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Open access

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.

Open access

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.

Open access

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.

Open access

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.

Open access

Runshi Xie, Bin Wu, Mengmeng Gu, Stacey R. Jones, James Robbins, Allen L. Szalanski, and Hongmin Qin

Crapemyrtle bark scale (CMBS; Acanthococcus lagerstroemiae Kuwana) is an invasive insect that was first discovered in the United States in 2004. The polyphagous feeding habit of CMBS has allowed it to infest a wide range of plant species beyond its primary host, Lagerstroemia. Using molecular approaches, we studied the genetic relationships between CMBS specimens and their hosts from different geographic locations. Naturally occurring CMBS infestations were confirmed on American beautyberry (Callicarpa americana L.), a native plant species in the United States, and spirea (Spiraea L.). The new infestation of CMBS found on Spiraea raises the alarm that other economically important crops in the Amygdaloideae subfamily (subfamily under Rosaceae) might be susceptible to CMBS attacks.

Open access

Shivani Kathi, Catherine Simpson, Alinna Umphres, and Greta Schuster

In arid and semi-arid climates, water scarcity and nutrient availability are major constraints for food production. Excess fertilization to make up for the limited nutrient availability in dry soils leads to nitrogen runoff and groundwater contamination. Reducing nitrogen leaching into surface water while providing adequate nutrition remains a major challenge. Superabsorbent polymers (SAPs) can reduce water loss and improve nutrient retention and therefore minimize leaching and increase crop yields. SAPs are made from petroleum or natural products, but plant-based SAPs have been gaining popularity because they have fewer long-term effects on the environment. However, there is little known about how SAPs made from cornstarch effect plant growth and production in tomatoes. So, we evaluated total nitrogen and water retention in SAP-treated soils and evaluated their effects on growth and development of tomatoes (Solanum lycopersicum). Soils were amended with different rates of cornstarch-based SAP (i.e., 0 kg SAP, 0 kg SAP+N, 0.5 kg SAP+N, 1 kg SAP+N, 1.5 kg SAP+N, and 2 kg SAP+N). Results indicate that the mean volume of water and nitrates retained in the soils amended with cornstarch-based SAPs increased with increasing rate of SAP. The treatment containing the highest dose (i.e., 2 kg SAP) decreased the amount of leachate and nitrates from soil 79.34% and 93.11% at 3 days after fertilization (DAF) and 78.84% and 81.58% at 9 DAF in comparison with the soil-only and fertilizer-only treatments, respectively. The results also indicate cornstarch-based SAP significantly improved plant growth and yield parameters compared with the treatments without SAP. Furthermore, the greatest number of leaves, flowers, fruits, and dry matter production were found in the 1-kg SAP treatment. Therefore, application of cornstarch-based SAPs can improve tomato production in times of drought stress by retaining more water and nutrients in the active rooting zone and can reduce environmental pollution by reducing nitrogen runoff.

Open access

Marife B. Anunciado, Larry C. Wadsworth, Shuresh Ghimire, Carol Miles, Jenny C. Moore, Annette L. Wszelaki, and Douglas G. Hayes

Plastic mulch films contribute to improved crop yield and quality for vegetable and small fruit cropping systems. Although the single-season agronomic performance of conventional polyethylene mulches and soil-biodegradable mulches (BDMs) are similar, over time BDMs can begin to break down during storage and subsequently not provide season-long soil coverage. In this study, the changes in physicochemical properties of BDMs were investigated over 3 years of indoor storage (2015–18) under ideal environmental conditions in two laboratories. Mulches evaluated were black, 20–40 µm thick, suitable for annual vegetable production, and included three BDMs: two polybutylene adipate terephthalate (PBAT)-enriched mulches that are commercially available in North America, an experimental polylactic acid (PLA) and polyhydroxyalkanote-based film, and a conventional polyethylene mulch as a control. Tensile properties, specifically peak load and elongation at maximum tensile stress, decreased during storage, particularly for the PBAT-based BDMs, indicating a loss of strength. During year 3 of storage, the tensile properties declined extensively, suggesting embrittlement. The average molecular weight of PLA and PBAT slightly increased during year 1, perhaps due to release of monomers or oligomers, and then decreased extensively during years 2 and 3 due to hydrolysis of ester bonds (confirmed by Fourier transform infrared spectroscopic analysis). The structural integrity of BDMs was assessed during years 2 and 3 of the study (2017–18) in field trials at the locations where they were stored, Knoxville, TN, and Mount Vernon, WA, for vegetable production. The degradation of the BDMs during the cropping season was higher in 2018 compared with 2017, suggesting that degradation of mechanical and chemical properties while in storage may have contributed to rapid degradation of mulches in the field. In summary, BDMs undergo degradation even under ideal storage conditions and may perform best if deployed within 2 years of their receipt date. The farmer should verify that proper storage conditions have been used before receipt and that manufacturing date precedes the receipt date by no more than 6 months.

