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Open access

Bernadine C. Strik, Amanda J. Davis, Patrick A. Jones, and Chad E. Finn

‘Mini Blues’ highbush blueberry (Vaccinium sp.) was released in 2016 as a high-quality, machine-harvestable alternative to lowbush (V. angustifolium Ait.) or other small-fruited highbush blueberry cultivars for processed markets. A planting was established in Oct. 2015 in western Oregon to evaluate the effects of pruning method on yield, machine-harvest efficiency (MHE), berry weight and total soluble solids (TSS), leaf tissue nutrients, pruning weight, pruning time, and costs. Plants were pruned for shape and to remove flower buds in 2015–16 and 2016–17. Pruning treatments began in 2017–18 and included: 1) conventional highbush pruning (HB); 2) removing one or two of the oldest canes per bush (Speed); 3) leaving plants to grow from 2017 to 2021 (Unpruned) before doing a hard renovation prune in 2021–22 (cutting the plants back to a height of ≈0.3 m and leaving the best 8–10 canes/plant); and 4) hedging after fruit harvest in 2018 (Hedge) and then unpruned afterward until renovation in 2021–22. The pattern of yield progression, observed wood aging, and reduced berry size after 4 years of no pruning indicated renovation was necessary in the unpruned and hedge treatments. Low growth was removed each year in all treatments, and hedging was only done in 2018 because it severely reduced yield the following year and, therefore, was not a viable option. An over-the-row machine harvester was used from 2018 to 2021. Speed-pruned plants, averaged over 4 years, had the greatest potential yield (3.75 kg/plant) compared with the other treatments (averaged 2.99 kg/plant) but had a similar yield as HB because more fruit remained on the bush after harvest with speed pruning. In 2021, speed pruning resulted in the highest yield (4.2 kg/plant), followed by HB (3.8 kg/plant) and the unpruned and hedge methods (averaged 3.1 kg/plant). MHE increased from 43% in 2018 to 74% in 2021, mainly because, as the plants aged, a larger proportion of the canopy was above the catcher plates on the harvester. On average, MHE was highest with HB pruning (70%), intermediate in the unpruned and speed-pruned plants (59%), and lowest in the hedged plants (49%). In 2021, ground drop loss was highest for hedge (18%), lowest for speed (14%), and intermediate for HB and unpruned (averaged 16%) methods. HB-pruned plants had heavier berries (0.64 g) than unpruned and hedge treatments (averaged 0.57 g) and a similar berry weight as the speed-pruned plants (0.61 g). Pruning had no effect on berry TSS. In contrast to leaf K, leaf Mg and Ca concentrations were lowest in HB and higher in all other treatments. In 2020–21, HB pruning required 471 h·ha−1, while speed pruning took 79 h·ha−1; the hedge and unpruned treatments required an average of 60 h·ha−1 to remove low-growing branches that would interfere with machine harvest. In 2021–22, renovation of the unpruned and hedge treatments took 290 h·ha−1. While leaving bushes unpruned during establishment appears to be a promising option for ‘Mini Blues’, further work is needed to evaluate fruit production after renovation and to determine how long the plants could remain unpruned thereafter. Speed pruning is also a good option, reducing pruning costs by 85%.

Open access

Xunzhong Zhang, Zachary Taylor, Mike Goatley, Jordan Booth, Isabel Brown, and Kelly Kosiarski

