Boston and Australian swordferns (Nephrolepis sp.) are popular tropical ferns for hanging baskets and containers; however, greenhouse production occurs during times of the year when growers may need to deploy shade or supplemental lighting to manage the growing environment. Our objectives were to quantify the impact of the daily light integral (DLI) on growth, morphology, physiology, and ornamental quality of containerized Nephrolepis species and cultivars, and to establish optimal DLIs for containerized swordferns to assist commercial greenhouse growers with light management strategies during production. Eleven cultivars of Boston swordfern [N. exaltata (L.) Schott Blue Bells, Compacta, Fluffy Ruffles, Gold, Montana, Nevada, Petticoat, Pom Pom, Super, Tiger, and True] and one cultivar of Australian swordfern [N. obliterata (R. Br.) J. Sm. Western Queen] were investigated. Plants were grown for 58 days at 20 °C and placed under one of four different fixed-woven shadecloths providing ≈86%, 62%, 42%, or 26% shade or no shade, thereby establishing mean DLIs of 3.2, 6.4, 10.7, 12.4, and 17.1 mol⋅m−2⋅d−1, respectively. For most cultivars, the growth index, which is an integrated measurement of height and diameter, decreased linearly as the DLI increased from 3.2 to 17.2 mol⋅m−2⋅d−1, resulting in smaller compact plants. Increasing the DLI significantly affected the frond number of each cultivar differently, whereas dry mass generally increased as the DLI increased from 3.2 to 10.7 to 12.4 mol⋅m−2⋅d−1 for most cultivars. For each cultivar, as the DLI increased from 3.2 to 17.1 mol⋅m−2⋅d−1, the chlorophyll concentration index decreased, whereas the hue angle increased and chroma was unaffected. Our results indicate that growers should maintain ≈10 to 12 mol⋅m−2⋅d−1 during greenhouse Nephrolepis production; however, DLIs ≥5.5 mol⋅m−2⋅d−1 and ≤16.5 mol⋅m−2⋅d−1 also improved the quality of some Nephrolepis cultivars.
Lauren Seltsam and W. Garrett Owen
Robert E. Paull, Benjamin Wiseman, and Gail Uruu
Slips are side-shoots or fruit with large crowns that grow from buds on the pineapple (Ananas comosus L.) peduncle. The slips are widely used for pineapple vegetative propagation when crowns are left attached to the fruit that is marketed. There is a difference between the two most popular low-acid pineapple hybrids grown worldwide. The ‘Pineapple Research Institute 73-50’ (CO-2, MD-1) slips develop few roots when planted compared with ‘Pineapple Research Institute 73-114’ (MD2). The slow rooting of 73-50 leads to slow field establishment and can extend the crop cycle. Our objective was to determine the cause of this reduced rooting and evaluate treatments to increase the rooting rate. Rooting trials in moist, coarse vermiculite showed that larger slips and green slips with red hues also had a greater number of roots compared with smaller slips and green or yellow slips. Delaying harvesting of the slips after the fruit were harvested also resulted in a greater number of roots. Treatments including components frequently used for rooting cuttings did not significantly increase root numbers. An exception was a tendency for slips treated with potassium nitrate to have greater rooting during some tests. We present data that support the conclusion that the poor root development is associated with the mechanical impedance of the root from the tightly affixed basal leaf bracts. Removal of the lower ten bracts can lead to greater root numbers. When the slip with the bracts removed was tightly wrapped in plastic wrap and masking tape, rooting was reduced. The sizing and selection of slips that are green with a red hue and collected as late as possible after fruit harvest had the best rooting response.
