Blueberries are an important fruit crop in the Ericaceae represented by multiple Vaccinium species and ecotypes. In addition to their economic value, blueberry fruit is known for an abundance of specialized metabolites with known human health benefits. Phenolic compounds, which include flavonoids and anthocyanins, are an important class of compounds found in blueberry that are known to contribute to fruit flavor and quality and for having health-promoting properties. Previous surveys of phenolic compounds in blueberry have demonstrated considerable variability in concentration of these metabolites, which is associated with differences in environmental factors and cultivars surveyed. This study expands this knowledge by surveying total phenolic, flavonoid, and anthocyanin content in ripe fruits of 71 blueberry cultivars from one growing season in Michigan. Included in this diversity panel are three ecotypes of blueberry (northern highbush, southern highbush, and half highbush). Rubel, Legacy, and Friendship were among the seven cultivars with the highest content of each compound. Total phenolic content showed a 5.03-fold difference among the lowest and highest cultivars, and total flavonoid content and total anthocyanin content demonstrated a 2.66-fold and 6.37-fold difference between the lowest and highest content across cultivars, respectively. There was no significant impact of ecotype on phytochemical composition of ripe fruits. This study also represents the first large-scale analysis of total phenolic content using the Fast Blue BB (FBBB) reagent. Data from this study have the potential to aid in future breeding efforts to enhance the human health benefits of this economically important fruit crop.
Giovani Rossi, Floyd M. Woods, and Courtney P. Leisner
Qingyang Sun, Yue Zhao, Shusheng Zhu, Fei Du, Ruzhi Mao, Lijing Liu, Yifan Zhu, Su Li, Meng Sun, and Bin Tian
Rain-shelter cultivation could protect grape berries from many diseases and affect grape berry quality. However, there have been few studies of the effects of rain-shelter cultivation on the accumulation of volatiles in Shuijing grapes grown in Yunnan Province. Therefore, the goal of this research was to explore the effects of rain-shelter cultivation on the accumulation of volatiles in Shuijing grape berries during development. The Shuijing grapes used during this study were grown in the Yunnan Province of southwest China in two consecutive vintages (2018 and 2019). The results showed that rain-shelter cultivation promoted grape ripening and inhibited volatiles synthesis in Shuijing grape berries. However, the application of rain shelters did not affect the accumulation patterns of volatiles; instead, it affected the concentrations of volatiles in Shuijing grape berries, especially during the maturation phase [12–15 weeks after flowering (WAF)]. The concentrations of isoprenoid-derived volatiles (2019), fatty acid-derived volatiles, and amino acid-derived benzenoids in Shuijing grape berries were decreased by rain-shelter cultivation during the maturation phase. The concentration of 2,5-dimethyl-4-methoxy-3(2H)-furanone (mesifurane) was also decreased by rain-shelter cultivation during the late maturation phase (14 and 15 WAF). A principal component analysis (PCA) indicated that the vintage had a much greater influence on the physicochemical parameters and volatiles of the Shuijing grape berries than the cultivation method. This work reveals the formation and accumulation patterns of volatiles of Shuijing grape berries under rain-shelter cultivation during development and has significance for exploring the potential of rain-shelter cultivation in grape-producing regions with excessive rainfall.
Maria Brym, Yuqing Fu, Noah Frade, Elizabeth Baldwin, and Alan H. Chambers
Strawberry (Fragaria ×ananassa) is grown during the winter months in subtropical southern Florida and must thrive in higher than average temperatures and limestone soils. This is the first strawberry cultivar trial in southern Florida to include ‘Florida Beauty’, ‘Florida Brilliance’, ‘Strawberry Festival’, ‘Florida Radiance’, ‘Sensation FL127’, and ‘Winterstar’. Overall, ‘Strawberry Festival’ and ‘Sensation FL127’ were the top yielding cultivars, with the highest average total yields of 0.7 and 0.8 kg/plant fresh fruit, respectively. ‘Sensation FL127’ had a 36% greater late-season marketable yield compared with ‘Strawberry Festival’. ‘Sensation FL127’ consistently had the greatest soluble solids content (7.6% to 8.7%). Overall, this study demonstrates significant differences in yield and fruit quality among the cultivars tested in southern Florida.
Marina L. Curtis and Gerardo H. Nunez
Courses are the main source of data analysis training for students. The statistical software training taught in those courses can affect student career readiness. However, lack of information about statistical software use in horticulture leads students and mentors to select statistics courses based on course availability and/or anecdotal evaluations. This research aimed to describe statistical software use trends in horticulture research to inform student course selection. We surveyed ≈50% of all articles published in HortScience, HortTechnology, and the Journal of the American Society for Horticultural Science (JASHS) between 2005 and 2020. We found that SAS, SPSS, and R were the most frequently used software packages in this period. SAS use frequency decreased in HortScience and JASHS, but not in HortTechnology. SPSS use increased in JASHS and R use increased in all journals. Results from this retrospective survey suggest that training in SAS, SPSS, and R can help align students with horticulture research practices.
Katherine Brewer, Mary Hockenberry-Meyer, Susan Galatowitsch, and Stan C. Hokanson
Prairie dropseed [Sporobolus heterolepis (A. Gray) A. Gray] is a critical North American native grass that is often not incorporated into prairie restoration seed mixes due to its low survival and growth rates. This project investigated using hydrogels, landscape plugs, and native field soil to improve the survival and growth of prairie dropseed. At three tallgrass prairie restoration sites at the Minnesota Landscape Arboretum, we planted prairie dropseed plugs in Fall 2019, Spring 2020, and Fall 2020. When grown in the field from 42 to 94 weeks, we found that potting mix–grown plugs had increased growth as measured by dry weight compared with plugs grown in native soils. Soil medium did not influence survival rates. The use of hydrogels did not demonstrate increased survival or growth compared with plugs planted with water. We recommend land managers and restorationists use plugs grown in commercial potting mix rather than grown in native soils, and we found no advantage in using hydrogels over watering at planting.