Bermudagrass is a warm-season turfgrass species widely used for sports fields, home lawns, and golf courses. Ultradwarf bermudagrass has been used for golf course greens, but its quality declines with abiotic stresses. This 2-year study was designed to investigate if foliar applications of seaweed extract-based biostimulant Utilize® could improve ultradwarf bermudagrass photosynthetic function, nitrate reductase activity, root growth, and root function while under heat stress and drought stress conditions. Utilize® was applied to ultradwarf bermudagrass canopy at 0, 88, 117, 175, and 234 μL⋅m−2. Two weeks after the initial application of Utilize®, bermudagrass was subjected to heat (40/36 °C, day/night) and drought stress (40–50% evapotranspiration replacement) for up to 42 days. Heat stress and drought stress caused decline of the turf quality. Foliar application of Utilize® at 117, 175, and 234 μL⋅m−2 biweekly consistently improved turf quality and leaf color ratings and increased leaf chlorophyll and carotenoid concentrations, net photosynthetic rate, nitrate reductase activity, and root growth and viability. On average, Utilize® at 117, 175, and 234 μL⋅m−2 increased turf quality ratings by 9.1%, 12.1%, and 10.6%, respectively, net photosynthetic rates by 32.4%, 45.0%, and 35.0%, respectively, and nitrate reductase activity by 16.7%, 18.8%, and 14.6%, respectively, compared with the control. Utilize® at 117, 175, and 234 μL⋅m−2 increased the root biomass, root length, surface area, and root volume compared with the control. Utilize® at 88, 117, 175, and 234 μL⋅m−2 increased root viability by 46.2%, 73.1%, 88.5%, and 74.4%, respectively, relative to the control. The results of this study suggest that seaweed extract-based biostimulant Utilize® improves nitrogen metabolism, photosynthetic function, root growth, and root viability. Foliar application of Utilize® at rates between 117 and 175 μL⋅m−2 biweekly can be considered an effective approach to improving ultradwarf bermudagrass performance under heat stress and drought stress environments.

Open access

Jeb S. Fields, Kristopher S. Criscione, and Ashley Edwards

Substrate stratification is an emerging substrate management strategy involving layering multiple substrate materials within a single container to modify physiochemical characteristics of the substrate system. Specifically, stratifying allows growers and researchers to rearrange the air–water balance within a container to modify hydraulic characteristics. Moreover, fertilizer can be incorporated into just the upper strata to reduce leaching. Research to date has shown benefits associated with resource efficiency, production timing, and weed control. With the associated benefits for substrate stratification, interested growers will need pragmatic solutions for onsite trials. Therefore, the objective of this study was to identify a cost-effective solution for growers interested in exploring stratification options. As such, this research was designed to identify a single-screen bark separation to generate fine and coarse bark textures suitable for use as the top and bottom substrate strata. Loblolly pine bark (Pinus taeda) was screened with either a 4.0-mm, 1/4-inch, or 3/8-inch screen, with the particles passing through the screen (unders) separated from retained particles (overs). Stratified substrate systems were engineered with an individual screen wherein the fines were layered atop the coarse particles from the same screen. ‘Natchez’ crepe myrtle (Lagerstroemia indica) liners were planted in either of the three stratified substrate treatments or a nonstratified control. Substrate physical characteristics were assessed for each strata by pre- and postproduction properties to identify changes of substrate. The final growth index of the crop was unaffected by the substrate treatment (P = 0.90); however, stratified substrates did increase dry root weight (P = 0.02), with the smallest screen (4.0 mm) resulting in the greatest root weight. Separation of roots between the two strata indicated the presence of more roots in the upper strata in all substrates. However, the stratified substrates resulted in a greater shift in root location, encouraging increased rooting in the upper strata with fine particles, with the largest screen (3/8 inch) resulting in the greatest differentiation between upper and lower rooting. Each stratified treatment had increase in water-holding capacity in the lower (coarser) strata without changes in the upper strata. Thus, we conclude that single screens can be used to build stratified substrate systems. Moreover, screen aperture size may be used to achieve different outcomes with regard to root growth and development as well as water–air balance. Further research may indicate that screen selection may be used to target specific crop needs.

Open access

Xiaoli Zhang, Qiang Liu, Shengyang Niu, Chonghuai Liu, Xiucai Fan, Ying Zhang, Lei Sun, and Jianfu Jiang