Haiyan Li, Junhai Niu, Luping Sun, Ya Li, Qingyun Leng, Jinhua Chen, Jinran Zhang, Yanan Yanan, Chao Ma, and Hernán Ariel López
Bougainvillea Comm. ex Juss. (Nyctaginaceae; Bougainvillea) is a popular ornamental plant with vigorous growth, luxuriant blooming, colorful bracts, and a high tolerance to the stresses of temperature, drought, and soil pollution, and thus is widely cultivated in tropical and subtropical regions. However, the paucity of information on ploidy and the genomic constitution is a significant challenge to genome research and cultivar improvement. We present a flow cytometry method for ploidy detection in bougainvillea based on evaluating different lysates and tissues, identify the ploidy level of a batch of bougainvillea accessions, and infer the genome size of horticultural species Bougainvillea glabra, Bougainvillea spectobilis, and Bougainvillea peruviana. The results show that tender leaves and woody plant buffer (WPB) were optimal for flow cytometry analysis. The 2C nuclear DNA amounts in 176 bougainvillea accessions ranged from 4.66 ± 0.04 to 12.26 ± 0.1 pg, which represents 161 diploids, 13 triploids, 1 tetraploid, and 1 di-tetraploid mixoploid. For B. glabra, B. spectobilis, and B. peruviana, the mean 1C values were 3.201, 3.066, and 2.915 pg, respectively. The genome size of B. glabra was significantly larger than that of B. peruviana (P = 0.0004), but had no significant variation with that of B. spectobilis (P = 0.1061). These results reveal fundamental cytogenetic information for bougainvillea that are beneficial to whole-genome sequencing and hybrid breeding programs.
Annie R. Vogel, Marc W. van Iersel, Lynne Seymour, Brett Forman, Jordyn Gulle, Chloe MacIntyre, and Cain C. Hickey
Fruit zone leaf removal effects on grapevine (Vitis sp.) productivity and fruit quality have been widely researched. Many fruit zone leaf removal studies state that grape temperature influences grape composition; however, few studies have quantified grape berry temperature fluctuations over time, likely because of technical challenges. An efficient, simple, and economical way to estimate grape berry temperature would be valuable for researchers and industry. Consistent quantification of grape temperature would allow researchers to compare the effects of leaf removal on grape composition across varying climates and regions. A cost-effective means to quantify berry temperature would also provide industry members site-specific information on berry temperature patterns and guide leaf removal practice. Our goals were to develop a method and model to estimate berry temperature based on air temperature and berry mimics, thereby precluding the need to measure solar radiation or obtain expensive equipment. We evaluated the ability of wireless temperature sensors, submerged in various volumes of water within black or white balloons, to predict berry temperature. Treatments included 0-, 10-, 30-, 50-, and 70-mL volumes of deionized water in black and white balloons and a clear plastic bag with no water. Regression analysis was used to determine the relationship between sensor-logged temperatures and ‘Camminare noir’ berry temperatures recorded with hypodermic thermocouples. Nighttime berry temperatures were close to air temperature in all treatments. Using a piecewise regression model, the 30-mL white- and 30-mL black-balloon treatments predicted berry temperature with the greatest accuracy (R 2 = 0.98 and 0.96, respectively). However, during daytime hours only, the 30-mL white-balloon treatment (R 2 = 0.91) was more effective at estimating temperature than the 30-mL black-balloon treatment (R 2 = 0.78). Housing temperature sensors in balloons proved to be an accurate, practical, and cost-effective solution to estimate berry temperature. Further refinement of this method in different regions, row orientations, training systems, and cultivars is necessary to determine applicability of this approach under a wide range of conditions.
