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Knowledge of the genes underlying a given trait is highly useful for developing molecular markers for breeding and is the foundation for future genomic crop improvements. The cultivated strawberry, F. ×ananassa, is a valuable horticultural crop. Genome sequencing revealed that of the four diploid strawberry subgenomes contributing to the F. ×ananassa octoploid genome, the woodland strawberry, F. vesca, subgenome is dominant. Thus, F. vesca is an important system for determining gene function and should be used as a source of genetic diversity for F. ×ananassa breeding. Ethyl methanesulfonate mutagenesis of H4 F7-3, an inbred line of F. vesca, resulted in one M2 line that did not produce any strawberries over a 3-year period in the greenhouse. This line was named fruitless 1. The fruitless 1 phenotype results from a single gene recessive mutation. Microscopic characterization revealed that fruitless 1 failed to produce fruit because anthers fail to develop properly before meiosis, resulting in no pollen production. This report of fruitless 1 facilitates further studies of the line.

Open Access

Lettuce drop caused by Sclerotinia minor is a damaging disease of romaine lettuce (Lactuca sativa L.) production in California. Introgression of partial resistance from wild, primitive, or heirloom accessions into modern cultivars could improve integrated management approaches to the disease. Breeding methods for lettuce drop resistance are not well developed and hinder the development of new lettuce drop–resistant cultivars. The objective of this work was to develop a pedigree-based breeding method for introgression of lettuce drop resistance into modern romaine germplasm. Progeny from crosses between the partially resistant cultivar Eruption and the susceptible romaine cultivars Darkland and Hearts Delight were selected in a modified pedigree breeding scheme. Families were evaluated for disease incidence and selected for lettuce drop resistance in artificially infested field experiments conducted in the summer and fall. Infected plants of partially resistant lines commonly do not produce seed, and therefore selection of resistant plants from infested nurseries is not possible. Noninfested field experiments were used to select individual plants with improved horticultural characteristics for seed production, but from within resistant families only. Evaluation and selection of progeny using this breeding scheme occurred from the F2:3 through the F5:6 generations. In all generations, superior resistance was identified in the ‘Eruption’ × romaine crosses. The breeding scheme generated eight green romaine-type inbred lines with better resistance than the romaine parent and better head weight than ‘Eruption’. Use of the new romaine lines as parents in backcrosses to romaine produced F2:3 families with high levels of resistance. The pedigree method used in this research can be implemented with any source of resistance, but is constrained by the use of family selection and the inability to select individual plants for resistance directly. Breeding schemes that use single seed descent or molecular markers are alternative approaches that would enable selection for resistance on individual genotypes.

Open Access
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Chrysanthemum ‘Bai Tian Xing’, ‘Huang Ching Chin’, ‘Pink Pearl’, and ‘NCHU-001’ plants were preheated at 35 °C for 24 hours to induce heat tolerance. The recently fully expanded leaves were detached, kept in a moist Ziploc bag, and then subjected to 35, 40, 45, 47.5, 50, 52.5, 55, 60, or 65 °C for 20 minutes. After dark-acclimatized at room temperature for 30 minutes, leaves were measured for Fv/Fm value with a chlorophyll fluorescence parameter. Results showed that ‘Bai Tian Xing’ had the highest critical (Tcrit) and midpoint temperature (Tmid). Mean Tcrit and Tmid were shown to be 47 and 50 °C, respectively, and Tmid gave greater distinguishment of Fv/Fm value among cultivars. Plants of four cultivars were acclimatized at 15 to 40 °C for 3 days and 35 °C being the most effective temperature to induce a heat-tolerant response in chrysanthemum. Required inducing time to reach a stable leaf Fv/Fm value ranged from 4.6 to 11.1 hours among cultivars. All cultivars had similar required time to reach visible bud between summer and autumn crops (except NCHU-001), but all had delayed flowering in the summer crop. There is a negative linear relationship between flowering heat delay and leaf Fv/Fm value (R2 = 0.93). Progenies from reciprocal crossing of ‘Bai Tian Xing’ × ‘NCHU-001’ and ‘Huang Ching Chin’ × ‘Pink Pearl’ were also subjected to treatments for Fv/Fm measurements and observed for time to flowering in the summer crop. All combinations showed negative linear relationship between time to flowering and leaf Fv/Fm value (R2 = 0.70–0.87). Two plants, 109-W001Y and 109-W003Pi, showed early flowering habit and good flower performance under heat conditions were selected. All four cultivars and the two selected lines were measured for photosynthetic parameters under day/night temperatures of 35/30 or 25/20 °C in growth chambers. All cultivars and lines showed decreased net photosynthetic rate and dark respiration rate under 35/30 °C when compared with 25/20 °C. Relatively higher net photosynthetic rate and lower dark respiration rate in ‘Bai Tian Xing’, ‘109-W001Y’, and ‘109-W003Pi’ under 35/30 °C, when compared with the other three cultivars, might have contributed to better flowering performance in the summer.

