In the quest to identify minimum daily light integrals (DLIs) that can sustain indoor gardening, we evaluated DLIs less than the recommended ranges for commercial production of basil (Ocimum basilicum). Experiments were conducted for 8 weeks to evaluate the effect of providing a constant vs. an increasing DLI over time (DLIInc) on growth and photosynthetic capacity of green (‘Genovese Compact’) and purple (‘Red Rubin’) basil grown hydroponically under a constant ambient temperature of 21 °C. Plants were grown under a 14 h·d–1 photoperiod and were subjected to the following DLI treatments: 4 (DLI4), 6 (DLI6), 8 (DLI8), or 10 (DLI10) mol·m–2·d‒1 (80, 119, 159, and 197 µmol·m‒2·s‒1, respectively); DLIInc was used as a fifth treatment and was achieved by transitioning hydroponic systems systematically to treatments with greater DLIs every 2 weeks. In general, regardless of cultivar, leaf area, leaf number, and overall growth [shoot fresh weight (SFW) and shoot dry weight (SDW)] were similar for plants grown under DLIInc to DLI4 and DLI6 during weeks 2, 4, and 6. However, plants grown under DLIInc produced the same leaf area as those grown under DLI10 at week 8. Nonetheless, across weeks, growth was significantly less under DLIInc compared with DLI10, but similar to that produced by DLI8 at week 8. Photosynthetic responses were significant only at week 8, for which leaves of plants grown under DLI8, DLI10, and DLIInc had 15% to 25% greater maximum gross carbon dioxide (CO2) assimilation (A max) than plants grown under DLI4. The light saturation point of photosynthesis was unaffected by DLI, but showed a general increasing trend with greater DLIs. Overall, our results suggest that providing a constantly high DLI results in greater growth and yield than increasing the DLI over time. In addition, we found that changes in A max and the light saturation point are not good indicators of the capacity of whole plants to make use of the available light for photosynthesis and growth. Instead, morphological and developmental traits regulated by DLI during the initial stages of production are most likely responsible for the growth responses measured in our study.
Elisa Solis-Toapanta and Celina Gómez
Cristian E. Loyola, John M. Dole and Rebecca Dunning
Imports of cut flowers into the United States have doubled in the last 20 years and come mainly from Colombia and Ecuador. We surveyed the cut flower industry in South and Central America, focusing on Colombia and Ecuador, to determine their production and postharvest problems. We received a total of 51 responses, of which 62% of the respondents had 100 or more employees. The most commonly grown or handled crops were rose (Rosa hybrids), carnation (Dianthus caryophyllus), chrysanthemum (Chrysanthemum ×grandiflorum), alstroemeria (Alstroemeria cultivars), gerbera (Gerbera jamesonii), and hydrangea (Hydrangea species), in order of ranking. The most significant production problem was insect management, with disease management and crop timing the next most important issues. The most important species-specific issues in production were phytosanitary problems, disease (causal organism not specified), leaf miner (Lepidoptera, Symphyta, or Diptera), and thrips (Thysanoptera). The main overall postharvest problem was temperature management, followed by hydration and flower food management and botrytis (Botrytis cinerea). In regard to on-farm postharvest handling, damage to the flowers was the most mentioned issue. For the postharvest during storage and transport phase, temperature management, air transport, damage, and botrytis were the most important problems. The most mentioned customer complaints were damage, botrytis, and phytosanitary problems. The results of this survey can be used by researchers to focus their work on topics of most need. Improved production and postharvest handling will support the continued growth of the cut flower industry.
