Browse

You are looking at 1 - 10 of 29,147 items for :

  • HortScience x
Clear All

Bermudagrass (Cynodon spp.) is a drought-resistant warm-season turfgrass adapted to the southern and transitional zones in the United States. Multiple hybrid cultivars have been developed and released for use as turfgrass, and others are still undergoing development. Increasing genetic diversity of commercial cultivars is vital to stress tolerance. A DNA profiling study of 21 experimental selections from the Oklahoma State University turfgrass breeding program and 11 cultivars was conducted using 51 simple sequence repeat primer pairs across the bermudagrass genome. A pairwise genetic relationship analysis of the genotypes using 352 polymorphic bands showed genetic similarity coefficients ranging from 0.59 to 0.89. The average pairwise population differentiation values were 0.012 for the 11 cultivars and 0.169 for the 21 selections. A cluster analysis using the unweighted paired group with the arithmetic average method grouped the entries into six clusters. A correlation analysis identified different levels of pairwise genetic relationships among the entries that largely reflected parental relationship. Directional breeding and selection for cold hardiness or drought resistance created progeny that had distinct genetic diversity in the tested bermudagrasses. It is evident that an increase in genetic diversity of the existing cultivar pool with the release of one or more experimental selections for commercial use will strengthen and improve bermudagrass systems.

Open Access

Irrigation decision support systems evolving in the domestic temperate tree fruit production industry incorporate measures of soil moisture status, which diverges from classic physiological indicators of edaphic stress. This study used an autonomous sensor-based irrigation system to impose a water deficit (soil matric potential targets of –25, –40, –60, and –80 kPa) on ‘Autumn Gala’, ‘CrimsonCrisp’, and ‘Golden Delicious’ apple (Malus domestica) cultivars grafted to ‘Budagovsky 9’ rootstock in the greenhouse (n = 60). It was hypothesized that relationships between physiological plant function, assessed via infrared gas exchange and chlorophyll fluorescence, and the soil matric potential may be used to advance emerging irrigation decision support systems. Complications arising from defoliation by day 11 at –60 and –80 kPa indicate the generation of substrate-specific soil–water relationships in research applications of autonomous sensor-based irrigation systems. ‘Autumn Gala’ carbon assimilation rates at –80 kPa declined from day 0 to day 8 (9.93 and 5.86 μmol⋅m–2⋅s–1 carbon dioxide), whereas the transpiration rate was maintained, potentially reducing observed defoliation as other cultivars increased transpiration to maintain carbon assimilation. Correlation matrices revealed Pearson’s r ≤ |0.43| for all physiological metrics considered with soil matric potential. Nevertheless, exploratory regression analysis on predawn leaf water potential, carbon assimilation, transpiration, stomatal conductance, and nonphotochemical quenching exposed speculatively useful data and data shapes that warrant additional study. Nonlinear piecewise regression suggested soil matric potential may useful as a predictor for the rate of change in predawn leaf water potential upon exposure to a water deficit. The critical point bridging the linear spans, –30.6 kPa, could be useful for incorporating in emerging irrigation decision support systems.

Open Access

Nonpoint-source phosphorus (P) from agricultural fields is a contaminant of surface waters, and high soil P fertility exacerbates this problem. Many vegetable growers and gardeners have a history of applying more P than is necessary for optimum plant growth. Avoiding unnecessary P applications is an important part of the long-term solution to reducing P loading in water. When soil P levels are very high, management practices that result in more intense P removal are recommended to reduce these levels and the potential for aquatic ecosystem contamination with P. Growers may apply soluble starter fertilizer containing P to encourage rapid transplant establishment; however, the effectiveness of this practice is unknown for soil P levels considered high or very high. Grafting tomatoes (Solanum lycopersicum L.) onto vigorous rootstocks may help the plant remove more P from the soil than nongrafted plants. This study investigated the effects of organic starter P fertilizers applied to three hybrids of nongrafted tomato and the same hybrids grafted onto ‘Estamino’ rootstock in field-grown conditions during three site-years with high preplant P fertility. The yield, fruit P concentration, and amount of P removed from the field were measured to elucidate starter P and grafting impacts on P removal. Starter P was not impactful on all responses. Grafting increased the total yield by 11.6%, fruit P concentration in a genotype-dependent manner (average of 12.6%), and net P removal from the field by 28.4% (6.0 kg P/ha). Net P removal was positively correlated with the total yield (r = 0.821) and fruit P concentration (r = 0.502), suggesting that practices to increase the yield or P concentration independently increase net P removal.

