl, the longest vase life was achieved with 0.5 dS·m–1. The addition of holding solution not only extended vase life but also counteracted the negative effects of high EC with maximum vase life occurring at 1.0 dS·m–1. Furthermore, stems in the holding solution experienced significantly less bent neck and the flowers opened more fully than those in DW. Stems placed in DW with a holding solution also experienced more petal bluing, pigment loss, necrotic edges, and wilting than those held in DW alone. This effect was likely due to increased vase life. Salt solutions containing Na2SO4 and CaCl2 resulted in extended vase life at 1.0 dS·m–1, but increasing salt levels decreased overall vase life. As EC increased, regardless of salt type, water uptake also increased up to a maximum at 0.5 or 1.0 dS·m–1 and then continually declined. Maximum vase life was observed at 1.5 dS·m–1 for cut ‘Charlotte’ stems, and at 1.0 dS·m–1 for ‘Classy’ with the addition of a holding solution. Physiological effects were different based on cultivar, as observed with Charlotte and Freedom flowers that opened further and had less petal browning than Classy flowers. ‘Freedom’ had the greatest pigment loss, but this effect decreased with increasing EC. Further correlational analysis showed that in water-only solutions, initial and final EC accounted for 44% and 41% of the variation in vase life data, respectively, whereas initial pH accounted for 24% of variation. However, the presence of carbohydrates and biocides from the holding solution was found to have a greater effect on overall vase life compared with water pH or EC. Finally, in Expts. 5 and 6, cut ‘Freedom’ stems were subjected to DW solutions containing 0.1, 1, 10, or 100 mg·L–1 boron, copper, iron, potassium, magnesium, manganese, or zinc. None of these solutions increased vase life. Conversely, 10 or 100 mg·L–1 boron and 100 mg·L–1 copper solutions reduced vase life. Finally, the addition of NaCl to a maximum of 0.83 dS·m–1 increased the vase life in all solutions. These analyses highlight the importance of water quality and its elemental constituents on the vase life of cut rose stems and that the use of a holding solution can overcome the negative effects of high EC water.
Han-Na Seo, Hyo-In Lim, Yong-Yul Kim, Seung-Beom Chae, and Wonwoo Cho
Identifying the morphological characteristics that distinguish plant varieties is an important issue for plant breeders and researchers. The objective of the present study was to create a partial least squares discrimination analysis (PLS-DA) model with morphological characteristics for species discrimination and to select the characteristics most important for species discrimination. Data for 27 vegetative characteristics were obtained from Salix caprea and Salix gracilistyla, and their interspecific hybrid (S. caprea × S. gracilistyla), and used for PLS-DA. According to this analysis, seven of the 27 characteristics were identified as those that most influenced species discrimination, and the PLS-DA model with these seven characteristics had a classification accuracy of 86% to 100%. The classification performance of this model was not significantly different from that of the model with all 27 characteristics (full model). Therefore, these results indicated that the three species can be relatively well distinguished by the seven characteristics extracted by PLS-DA. In addition, the selected characteristics can be used to select cross-breeding parents in subsequent breeding programs and to test the distinction, uniformity, and stability (DUS test) of the hybrid variety. From this perspective, PLS-DA is thought to be a useful methodology for classifying new plant varieties and providing information for breeding.
Tanner Donahoo, Lisha Zhang, Matthew Cutulle, and Abolfazl Hajihassani
Increasing regulations and restrictions regarding on-farm chemical use and growing consumer demands for organic food products warrant the development of efficient biological methods for plant disease control and pest management. Grafting and anaerobic soil disinfestation are two sustainable crop production techniques developed to control and regulate weeds, root-knot nematodes (Meloidogyne incognita), and soilborne pathogens. Therefore, the present study explores the economic impact of using grafting and anaerobic soil disinfestation, independently and in conjunction, to determine the best combination in terms of yield and net returns for producers. This study drew from tomato (Solanum lycopersicum) field trials conducted in 2020 on a 0.5-acre plot at the Clemson Coastal Research and Education Center in Charleston, SC, where five grafting and three anaerobic soil disinfestation treatments were used in combinations for comparisons. Each treatment combination was subjected to sealed (plastic mulch covering a plot punctured 5 weeks after applying anaerobic soil disinfestation treatment) and unsealed (plastic mulch covering a plot punctured immediately after the application of anaerobic soil disinfestation treatment) plot conditions during the anaerobic soil disinfestation phase of plant bed preparation. Treatment combinations with cottonseed meal carbon-sourced anaerobic soil disinfestation were unviable because of lower net returns compared with treatment combinations without anaerobic soil disinfestation in nearly every case. Grafting (‘Roadster’ self-grafted) combined with molasses and chicken manure carbon-sourced anaerobic soil disinfestation under unsealed plot conditions was the most optimal treatment combination in the field trials with the greatest gains (net return per acre) to producers. The positive synergistic effects of combining these methods suggest that grafting and anaerobic soil disinfestation yield better results in conjunction than separately.