Hao Kai Yan, ShaoYing Ma, Xu Lu, Cong Cong Zhang, Lei Ma, Kang Li, Yun Chun Wei, Mei Shuang Gong, and Sheng Li
This study aimed to clarify the relationship between grape (Vitis vinifera L.) quality and environmental factors (climate and soil), and to elucidate the theoretical basis and provide technical guidance for the rational planning of the cultivation area and the precise regulation of the cultivation mode in the future. The fruits of three different grape cultivars, Pinot Noir, Merlot, and Vidal, as well as soil samples and meteorological data were collected from three wine grape growing areas (Wuwei, Zhangye, and Jiayuguan) in the Hexi Corridor, Northwest China. Principal-component analysis (PCA) and correlation analysis were conducted to understand the relationship of grape quality with weather conditions and soil properties. The results showed that the titratable acid content of grape berries was significantly negatively correlated with average temperature from August to September, average minimum temperatures from August to September, and from April to October, mean annual minimum temperature, growing degree days from August to September, and soil total nitrogen content, and significantly positively correlated with average rainfall from April to October, annual mean rainfall, and soil available potassium content. In addition, the pH of grape juice was significantly negatively correlated with annual mean rainfall and soil available potassium content. However, it was significantly positively correlated with average temperature and average minimum temperature from August to September, average minimum temperature from April to October, growing degree days from August to September, as well as soil total nitrogen content. In addition, the results of PCA showed that the fruit quality scores of ‘Vidal’ in Jiayuguan, ‘Merlot’ in Zhangye, and ‘Pinot Noir’ in Wuwei were the highest, respectively. In conclusion, the contents of titratable acid, pH, and Brix° are greatly affected by climate and soil factors. ‘Vidal’, ‘Merlot’, and ‘Pinot Noir’ were suitable for planting in Jiayuguan, Zhangye, and Wuwei, respectively. Nowadays, few reports focus on the relationship between grape quality and soil and climate conditions. Based on the investigation and analysis of the differences of climate, soil, and grape berries quality in the three production areas of Hexi Corridor, the relationship among climate, soil, and grape quality by using statistical methods was studied, which could provide references for clarifying the reasons why environmental factors affect grape quality and select the suitable area for wine grape cultivation.
Kelly Nascimento-Silva, María Benlloch-González, and Ricardo Fernández-Escobar
Silicon (Si) is a nonessential element for plant growth, but it influences the tolerance to biotic and abiotic stresses in many plant species. Most research about the uptake and beneficial effects of Si in plants has been carried out on monocotyledonous species, Si-accumulating plants. Little attention has been paid to woody crops, characterized as low-Si-accumulating plants. In this sense, available information about Si nutrition in olive trees is scarce. Therefore, this work aimed to study the effect of Si application on the uptake, accumulation, and organ distribution of Si in young olive plants by analyzing the influence of the dose, the method of application, and the cultivar. Three experiments were conducted under shade-house conditions with mist-rooted ‘Arbequina’ and ‘Picual’. The treatments consisted of different Si doses, ranging from 0 to 20 mg·L−1, depending on the experiment, applied by foliar sprays or through the irrigation water. Choline-stabilized orthosilicic acid (H4O4Si) was used as the source of Si. Results indicated that after 120 days of Si treatments, this element was accumulated in major proportion in the roots, followed by the leaves and the shoot of the plants. Si organ concentration increased according to the doses applied, independently of the olive cultivar and the method of Si application. Differences in leaf Si accumulation between treated and control plants were evident 60 days after its application. The dose of 20 mg·L−1 was the most effective to increase Si level in leaves under the trial conditions. Si is recommended to be applied periodically to ensure its accumulation in growing leaves.
Maxime Delisle-Houde, Pascal Dubé, Awa Barro, Valérie Tremblay, and Russell J. Tweddell
In this study, a crude ethanolic extract made of silver maple (Acer saccharinum L.) leaves (SML) was evaluated for antibacterial activity against the phytopathogenic bacteria Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, and Xanthomonas fragariae. The extract was shown to cause important inhibition zones against the three bacteria in the disc diffusion assays, revealing its antibacterial activity. The minimal inhibitory concentration (MIC) of the extract was determined thereafter for each bacterium. The extract showed the same MIC value (1.56 mg·mL−1) for the three bacteria. Using a semipreparative high-performance liquid chromatography system, crude ethanolic SML extract was divided in 15 fractions and each fraction was tested for antibacterial activity against X. fragariae with the disc diffusion assay. Among the six fractions causing an inhibition zone, fraction 10 caused the largest inhibition. Fraction 10 was further analyzed by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. According to quadrupole time-of-flight mass spectrometry, the main peak of fraction 10 was identified as a galloyl-bis-HHDP-glucose (C41H28O26, 936.6454 g·mol−1) isomer, an ellagitannin known for antibacterial activity and for stimulating plant natural defenses. The study opens new avenues of research on the valorization of SML and on the control of plant diseases caused by bacteria in organic and conventional production of horticultural crops.
