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Clinton C. Shock, Erik Feibert and Lamont D. Saunders

Onion (Allium cepa) cultivars for commercial production in eastern Oregon and southwestern Idaho are evaluated annually in replicated yield trials conducted at the Malheur Experiment Station, Oregon State University, Ontario. Market demand has progressively called for larger bulb size and bulbs with single centers. At harvest onions were evaluated for maturity, number of bolters, and single centeredness. Cultivars showed a wide range of bulbs with only one growing point or “bullet” single centers, ranging from 1% to 57% in 2000, from 7% to 70% in 2001, and from 1% to 74% in 2002. The percentages of bulbs functionally single-centered for processing uses ranged from 18% to 88% in 2000, from 24.7% to 91.3% in 2001, and from 14.4% to 92% in 2002. Bulb yield and market grade were evaluated out of storage. Marketable yield after 4 months of storage varied significantly by cultivar from 643 to 1196 cwt/acre (72.1 to 134.1 Mg·ha–1) in 2000, from 538 to 980 cwt/acre (60.3 to 109.8 Mg·ha–1) in 2001, and from 583 to 1119 cwt/acre (65.3 to125.4 Mg·ha–1) in 2002. Averaging over cultivars, super colossal bulb size averaged 26%, 14%, and 10% in 2000, 2001, and 2002, respectively.

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Clinton C. Shock, Erik Feibert, Lynn Jensen, S. Krishna Mohan and Lamont D. Saunders

Onion (Allium cepa) varieties for commercial production in eastern Oregon and southwestern Idaho are evaluated annually in replicated trials conducted at the Malheur Experiment Station, Oregon State University, near Ontario, Oregon. Characteristics evaluated include bulb yield, market grade, and the frequency of single centers. After the emergence of iris yellow spot virus (IYSV) as a threat to commercial onion production in the early 2000s, onion varieties at the Malheur Experiment Station have been evaluated for virus symptoms since 2004. Varieties showed differences in the severity of IYSV symptoms each year. Symptom severity increased over the years from 2004 to 2006, and variety virus ratings showed a strong negative correlation of severity with yield in 2005 and 2006. Marketable yield after 3 months of storage averaged 781, 534, and 551 cwt/acre in 2004, 2005, and 2006, respectively. Averaging over varieties, yield of bulbs larger than 4 inches in diameter was 438 cwt/acre, 56 cwt/acre, and 76 cwt/acre, and the average virus severity ratings were 1.1, 1.3, and 2.7 in 2004, 2005, and 2006, respectively. A few varieties showed a combination of high yield, large bulb size, low incidence of virus symptoms, and a predominance of single-centered bulbs. With the prevalence of IYSV, variety tolerance to IYSV has become an important production factor in the Treasure Valley.

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Clinton C. Shock, Joey K. Ishida, Eric P. Eldredge and Majid Seddigh

Potential new onion (Allium cepa L.) cultivars for commercial production in eastern Oregon and southwestern Idaho are evaluated annually in yield trials conducted at the Malheur Experiment Station, Oregon State University, Ontario, Ore. Bulb yield and market grade were determined in field trials for 63 yellow onion cultivars and lines in 1996 and for 49 cultivars and lines in 1997. Marketable yield out of storage in January ranged from 478 to 1131 cwt/acre (54 to 127 Mg·ha-1) in 1996, and from 383 to 912 cwt/acre (43 to 102 Mg·ha-1) in 1997. Marketable yields of `9003C', `Seville', `El Charro', `Sunre 1430', `El Padre', `Golden Security', `Bravo', and `X 202' were greater than 1000 cwt/acre (112 Mg·ha-1) in 1996. In 1997, marketable yields of `Seville', `Bravo', `Quest', `T-433', `9003C', `Goldstar', `Superstar', `RNX-10020', `Vision', and `Sweet Perfection' were greater than 850 cwt/acre (95 Mg·ha-1). Of the 30 cultivars evaluated both years, the average marketable yields of `Seville', 9003C, `Bravo', `Quest', and `Sweet Perfection' were among the highest. Many others showed potential for high yields and merit further evaluation. In both years, most bulbs of all selections graded jumbo [3 to 4 inch (7.6 to 10.2 cm) diameter] and colossal [>4 inch (10.2 cm) diameter], and only a few cultivars had more than 2% medium-size [2.25 to 3 inch (5.7 to 7.6 cm) diameter] bulbs. Infection by neck rot (Botrytis allii Munn.) and plate rot [Fusarium oxysporum f. sp. cepa (H. N. Hans.) W.C. Snyder & H.N. Hans.] during storage was more severe in 1996 than in 1997, but in general, most cultivars showed relatively low levels of these diseases in both years. Averaged across all cultivars, bolting was evident in less than 1% of bulbs in both years.

