One principle for reducing undesirable stem extension in greenhouse production is to counteract the decrease in red-to-far red ratio that occurs naturally during twilight periods. This study evaluated three lighting treatments on the morphology of easter lily (Lilium longiflorum): 1) a 1-hour end-of-day treatment providing 20 μmol·m−2·s−1 of monochromatic red light (EOD R), 2) blackout curtains closed 45 to 75 minutes before sunset and kept closed until 0 to 60 minutes after sunrise (BO), and 3) a control with natural twilight (CTRL). Plants under the BO treatment were 11% shorter than CTRL, while plants exposed to EOD R did not differ in height compared with BO or CTRL. There were no treatment effects on any other measured parameters, including aspects of flowering.
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Jasmine Jenji Mah, David Llewellyn and Youbin Zheng
Qin Yang and Yan Fu
Loquat [Eriobotrya japonica (E. japonica)], a small genus of the subtribe Malinae that consists of ≈30 species, is an evergreen rosaceous fruit tree that is native to southeastern China, and some wild species that possess novel, favorable traits have excellent breeding potential. For example, Eriobotrya bengalensis blooms in late spring and ripens in early autumn in Guizhou Province, China, which prevents cold injury in winter by breeding spring-flowering cultivars using the special characters. Therefore, in the present study, the pollination treatments of cut-style pollination were evaluated that may promote successful distant hybridization in Eriobotrya japonica ‘Dawuxing’ × Eriobotrya deflexa and E. japonica ‘Dawuxing’ × E. bengalensis. The results indicated that the impairment of the pollen tube growth in the upper third of the style after pollen germination is an important factor leading to the failure of distant hybridization between the species tested in E. japonica, and that cut-style pollination can effectively overcome prefertilization barriers of the distant hybridization combination. Furthermore, the results of allele-specific polymerase chain reaction (AS-PCR) showed that S-genotypes, in accordance with the S-RNase heredity to separate the rule completely in offspring, should be both parents' S-RNase, and that the random 50 seedlings of Eb-2 and Ed-2 are true hybrids.
Heather Kalaman, Gary W. Knox, Sandra B. Wilson and Wendy Wilber
As land-use patterns change over time, some pollinating insects continue to decline both in abundance and diversity. This is due, in part, to reductions in floral resources that provide sufficient nectar and pollen. Our overall goal is to help increase the use of plants that enhance pollinator health by providing research-based information that is easily accessible to the public. To assess the most successful mode of sharing this information, a survey was distributed to more than 4000 Master Gardener (MG) volunteers of Florida. The objectives of our survey were to gauge both knowledge and interest in common pollinators, common pollinator-friendly floral resources, and a favored means of accessing material about additional pollinator-friendly plants for landscape use. With a response rate of just over 18%, results showed that there is a clear interest among Florida MGs in learning more about pollinators and pollinator-friendly plants with face-to-face classes followed by a website as the preferred modes of accessing educational materials on this topic. Respondents on average were extremely interested in learning more about pollinator plants [mean of 4.41 out of 5.0 (sd = 0.89)], with greatest interest in butterflies/moths (Lepidoptera), followed by bees (Hymenoptera), birds (Aves), bats (Chiroptera), and beetles (Coleoptera). Overall, MG participants felt more confident (P < 0.0001) in their knowledge of pollinator-friendly plants (mean 3.24 out of 5.0) than pollinator insects (mean 3.01 out of 5.0). When tested, 88.5% were able to correctly identify black-eyed susan (Rudbeckia hirta), with 70.1% correctly identifying spotted beebalm (Monarda punctata). Variations were observed in tested knowledge of pollinating insects, with 90.2% correctly identifying a zebra longwing (Heliconius charithonia) and only 32.6% correctly identifying a striped-sweat bee (Agapostemon splendens). These results revealed that MGs perceived themselves to be fairly knowledgeable about both pollinator plants and pollinating insects, yet their tested knowledge ranged widely depending on the actual plant and pollinator type. This suggests an emphasis be given for future MG training focused on diverse plant and pollinator species, preferably in a face-to-face environment. Results also show that additional resources regarding pollinator-friendly plants, as well as identification material on pollinating insects, are both desired and valued by our Florida MG community.
