ASHS 2025 Conference

Global olive oil production tripled over the past six decades to 2.76 million tons in the 2022/23 year. California is the largest producer of olive oil in the United States, and its planting is increasing at an estimated rate of 3000 acres per year. Most of the new plantings for oil in California are in hedgerows under intensive management either in a super high (SHD) or medium (MD) density systems. Of these plantings, an estimated ~80% is ‘Arbequina’, ~15% ‘Arbosana’, and ~5% ‘Koroneiki’. As expected, the industry is continuously searching for novel cultivars that can improve productivity, as well as extra virgin olive oil (EVOO) quality, thereby increasing  returns for their operation. With industry support, a trial was planted at the Wolfskill Experimental Orchard in Winters, CA in 2019 with the exception of ‘Lecciana’ which was planted in 2020. Four acres were planted at a SHD rate of of 620 trees per acre, with 5 feet between trees and 14 feet between rows. ‘Arbequina’, ‘Arbosana’, and ‘Koroneiki’ were planted alongside two new cultivars, ‘Lecciana’ (Olea europaea ‘Arbosana’ x ‘Leccino’) and ‘Sikitita’ (Olea europaea ‘Arbequina’ x ‘Picual’), and one numbered selection, Agromillora 9805-01. The orchard was planted with five complete replicates of the six cultivars, each cultivar row was randomized within each replicate. Seasonal and cumulative yield were measured from the 2021 through the 2024 growing seasons. Fruit weight, oil content, basal shoot prevalence, and maturity index were measured over the 2023 and 2024 growing seasons. The entire orchard was managed following industry agronomic practices for all replicates. During the four years ‘Koroneiki’ had the greatest cumulative yield on average, followed by ‘Arbequina’ and ‘Arbosana’, ‘Lecciana’, ‘9805-01’, and ‘Sikitita’ (16.60, 13.38, 13.37, 10.61, 8.17 and 7.76 tons per acre respectively). Alternate bearing behavior was more prevalent for ‘9805-01’ and ‘Sikitita’. Further, ‘Sikitita’ took an additional year to come into production. These results, alongside seasonal yield, oil content, basal shoot prevalence, and fruit weight, show why ‘Arbequina’, ‘Arbosana’, and ‘Koroneiki’ are the prevalent cultivars in California SHD plantings. In our trial, ‘Arbosana’ and ‘Koroneiki’ performed as well or better than ‘Arbequina’, but California growers have planted less of those two cultivars due to concerns with disease resistance and/or vigor management over time across California’s climatic conditions. Our research shows that further evaluation of novel cultivars is essential for a growing industry.

The probiotic strain Lactobacillus plantarum ATCC 8014 is an ideal model for studying prebiotic interactions primarily due to its demonstrated ability to metabolize a wide range of prebiotic compounds. Hence, this study examines the potential synergistic effects of limonoid glucoside (LG), a citrus-derived phytochemical, in combination with dietary fibers on growth kinetics, amino acid metabolism, biofilm formation, and bacterial performance under salt stress conditions. Treatments included de Man, Rogosa, and Sharpe Agar (MRS) media supplemented with various individual and combinations of LG and dietary fibers, pectin (PEC), and inulin (IN). Individual treatments contained 1 mg/mL of LG, PEC, and IN, while combination treatments used a 0.5 mg/mL concentration of each component. Among the tested NaCl salt concentrations of 1%, 2%, and 4%, concentrations below 2% showed sustained bacterial growth for all the combinations (LG: PEC/IN). Salt concentrations at 4 % negatively impacted the bacterial growth in all the treatments and control; however, an exponential rise in growth was observed after the 18th hour of incubation in PEC: LG, indicating a delayed lag phase. Such a pattern of growth at high salt stress possibly indicates that the co-treatment with LG and PEC could potentially maintain growth, help conserve energy demands, and display osmoregulatory effects to overcome salt stress. Additionally, differences in cell surface hydrophobicity between treatments suggest improved bacterial adhesion and biofilm formation. The LG treatment resulted in significantly increased hydrophobicity, indicating enhanced adhesion potential. IN, LG: PEC/IN treatments showed moderate hydrophobicity, comparable to the MRS control, while PEC exhibited the least. These findings are important, as higher cell surface hydrophobicity is crucial for providing protection against environmental stressors and supporting healthy microbial interactions. Amino acid profiling showed treatment-dependent changes, suggesting that LG and PEC/IN combinations affect amino acid metabolism significantly. Additionally, digested samples exhibited enhanced radical scavenging, indicating potential antioxidative synergy between digested LG and dietary fibers. By analyzing the effects of limonoid glucosides in combination with dietary fibers, this study highlights the potential synergistic benefits of these compounds in enhancing their functional properties and supporting a healthy gut microbiome.

This presentation is hosted by the Collegiate Activities Committee and undergraduates are encouraged to attend!

Specialty teas made from the tender tips of Camellia sinensis have been enjoyed for centuries, and their cultivation in the U.S. is gaining growing interest. Join us at this Hort Theater presentation to discover the exciting world of U.S.-grown specialty tea. Experience a tasting of select green and black teas from Hawaii, Louisiana, and Mississippi. Bring your curiosity and your questions about the health benefits, production, processing, and preparation of tea – we’ll entertain these topics with fun facts and our latest research insights.

Audience will take part in the discussion by doing a tea tasting of 4 or 5 different U.S.-grown teas. There will be new 2025 tea products from a local grower and growers from Mississippi, Oregon, and Hawaii. We will be offering these teas as cold-brew and hot-water brewed sample.

Speaker:
Dr. Tan Chen, Louisiana State University