Spine grape (Vitis davidii Foëx), an important wild grape species in South China, has gained attention because of its health-promoting effects and use in the wine industry. Fruit quality plays an important role in determining the quality of wine; however, a suitable evaluation system to monitor its fruit quality has not been established. The fruit quality characteristics (phenolics and aromas) of 15 spine grapes grown in China were evaluated using a combination of principal component and cluster analyses. The total sugar, organic acid, and phenolic content ranged from 81.80 to 154.89 mg·g−1, 8.02 to 15.48 mg·g−1, and 5.58 to 20.12 mg·g−1, respectively. The comprehensive assessment by principal component analysis revealed that ‘Red xiangzhenzhu’ had the highest quality and ‘Hongjiangci10’ and ‘Ziluolan’ the lowest quality. Cluster analysis using k-means grouped the cultivars into three clusters based on their quality: Cluster 1 grouped those with inferior quality (‘Hongjiangci09’, ‘Hongjiangci10’, ‘Hongjiangci11’, and ‘Hongjiangci07’, etc.), Cluster2 grouped those with average quality (‘Ciputao3#,’ ‘Ziluolan’, and ‘Xiangci4#’), and Cluster3 grouped those with superior quality (‘Red xiangzhenzhu’ and ‘Green xiangzhenzhu’). A combination of principal component analysis and cluster analysis provides a comprehensive and objective evaluation system for determining the quality of grape cultivars. This study is important for the systematic evaluation and utilization of spine grape resources.

Open access

Xinpeng Zhang, Zongda Xu, Wenli Wang, Deyu Mu, Xiang Meng, Min Lu, and Cheng Li

Plants with the flower color phenotype of double-color flowers are very precious and attractive and can usually be regarded as valuable germplasm resources for studying and improving flower color. This paper summarizes the coloring mechanism of double-color flowers in plants from three aspects: the formation of double-color flowers, the physiological factors affecting the coloring difference of double-color flowers, and the molecular mechanism affecting the coloring difference of double-color flowers, to provide a theoretical reference for the in-depth study of the coloring mechanism and molecular breeding of double-color flowers in the future.

Open access

Connor Bolton, Miguel Cabrera, Mussie Habteselassie, Daniel Poston, and Gerald Henry

The incorporation of biostimulants, including microbial inoculants, into turfgrass management programs has increased during the past decade as a result of the potential benefits of their use, including increased nutrient uptake, enhanced growth, and improved stress tolerance. However, minimal research has been conducted on warm-season grasses, and questions still exist regarding microbial inoculant application timing, frequency of inoculation, and need for supplemental nitrogen. Therefore, the objective of our research was to investigate the influence of nitrogen fertilizer and microbial inoculant application timings on the establishment of common bermudagrass [Cynodon dactylon (L.) Pers.] in the field and in a controlled environment. Treatments containing fertilizer had a consistently greater normalized difference vegetation index, turfgrass color, and turfgrass quality than treatments that contained only the Klebsiella variicola microbial inoculant (KV). Establishment of bermudagrass plots in response to treatments containing fertilizer had more than 90% cover at the conclusion of the study (8 weeks after seeding), whereas KV treatments and the untreated check never exceeded 70% cover. However, the greatest change in carbon efflux was often observed in the field in response to treatments that supplied KV 3 weeks after seeding. In the greenhouse, the greatest root and shoot weights were typically observed in response to treatments containing fertilizer, whereas KV-alone treatments resulted in root and shoot weights either similar to or less than the untreated check.

Open access

Young-Sik Park, Je-Chang Lee, Nam-Yong Um, Haet-Nim Jeong, and Jae-Yun Heo

Open access

John Berkomah, Haiwen Li, Rafat Siddiqui, Chyer Kim, and Harbans Bhardwaj

This student-led project studied the production of cilantro (greens stage) and coriander (seed stage) of Coriandrum sativum L. with the objective of developing this crop as an alternate specialty crop in Virginia. Results indicated that both fall-planted for spring harvest and spring-planted for summer harvest are possible in Virginia. Rows spaced 37.5 cm apart resulted in the superior yield of both cilantro and coriander over rows 75 cm apart. Mean cilantro fresh yields from fall-planted experiments (three cultivars during 2015 and five cultivars during 2016) varied from 3301 to 5775 kg⋅ha−1, whereas those from spring-planted experiments varied from 4971 to 11811 kg⋅ha−1. Corresponding values for dry cilantro yields varied from 274 to 1129 kg⋅ha−1 and 862 to 2280 kg⋅ha−1, respectively. Mean coriander seed yields from three fall-planted cultivars varied from 818 to 1554 kg⋅ha−1, and those from three spring-planted cultivars varied from 869 to 1277 kg⋅ha−1. The total phenolic content in cilantro was significantly greater than that in coriander seed (4.95 and 1.15 g of gallic acid equivalent per 100 g of material, respectively). The total mesophiles, yeast and mold, and coliforms from three grocery store-bought cilantro were considerably higher than those of greenhouse-grown cilantro. Even though both spring and fall plantings are possible for supplying cilantro in Virginia, fall planting for spring harvest might be more profitable for producers because of the earlier availability of locally grown cilantro.

