MicroRNAs (miRNAs) are short noncoding RNAs (20–25 nucleotides) that regulate gene expression posttranscriptionally. However, identification and characterization of miRNAs remain limited for conifer species. In this study, we applied transcriptome-wide miRNAs sequencing to a conifer species Platycladus orientalis, which is highly adaptable to a wide range of environmental adversities, including drought, barren soil, and mild salinity. A total of 17,181,542 raw reads were obtained from the Illumina sequencing platform; 31 conserved and 91 novel miRNAs were identified, and their unique characteristics were further analyzed. Ten randomly selected miRNAs were validated by quantificational real-time polymerase chain reaction. Through miRNA target predictions based on psRNATarget, 2331 unique mRNAs were predicted to be targets of P. orientalis miRNAs that involved in 187 metabolic pathways in KEGG database. These targets included not only important transcription factors (e.g., class III homeodomain leucine zipper targeted by por-miR166d) but also indispensable nontranscriptional factor proteins (i.e., por-miR482a-3p regulated nucleotide-binding site leucine-rich repeat protein). Interestingly, six miRNAs (por-miR16, -miR44, -miR60-5p, -miR69–3p, -miR166b-5p, and -miR395c) were found in adaptation-related pathways (e.g., drought), indicating their possible involved in this species’ stress-tolerance characteristics. The present study provided essential information for understanding the regulatory role of miRNAs in P. orientalis and sheds light on their possible use in tree improvement for stress tolerance.
Ying Yang, Xian-Ge Hu, Bingsong Zheng, Yue Li, Tongli Wang, Anket Sharma, Huwei Yuan, and Jian-Feng Mao
Fan Cao, Cong Guo, Ling Wu, Xin Huang, Qiuxia Xu, and Yujuan Li
Ryan J. Hill, David R. King, Richard Zollinger, and Marcelo L. Moretti
Three 2-year field studies were conducted to evaluate 1-naphthaleneacetic acid (NAA) as a suppressant of suckers in European hazelnut (Corylus avellana L.). Treatments were basal-directed applications of NAA at 5, 10, and 20 g·L−1 a.i. applied once per season, and two sequential applications of NAA 10 g·L−1 a.i., 28 days apart, compared with 2,4-D (3.8 g·L−1 acid equivalent), and a nontreated control. Treatments were applied early in spring and repeated the following year. Both NAA and 2,4-D delayed sucker growth by 1.2- to 3.0-fold compared with the nontreated control, and response varied with experimental site and year. Sequential treatments of NAA significantly reduced sucker height and fresh weight 120 days after treatment. NAA applied in sequential treatments increased tree trunk cross-sectional area and canopy volume in two of the three experimental sites. Yield of hazelnuts increased when suckers were removed with NAA or 2,4-D compared with nontreated. Results indicate that NAA is an effective option to control suckers in hazelnuts and can help reduce herbicide and labor in sucker control.
Eric T. Stafne, Jenny B. Ryals, and Barbara J. Smith
White drupelet disorder (WDD) in blackberry (Rubus subgenus Rubus) is an abiotic condition resulting from a cultivar and environment interaction. Although high temperatures and light intensities have been implicated, little is known why this disorder manifests. Other factors, such as overall plant stress, may be contributing influences. In this study, three treatments were applied to examine whether the addition of nitrogen (N) can reduce WDD on ‘Sweetie Pie’ erect blackberry over three seasons. An initial 50 lb/acre (56.0 kg⋅ha–1) N was applied to all plots at budbreak. Two additional N application treatments of 100 kg⋅ha–1 were applied at one time (1×) or five, 20-kg⋅ha–1 applications (5×), spaced 1 week apart for 5 weeks starting at bloom. One control treatment of no additional N (0×) was also included. Berries were harvested and weighed as a total, then berries with white drupelets were separated out and weighed. The two values were divided to create a proportion and were then multiplied by 100 to determine the percentage. Nitrogen application decreased the percentage of white drupelet berries from 13.0% (control) to 10.0% (one additional application) and 9.1% (five additional applications). WDD for the 0× treatment correlated negatively to maximum high daytime temperatures during May (r = –0.58, P = 0.03) over the three seasons. Occurrence of white drupelets by treatments 0×, 1×, and 5× correlated significantly with the cumulative number of rainfall events (r = 0.49, 0.47, and 0.46, respectively). Leaf chlorophyll index and photosynthesis measurements were unaffected by treatment. Although it is likely that multiple factors are involved in the development of white drupelets, additional N may reduce the problem.
Lisa Wasko DeVetter, Suzette Galinato, Troy Kortus, and Jonathan Maberry
Floricane red raspberry (Rubus idaeus) produces biennial canes that are traditionally managed by annual selective removal of previously fruited floricanes and training of primocanes that will bear fruit in the next growing season. This process of pruning and training is labor intensive and costly, and growers would benefit from more economical methods of pruning and training. This 6-year project evaluated the economic viability of alternate-year (AY) production in a commercial floricane red raspberry field in northwest Washington and compared it to traditional, every-year (EY) production to assess whether the former could save costs. Despite savings from reduced chemicals, fertilizers, labor, general farm supplies, and other variable costs, the overall benefits of AY production were not enough to offset losses in revenue resulting from reduced yields under the conditions of this experiment in northwest Washington.
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.
