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- Author or Editor: George H. Clough x
Field trials were conducted at Hermiston, Ore., from 1995 through 1998, to determine impact of stand loss and plant damage at different growth stages on yield of onions (Allium cepa) grown for dehydration. Stand reduction (0%, 20%, 40%, 60%, 80%) and foliage damage (0%, 25%, 50%, 75%, 100%) treatments were applied at three-, six-, nine-, and twelve-leaf onion growth stages. Although average bulb weight increased as stand was reduced, marketable, cull, and total yields decreased as stand reduction increased (plant population decreased) at all plant growth stages. Bulb weight was not changed by up to 100% foliage removal at the three-leaf stage. At the six- and twelve-leaf stages, weight was reduced when ≥50% of the foliage was removed. The most severe response occurred at the nine-leaf stage. At the three-leaf stage, yield was not affected by foliage damage. At the six-leaf growth stage, yield was reduced by 75% or more foliage loss, but at the nine- and twelve-leaf stages, ≥50% foliage removal reduced expected yields. As with bulb weight, the impact of foliage removal on yield was most severe at the nine-leaf growth stage.
Field trials were conducted at Hermiston, Ore., from 1995 through 1998 to determine the impact of stand loss and plant damage at different growth stages on yield of onions grown for dehydration. The experiment was a complete factorial with four replications. Stand reduction (0%, 20%, 40%, 60%, 80%) and foliage damage (0%, 25%, 50%, 75%, or 100%) treatments were applied at 3-, 6-, 9-, and 12-leaf onion growth stages. All average onion production characteristics decreased linearly as stand reduction increased (plant population decreased) at all plant growth stages except average bulb weight which increased as stand was reduced. Bulb weight was not changed by up to 100% foliage removal at the three-leaf stage of growth. At the 6- and 12-leaf stages, bulb weight was reduced when >50% of the foliage was removed. The most severe response occurred at the nine-leaf stage when bulb weights were reduced the most. At the three-leaf stage, yield was not affected by foliage damage. At the six-leaf growth stage, yield was reduced by 75% or more foliage loss, but at the 9- and 12-leaf stages, >50% foliage removal reduced expected yields. As with bulb weight, the impact of foliage removal on yield was most severe at the nine-leaf growth stage.
Potato (Solanum tuberosum) cv. `Russet Burbank' response to source of side-dress Ca fertilization applied at 0, 28 and 56 kg·ha-1 Ca on fine sandy loam soil was evaluated. Side-dress Ca source and rate did not affect number or total weight of tubers/hill, average tuber weight, or tuber macronutrient concentrations at mid-season. Tuber B concentration was significantly greater with the 12-0-0-10.5 source as compared to the check. Tuber Fe concentration decreased linearly as 22-0-0-7 rate increased from 0 to 56 kg·ha-1 Ca. No other micronutrient concentration was affected by the applied treatments. Calcium fertilization had no effect on tuber yield, grade distribution, or specific gravity. The predominant internal defect observed was brown center, which was reduced at harvest by side-dress Ca application. Internal quality and french fry color were evaluated after storage for 4 months.
In a 3-year study on a fine sandy loam soil, potato (Solanum tuberosum) cvs. `Atlantic' (1989), `Frontier' (1990, 1991) and `Russet Burbank' (1989-1991) response to rate and time of Ca fertilization was evaluated. Calcium was applied preplant at 0, 90, 180, and 270 kg·ha-1 as CaSO4 and side-dress at lay-by at 0, 67 and 134 kg·ha-1 as Ca(NO3)2, with treatments combined in a complete factorial. Preplant Ca fertilization increased soil Ca each year. Calcium fertilization had little effect on yield or grade distribution. Tuber P, K and S concentrations increased with increasing preplant and sidedress fertilization rates in 1989. Concentrations of S and Ca in Russet Burbank and Frontier increased linearly with preplant CaSO4 application rate in 1990 and 1991. Little or no internal brown spot (IBS) occurred in Atlantic or Russet Burbank, but in Frontier IBS was reduced both years by pre-plant and/or side-dress Ca application. The incidence of IBS did not change after storage for 4 months for any cultivar. In 1990, Russet Burbank fry color improved as pre-plant Ca fertilization rate increased.
In a 3-year study on a fine sandy loam soil, `Atlantic' (1989), `Frontier' (1990-91), and `Russet Burbank' (1989-91) potato (Solanum tuberosum L.) response to rate and time of Ca fertilization was evaluated. Calcium was applied preplant at 0, 90, 180, and 270 kg·ha-1 as CaSO4 and side-dressed at 0, 34, and 68 kg·ha-1 as Ca(NO3)2, with treatments combined in a complete factorial. Preplant Ca fertilization increased soil Ca concentration each year. Calcium fertilization did not affect tuber yield or grade distribution. Tuber concentrations of P, K, and Ca in `Russet Burbank', Ca in `Frontier', and S in all cultivars increased with increasing preplant Ca rate. `Russet Burbank' tuber P, K, Ca, and Cu concentrations and `Frontier' tuber S concentration increased as side-dressed Ca rate increased. Tuber concentrations of most nutrients decreased between midseason and harvest. The incidence of internal brown spot (IBS) was very low in `Atlantic' and `Russet Burbank' tubers and was reduced in `Atlantic' by preplant Ca application. In 1990, IBS severity and incidence in `Frontier' were reduced by preplant and side-dressed Ca fertilization. In 1991, after 4 months of storage at 7C, severity and percentage of tubers with IBS were reduced by preplant and side-dressed Ca fertilization. During storage, IBS decreased in `Russet Burbank'. Brown center in `Russet Burbank' decreased as side-dressed Ca rate increased. In 1990, `Russet Burbank' french-fry color improved as preplant Ca rate increased.