Open access

Trent J. Davis, Miguel I. Gómez, Scott J. Harper, and Megan Twomey

Hop stunt viroid (HSVd) is one of the most important pathogens impacting hop production worldwide. It reduces yields, stunts growth, and is easily transmissible. HSVd can cause significant yield losses upward of 62% depending on the hop variety. This study uses a net present value (NPV) approach over a 6-year production cycle of one acre of hops to examine the potential economic impact of HSVd on aroma and alpha hop varieties. The estimated economic impact of HSVd ranges from about $432 (for a 1% yield reduction) to $26,795 (for a 62% yield reduction) per acre. Using the NPV approach the study then analyzes potential economic benefits of using certified disease-free planting stock as a strategy to mitigate the risk of HSVd infection. If expected yield losses of aroma and alpha hops exceed 6% and 7%, respectively, then the NPV of investing in certified clean planting stock is greater than that of the infected hops over the 6-year production cycle. Complete removal and replanting of an entire acre of aroma and alpha hops with certified clean planting stock is economically beneficial once expected yield losses exceed 35% and 36%, respectively. These findings are valuable for giving hop producers information to devise profit-maximizing planting strategies and to create incentives for extended usage of certified clean planting materials.

Open access

Tong Zhang, Zheng Zhang, Qi Qiao, Wei Liu, and Xiaogai Hou

Paeonia ostii is recognized as an important oilseed tree peony species with potential as a raw material source for cosmetic and health care products, strong seed setting capacity, high seed oil yield, and abundant omega-3 polyunsaturated fatty acids. P. ostii, commonly called Fengdan, is widely cultivated in China. The cultivation method difference has an important influence on the oil-use feature, which is a key index for evaluating the quality of oilseed crops. This study aimed to select an optimal cultivation method to provide the first reference data for high-yield and high-quality seed oil harvesting and to facilitate the understanding of the quality difference in the formation mechanism of seed oil in cultivated P. ostii. This study selected five representative cultivation methods, open field cultivation, sunny slope cultivation, shady slope cultivation, understory intercropping cultivation, and high-altitude cultivation, and investigated the influence of cultivation method differences on the oil-use feature based on the three aspects of seed yield traits, oil yield, and fatty acid compositions. Six seed yield traits (fruit pod length, fruit pod width, fruit pod thickness, number of fruit pods per plant, 1000-grain weight, and seed yield per plant) and oil yield reached the maximum values of 7.75 cm, 6.99 cm, 1.57 cm, 11.33, 290.45 g, 85.8 g, and 30.41%, respectively, using the understory intercropping cultivation method. Fatty acid compositions were mainly identified as α-linolenic acid, linoleic acid, oleic acid, stearic acid, and palmitic acid, with significant content differences among different cultivation methods (P < 0.05). Functional component α-linolenic acid and total amounts of unsaturated fatty acids reached the maximum values of 46.85% and 65.23%, respectively, with high-altitude cultivation and understory intercropping cultivation. The seed yield traits, oil yield, and total amounts of unsaturated fatty acids were optimal with the understory intercropping cultivation method, whereas high-altitude cultivation was conducive to the accumulation of α-linolenic acid. Understory intercropping cultivation with appropriate altitude increases is recommended as a preponderant cultivation method for high-yield and high-quality seed oil harvesting for this crop.

Open access

Sofia Flores, Marlon Retana-Cordero, Paul R. Fisher, Rosanna Freyre, and Celina Gómez

The objectives were to 1) compare growth and yield of different ginger (Zingiber officinale) and turmeric (Curcuma longa) propagules grown under two photoperiods (Expt. 1); and 2) evaluate whether their growing season could be extended with night interruption lighting (NI) during the winter (Expt. 2). In Expt. 1, propagules included 1) micropropagated tissue culture (TC) transplants, 2) second-generation rhizomes harvested from TC transplants (2GR), and 3) seed rhizomes (R). Plants received natural short days (SDs) or NI providing a total photon flux density (TPFD) of 1.3 µmol·m−2·s−1. Providing NI increased number of new tillers or leaves per plant, rhizome yield (i.e., rhizome fresh weight), and dry mass partitioning to rhizomes in both species. There was no clear trend on SPAD index in response to photoperiod or propagative material. Although TC-derived plants produced more tillers or leaves per plant, 2GR ginger and R turmeric produced a higher rhizome yield. In Expt. 2, seed rhizomes of ginger and turmeric were grown under five treatments with different photoperiods and/or production periods: 1) 20 weeks with NI (20NI), 2) 24 weeks with NI (24NI), 3) 28 weeks with NI (28NI), 4) 14 weeks with NI + 10 weeks under natural SDs (24NISD), and 5) 14 weeks with NI + 14 weeks under natural SDs (28NISD). NI provided a TPFD of 4.5 µmol·m−2·s−1. Lengthening the production period and providing NI increased rhizome yield and crude fiber content in both species. SPAD index decreased when plants were exposed to natural SDs at the end of the production period (NISD treatments). Results demonstrate the potential to overcome winter dormancy of ginger and turmeric plants with NI, enabling higher rhizome yield under natural SDs.