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"O'Connell, Suzanne"
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Miniature Head Lettuce Yield and Anthocyanin Concentration under High Tunnels and the Field in Georgia
This study evaluated the yield of eight miniature lettuce ( Lactuca sativa ) cultivars (i.e., mini-lettuce) grown under organically managed high tunnels compared with a field system during two spring seasons in Georgia. Mini-lettuce required an average of 36 to 40 days to harvest in both systems with a 86% to 97% marketability rate. The high tunnels provided a heat gain on the coldest days, decreased leaf wetness, and resulted in a lower daily light integral compared with the field. In 2015, mini-lettuce yields were similar between the high tunnel and field, but in 2016, yields were greater under the high tunnels. In 2016 only, there was a significant system by cultivar interaction for yield, suggesting that the high tunnels provided a yield increase for ‘Baby Green Oakleaf’ and ‘Spretnak’ mini-lettuce. Differences in the daily light integral between the high tunnels and field appeared to affect the accumulation of anthocyanins in red-pigmented mini-lettuce. Anthocyanin concentrations were 26% to 194% greater in mini-lettuce grown in the field compared with under high tunnels. The cultivar Rhazes had the greatest anthocyanin concentrations of all red-pigmented mini-lettuce evaluated but also lower yields.
Journal Article
Ancient marine sediment DNA reveals diatom transition in Antarctica
Antarctica is one of the most vulnerable regions to climate change on Earth and studying the past and present responses of this polar marine ecosystem to environmental change is a matter of urgency. Sedimentary ancient DNA (
sed
aDNA) analysis can provide such insights into past ecosystem-wide changes. Here we present authenticated (through extensive contamination control and
sed
aDNA damage analysis) metagenomic marine eukaryote
sed
aDNA from the Scotia Sea region acquired during IODP Expedition 382. We also provide a marine eukaryote
sed
aDNA record of ~1 Mio. years and diatom and chlorophyte
sed
aDNA dating back to ~540 ka (using taxonomic marker genes SSU, LSU,
psbO
). We find evidence of warm phases being associated with high relative diatom abundance, and a marked transition from diatoms comprising <10% of all eukaryotes prior to ~14.5 ka, to ~50% after this time, i.e., following Meltwater Pulse 1A, alongside a composition change from sea-ice to open-ocean species. Our study demonstrates that
sed
aDNA tools can be expanded to hundreds of thousands of years, opening the pathway to the study of ecosystem-wide marine shifts and paleo-productivity phases throughout multiple glacial-interglacial cycles.
Sedimentary ancient DNA can indicate ecosystem-wide changes. Here, the authors show association between warm phases and high diatom abundance in the Antarctic Scotia Sea, in addition to presenting ancient eukaryote sedimentary DNA spanning the last approximately 1 million years.
Journal Article
Ornamental Kale as a Cut Flower under High Tunnels in the Southeastern United States
The potential to expand the production of ornamental kale ( Brassica oleracea var. acephala ) grown as a specialty cut flower in the southeastern United States appears promising, especially for the winter holidays. This 2-year replicated study investigated the effects of two fall plantings and three cultivars on ornamental kale yields grown under organic high tunnels. In addition to the production study, informal interviews of local florists were conducted. The earlier planting dates resulted in longer stem lengths (≥5 cm) and fewer days to harvest (≥5 days) across both seasons. Commercial stem length goals were not achieved (≥60 cm) but local florists did not appear to have the same standards (≥31 cm). The cultivars Crane Bicolor and Lucir White had longer stems and larger heads than Crane Red. Our high tunnel system provided favorable air temperatures for vegetative growth from late September through early November indicating an earlier planting date may be possible. Commonly accepted nighttime temperatures required to induce color changes occurred in early to mid-November during our study period.
Journal Article
A Comparison of 13 Sweet Pepper Varieties under an Organic Farming System
There is a dearth of information on pepper ( Capsicum annuum ) variety production under organic conditions; therefore, a randomized complete block designed experiment of 13 pepper varieties were evaluated in 2016 and 2017 using organic production practices on land managed organically for the 6 previous years. Total yield, graded yield, and early yield were the main factors of interest. There were by-year interactions, so the data were analyzed separately for each year. All of the peppers evaluated except for ‘Sweet Chocolate’ were bell pepper types. The average total yield was 1229 and 1754 boxes/acre (28 lb/box) in 2016 and 2017, respectively. There were no statistically significant differences for total yield or early total yield in 2016. In 2017, the top five highest yielding varieties were Aristotle X3R ® , Gridiron, King Arthur, Flavorburst, and Blitz. With the exception of ‘Flavorburst’, all of these entries were among the highest yielding for fancy fruit (≥3 inches diameter and 3.5 inches length). The greatest early yield in 2017 included ‘Aristotle X3R ® ’, ‘Flavorburst’, ‘Touchdown’, ‘Islander’, and ‘Gridiron’. In 2017, early yields of fancy fruit greater than 100 boxes/acre included ‘Aristotle X3R ® ’, ‘Red Knight X3R ® ’, ‘Blitz’, and ‘Gridiron’.
Journal Article
Evaluation of Watermelon Varieties under Organic Production Practices in Georgia
Organic production is a fast-growing sector of agriculture in need of variety evaluations under their unique production systems. This study evaluated 16 watermelon ( Citrullus lanatus ) varieties for their performance characteristics under organic production practices. Plants were grown on plastic mulch-covered beds on land that had been certified organic in accordance with the U.S. Department of Agriculture National Organic Program. Six of the entries were F 1 hybrids; the remaining entries were open-pollinated (OP) varieties. Of the 10 OP varieties, three were considered heirloom varieties, including Cream of Saskatchewan, Georgia Rattlesnake, and Moon & Stars. ‘Georgia Rattlesnake’ was the highest yielding variety and had the greatest average fruit weight. Along with ‘Georgia Rattlesnake’, ‘Nunhems 800’, ‘Nunhems 860’, ‘Orangeglo’, and ‘SSX 8585’ were included in the top five yielding varieties. The top five yielding varieties had fruit size that averaged more than 20 lb. Fruit size correlated with rind thickness, with lighter fruit having thinner rind (Pearson’s correlation, r = 0.779), which is not unexpected. ‘Sangria’ had the greatest average soluble solids content at 11.2%, which was greater than all entries with soluble solids less than 10%.
Journal Article
