Carrot (Daucus carota) production has increased in North Florida and South Georgia since 2015. Deep sandy soils, moderate winter climate, availability of irrigation water, and proximity to eastern markets are favorable for carrot production in the region. Nitrogen (N) is required for successful carrot production, and the current recommended N application rate in Florida is 196 kg·ha−1. The objective of this study was to verify the recommended N rate for the sandy soils of North Florida using current industry standard cultivars and practices. Carrot cultivars for the whole carrot fresh market, Choctaw and Maverick, and cultivars for the cut-and-peel market, Triton and Uppercut 25, were direct seeded on 102-cm-wide pressed bed tops on 29 Oct. 2016 and 2 Nov. 2017 in Live Oak, FL. Eight N application rates (56, 112, 168, 224, 280, 336, 392, and 448 kg·ha−1) were tested, and all N applications were placed on the bed top. N rates were split and timed to increase N use efficiency. Regression analyses were used to determine the optimal N rate for carrots in North Florida. A quadratic plateau regression for both seasons combined indicated 206 kg·ha−1 N was the optimal rate for carrots, with marketable yield of 71.3 Mg·ha−1, regardless of cultivar. All four cultivars attained acceptable yield including Uppercut 25, which exhibited significant foliage damage following freezing temperatures. This study resulted in updated information on best management practices for carrot production in Florida, especially nutrient stewardship.
Robert Conway Hochmuth, Marina Burani-Arouca, and Charles Edward Barrett
Gerardo H. Nunez and Mariana Neves da Silva
Hands-on activities are an essential part of horticulture education. However, facilitating hands-on activities in online horticulture courses is challenging partly due to a lack of literature that describes remote laboratories in the discipline. Here we describe our experience planning and executing a remote strawberry-growing activity in an online horticulture course at the University of Florida, Gainesville. Students received strawberry-growing kits that contained a strawberry (Fragaria ×ananassa) plant, substrate, and fertilizer. Instructions on growing the strawberry plant were delivered online and students had to provide weekly updates about the status of their plant for 5 weeks. At the end of the semester, students provided feedback about the hands-on activity in the form of an essay. Their answers were analyzed using text mining to gauge their perception of the activity. About 77% of students expressed positive sentiments about the remote activity including excitement, enjoyment, and knowledge gain. Students who expressed negative sentiments about the activity (≈23% of the total) focused on plant casualties and difficulties related to management practices. Overall, student essays and weekly updates reflected a relevant and engaging cognitive exercise in horticulture. Our results suggest that remote laboratories can improve the student experience in online courses and provide a footprint for successful implementation of similar activities in online horticulture courses.
Matthew S. Lobdell
A long-term evaluation of The Morton Arboretum’s Public Horticulture Internship Program was conducted. Of the 33 alumni of the internship between 2003 and 2019, 22 were contacted and asked to complete a survey and semistructured interview. Fourteen responded, representing interns who completed the program since 2003 though skewed somewhat toward more recent graduates. Results portrayed a well-received program that was generally effective in its goals. Forty-six percent of respondents were currently working in public gardens, including several in high-level administrative and leadership positions. Some that were not currently in the field pursued employment at public gardens, but were unsuccessful due to residing too far from a public garden, lack of available positions, failure to meet credential requirements of entry-level positions, or inability to earn a starting salary meeting their expectations. Others pursued adjacent green industry careers including environmental journalism or consulting. All respondents commented that the program provided effective exposure to public horticulture and careers at public gardens, although could be somewhat fast paced and overwhelming.
