Robotic technologies are being developed to aid rapid and gentle harvest of fresh-market blackberries (Rubus L. subgenus Rubus Watson). Berry size and composition and their relationship to detachment force were followed to inform robotic harvesting design. For each of the four blackberry cultivars, fruit was harvested from two rows (>120 berries/row) and two harvests (1849 blackberries total) in 2025. Detachment force, berry size (weight, length, and width), and berry composition (soluble solids and pH) were influenced by cultivar. ‘Sweet-Ark® Caddo’ (2.27 N) and ‘Von’ (2.26 N) had the highest detachment force followed by ‘Ouachita’ (2.12 N), then ‘Sweet-Ark® Ponca’ (1.95 N). Of the berry size and composition attributes evaluated, only pH (r = −0.29) was most related to detachment force, regardless of cultivar. Generally, as pH increased, detachment force decreased in all cultivars, more significantly than with berry weight or soluble solids. This study provided insight on the associations between detachment force, with berry size and composition attributes and served to build datasets to inform development of robotic solutions for harvesting.
Sweetpotato (Ipomoea batatas L.) produces edible roots and leaves, which may offer two crops from the same plant for direct-market farmers. Other studies indicate that harvesting sweetpotato greens impacts root yield negatively; however, little is known about how the timing of the greens harvest changes the impact on root yield. Furthermore, it is not known whether the decrease in root yield may be offset economically by an increase in greens yield. A field study was conducted in Mount Vernon, WA, USA, in 2023 and 2024 to evaluate greens and root yield of three sweetpotato advanced breeding lines (USDA-04-136, USDA-04-284, and USDA-04-791) being evaluated for potential cultivar release. The study included four greens harvest schedules: early [greens harvest at 8, 10, 12, and 16 weeks after transplanting (WAT)] mid-late (greens harvest at 12, 14, and 16 WAT), continuous (greens harvest at 8, 10, 12, 14, and 16 WAT), and late (greens harvest at 16 WAT, just before root harvest; control). For each greens harvest, 15-cm vine tips were cut from all vines that were at least 15 cm in length. Greens harvest in the early, continuous, and mid-late harvest treatments reduced canopy cover. Greens yield was greatest for the early and continuous harvest treatments and averaged 4.02 t.ha–1 for the three breeding lines. Greens fresh weight peaked at 10 WAT, but production continued throughout the season, suggesting that repeated greens harvest at 2-week intervals is suitable for this region. Harvesting sweetpotato greens decreased total root yield by 47%, 54%, and 37% for the early, continuous, and mid-late harvest treatments, respectively. However, the decrease in root yield was offset by the greens yield in the continuous harvest treatment, and gross economic returns were similar for the continuous and late harvest treatments when greens were sold at $3 per bunch (20 stems) and roots were sold at $6.60 per kg ($3 per lb), which was common for direct-market growers in Northwest Washington. Thus, dual-cropping sweetpotato for greens and roots may be economically viable for direct-market farmers.
Rooting ornamental cuttings in vertical indoor propagation (VIP) systems using light-emitting diode (LED) fixtures can help reduce plant losses and improve liner quality compared with greenhouse (GH) propagation. However, optimal light-quality conditions for cuttings in VIP systems remain largely unknown, and species-specific responses are expected. Therefore, the objective of this study was to characterize growth responses of cuttings from multiple species with contrasting propagation characteristics to different light-quality treatments, aiming to develop general recommendations for commercial VIP systems. During an acclimation phase that lasted 9 to 19 days, cuttings of yarrow (Achillea millefolium), lavender (Lavandula × intermedia), lamb’s ear (Stachys byzantina), chrysanthemum (Chrysanthemum indicum), Martin’s spurge (Euphorbia × martinii), moss phlox (Phlox subulata), begonia (Begonia × hiemalis), and lithodora (Lithodora diffusa) were placed indoors under LEDs providing monochromatic blue (MB), white with 30% blue (WB), white with 30% far-red (WFR), or white with 18% blue and 26% far-red. All treatments provided a total photon flux density of 100 µmol·m−2·s−1 for 24 h·d−1 [daily light integrals (DLI) of 6.1 to 8.8 mol·m−2·d−1, depending on the far-red contribution from each treatment]. Cuttings were also placed in a glass-glazed GH under mist with an average DLI of 10.8 mol·m−2·d−1. A 10-day finishing phase was conducted either indoors under white LEDs or in the GH to evaluate carryover treatment effects. Cuttings under MB or WFR were taller than those under WB in four (yarrow, lavender, chrysanthemum, and moss phlox) and six species (yarrow, lavender, chrysanthemum, Martin’s spurge, moss phlox, and lithodora), respectively, during one or both phases of the experiment. However, cuttings under MB were shorter than those under WFR for three species (lavender, Martin’s spurge, and moss phlox). Although rooting responses could not be clearly grouped across species, MB provided rooting benefits for five species (lavender, lamb’s ear, chrysanthemum, Martin’s spurge, and moss phlox) and WFR did so for four species (yarrow, chrysanthemum, Martin’s spurge, and begonia), as indicated by increases in root number, root length, root dry mass (DM), and/or root mass fraction during one or both phases. In general, cuttings propagated in the VIP system were taller and had longer roots and greater root DM than those propagated in the GH. Overall, our results indicate potential production benefits of VIP systems through reduced plant losses (shrinkage) and improved root growth compared with GH. MB appears promising for use in VIP systems, as it improved rooting more consistently across species than the other light-quality treatments evaluated, while inducing less shoot elongation than WFR.
We investigated how root-zone calcium (Ca) concentration influences shoot development, tissue Ca accumulation, and antioxidant-related secondary metabolism in in vitro potato (Solanum tuberosum L. cv. Russet Burbank) plantlets. Micropropagated shoots were cultured on Murashige and Skoog medium modified with a gradient of Ca levels (6.8–3000 µM calcium chloride) under controlled environmental conditions. Morphological features, Ca content in plant tissue, total phenolic content, and antioxidant capacity [Trolox equivalent antioxidant capacity (TEAC) and ferric-reducing antioxidant power (FRAP) assays] were evaluated after 4 weeks. Results showed a strong Ca-dependent shift in plant growth and metabolic profiles. Low Ca induced shoot tip necrosis, loss of apical dominance, and increased axillary branching, whereas Ca concentrations ≥ 1360 µM supported normal shoot architecture and sustained growth. The content of Ca in plant tissues increased proportionally with higher Ca levels, increasing 12.7-fold from 153.63 to 1950.44 mg·L–1. In contrast, phenolic levels and TEAC antioxidant capacity showed an inverse trend, decreasing from 928.44 to 515.27 µg gallic acid equivalents·g–1 dry weight (DW) and from 84.26 to 43.88 mg·g–1 Trolox DW, respectively, with increasing Ca levels. In contrast, FRAP activity increased from 100.95 to 427.20 mg·g–1 Trolox DW at higher Ca levels. Regression analyses revealed negative correlations between tissue Ca and both phenolics and TEAC, and a positive correlation between tissue Ca and FRAP. These findings demonstrate that Ca regulates growth and defense metabolism in potato plants. Low Ca appears to trigger phenolic-based defense pathways, whereas Ca applied at adequate levels supports optimal structural development but alters antioxidant composition. Our results suggest that Ca acts as a key regulatory factor in morphogenesis and secondary metabolism, and unlocks possibilities for optimizing nutrient strategies in controlled environments and micropropagation systems.