S. Christopher Marble, Shawn T. Steed, Debalina Saha and Yuvraj Khamare
Mulches have been evaluated extensively as a weed management tool in container plant production, but most research has focused on loose-fill wood-derived mulch materials, such as pine bark or wood chips. In this experiment, pine (mixed Pinus sp.) bark (PB), shredded hardwood (HW), and pine sawdust were evaluated for weed control and crop response both alone and in combination with a guar gum tackifier alongside a plastic film mulch, a paper slurry mulch, and the paper slurry mulch + PB and compared with a nonmulched, nontreated control and a single application of preemergence herbicide (oxyfluorfen + pendimethalin). Mulch materials were applied to nursery containers ranging from 7 to 25 gal at two different nurseries and at two research centers in central Florida in 2017 and 2018. Results showed that the plastic mulch provided more than a 90% reduction in hand weeding time and weed weight over a 6-month period, and similar control was achieved with PB, paper slurry + PB, and the HW treatment (64% to 91% reduction in weeding time and weed weight). No growth differences were observed with any mulch treatment in any species evaluated including ligustrum (Ligustrum japonicum), Chinese elm (Ulmus parvifolia), or podocarpus (Podocarpus macrophyllum).
Susan C. Miyasaka, Marisa Wall, Don LaBonte and Alton Arakaki
Twelve sweetpotato (Ipomoea batatas var. batatas) accessions/cultivars/landraces (entries) were evaluated for yield, resistance to pests, and quality in five field trials planted at Pepe`ekeo, Hawai‘i Island, and replicated over time with blocks planted on May and Oct. 2014, Feb. and July 2015, and Jan. 2016. Plots were harvested at 4.5 to 6 months after planting. In the first two field trials, local entries planted were ‘Okinawan’, ‘Mokuau’, and ‘Kona B’, as well as PI 531094, ‘Beauregard’, PI 573309, PI 573330, ‘Darby’, ‘Pelican Processor’, and ‘Picadito’. Yields of ‘Mokuau’ and ‘Kona B’ were low and were replaced in the latter three field trials with ‘Murasaki-29’ and ‘LA 08-21p’ from Louisiana State University (LSU) AgCenter, Baton Rouge. At harvest, storage roots were graded according to State of Hawai‘i standards and marketable yields included grades AA, A, and B. Then, injuries of storage roots due to infestations of sweetpotato weevil (Cylas formicarius elegantulus) in each category were estimated. Finally, sugar concentrations, anthocyanins, and β-carotene contents were measured in storage roots. Marketable fresh weight yields of entries differed significantly, with ‘LA 08-21p’ having the greatest marketable yield. However, ‘LA 08-21p’ also had the greatest incidence of damage due to sweetpotato weevil, perhaps because of its growth habit as a tight cluster of storage roots located close to the soil surface. Entries also had significantly different sugar concentrations (fructose, glucose, sucrose, maltose, and total sugars). Concentrations of sucrose ranged from 25 to 68 mg·g−1 fresh weight and were greater than those of monosaccharides analyzed. ‘Beauregard’ had the highest sucrose concentration and total sugars. Purple-fleshed cultivars Okinawan and LA 08-21p contained total monomeric anthocyanins that ranged from 34 to 37 mg/100 g dry weight. Orange-fleshed cultivars Beauregard and Darby contained β-carotene that ranged from 5485 to 8302 µg/100 g fresh weight. These results provide yields of storage roots, susceptibility to sweetpotato weevils, and amounts of antioxidants in purple- and orange-fleshed sweetpotato cultivars to growers interested in producing new sweetpotato cultivars.