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Gerry H. Neilsen, Denise Neilsen, Frank Kappel, Peter Toivonen and Linda Herbert

, strongly affected by irrigation frequency in 2008, when more than a minimal crop was harvested and quality was assessed ( Table 3 ). Decreasing the frequency of irrigation (I2) appeared to accelerate crop maturity as indicated by increased skin color and

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Charlene M. Grahn, Barbara Hellier, Chris Benedict and Carol Miles

, which leads to uneven crop maturity ( Herner, 1986 ). This is problematic in a production system that uses once-over harvesting, as with mechanically harvested baby leaf lettuce. Slow stand establishment also results in a lengthened amount of time to

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T.K. Hartz, E.M. Miyao and C. Giannini

Three field trials were conducted in central California in 1999 to assess the effects of transplant production and handling practices on yield, crop maturity, and fruit quality of processing tomato (Lycopersicon esculentum Mill.). For each trial, transplants of `Halley' tomato were obtained from a variety of commercial greenhouse transplant growers and subjected to various conditioning treatments during the week prior to planting. These treatments included N and/or P fertilization, varying temperature exposure or degree of water stress, or storage in the dark for 2 days before transplanting to simulate shipment from greenhouse to field. Nine transplant treatments (combinations of transplant source and conditioning treatment) were evaluated in each trial, with five 30 m long single-row plots per treatment arranged in a randomized complete-block design. Plots were mechanically harvested. Despite large differences among treatments in initial transplant characteristics (plant height, root cell volume, macronutrient content), there were no significant treatment differences in fruit yield in two trials; in the third trial, one treatment had significantly lower yield than the highest yielding treatment. In no trial were treatment differences in crop maturity (percent green fruit) or fruit quality (soluble solids content or juice color) significant. Across trials, the only transplant characteristic positively correlated with relative fruit yield (treatment yield/mean yield of that trial) was shoot P concentration, which varied among treatments from 1.3 to 11.7 g·kg–1.

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Robert E. Call and Michael E. Matheron

Studies were established in 1992 and 1993 in a mature commercial pistachio orchard to determine the effectiveness of several fungicides for control of septoria leaf spot (Septoria pistaciurum). Fungicide treatments used in 1992 were Bravo 720F at 3.0 lbs./A (ai.) and 4.5 lbs./A a.i.; Kocide 101 50W at 8.0 lbs./A a.i. plus Benlate 50W at 1.0 lb./A a.i. Fungicide treatments in 1993 were Bravo 825 WDG at 3.0 and 4.5 lbs./A a.i. and Benlate 50W at 2.0 lbs./A a.i. Treatment replications consisted of two treated trees separated by nontreated trees within the row and nontreated tree rows dividing treated rows. At crop maturity, disease severity was determined by counting the number of leaf spots caused by septoria on ten leaves collected at random from each of the two trees of each replicated plot. All treatments significantly reduced disease severity compared to trees receiving no fungicide treatments. Experimental plots were too small to detect any apparent effect of fungicide treatments on yield. Leaves around nut clusters not receiving fungicide treatments were senescent at crop maturity, while leaves on treated trees showed no sign of senescence.

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Michael E. Bartolo, Howard F. Schwartz and Frank C. Schweissing

Severe storms with high winds, hail, rain, and blowing soil particles can injure onion (Allium cepa L.) leaf and neck tissues. Our study was conducted to determine the growth response of onions to simulated storm damage during bulb development. The effect of removing 33% and 67% of the onion foliage at 14, 28, 42, and 56 days before maturity was examined. In 2 years, 67% defoliation reduced yields more than 33% defoliation. At both levels, defoliation had a greater impact on total marketable yield and yield of individual market classes when it occurred near the onset of bulbing. Of the different market classes of onions, the jumbo (>8.25 cm in diameter) was most consistently affected by defoliation. A moderate (33%) and a severe (66%) foliage loss delayed crop maturity, decreased total marketable yield and potential market value, and changed the market class distribution of a sweet Spanish-type onion.

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Leslie A. Weston and M.M. Barth

Vegetables provide a major source of essential vitamins such as ascorbic acid and beta carotene and other quality components in the human diet. Postharvest yield and quality of vegetables depend upon genetic, biotic, edaphic, chemic and other factors, as well as combinations of these factors. Successful production, quality and nutritional value of vegetables are related to both primary and secondary metabolic processes occurring during vegetable growth and development. Related research has focused upon cultivar selection, cultural practices used during production, interaction of light and temperature, and use of chemicals for growth regulation, and pest control. We will discuss the effects of genetic, pest, and soil management; crop maturity at harvest; environmental modification; and climatic conditions. Postharvest vegetable quality will be characterized in terms of vitamin content, appearance, yield, and flavor.

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Linda Gaudreau, Josée Charbonneau, Louis-Philippe Vézina and André Gosselin

`Karlo' and `Rosana', two Boston-type lettuce (Lactuca sativa L.) cultivars, were subjected to various light treatments in greenhouses equipped with one of two propane heating systems. Photoperiods of 16, 20, 24, or 24 hours for 2 weeks after transplanting and then 16 hours (24–16) and photosynthetic photon flux of 50 or 100 μmol·m–2·s–1 provided by supplementary lighting (high-pressure sodium vapor lamps) were compared to natural light during four experiments performed in greenhouses between Sept. 1989 and May 1990. Using supplementary lighting resulted in significant increases in biomass (≤270%), head firmness, and tipburn incidence and decreases in production cycle length (≈30%). Treatment effects were most pronounced during the months when natural-light levels were low. Fresh weights were higher for `Karlo' than `Rosana'; however, `Rosana' was less susceptible to tipburn than `Karlo'. In general, the radiant heating system resulted in earlier crop maturity and a higher incidence of tipburn than the hot-air system.