Renata Goossen and Kimberly A. Williams
Hydrogen peroxide (H2O2) is a well-known oxidizing agent often used as a remedy by consumers to treat algae and root decay from presumed root disease on interior plants, as well as to encourage root growth and health. To characterize the phytotoxic effects and define the safe concentration threshold for H2O2 use on ‘Vivaldi’ hybrid phalaenopsis orchid (hybrid Phalaenopsis), root systems were dipped for 3 minutes in 0%, 3%, 6%, or 12% H2O2 one time and observed in greenhouse conditions for the following 27 days. Root systems of each plant were assessed over time for percent visible root damage; ratings of root health on a scale of 1 to 5 points, with 5 points indicating “very healthy”; and final fresh and dry weights. To determine when symptoms manifested above the root zone, foliage and flower damage was evaluated over time by assessing percent visible foliage damage, ratings of foliage health, percent foliar wilt, flower/bud count, and final foliage and flower fresh and dry weights. Over the evaluation period, the root health rating of the ‘Vivaldi’ hybrid phalaenopsis orchids treated with 12% H2O2 decreased from 5 to 1.13, whereas those treated with 3% H2O2 only decreased from 5 to 4.13. H2O2 concentrations of 6% and 12% damaged root health permanently, whereas the 3% H2O2 concentration only caused minor damage to overall root health. However, algae were not killed at the 3% rate. Neither foliage nor flowers were seriously affected during the 3 weeks after application, but foliage wilt did result in the 6% and 12% treatments by week 4. As H2O2 concentration increased, fresh weights decreased in roots and leaves. Although a single 3% H2O2 root dip did not result in severe symptoms of phytotoxicity, the treatment’s long-term plant health effects are unknown. Because the 3% H2O2 root dip caused minor plant health setbacks and failed to subdue algae populations in the root zone, consumers should be wary of using H2O2 to improve orchid (Orchidaceae) root health and should instead focus on altering care and watering practices.
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.
Fang Xu, Junqin Zong, Jingbo Chen, Jianjian Li, Dandan Li, Jianxiu Liu, and Fang Xu
A static experiment in greenhouse was conducted to investigate the growth of three grasses in high and medium eutrophic water and the effects of their removal on ammonia nitrogen (NH4 +-N), nitrate nitrogen (NO3 −-N), total nitrogen (TN), total phosphorus (TP), and the chemical oxygen demand (COD), and compared with cattail (Typha angustifolia). The results showed that 1) the removal efficiency of NH4 +-N, NO3 −-N, TN, TP, and COD treated by the four plants in eutrophic water were significantly higher than that in non-plant water. With the extension of treatment time, the concentrations of NH4 +-N, NO3 −-N, TN, TP, and COD in the eutrophic water decreased first and then tend to be stable. 2) Cynodon dactylon ‘Tifton 85’ (C. dactylon ‘Tifton 85’), Cortaderia selloana ‘Pumila’ (C. selloana ‘Pumila’) and T. angustifolia absorbed more than 95.7% and 88.6% of TN and TP in eutrophic water, and accumulate more than 89.5% and 82.0% in plants, respectively. However, the ratio of Cortaderia selloana ‘Silver Comet’ (C. selloana ‘Silver Comet’) was significantly lower. 3) The high abilities of these three plants to purify eutrophic water may be directly related to their rapid growth. 4) The comprehensive purification ability of the four plants to eutrophic was significantly different, in the order of C. dactylon ‘Tifton 85’ > C. selloana ‘Pumila’ ≈ T. angustifolia > C. selloana ‘Silver Comet’. These results indicated that C. dactylon ‘Tifton 85’ and C. selloana ‘Pumila’ can be used as alternative plants to T. angustifolia for the purification of eutrophic water. The results of this study can provide new materials and ideas for phytoremediation.
Danny Hillin, Pierre Helwi, and Justin J. Scheiner
Bunch grapes (Euvitis) are classified as moderately salt-tolerant. However, little is known about the salt tolerance of muscadine grapes (Vitis rotundifolia). The objective of this research was to evaluate the salt exclusion capacity of muscadine grapes relative to common bunch grape rootstocks and hybrid winegrapes using a greenhouse screening assay. In two separate experiments, 31 muscadine, six bunch grape rootstocks, and five hybrid winegrape cultivars were irrigated daily with a 25-mm sodium chloride salt solution for a period of 14 d, followed by a destructive harvest to determine sodium (Na) and chloride (Cl) concentrations in root and shoot tissues. Generally, the muscadines studied exhibited a greater range of salt concentration relative to bunch grape rootstocks. Total tissue (shoot and root) salt varied by 250% and 430% across muscadines and by 180% and 190% across bunch grape rootstocks for Na and Cl, respectively. Despite the wider range, muscadine grapes expressed significantly less leaf necrosis than the bunch grape rootstocks. The most effective salt-excluding muscadines, ‘Janebell’, ‘Scuppernong’, ‘Late Fry’, and ‘Eudora’, were not distinguishable from the bunch grape rootstocks [‘Paulsen 1103’ (1103P), ‘Ruggeri 140’ (140Ru), ‘Schwarzmann’, ‘Millardet et de Grasset 101-14’ (101-14 Mgt.), ‘Millardet et de Grasset 420A’ (420A), and ‘Matador’]. Overall, there was no discernable difference between the salt exclusion capacity of muscadine and bunch grapes. The hybrid winegrape ‘Blanc Du Bois’ displayed poor Na and Cl exclusion properties but showed only moderate leaf necrosis symptoms. In both experiments, ‘Blanc Du Bois’ accumulated more than two-fold higher root and shoot concentrations of Na and Cl compared with the best-performing rootstocks (1103P, 140Ru, 101-14 Mgt.), suggesting that ‘Blanc Du Bois’ could benefit from grafting if salinity is a limiting factor.