Xiangli Ma, Min Tang, Yufen Bi, and Junbo Yang
Cymbidium tortisepalum is a primary orchid species in Yunnan Province, China, and has an extremely high ornamental and economic value. To reveal the levels and distribution of genetic variation and structure of wild C. tortisepalum resources, sequence variations of six chloroplast DNA intergenic spacers (psbM-trnD, trnV-trnA, accD-psal, rrn23, trnk-rps16, and ycf1) were analyzed in 404 wild individuals from 28 populations in the three river area in Yunnan Province, China. The results showed that the six chloroplast DNA sequences were aligned with 61 polymorphic sites, including 50 indels and 11 haplotypes in 404 individuals, which revealed a low level of genetic diversity (total genetic diversity = 0.240, and the average value of nucleotide diversity = 0.00024). In addition, a fairly low genetic differentiation [coefficients for genetic differentiation among populations (GST) = 0.099, number of substitution (NST) = 0.081] was found among the studied populations, and NST value was less than GST, which indicated that no significant phylogeographic structure existed in those populations. Furthermore, analysis of molecular variance revealed that great genetic variance (91%) came from individuals within the populations, which indicated that there was no clear genetic differentiation among populations. On the basis of these findings, a conservation plan was proposed to sample or preserve fewer populations but with more individuals from each population.
Tong Zhang, Yingjie Yan, Chuantong Li, Junmei Liu, Dongxue Yin, Xiangying Xiong, Wei Liu, and Yueqin Yang
This study investigated the effects of illumination time and soil moisture on seed germination and seedling establishment of Magnolia sprengeri Pamp. to improve the seed germination percentage and seedling survival percentage of M. sprengeri. It is of great significance for rapid propagation, seedling regeneration, field management, and artificial high-efficiency cultivation of M. sprengeri. In this study, the seeds of natural M. sprengeri populations from original habitat were used as test materials. Seed germination and seedling establishment of M. sprengeri were performed under different illumination time and soil moisture treatments in artificial climate incubator. The study found that there were significant differences among various key parameters related to seed germination and seedling establishment under different treatments (P < 0.05). Germination percentage, germination potential, germination index, vigor index, germination rate, plant height, number of leaves, base diameter, taproot length, number of lateral roots, maximum lateral root length, single plant leaf area, fresh weight, and seedling survival rate reached the maximum at continuous illumination and 13% of soil moisture, respectively. By the integrative evaluation for the influence of these two factors on seed germination and seedling establishment, soil moisture is a dominant factor affecting seed germination and seedling establishment, whereas illumination is an important promoting factor for seedling establishment of M. sprengeri. Continuous illumination and 13% of soil moisture content is suitable for seed germination and seedling establishment of M. sprengeri.
Alexander Levin and Lloyd Nackley
Many consider tools for plant-based irrigation management methods to be the most precise way to manage irrigation in either a research or a commercial settings. Although many types of tools are available, they all measure some aspect of water movement along the soil–plant–atmosphere continuum. This article presents some of the more commonly used tools and the methods involved to properly employ them. In addition, recent literature is reviewed to provide context to the methods themselves and also to highlight each one’s specific advantages and disadvantages. Ultimately, there is no clear winner or “best” tool as all have disadvantages, either due to prohibitive cost, the amount of data output, the difficulty of data interpretation, lack of signal resolution, or lack of dynamic ability to provide decision support. Therefore, we conclude that the user should carefully weigh these varied advantages and disadvantages in the context of their production goals before deciding on a given tool for irrigation management.
Coleman L. Etheredge and Tina M. Waliczek
As Generation Z (born 1995–2012) students replace Millennial (born 1981–94) students on college campuses, instructors may begin to evaluate and structure their courses based on how this new generation best learns. Generation Z students were exposed to such things as the internet, smart phones, personal computers, and laptops since infancy and, hence, are very comfortable with technology and multitasking. The purpose of this study was to compare students’ overall grades and perceptions of the course and instructor in a face-to-face vs. an online/hybrid basic floral design course taken by a majority Generation Z student population. The face-to-face course consisted of live lectures that met twice per week for 50 min at an assigned time; reading materials and standard lecture slides were used. The hybrid course had content placed online within weekly modules and released to students in an asynchronous manner each Monday. Both versions of the course had a face-to-face laboratory that met once per week. Comparisons of grades between the face-to-face and hybrid course formats were made using analysis of variance tests. A Mann-Whitney U test was used to determine if there were statistically significant differences in the way students in each course format answered the end of semester course and instructor evaluation survey. Of those that took the course, a majority [466 (98.3%)] was between the ages 18 and 24 years, within the Generation Z era. When comparing grades within this group, it was found students in the hybrid course received more A and B letter grades overall [223 (91%)] compared with the students of the same age range in the face-to-face course [198 (88.7%)]. Overall, seniors and juniors scored higher grades in both the hybrid and face-to-face course when compared with the sophomore and freshmen within the same class. No significant difference was found between the face-to-face and hybrid students’ responses to any of the 11 questions on the course and instructor evaluation survey. Results showed an overall high level of satisfaction (4.50) for both the face-to-face and hybrid format.