Job Teixeira de Oliveira, Rubens Alves de Oliveira, Lucas Allan Almeida Oliveira, Paulo Teodoro and Rafael Montanari
Among the crops that are usually grown under irrigation, one can mention garlic, which is a product with high demand in Brazil and the world, it is highly valued in the cuisine of several countries, and is an aggregated crop with high economic value. In 2018, this work was conducted in Yellow Red Latosol. The objective was to characterize the structure and magnitude of the spatial distribution of garlic production components and to map the productive components to visualize spatial distribution and to evaluate the spatial correlation between garlic bulb yield (BY) and other variables of the crop: total plant mass (TPM), number of leaves (NL), floral tassel length (FTL), leaf length (LL), leaf width (LW), pseudostem diameter (PD), shoot wet mass (SWM), shoot dry mass (SDM), number of cloves per bulb (NCB), clove mass (CM), root dry mass (RDM), and irrigation (IRR). All these traits were sampled in a 90-point grid georeferenced. Data analysis using statistical and geostatistical techniques made it possible to verify that the production components and BY, TPM, NL, FTL, LL, LW, PD, SWM, SDM, CM, and IRR presented special dependence. The spatial correlation between BY and TPM, LW, and CM showed a moderate spatial dependence.
Young-Sik Park, Sang-Hyun Lim and Jae-Yun Heo
Chase Jones-Baumgardt, David Llewellyn and Youbin Zheng
Low natural daily light integrals (DLIs) are a major limiting factor for greenhouse production during darker months (e.g., October to February in Canada). Supplemental lighting (SL) is commonly used to maintain crop productivity and quality during these periods, particularly when the supply chain demands consistent production levels year-round. What remains to be determined are the optimum SL light intensities (LIs) for winter production of a myriad of different commodities. The present study investigated the growth and yield of sunflower (Helianthus annuus L., ‘Black oil’), kale (Brassica napus L., ‘Red Russian’), arugula (Eruca sativa L.), and mustard (Brassica juncea L., ‘Ruby Streaks’), grown as microgreens, in a greenhouse under SL light-emitting diode (LED) photosynthetic photon flux density (PPFD) levels ranging from 17.0 to 304 μmol·m−2·s−1 with a 16-hour photoperiod (i.e., supplemental DLIs from 1.0 to 17.5 mol·m−2·d−1). Crops were sown in a commercial greenhouse near Hamilton, ON, Canada (lat. 43°14′N, long. 80°07′W) on 1 Feb. 2018, and harvested after 8, 11, 12, and 12 days, resulting in average natural DLIs of 6.5, 5.9, 6.2, and 6.2 mol·m−2·d−1 for sunflower, kale, arugula, and mustard, respectively. Corresponding total light integrals (TLIs) ranged from 60 to 188 mol·m−2 for sunflower, 76 to 258 mol·m−2 for kale, 86 to 280 mol·m−2 for arugula, and 86 to 284 mol·m−2 for mustard. Fresh weight (i.e., marketable yield) increased asymptotically with increasing LI and leaf area increased linearly with increasing LI, in all genotypes. Hypocotyl length of mustard decreased and hypocotyl diameter of sunflower, arugula, and mustard increased with increasing LI. Dry weight, robust index, and relative chlorophyll content increased and specific leaf area decreased in kale, arugula, and mustard with increasing LI. Commercial microgreen greenhouse growers can use the light response models described herein to predict relevant production metrics according to the available (natural and supplemental) light levels to select the most appropriate SL LI to achieve the desired production goals as economically as possible.
The objective of this study was to analyze the effects of low storage temperatures on the quality of pollen obtained from the sweet cherry cultivars 0900 Ziraat, Regina, Starks Gold, and Sweet Heart. The pollen was stored at 4 °C, –20 °C, and –80 °C for 12 months, and its viability and germinability were determined at 3-month intervals. The results demonstrated that the initial pollen viability varied between 73.62% and 79.37%, while pollen germinability varied between 41.24% and 53.56%. The percentage of pollen viability declined remarkably from the third to 12th month by almost 3% in 4 °C storage. The pollen viability for the other two storage temperatures (–20 °C and –80 °C) was greater than 50% by the end of the 12th month. It can be concluded that the pollen quality of these cultivars can be preserved sufficiently at temperatures less than –20 °C.