Esmaeil Fallahi, Pontia Fallahi and Shahla Mahdavi
The history of Persian gardens goes back to a few millennia before the emergence of Islam in Iran (Persia). Designs of Persian gardens have influenced and are used extensively in the gardens of Al-Andalus in Spain, Humayun’s Tomb and the Taj Mahal in India, and many gardens in the United States and other countries around the globe. Bagh in the Persian language (Farsi) means garden and the word Baghdad (the capital city of Iraq) is rooted from the words bagh and daad (meaning “the garden of justice”). Pasargadae, the ancient Persian capital city, is the earliest example of Persian garden design known in human civilization as chahar bagh or 4-fold garden design. Bagh-e-Eram, or Garden of Eden or Eram Garden, is one the most attractive Persian gardens and is located in Shiraz, Iran. There are numerous other urban ancient gardens in Iran, including Bagh-e-Shahzadeh (Shazdeh), meaning “The Prince’s Garden” in Mahan, Golestan National Park near the Caspian Sea; Bagh-e-Fin in Kashan; Bagh-e-El-Goli in Tabriz; and Bagh-e-Golshan in Tabas. The design of each Persian garden is influenced by climate, art, beliefs, poetry, literature, and romance of the country and the region where the garden is located. In addition, each garden may have a gene bank of fruits, flowers, herbs, and vegetables. Although countless gardens were destroyed in the hands of invaders throughout the centuries, Persians have attempted either to rebuild or build new gardens generation after generation, each of which has become a favorite destination to tourists from around the world.
Anthony L. Witcher, Fulya Baysal-Gurel, Eugene K. Blythe and Donna C. Fare
Flowering dogwood (Cornus florida) is a valuable nursery product typically produced as a field-grown crop. Container-grown flowering dogwood can grow much faster than field-grown plants, thus shortening the production cycle, yet unacceptable crop loss and reduced quality continue to be major issues with container-grown plants. The objective of this research was to evaluate the effects of container size and shade duration on growth of flowering dogwood cultivars Cherokee Brave™ and Cherokee Princess from bare-root liners. In 2015, bare-root liners were transplanted to 23-L (no. 7) containers and placed under shade for 0 months (full sun), 2 months (sun4/shade2), 4 months (sun2/shade4), or 6 months (full shade) during the growing season. In 2016, one-half of the plants remained in no. 7 containers and the other half were transplanted to 50-L (no. 15) containers and assigned to the same four shade treatments. In 2015, plant height was greatest with full shade for both cultivars, whereas stem diameter and shoot dry weight (SDW) were greatest in full shade for Cherokee Brave™. In 2016, both cultivars in no. 15 containers had greater plant height, stem diameter, root dry weight (RDW), and SDW. Full shade resulted in the greatest height, stem diameter, RDW, and SDW for Cherokee Brave™, and improved overall growth for ‘Cherokee Princess’. However, vigorous growth due to container size and shade exposure increased the severity of powdery mildew (Erysiphe pulchra) in both years. Substrate leachate nutrient concentration (nitrate nitrogen and phosphate) was greater in no. 15 containers but shade duration had no effect.
Zachary D. Small, James D. McCurdy, Erick D. Begitschke and Michael P. Richard
Wild garlic (Allium vineale) is an annual winter weed in managed turfgrass. Its dark green, upright stems are easily distinguishable among low-lying, dormant warm-season grasses. Experiments were conducted to determine the effectiveness of synthetic auxin and acetolactate synthase (ALS) inhibiting herbicides for post-emergence control of wild garlic. Trials were conducted in 2016 and 2017. Throughout both trial years, synthetic auxin herbicides exhibited visual control quicker than ALS inhibitors at the initial assessment date 20 d after application (DAA). Conversely, at the final assessment date 49 DAA, ALS inhibitors were the only treatments that controlled wild garlic by more than 85%. In 2016, plots treated with 2,4-D + dicamba + mecoprop at 4 pt/acre exhibited 88% visual control when assessed 20 DAA, but this level had decreased to 51% by 49 DAA. Similarly, visual control in plots treated with 2,4-D + mecoprop + dicamba + carfentrazone-ethyl at 4 pt/acre decreased from 59% to 56% and 82% to 18% between assessment dates in 2016 and 2017, respectively. Metsulfuron-methyl at 0.5 fl oz/acre controlled wild garlic 94% and 91% at the 49 DAA assessment date, whereas sulfentrazone + metsulfuron-methyl at 0.41 lb/acre controlled wild garlic 93% and 95% at the same assessment dates in 2016 and 2017, respectively. Future research should consider tank mixes of auxin-mimicking and ALS-inhibiting herbicides as potential routes for quick burndown and season-long control.