Open access

Shoufu Gong, Bailing Miao, and Xiangxiang Dong

Gardenia jasminoides, belonging to the Rubiaceae family, is widely distributed and planted in China. It has traditionally been used as an ornamental and medicinal plant in several Asian countries. The rapid development of high-throughput sequencing technology makes it feasible to obtain complete chloroplast (cp) genome sequences and will deepen our understanding of evolution of G. jasminoides. In this study, we sequenced the complete cp genomes of two botanical varieties of G. jasminoides. The complete cp genomes of both botanical varieties of G. jasminoides showed highly conserved structures and the length was 154,954 base pairs (bp) for G. jasminoides var. radicans (GJR) and 155,098 bp for G. jasminoides var. grandiflora (GJG). A total of 132 and 133 genes were identified in GJR and GJG, respectively. The cp genomes of two newly sequenced G. jasminoides were further compared with two published G. jasminoides cp genomes. Multiple repeats and simple sequence repeats (SSRs) were detected among different genotypes of G. jasminoides. The intron sequences of rps16 and rpl16 genes were slightly divergent among four genotypes of G. jasminoides. Phylogenetic analyses based on the complete cp genome sequences showed that G. jasminoides was closely associated with Fosbergia shweliensis, with Coffea as their close relative. Taken together, the complete cp genomes of GJG and GJR provided significant insights and important information that can be used to identify related species and reconstruct their phylogeny.

Open access

Andrew Mullin, Bárbara Nogueira Souza Costa, Jason Downing, and Amir Ali Khoddamzadeh

Florida is home to 106 native orchid species, of which 77 are listed as endangered or threatened by the State of Florida. The Institute for Regional Conservation (IRC) has classified 62 of these species as either critically imperiled, imperiled, or rare in South Florida. Because of lack of endosperm, orchid germination rates are very low in nature, as they depend on an obligate relationship with mycorrhizal fungi for nutrients. Most orchid seeds can be germinated in vitro without the need for specific mycorrhizal fungi. This study aims are to establish a fast and efficient protocol for in vitro seed germination using different nutrient media and plant growth regulator (PGR) combinations, and to optimize seedling acclimatization protocols using different greenhouse media. To determine germination preferences, three different in vitro seed germination media were tested supplemented with PGRs, including 1) Murashige & Skoog (MS) (control), 2) MS supplemented with 1.5 mg/L 6-benzylaminopurine (BAP), and 3) MS supplemented with 1 mg/L BAP and 0.5 mg/L 1-Naphthaleneacetic acid (NAA) on Cyrtopodium punctatum, a state-listed endangered, IRC critically imperiled epiphytic orchid. There was no significant difference amongst the treatments after 2 and 6 weeks of seed sowing culture. To understand post-culture survivorship, two epiphytic and one terrestrial native species (Trichocentrum undulatum, Encyclia tampensis, and Oncidium ensatum) were chosen for the acclimatization study with two commercially available potting substrates (coir, sphagnum). To measure seedling growth rates, phenotypic measurements [leaf number, leaf length, root length, plantlet height, light intensity, pH, and electrical conductivity (EC)] and Soil Plant Analysis Development (SPAD) and Normalized Difference Vegetation Index (NDVI) values were recorded monthly for five months. All media/PGR combinations resulted in an initial high percentage of stage I growth but inhibited Protocorm-like bodies (PLBs) development, suggesting more research is necessary to determine later improvements or detriments to MS basal media with BAP and NAA. Comparing acclimatization media with the three species of orchid chosen for this experiment, neither O. ensatum nor E. tampensis showed a marked preference for sphagnum moss or coir. However, T. undulatum did perform better with coir compared with sphagnum. This research will help botanical gardens and commercial plant tissue culture laboratories to have a better understanding on selection of PGR combinations for in vitro cell culture and acclimatization media on increasing the viability and plant health and decreasing the mortality of endangered plants.