Marzieh Keshavarzi, Keith A. Funnell, David J. Woolley, and Julian A. Heyes
We investigated the possibility of either exogenous ethylene or endogenous ethylene production having an association with the increase in shoot number when nodal explants of Gentiana spp. ‘Little Pinkie’ were cultured in an in vitro medium supplemented with ethephon (10 mg⋅L–1). For the first time within an in vitro system, we report the application of laser ethylene detector technology, and optimization of the methodology to quantify concentrations of ethylene (in the part-per-billion range) released from ethephon decomposition within the atmosphere of gas-exchangeable culture vessels including nodal explants. Compared with continuous (continuous measurements on the same replicate of vessels) and repeated (sampling same replicate of vessels every 48 hours) sampling methodologies, the nonrepeated (sampling fresh replicate of vessels every 48 hours) method of measurement of ethylene concentration was more representative of the actual condition within vessels. Although no prior published data exist showing the positive or negative effect of gaseous ethylene in the headspace of culture vessels on bud outgrowth in gentian, our study shows gaseous ethylene in the headspace of culture vessels was not effective in increasing shoot formation in gentian explants cultured in vitro, whereas ethephon supplementation in agar was effective. Plant material in culture vessels did not have a significant effect on ethylene production regardless of the presence or absence of ethephon. Therefore, although ethephon supplementation in the medium produced gaseous ethylene in the headspace, it was unlikely to cause endogenous ethylene production in explants, but it did trigger shoot formation in ‘Little Pinkie’, perhaps through decomposition to ethylene within the explant tissue, enhancing the internal ethylene level possibly at a locally high concentration.
David Campbell, Jeffrey K. Brecht, Ali Sarkhosh, Oscar Liburd, and Danielle Treadwell
The use of paper or nylon bags (fruit bagging) to surround tree fruit during development provides protection from a variety of pest-disease complexes for peach without yield reduction and different-colored bags have the potential to improve fruit quality based on findings from other crops. An experiment was conducted in 2019 at two locations in central Florida on peach [Prunus persica (L.) Batch] ‘TropicBeauty’ and ‘UFSun’ to analyze the impact of a commercially available white paper fruit bag combined with a photoselective insert. The insert reduced the amount of light outside the spectrum range of interest for blue (400–500 nm), green (500–600 nm), or red (>600 nm) wavebands, or decreased fluence rate with a neutral density black (>725 nm) insert. Relative to ambient, temperature inside all bagging treatments during the daytime hours was increased by 5.1 °C. During the same time, relative humidity was reduced by 10.1%, but calculations revealed that the water vapor pressure was elevated only for treatments that had a plastic colored (blue, green, or red) insert. An orthogonal contrast revealed that the elevated water vapor around the fruit in a colored bag increased the concentration of chlorophyll at harvest but had no effect on other quality parameters. Compared with unbagged fruit, red-bagged fruit were 1.8 times firmer and green-bagged fruit and had a lower peel chroma. White-bagged (without photoselective insert) fruit had similar nutrient concentrations for the peel, flesh, and pit when compared with unbagged fruit. When bags remained on the fruit until harvest, anthocyanin concentration in unbagged fruit peel was double the amount in white bags and 6-fold more than the bags with color inserts. Different-colored bagging treatments did not influence insect attraction or fruit quality parameters, such as fruit size, diameter, difference of absorbance (DA) index, total soluble solids (TSS), titratable acidity (TA), pH, peel lightness, peel hue, flesh lightness, flesh hue, or flesh chroma. Relative to full sun, the colored bag treatments allowed between 3.7% (black) and 17.4% (red) of the photosynthetically active radiation (PAR). Additional research is needed to determine if an increase in fluence rate at specific spectral wavelengths can affect the quality for peach grown in bags in the field.