Open Access

This research study evaluated the suitability of controlled-release urea (CRU) as an alternate nitrogen (N) fertilizer source to conventional soluble urea (U) for tomato production under a humid, warm climate in coastal plain soils. Tomatoes are typically produced on raised plastic-mulched beds, where U is fertigated through multiple applications. On the other hand, CRU is applied once at planting, incorporated into soil before the raised beds are covered with plastic mulch. N source and management will likely impact tomato yield, N use efficiency (NUE), and apparent recovery of N fertilizer (APR). A 2-year field study was conducted on fall and spring tomato crops in north Florida to determine the crop N requirement and NUE in tomatoes (var. HM 1823) grown in sandy soils under a plastic-mulched bed system. In addition to a no N fertilizer treatment, three urea N sources [one soluble source and two polymer-coated CRU sources with different N release durations of 60 (CRU-60) and 75 (CRU-75) days] were applied at three N rates (140, 168, and 224 kg⋅ha−1). Across all N sources and N rates, fall yields were at least 20% higher than spring seasons. At the 140 kg⋅ha−1 N rate, APR and NUE were improved, especially when U was applied in fall tomato, whereas preplant CRUs improved N efficiency in spring tomato. Based on the lower APR values found in spring production seasons (0% to 16%) when compared with fall (57.1% to 72.6%), it can be concluded that residual soil N was an important source for tomatoes. In addition, the mean whole-plant N accumulation of tomato was 102.5 kg⋅ha−1, further indicating that reducing the N rate closer to crop N demand would greatly improve conventional vegetable production systems on sandy soils in north Florida. In conclusion, polymer-coated CRU and fertigation U applications were able to supply the N requirement of spring and fall tomato at a 38% reduction of the recommended N rate for tomato in Florida (224 kg⋅ha−1). Preliminary results show that adoption of CRU fertilizers can be considered a low-risk alternative N source for tomato production and the ease of applying CRU once during the bed preparation period for tomato may be an additional incentive.

Open Access

Mutants are useful for determining the genes that underlie a given trait. This information is highly useful for developing molecular markers for breeding and is the foundational knowledge required for future genomic crop improvements. The dessert strawberry, Fragaria ×ananassa, is a valuable crop with high potential for increased use in controlled environment agriculture. The genome of the woodland strawberry Fragaria vesca is the dominant genome of the four diploid strawberry subgenomes that contribute to the octoploid F. ×ananassa genome. F. vesca is therefore a useful reference system for determining gene function and should be a useful source of gene diversity for breeding of F. ×ananassa. Chemical mutagenesis of the inbred F. vesca line H4 F7-3 resulted in one M2 line with a smaller stature overall and which produces flowers on very short peduncles close to the crown. This line was named short inflorescence (sin). The sin phenotype results from a single gene recessive mutation that is pleiotropic in that the mutation also affects internode lengths of runners as well as petiole elongation of sin plants. Microscopic characterization revealed that sin peduncles are most likely short because of a failure of cells to elongate. Inflorescences, runners, and petioles of sin plants were found to elongate in response to exogenous gibberellin, indicating that sin could be a gibberellin biosynthesis or transport mutant. A brief characterization of sin plants is presented to facilitate collaborative studies of the line.

