Blueberries (Vaccinium spp.) exhibit a high degree of asynchrony during flowering, fruit set, and ripening. Fruit pigmentation is highly dependent on direct solar radiation, resulting in significant differences between sun-exposed and shaded berries within the same cluster. This study evaluated the effect of two plant growth regulators (PGRs), abscisic acid (ABA) and methyl jasmonate (MeJas), on fruit coloration and firmness under in vitro conditions. Clusters from two cultivars, ‘Duke’ and ‘Brigitta’, were collected at the green berry stage, two weeks before the expected start of commercial harvest in the 2024–25 season. Half of the clusters were taken from the outer canopy (sun-exposed) and half from the inner canopy (shaded). In the laboratory, clusters were placed in Falcon tubes with their twigs immersed in one of six solutions: (1) water (Control 1), (2) sucrose (Control 2), (3) ABA 500 ppm sucrose, (4) ABA 1000 ppm sucrose, (5) MeJas 0.1 mM sucrose, and (6) MeJas 1 mM sucrose. The samples were maintained in a growth chamber under controlled temperature (22 °C) and photoperiod (16 h light at 70 µmol/m²/sec). Fruit were evaluated at 3, 6, and 9 days post-treatment for coloration (percentage of blue fruit) and firmness (g mm⁻¹). ABA treatments significantly accelerated fruit coloration in both cultivars. In ‘Duke’, ABA-500 and ABA-1000 reached 80% and 100% blue fruit by day 6, respectively, compared to
Many traditional European cider cultivars are known to have biennial bearing tendencies and growers have reported that conventional thinners such as 1-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (6-BA) are ineffective. The goal of this two-year study is to determine the efficacy of plant growth regulators (PGRs) on traditional European cider cultivars in reducing biennial bearing and improving juice and cider quality, while also maintaining sufficient yield to ensure profitability. The chemical thinners used in this study were applied with a backpack sprayer and consisted of the lowest and highest labelled rates of NAA (PoMaxa; Valent BioSciences LLC, Libertyville, IL) and 6-BA (MaxCel; Valent BioSciences LLC, Libertyville, IL) mixed with 1-naphthyl methylcarbamate (Carbaryl; Sevin SL; Loveland Products Inc, Greeley, CO). The chemical thinners were applied to the high-tannin cider cultivars, ‘Binet Rouge’, ‘Chisel Jersey’, ‘Dabinett’, ‘Harry Masters Jersey’, and ‘Porter’s Perfection’. The experiment was conducted at the Cornell research orchards in Ithaca and Lansing, NY, as well as commercial orchards in Walden, Lyndonville, and Trumansburg, NY. Each site was a fully replicated (n = 5) randomized complete block design. Preliminary data found that chemical thinning reduced crop load between 24% and 62% (measured as the total number of fruit per tree) and increased individual fruit weight (measured in grams) between 24% and 70%. Additionally, chemical thinning increased soluble solids concentration in the juice (measured in degrees Brix) between 6% and 29% and increased titratable acidity (measured in grams/liter) between 9% and 29%. These results demonstrate that PGRs can be effectively used to manage crop load for European cider cultivars. A second field season is planned for 2025.
Photosynthesis, the process by which light is converted into chemical energy, occurs in chloroplasts and involves two photosystems (PS II and PS I) connected by the cytochrome b6f complex. PS II is responsible for water splitting in oxygenic photosynthesis and is composed of a dimeric core and peripheral antennae. These antennae regulate excitation pressure under varying light conditions, preventing damage to PS II. In high-light environments, dissociation of the antennae is crucial for optimizing light harvesting and enabling self-repair of PS II. Phosphorylation of core proteins, particularly at the Thr2 residue in PsbA (D1) and PsbD (D2), plays a key role in antenna regulation and PS II repair. However, the mechanisms underlying phosphorylation-dependent disassembly of PS II are not well understood. In this study, we generated mutated PsbA and PsbD genes with alanine substitutions at the Thr2 phosphorylation site. These mutated genes were introduced into the chloroplast genome via particle bombardment, and homologous recombination was used to replace the native genes. Characterizing plants with these mutations will provide insight into the role of phosphorylation in the disassembly of PS II, a process crucial for light-harvesting efficiency and repair. This work aims to enhance our understanding of photosynthetic regulation and inform strategies for improving crop efficiency.
Funding Source This work was supported in part by a DOE-Office of Science Grant to SP & AD; Texas A&M AgriLife Hatch Project #TEX0-9950-0, and startup funds from Texas A&M AgriLife Research and Texas A&M University to AD.
Gillenia stipulata, commonly known as Wester Indian Physic, is an ornamental herbaceous perennial in the Rosaceae family native to the Midwest and Eastern North America. Ethephon has been previously shown to affect plant growth, development and early flowering in apple seedlings. In the present study, interaction of ethephon and light quality on G. stipulata plant growth and development was examined. Plants were grown from seed purchased from Prairie Moon Nursery (Winona, MN) and when 4-5 leaves had been initiated, seedlings were treated with 0 (Control), 500 ppm, 1000 ppm, or 2000 ppm Florel (Monterey Lan