Ved Parkash, Sukhbir Singh, Manpreet Singh, Sanjit K. Deb, Glen L. Ritchie, and Russell W. Wallace
Water scarcity is increasing in the world, which is limiting crop production, especially in water-limited areas such as Southern High Plains of the United States. There is a need to adopt the irrigation management practices that can help to conserve water and sustain crop production in such water-limited areas. A 2-year field study was conducted during the summers of 2019 and 2020 to evaluate the effect of deficit irrigation levels and cultivars on root distribution pattern, soil water depletion, and water use efficiency (WUE) of cucumber (Cucumis sativus). The experiment was conducted in a split-plot design with four irrigation levels [100%, 80%, 60%, and 40% crop evapotranspiration (ETc)] as main plot factor and two cultivars (Poinsett 76 and Marketmore 76) as subplot factor with three replications. Results showed that root length density (RLD) was unaffected by the irrigation levels in 2019. In 2020, the RLD was comparable between 100% and 80% ETc, and it was significantly higher in 100% ETc than both 60% Eand 40% ETc. Root surface area density (RSAD) was not significantly different between 100% and 80% ETc, and it was significantly lower in both 60% and 40% ETc than 100% ETc in both years. Soil water depletion was the highest in 40% ETc followed by 60% and 80% ETc, and it was least in 100% ETc in both years. Evapotranspiration (ET) was the highest in 100% ETc followed by 80%, 60%, and 40% ETc. The WUE was not statistically different among the irrigation treatments. However, numerically, WUE was observed in the following order: 80% ETc > 100% ETc > 60% ETc > 40% ETc. The RLD, RSAD, soil water depletion, and ET were not significantly different between ‘Poinsett 76’ and ‘Marketmore 76’. However, fruit yield was significantly higher in ‘Poinsett 76’ than ‘Marketmore 76’, which resulted in higher WUE in Poinsett 76. It can be concluded that 80% ETc and Poinsett 76 cultivar can be adopted for higher crop water productivity and successful cucumber production in SHP.
Maheshwari Asha, Mmbaga Margaret, Bhusal Bandana, and Ondzighi-Assoume Christine
Bacterial endophytes selected for their capability to suppress diverse fungal pathogens in vitro and in greenhouse studies have been shown to promote plant growth. The effect of volatile compounds emitted by selected bacteria on plant growth in Arabidopsis thaliana, tomato (Solanum lycopersicum), sweet pepper (Capsicum annuum), and cucumbers (Cucumis sativus) was evaluated on container-grown plants nested above bacterial cultures, with roots exposed to the volatiles without direct contact between bacterial cells and the plant roots. Significant increases in plant growth were observed in plant height, root length, leaf size, fresh weight, and chlorophyll content in all plants tested. Although diverse chemical compounds may be involved in promoting plant growth, including volatile and nonvolatile compounds, observations in this study have implications for the potential role of the selected bacteria in plant production as biofertilizers and biopesticides.
Juliano Martins Ramalho Marques, Ariana P. Torres, Bridget K. Behe, Petrus Langenhoven, and Luiz Henrique de Barros Vilas Boas
Before consumers choose what and how much fruit to buy, they first decide where to buy it. To address the choices of stores for fresh fruits, this study investigated the influence of market attributes and customers’ attitudes toward their purchasing decisions. Data from a web-based survey of 1658 U.S. consumers were used to conduct multinomial logit regression to investigate the factors guiding their choices regarding four types of stores: chain, independent, club/warehouse, and direct-to-consumer. We found attitudinal scales and market attributes have different effects on the choice of marketplace for fresh fruits. Driven by price and convenience, most consumers prefer chain stores when buying fresh fruits, whereas those same factors deter them from choosing independent and ethnic stores for fresh fruits. The supply of local fruits, friendly atmosphere, and access to desirable fresh fruits positively influenced consumers to purchase fruits at local markets. Our findings can provide insight regarding food retailers and farmers targeting fresh fruit consumers. For example, our findings highlight the importance of providing a friendly atmosphere and outstanding customer service to positively influence purchasing behavior.
Analena B. Bruce, Elizabeth T. Maynard, Julia C.D. Valliant, and James R. Farmer
High tunnels are a low-cost technology that can strengthen local and regional food systems and have been shown to help farmers extend the growing season and increase the yield and shelf life, and improve the quality of their crops. This study addresses a need for a better understanding of farmers’ experience with integrating high tunnels into their operations, to understand the human dimensions of high tunnel management. We present an analysis of survey and interview data to examine how farm characteristics affect the outcomes of growing specialty crops in high tunnels. Our findings show that farmers managing different types of farms have taken distinct approaches to integrating and managing high tunnels on their farms, with important implications for farm-level outcomes. We identify three types of farms commonly adopting high tunnels in Indiana: 1) alternative food and agriculture enterprises (AFAEs) are consumer-oriented, small-scale farms that sell their products directly to their customers in relationship-based market networks such as farmers’ markets and community-supported agriculture; 2) mixed enterprise farmers have larger operations and sell into both conventional commodity markets and direct markets; and 3) side enterprise farmers operate small-scale enterprises and their primary household income comes from off-farm employment or another business. Farm type is associated with divergent levels of time and labor investment, resulting in higher capacity use of high tunnels and greater financial return for AFAE farmers who make high tunnels central to their business, compared with mixed and side enterprise farmers who invest less time and labor into their high tunnels. We explain how farm characteristics and approaches to adopting the infrastructure shape farmers’ success and high-capacity use of high tunnels.
Yasmina Chourak, El Hassan Belarbi, Evelynn Y. Martínez-Rivera, Tatiana Pagan Loeiro da Cunha-Chiamolera, Ana Araceli Peña-Fernández, José Luis Guil-Guerrero, and Miguel Urrestarazu
Saffron is one of the most appreciated, traditional, and expensive spices in the world. The objective of our study was to evaluate the effect of cooling the nutrient solution on the production, and organoleptic and commercial qualities of saffron grown in soilless culture. The nutrient solution was cooled to 4 to 5 °C whereas the control treatment was the fertigation supplied at ambient temperature. Corms were placed in a controlled cultivation chamber. The number of flowers per corms, and the weight and length of stigmas were measured. The amounts of safranal, crocin, and picrocrocin were analyzed spectrophotometrically according to the International Organization for Standardization [ISO/TS 3632-2 (2011) Normative]. Our results show that cooling of the nutritive solution increased flower production, the commercial phytochemical content, and organoleptic properties.