Yue Gong, Wangbin Ye, Gongfa Shi, Lijuan Fan, and Ling Wang
Wenjing Guan, Dean Haseman, Laura Ingwell, and Daniel S. Egel
Locally produced strawberries (Fragaria ×ananassa) have outstanding market potential. But strawberry production has been decreasing in the north-central United States, partly because of high production risks associated with the traditional matted-row system. The annual plasticulture system attracts attention but its low yield limits the wide adoption of the production system in the north-central United States. High tunnels are widely used to extend strawberry seasons worldwide, but the system was not fully explored in the United States. Although the benefits of growing strawberries in high tunnels were recognized, information on suitable strawberry cultivars specific for the fall-planted high tunnel production system is limited. A wide range of short-day and day-neutral strawberry cultivars, including recently released cultivars, were evaluated in the fall-planted annual plasticulture high tunnel systems for three seasons. Averaged among cultivars, the marketable yields were 1.96, 1.35, and 2.27 lb/plant for 2015–16, 2019–20, and 2020–21 seasons, respectively. The combined use of high tunnels and floating rowcovers created favorable microclimate conditions that led to high yields. Florida Radiance, San Andreas, Chandler, and Rocco were the top-yielding cultivars. Besides Chandler, the other top-yielding cultivars entered peak harvest in the second half of April. Harvests ended at the end of May or early June. All cultivars reached the US Department of Agriculture standard for total soluble solids in all three seasons, although Camino Real, FL Radiance, and Sweet Sensation consistently had relatively lower sugar content. Considering a warm-season crop could grow in high tunnels before or after strawberry, a diversified cropping system involving strawberry and other vegetables is highly valuable for high tunnel production systems in the north-central United States. This study did not compare cultivars’ resistance to diseases, but it should be a critical factor in selecting cultivars. Future studies are also warranted to evaluate the effects of incorporating soil treatments and cover cropping for suppressing diseases in the soil-based high tunnel system. Sustainable management strategies to control two-spotted spider mites (Tetranychus urticae) are also crucial in successfully using the system in the north-central United States.
Shuxia Yin, Lisa A. Beirn, Trent M. Tate, Daniel L. Ward, Ruying Wang, William A. Meyer, and Bruce B. Clarke
Anthracnose, caused by the fungal pathogen Colletotrichum cereale Manns sensu lato Crouch, Clarke & Hillman, can be a damaging disease on many cool-season turfgrasses; however, it has not been reported as an aggressive pathogen on fine fescue species (Festuca spp.). Symptoms and signs associated with anthracnose disease were observed in fine fescues on the Rutgers University Plant Science Research and Extension Farm in Adelphia, NJ, in Jun 2014. The objectives of this study were to identify the causal agent, determine if the isolate of C. cereale (FF1A) obtained from symptomatic Chewings fescue (Festuca rubra L. ssp. commutata Gaudin) plants was pathogenic to Chewings fescue and hard fescue (F. brevipila Tracey) turfs, and whether cultivars and accessions collected from Europe varied in disease susceptibility. Pathogenicity of this fine fescue isolate was evaluated using four Chewings fescue and four hard fescue cultivars or accessions in a growth chamber. Disease symptoms were first observed at 5 days post-inoculation, and evaluations continued to 17 days post-inoculation. Infection was confirmed by morphological evaluations, re-isolation from symptomatic tissues, and real-time polymerase chain reaction (PCR). Three noncommercial accessions (two Chewings fescues and one hard fescue) were very susceptible to the fine fescue C. cereale FF1A isolate, whereas ‘Sword’ and ‘Beacon’ hard fescues exhibited low susceptibility. In addition, an isolate of C. cereale (HF217CS) from annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama] was included, and our data demonstrated that this isolate was also able to infect Chewings fescue and hard fescue. This study confirmed that C. cereale can be a damaging pathogen of fine fescues, and that breeding for resistance to anthracnose should be considered when developing new cultivars.