Kevin Athearn, Marina Burani-Arouca, Nicholas Dufault, Clyde Fraisse, Joshua Freeman, Robert Hochmuth, Tatiana Sanchez, Tatiana Borisova, Tyler Pittman, and Luke Harlow
Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] growers choose transplanting dates every year considering multiple risk factors. Earlier harvests linked to earlier planting typically find more favorable markets, but earlier planting has higher risk of freeze damage. Research also indicates that risk of fusarium wilt (caused by Fusarium oxysporum f. sp. niveum) is higher during cooler weather, adding to the risk of planting earlier. Thus, growers need to balance market risk (e.g., getting a low price) and production risk (e.g., lower harvest or higher cost due to freezing temperatures or disease) in selecting a planting date. The objective of this analysis is to examine the effect of planting date on the distribution of potential economic returns and evaluate whether late planting could be a favorable risk-management strategy. Probability distributions are estimated for key risk factors based on input from watermelon growers, published price data, historical freeze data, experiment station trials, and expert discussions. The distribution of economic returns is then simulated for three planting windows (early, middle, and late) using simulation software. Results demonstrate planting date risk–return tradeoffs and indicate that late planting is unlikely to be preferable to middle planting, even when risk of fusarium wilt is high.
John M. Ertle and Chieri Kubota
Grafted watermelon plants available in the United States are typically transported for a long distance from a specialized nursery to the production field. To investigate the effects of chilling stress during transportation on the early plant growth and development, grafted and nongrafted ‘Tri-X-313’ seedless watermelon (Citrullus lanatus) seedlings were subjected to low-temperature treatments applied over a 72-hour period. The first experiment exposed grafted and nongrafted seedlings to 0, 6, 12, 24, or 48 hours of 1 °C chilling, and then were moved to a 12 °C growth chamber for the remainder of the chilling treatment period. The second experiment exposed nongrafted seedlings to seven different combinations of chilling duration (0, 24, 32, 41, 44, or 48 hours) to create varied chilling degree hours (CDH) at different temperatures (between −0.4 °C and 1.2 °C). After 72 hours, seedlings were transplanted in pots filled with a commercial substrate in a greenhouse to evaluate the early plant growth and floral development. Each experiment had two repeats (spring and summer) with a randomized complete block design (n = 10). Although greater exposure to chilling negatively affected visual quality and photosynthetic capacity [measured by chlorophyll fluorescence parameter, variable fluorescence/maximum fluorescence (Fv/Fm)] in both repeats, delay in flowering after transplanting was significant in spring only and increased with increasing CDH (up to 6 days with 48 hours of 1 °C exposure). Grafting was found to mitigate the degree of flowering delay when the same chilling exposure was applied. When chilling temperatures were varied, visual damage of leaves, decrease in Fv/Fm, and delays in female flower development were best correlated with CDH at a base temperature of 15 °C, 3 °C, and 4 °C, respectively. Our experiments and further analyses with available literature data suggest that 50 to 70 CDH 4 [CDH with base temperature (BT) = 4 °C] seems to be a critical threshold to cause significant delay in female flower development (3.5 days for grafted and 1.3 days for nongrafted plants). Therefore, if temperatures lower than 4 °C are expected during transportation of seedlings, we suggest mitigation measures be taken so that CDH 4 do not reach greater than 50 degree hours.
Gerardo H. Nunez, Neil O. Anderson, Christopher S. Imler, Laura Irish, Chad T. Miller, and Mariana Neves da Silva
During the 2021 American Society for Horticultural Science annual conference, the Teaching Methods Professional Interest Group hosted the workshop “Going beyond Zoom: Tips and tricks for teaching horticulture online.” This workshop provided a forum for the dissemination of tools, materials, and approaches used to facilitate active learning in horticulture courses. Here we summarize the topics presented in the workshop as a resource for current and future horticulture instructors.
Zhenxu Liang, Mingde Sun, Yang Wu, Jun Liu, Yanyan Zhao, Haiqing Tian, Ruirui Du, and Songzhong Liu
To understand the soil nutrient status of pear orchards in Beijing, we investigated their fertilization situation, including the fertilizer type, amount, and period. Furthermore, soil samples were collected at a depth of 0 to 40 cm to determine the contents of soil nitrogen, phosphorus, and potassium. The status of nutrient profits and losses was analyzed. The results showed that 50% of the pear orchards received organic fertilizer as a single nutrient source, and 35.7% of the pear orchards received a combined application of organic fertilizer and chemical fertilizer. Most pear orchards received organic fertilizer in autumn, but the application of chemical fertilizer occurred mainly before germination and during fruit expansion. The average nutrient input to the investigated pear orchards was 569.6 kg/ha for N, 855.0 kg/ha for P2O5, and 448.1 kg/ha for K2O, and the corresponding proportion of organic fertilizer was 76.9%, 88.0%, and 85.8%, respectively. However, the pear orchards had surpluses of nitrogen, phosphorus, and potassium, with average surplus amounts as high as 445.5, 794.3, and 321.4 kg/ha, respectively. Among all pear orchards surveyed, 93.33% faced environmental risks and 37.04% faced leaching risks. The average content of soil phosphorus was 2.23 times its critical value, and 64.29% of the studied pear orchards exceeded the critical value. Most pear orchards had surplus potassium, with 26.92% exceeding 500 kg/ha. This study provides a basis for soil improvement, high-quality production of fruits, and efficient utilization of pear orchards in Beijing.