Open Access

Natural swimming pools (NSPs) rely on the interaction of bog vegetation, bacteria, and substrate to maintain water quality. Nitrogen (N) and phosphorus (P) levels in NSPs are critical because of their involvement in eutrophication. We conducted a 15-week greenhouse study to address the significant literature gap regarding nutrient removal capabilities of substrates and vegetation in the low-nutrient environment of NSPs. We used mass balance analyses to compare the performances of four substrates [river gravel (control), recycled glass, expanded clay, expanded shale] and two plant species [blue flag iris (Iris versicolor) and lizard’s tail (Saururus cernuus)] under two flow conditions: free water surface and subsurface flow. At the end of the experiment, except for the recycled glass group, all other substrate groups reduced water nitrate (NO3) levels to less than 30 mg⋅L−1, the standard of the 2011 Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau (FLL) guidelines. However, only the expanded clay group closely approached the P standard (≤0.01 mg⋅L−1). Expanded clay and expanded shale demonstrated potential as substrates for NSP bogs. The final aboveground biomass dry weight was strongly negatively correlated with the final NO3 and P water concentrations. However, direct plant uptake proved insufficient to remove all nutrient inputs, especially for P. Except for the recycled glass group (34%), a significant portion of N (79%–90%) from total N added was removed by aboveground biomass. However, P uptake by biomass was substantially lower (18%–37%). With acceptable vigor and biomass accumulation, blue flag iris may be a suitable species for vegetated NSPs, whereas lizard’s tail is not because of uncertain establishment. Compared with controlling N, managing P for FLL standards in NSPs will be more challenging. Our work begins to fill the essential gap in the NSP literature regarding nutrient removal capabilities of substrates and vegetation. Future work should continue to study alternative substrates and plant species for P removal, particularly in field conditions and over longer periods.

Open Access

The US landscape industry consists of 632,000 businesses with >1 million persons employed in 2022. The most common service that landscape service providers (LSPs) perform is pest management. Over the past 25 years, LSPs have been challenged to adopt more holistic approaches to pest management via the use of nonchemical and less toxic chemical controls. Integrated pest management (IPM), specifically scouting, may be a useful approach for LSPs to manage pests more sustainably and market new services, such as biological control releases. Scant literature is available on LSP scouting practices or consumer acceptance of scouting services. The goal of this study was to determine if IPM-aware consumers were more likely to purchase a scouting program offered by an LSP. An online survey was distributed across the United States through a third-party panel service. The final sample included 928 usable responses. Data were analyzed using a binary logistic regression model. Fifty-seven percent of respondents reported having some knowledge or were very knowledgeable of IPM. Respondents 65 years of age and older were 13.1% points less likely to purchase a scouting service. Education level did not influence purchase likelihood. Consumer knowledge of IPM had a positive influence on the purchase likelihood, respondents with “some knowledge” (5.6%) and “very knowledgeable” (8.6%) were more likely to buy IPM services. Further, if the consumer was open to purchasing the scouting program, it is plausible that they might be more willing to allow an LSP to use a combination of chemical and nonchemical methods to manage pests.

Open Access

A significant challenge faced by the US Pacific Northwest pear industry is the limited availability of diverse pear cultivars beyond conventional selections. This scant availability of new pear options that align with consumers’ consistent quality preferences falls short of their expectations and jeopardizes potential demand growth, which poses a threat to the industry’s long-term economic viability. We use a combined approach of sensory evaluation and contingent valuation to uncover preferences and willingness to pay (WTP) for specific pear cultivars, encompassing both novel and traditional types. The outcomes reveal that the key determinants driving WTP are taste and texture attributes. Particularly for early-season pears, a greater liking score for flavor, firmness, and juiciness corresponds to an elevated WTP. For late-season pears, the range of quality attributes expands to encompass overall appearance and sweetness, in addition to the aforementioned factors. Participants who use social media to access information about pears exhibit a heightened WTP. These findings provide valuable insights for the industry to consider revitalizing existing pear orchards through the incorporation of alternatives to conventional pear cultivars.

Open Access

Invasive and nuisance plants, both introduced as well as native, have negatively impacted native flora and fauna and altered hydrological processes. Economic damage estimates range from $1.4 trillion globally to as high as $120 billion in the United States. Eastern redcedar (Juniperus virginiana) is native to at least 37 states in the United States. A medium-sized tree, eastern redcedar is commonly used as a landscape ornamental given its ability to grow in a wide range of conditions and its tolerance to many environmental pollutants. A tenacious conifer, eastern redcedar is valued for its landscape value and other uses, including wildlife habitat, lumber, medicines, and more. However, with wildfires suppressed and prescribed fires often discouraged, eastern redcedar has grown outside its original habitat and is an example of the term “range change.” This species’ predisposition to be opportunistic has allowed it to encroach on both abandoned and cultivated fields as well as grasslands. When the tree exhibits nuisance tendencies, control measures are warranted including prescribed fire, mechanical control, and herbicides. Ultimately, integrated control measures culminate in the best long-term results. The objective of this article was to describe eastern redcedar’s desirable ornamental features as well as landscape and utilitarian uses for humans and animals but also outline that it can be weedy to invasive depending on several factors discussed herein.

Open Access