A 2-year study was conducted in eastern Oregon to evaluate the effects of hooped spunbonded polypropylene rowcovers and Ca fertilization on yield and quality of drip-irrigated bell pepper (Capsicum annuum L. Grossum group) grown on black plastic mulch. The experiment was a complete factorial with four replications of two cultivars, covered and uncovered plots, and three levels of supplemental Ca fertilization at 0, 34, and 68 kg·ha-1 applied through the drip irrigation system as Ca(NO3)2. Rowcovers increased marketable yields both at the first harvest and over the season. Blossom-end rot and sunscald were reduced substantially by rowcovers; the effect was greatest during the earlier harvests. First-harvest and season total yield of fancy grade peppers increased linearly as rate of supplemental Ca increased, as did total marketable yield at the first harvest. Both yield of fruit with blossom-end rot and the percentage of fruit with blossom-end rot at the first harvest decreased as Ca rate increased. Yield of fruit affected by sunscald decreased linearly as supplemental Ca rate increased at the first harvest; overall, yield of sunscalded fruit was reduced by application of Ca at either rate.
Three transgenic yellow crookneck squash (Cucurbita pepo var. melopepo) and five transgenic cantaloupe (Cucumis melo, Reticulatus group) lines were field-tested in 1993 and 1994, respectively, for resistance to Zucchini Yellow Mosaic Virus and Watermelon Mosaic Virus II. During both years, non-transgenic plants were inoculated with virus before transplanting to provide a high virus threat to the transgenic plants. Before and after transplanting, serological (ELISA) testing was used to obtain baseline information on transformed plants and to confirm field virus infection. In both years, plant disease development was rated weekly; yield was assessed during 1993. Disease progression, yield, and end-of-season ELISA indicated a significant reduction in frequency of disease incidence in the transgenic lines. Total squash yields did not differ between the transformed and unchanged lines, but the transgenic lines yielded more marketable fruit than the non-transgenic line.
A 2-year study was conducted in eastern Oregon to evaluate the effects of hooped spunbonded polypropylene rowcovers and calcium fertilization on yield and quality of drip-irrigated bell pepper grown on black plastic mulch. The experiment was a complete factorial with four replications of two varieties, covered and uncovered plots, and three levels of supplemental calcium fertilization at 0, 34 and 68 kg·ha–1 applied through the drip irrigation system as Ca(NO3)2. Marketable yields increased with rowcover, both at the first harvest and over the season. Blossom-end rot and sunscald were reduced substantially by rowcovers; the effect was greatest during the earlier harvests. First harvest and season total yield of fancy grade peppers increased linearly as rate of supplemental calcium increased, as did total marketable yield at the first harvest. There was a trend to decreasing yield of fruit with blossom-end rot as calcium rate increased, and the percent fruit with blossom-end rot at the first harvest decreased linearly with increasing rate of calcium fertilization. Yield of fruit affected by sunscald decreased linearly as supplemental calcium rate increased at the first harvest; overall, yield of sunscald fruit was reduced by application of calcium at either rate.
Impact of natural infection of common corn smut (Ustilago maydis) on processing characteristics of three F1 hybrid sweet corn (Zea mays L.) cultivars was evaluated in a two-year study with early and late spring-planting dates. At harvest maturity, size and location of galls were recorded and quality characteristics measured. Galls on the lower stalk, upper stalk and tassel reduced fresh weight and diameter of husked ears while galls on the base of the plant reduced fresh weight only. Ear length was reduced by galls on the upper stalk. As gall size increased from 0 to >10.2 cm. diameter, ear fresh weight and diameter decreased. The presence of galls >10.2 cm diameter reduced ear length. Kernel depth was not affected by size or location of gall. Additional ears of the same three cultivars were sampled from commercial fields planted in mid-season near Walla Walla and Patterson, Wash. Galls located on the upper and lower stalk reduced fresh weight, length, diameter and kernel depth, while galls on the tassel or base had reduced or no effect on these parameters. As gall size increased, fresh weight, length, diameter, and kernel depth decreased.
The impact of natural infection of Ustilago maydis (causal agent of common smut) on processing characteristics of three F1 hybrid sweet corn (Zea mays L.) cultivars was evaluated in a 2-year study with early and late spring planting dates. At harvest maturity, size and location of galls were recorded and quality characteristics measured. Galls on the lower stalk, upper stalk, and tassel reduced fresh weight and diameter of husked ears, whereas galls on the base of the stalk reduced fresh weight only. Ear length was reduced by galls on the upper stalk. As gall size increased from 0 to greater than 10.2 cm in diameter, ear fresh weight and diameter decreased. The presence of galls greater than 10.2 cm in diameter reduced ear length. Kernel depth was unaffected by size or location of gall. Additional ears of the same three cultivars were sampled from commercial fields planted in midseason near Walla Walla and Patterson, WA. Galls located on the upper and lower stalk reduced fresh weight, length, and diameter, whereas galls on the base of the stalk reduced fresh weight only. As gall size increased, fresh weight, length, diameter, and kernel depth decreased.