Michael J. Havey
The most common bulb colors of onion (Allium cepa) are red, yellow, and white; chartreuse is a relatively rare bulb color conditioned by the homozygous recessive genotype at the G locus. In this research, plants with chartreuse bulbs were crossed with inbreds with yellow bulbs to develop segregating families for genetic mapping of the G locus. For all of 17 F2 families, segregations for yellow vs. chartreuse bulbs fit the expected 3:1 ratio (P > 0.05). DNAs were isolated from one F2 family and genotyped for single nucleotide polymorphisms (SNPs) to produce a genetic map of the G locus and 380 SNPs, of which 119 SNPs have not been previously mapped. Segregations for yellow vs. chartreuse bulbs placed the G locus at the end of chromosome 7 at 6.7 cM from the nearest SNP (isotig28625_2789). This codominant SNP marker linked to the G locus should be useful for introgression of recessive chartreuse bulb color into diverse onion populations for commercial production of this uniquely colored onion.
Charles Fontanier, Justin Quetone Moss, Lakshmy Gopinath, Carla Goad, Kemin Su and Yanqi Wu
Cell and plastid membranes play a critical role in plant response to chilling stress. Fall color retention (chilling tolerance) of bermudagrass (Cynodon sp.) is known to vary with cultivar and management practices. A growth chamber study was conducted to characterize the lipid composition of three bermudagrasses in response to chilling stress. The grasses selected were ‘Tahoma 31’ (chilling-sensitive) and ‘Tifway’ (chilling-tolerant) interspecific hybrid bermudagrass (C. dactylon × C. transvaalensis) and ‘Celebration’ common bermudagrass (C. dactylon), which served as an internal standard. Plants were subjected to simulated fall conditions defined as an 8/2 °C (day/night) temperature regime with 10-hour photoperiod and evaluated for chilling response for 42 days before allowing plants to enter an apparent dormancy. Plant leaves were sampled for lipidomics analysis at 0, 14, and 42 days of chilling treatment (DOT) and again after 40 days of recovery from dormancy (during which temperatures were adjusted to mimic average spring conditions for Oklahoma). ‘Tifway’ demonstrated the lowest electrolyte leakage (EL) and visual discoloration at 42 DOT, while ‘Tahoma 31’ had the greatest EL and discoloration on the same date, and ‘Celebration’ was intermediate of the two. Prolonged exposure to chilling stress generally increased digalactosyldiacylglycerol and phosphatidylcholine (PC) content and decreased monogalactosyldiacylglycerol (MGDG) content, with ‘Tahoma 31’ showing the greatest increase in PC and decrease in MGDG. The double bond index, an indicator of fatty acid unsaturation, was greatest in ‘Tifway’ at 42 DOT. Each cultivar increased in fatty acid unsaturation, with Tifway demonstrating the greatest increase in MGDG unsaturation. Multivariate discriminant analysis identified six individual lipid species that contributed most to the cultivar response to chilling. These findings suggest unsaturation level of plastid lipids, particularly MGDG, is important for chilling tolerance and therefore fall color retention of bermudagrass. Furthermore, this study provides evidence that chilling tolerance can be negatively associated with freezing tolerance in bermudagrass.
Ruying Wang, James W. Hempfling, Bruce B. Clarke and James A. Murphy
Sand size can affect the ability to incorporate topdressing into the turf canopy and thatch on golf course putting greens; unincorporated sand interferes with mowing and play. This 3-year field trial was initiated to determine the effects of sand size on sand incorporation, surface wetness, and anthracnose (caused by Colletotrichum cereale Manns sensu lato Crouch, Clarke, and Hillman) of annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama] maintained as a putting green. The experimental design was a randomized complete block with four replications; treatments included a non-topdressed control and three topdressing sands (medium-coarse, medium, or medium-fine) applied every 2 weeks at 0.15 L·m−2 during the summer. Topdressing with medium-coarse sand was more difficult to incorporate than the medium and medium-fine sands, resulting in a greater quantity of sand collected with mower clippings. Analyzing the particle distribution of sand removed by mowing confirmed that coarser sand particles were more likely to be removed in mower clippings. Surface wetness measured as volumetric water content (VWC) at the 0- to 38-mm depth zone was greater in non-topdressed plots than topdressed plots on 35% of observations. Few differences in VWC were found among sand size treatments. Turf responses to topdressing were not immediate; however, as sand accumulated in the turf canopy, topdressed plots typically had lower anthracnose severity than non-topdressed turf after the first year. Additionally, topdressing with medium and medium-fine sands produced similar or occasionally lower disease severity than topdressing with medium-coarse sand. The lack of negative effects of medium and medium-fine sands combined with better incorporation after topdressing and less disruption to the putting surface should allow golf course superintendents to apply topdressing at frequencies and/or quantities needed during the summer to maintain high-quality turf and playing conditions.