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Eight winter squash varieties (Table Ace Acorn, Sweet Dumpling, Waltham Butternut, Honey Boat, Sugar Loaf, Spaghetti, Gold Keeper, and Kabocha) were placed in storage 3 weeks after harvested and were stored for 6, 12, or 16 weeks at 5, 10, or 15°C and 50, 60, or 70 percent relative humidity. Before storage Spaghetti squash had low dry weight and low sugars while Kabocha, Sugar Loaf, and Honey Boat had high dry weight and high sugars. Squash of all varieties suffered high spoilage when stored at 5°C. Water losses increased with temperature or with storage at 50 percent relative humidity. Considering both spoilage and water loss, marketable fruit was highest when squash was stored at 10°C or 15°C and 60 or 70 percent relative humidity. Squash sugars were maintained with storage at 5°C and 10%. Squash can be stored for several months at 10°C and 60 to 70 percent relative humidity with little fruit loss or loss of sugar.
Sweet worm wood is a source of the anti-malarial plant secondary compound artemisinin. The effects of water stress, nitrogen rates, plant growth regulators, and harvest timing on vegetative growth and yield of artemisinin were tested in separate experiments. In the harvest timing trial, total biomass, leaf yield, leaf artemisinin content and total artemisinin yield increased during the season. The wettest treatment tested decreased the total plant dry to fresh weight ratio, but had no effect on height, total biomass, leaf yield, leaf artemisinin content and artemisinin yield. Nitrogen fertilization increased plant height, but had no effect on total biomass, leaf yield, leaf artemisinin content and artemisinin yield. The plant growth regulators decreased plant height, increased total biomass, but had no effect on leaf yield, leaf artemisinin content and artemisinin yield. The effects of chemical weed control and post-harvest leaf drying will also be discussed.
Seven potato cultivars were grown in an adequately irrigated check (100% of crop evapotranspiration replaced at -60 kPa) and three deficit irrigation regimes in order to evaluate varietal response to water stress and to evaluate nitrate leaching below the crop root zone in relation to the irrigation management. Potatoes were grown with sprinkler irrigation on silt loam in 1882 and 1993. Water stress treatments were achieved by partial or complete crop evapotranspiration replacement when soil water potential reached -60 or -80 kPa. In 1992, over all varieties, tuber yield and grade were significantly reduced by the two higher levels of water stress. In 1993, a relatively cool year, yield was reduced by water stress, but grade was not. Tuber internal quality was affected more by variety than by deficit irrigation both years. A comparison of pre-plant and post-harvest soil nitrate and ammonium shows that a small amount of nitrate moved from the top two feet of soil to the third and fourth foot in the check plots. Soil nitrogen accounting for the season showed large surpluses, indicating the importance of natural sources of available nitrogen.
Onions were grown with different soil water potentials as irrigation criteria to determine the soil water potential at which optimum onion yield and quality occurs. Furrow irrigation treatments in 1992 and 1993 consisted of six soil water potential thresholds (-12.5 to -100 kPa). Soil water potential in the first foot of soil was measured by granular matrix sensors (Watermark Model 200SS, Irrometer Co., Riverside, CA) that had been previously calibrated to tensiometers on the same silt loam series. Both years, yield and market grade based on bulb size (more jumbo and colossal onions) increased with wetter treatments. In 1993, a relatively cool year, onion grade peaked at -37.5 kPa due to a significant increase in rot during storage following the wetter treatments. These results suggest the importance of using moisture criteria to schedule irrigations for onions.
Each year ≈24,000 acres of onions (Allium cepa) are produced in the Treasure Valley of eastern Oregon and southwestern Idaho, which accounts for 20% of U.S. dry-bulb onion acreage. Onions in this region are long-day onions and are irrigated by either furrow irrigation or drip irrigation, with drip irrigation having become the predominant system in the past 10 years. Onion production in the Treasure Valley faces many biotic pressures and changing market conditions that renders cultivar development and testing of critical importance to the onion industry. Direct-seeded yellow, white, and red onion cultivars have been evaluated yearly at the Malheur Experiment Station, Oregon State University, in Ontario, OR, USA, since 1975. From 2010 to 2020, 10 onion seed companies participated in the trials. There were 21 to 32 yellow cultivars, two to 10 red cultivars, and one to seven white cultivars entered in the trial each year. Only five cultivars were entered all 11 years. Total yields for the yellow cultivars ranged from an average of 680 cwt/acre in 2010 to 1277 cwt/acre in 2018, and averaged 961 cwt/acre over the 11 years. Yield of yellow bulbs larger than 4 inches (colossal and super colossal) ranged from 13% in 2010 to 61% in 2018, and averaged 34% over the 11 years. Single centered yellow bulbs ranged from 46% in 2013 to 70% in 2014. Total yields for the red cultivars averaged 520 cwt/acre and total yield of white cultivars averaged 988 cwt/acre over the 11 years. Over the 11 years, single-centered bulbs of red cultivars averaged 65% and single-centered bulbs of white cultivars averaged 45%. Some newer cultivars show improvements in single centeredness, resistance to Iris yellow spot virus, and yield of larger bulbs over cultivar Vaquero, which was released in 1993, indicating the success of breeding efforts. Yields of five yellow cultivars that were in the trials every year since 2010, increased over time. This increase can be partly attributed to improvements in cultural practices over the years: adoption of drip irrigation, more intensive nutrient management, refined onion thrips (Thrips tabaci) control, and higher plant population.