Open Access

Northern bayberry [Morella (formerly Myrica) pensylvanica] is an attractive, adaptable, semievergreen, northeastern North American native shrub that is sought for landscaping but difficult to propagate clonally. The impact of timing (June, July, or August) and concentration of indole-3-butyric acid [IBA (0, 2000, 4000 or 8000 ppm)] on propagation by stem cuttings was evaluated for genotypes of northern bayberry including the female cultivars Bobzam (Bobbee™) and UConn Compact and an unnamed male. Medium formulation and cytokinin type were evaluated for micropropagation of ‘Bobzam’ and ‘UConn Compact’. Stem cuttings of ‘Bobzam’ and ‘UConn Compact’ rooted poorly (at ≤55% and ≤20%, respectively) at all timings and concentrations of IBA; however, rooting success of ≥85% was achieved for the unnamed male genotype when cuttings were taken in June. Micropropagation of ‘Bobzam’ was successful using Woody Plant medium with 4 mg·L−1 zeatin and explants taken from shoots that had expanded 12 to 18 cm on containerized stock plants. Initiated explants of ‘Bobzam’ required eight subcultures before they began to produce shoots consistently at a 2× multiplication rate and eventually reached a 3× multiplication rate. Micropropagation attempts using Murashige and Skoog medium, the cytokinins 6-benzylaminopurine, meta-topolin, and thidiazuron, or the cultivar ‘UConn Compact’ were unsuccessful. Microshoots of ‘Bobzam’ rooted at ≥80% either by in vitro prerooting or ex vitro rooting directly in trays. Rooted microcuttings easily acclimated to greenhouse conditions and grew rapidly when potted to 1.04-L containers and then into 5.68-L containers. The micropropagation protocol developed for ‘Bobzam’ can be used by propagators to expand production of this popular female cultivar.

Open Access

Boxwood blight is a significant threat to nurseries, garden centers, landscaping businesses, and homeowners, causing both financial and ecological damage. This fungal disease is primarily caused by two species, with Calonectria pseudonaviculata being the only reported casual species in the United States. The pathogen is spread by wind-driven rain, water splash, and contaminated plants, emphasizing the need for exclusion, sanitation protocols, cultural practices, and fungicides to manage its spread. Recently, efforts have shifted from containment to disease management, focusing on fungicide efficacy, diagnostic assays, and boxwood production analysis. Agricultural extension programs promote best practices to prevent disease introduction into nursery and landscape environments. Understanding consumer awareness and perceived risk regarding infestations is crucial as control measures evolve. In our Jul 2020 survey, which had 2795 completed responses from across the United States, we assessed consumer knowledge and opinions regarding boxwood shrubs and Boxwood light. The findings revealed demographic variations in awareness and opinions. Suburban residents were more aware of boxwood blight, whereas urban residents had a higher opinion of boxwood shrubs. From the tobit model, men were more likely to purchase boxwood compared with women despite knowing about blight, and Caucasians compared with non-Caucasians exhibited decreased liking for boxwood after seeing pictures of blight-infected plants. These insights can inform targeted communication strategies and assist consumers, vendors, and related industries in addressing the challenges posed by Boxwood blight. Further research into alternative plant preferences among consumers is also warranted for better development of boxwood blight management strategies.

Open Access

The primary objective of this work was to generate species-specific information about root architectural adaptations to simulated natural levels of arsenic (As) during the establishment phase and onset of storage root formation in sweetpotato. Cultivars Bayou Belle and Beauregard were grown on sand substrate and provided with 0.5X Hoagland’s nutrient solution with varying levels of As (0, 5, 10, or 15 mg⋅L−1). During the first experiment, entire root systems were sampled at 5, 10, and 15 days, corresponding to key adventitious root developmental stages. Compared with the untreated controls at 15 days, ‘Bayou Belle’ and ‘Beauregard’ provided with 15 mg⋅L−1 As showed respective increases in the following root architectural attributes: 168% and 130% in main root length; 168% and 98% in lateral root length; and 140% and 50% in lateral root density. A second experiment was performed to produce storage root samples at 50 days. Storage root length, width, and length/width ratio did not vary with As levels. The accumulation of As in storage roots increased with increasing As levels. The results support the hypothesis that natural As levels stimulate adventitious root development in sweetpotato in a cultivar-dependent manner. The observations are consistent with findings of other species that show similar growth stimulation at low As levels. This is the first report of sweetpotato root system architecture responses to experimental levels of As that are known to be present in agricultural soils. Standardization of experimental procedures and understanding of root system adaptations to natural levels of As could lead to a more systematic exploitation of genome-wide techniques and characterization of the molecular basis of reduced As uptake in plants.

Open Access