Yasser Ismail El-Nashar and Yaser Hassan Dewir
Breaking of dormancy in african juniper (Juniperus procera) seeds is a challenge faced by nurseries attempting to grow large numbers of this plant for restoration projects. The purpose of this study was to develop a protocol for breaking dormancy and stimulating germination in african juniper. Seeds were presoaked in different concentrations (0, 1, 10, or 20 mg·L−1) of gibberellic acid (GA3), indole-3-butyric acid (IBA), and naphthalene acetic acid (NAA), and incubated under different air temperatures (10, 15, and 20 °C). The petri dishes were monitored daily for 84 days, to record germination percentage, rate, and uniformity, and the growth of shoots and roots, and biomass production. The highest germination percentages were obtained under 20 °C with a high concentration of NAA (20 mg·L−1). The greatest seedling growth was under 20 °C with IBA. The greatest seedling length was under 20 °C with a low concentration of IBA (1 mg·L−1). The greatest shoot fresh weight was under 20 °C with medium GA3 concentration (1 mg·L−1). Compared with the control, almost all growth regulator treatments stimulated higher germination percentages and vigor indices with increased temperatures.
Lauren M. Garcia Chance, Joseph P. Albano, Cindy M. Lee, Staci M. Wolfe and Sarah A. White
Floating treatment wetlands (FTWs), a modified constructed wetland technology, can be deployed in ponds for the treatment of nursery and greenhouse irrigation runoff. The pH of nursery and greenhouse operation irrigation water varies from 3.3 to 10.4 across the United States. Water flow rate, plant species selection, and variable nutrient inputs influence the remediation efficacy of FTWs and may interact with the pH of inflow water to change nutrient remediation dynamics. Therefore, an experiment was designed to quantify the effect of pH on the growth and nutrient uptake capacity of three macrophyte species using a mesocosm FTW system. ‘Rising Sun’ japanese iris (Iris ensata), bushy bluestem (Andropogon glomeratus), and maidencane (Panicum hemitomon) were grown for two 6-week periods and exposed to five pH treatment levels representing the range of nursery and greenhouse irrigation runoff, 4.5, 5.5, 6.5, 7.2, and 8.5, for a total of 15 plant and pH combinations. Water was treated with either hydrochloric acid to decrease the pH or sodium hydroxide to increase the pH. The pH-adjusted solutions were mixed with 12 mg·L−1 nitrogen (N) and 6 mg·L−1 phosphorus (P) fertilizer (64.8 g·m−3 N and 32.4 g·m−3 P). Differences in pH impacted both N and P removal from the FTW systems for two of the three species studied, maidencane and bushy bluestem. Higher pH treatments reduced nutrient removal efficacy, but plants were still capable of consistently removing nutrients across all pH treatments. Conversely, ‘Rising Sun’ japanese iris maintained similar remediation efficacies and removal rates across all pH treatments for both N and P, possibly due to the ability to acidify its rhizosphere and modify the pH of the system. Average N and P loads were reduced by 47.3 g·m−3 N (70%) and 16.6 g·m−3 P (56%). ‘Rising Sun’ japanese iris is a promising plant for use in highly variable conditions when the pH of irrigation runoff is outside the typical range (5.5–7.5). Results from model simulations poorly predict the nutrient availability of P and ammonium in effluent, most likely due to the inability to determine plant and biological contributions to the system, such as N-fixing bacteria.
Liang Zheng, Huaming He and Weitang Song
Plant growth and development relies on light and is influenced by light. Light-emitting diode (LED) technology is nowadays providing the possibility for regulating plant growth and development by modifying light spectral composition. Many researches have been carried out to figure out the effects of light quality on various aspects of plant behaviors, including plant morphology, physiology, and biochemistry. In this review, we summarized those research outputs, in order to give suggestion of light quality application for both research and production purposes, in the field of productional yield, productional quality for horticultural plants including vegetables or ornamentals in difference with cultivation goals.