ABSTRACT Survey data on expected and actual prices received by individual vegetable growers in Florida, Michigan, and Texas in 1990 are used to test the rational expectations hypothesis. The use of individual grower data overcomes many of the aggregation, risk premia and model specification issues that have limited previous tests of this hypothesis in agriculture. Overall, price expectations of vegetable growers are found to be inconsistent with the rational expectations hypothesis for the majority of vegetable/state combinations studied.
ABSTRACT Horseradish has been reported to be frequently sterile and therefore difficult to improve by traditional sexual crosses. In this paper we report a simple method to perform embryo rescues on Murashige and Skoog medium without growth regulators. We then demonstrate the usefulness of the method by making crosses and self-pollinated seeds of several horseradish lines, rescuing the embryos in vitro, and growing the seedlings in soil in a greenhouse. Seedlings obtained in these experiments are being prepared for field plantings. We hope that this simple procedure will speed worldwide efforts to improve horseradish germplasm.
The Precision Cultural System (PCS) developed by the Louisiana Agricultural Experiment Station allows simple and precise cultivation of vegetable crops; however, speed of the cultivators in small vegetable crops has been limited. The standard PCS sweep cultivator was limited to about 1.6–2.4 km·h –1 in small crops because it would throw soil over the crop plants at higher speed. The standard PCS rotary tiller cultivator could operate at 3.2–4.8 km·h –1 in small crops but could not be operated faster in larger crops, due to its tendency to “walk” out of the soil at higher speeds. The standard PCS sweep cultivator was modified by replacing the sweeps between the twin drills with two pairs of straight finger-wheel (“rolling cultivator”) spiders non-angled and in tandem. The finger-wheel gangs on the bed sides were also inactivated by raising them above the soil. The resulting PCS cultivator was successfully operated in very small crop plants (≤25 mm high) at speeds of 8–10 km·h –1 with no crop damage. The cultivator could then be easily refitted for standard sweep cultivation on subsequent passes. No reductions in weed control or yield of mustard, kale, turnip, or spinach were noted when using the high-speed system.
ABSTRACT Commercial lettuce fields in Alaska were surveyed for aphid infestations and species composition. Sixteen species were collected in green tile trap pans. The majority were Lipaphis erysimi (Kaltenbach), Macrosiphum euphorbiae (Thomas), and Pemphigus spp. Pemphigus populitransversus Riley, Subacyrthosiphon, and Cryptobium Hille Ris Lambers were added to Alaska collection records. Macrosiphum euphorbiae complex were the only aphids to colonize lettuce during the 1994 season. Seedlings were infested with aphids within four days of transplanting and more alates landed on 1–3 week old seedlings than on older plants. During the 1–3 week seedling period, more alates were recorded on head lettuce than leaf lettuce. Percent infested plants averaged 9.2 and 19.3 for leaf and head lettuce, respectively, during that period. Green tile trap pans were not effective indicators of aphid activity in lettuce fields under these test conditions.
ABSTRACT Optimum age of onion (Allium cepa L.) transplants for use in current and expanding onion-growing areas in Ghana is not well understood. Field studies were conducted at two locations in Ghana during the 1996–97 and 1997–1998 onion growing seasons. Transplants that were 20, 30, 40, 50, 60 or 70 days old, and of uniform size at each age, were used. The effect of transplant age on bulb yield components of onion was determined. The tallest plants were developed from 40-day-old transplants and the shortest were developed from 70-day-old transplants. Harvest index (bulb weight/total biomass weight) of onion decreased significantly as transplant age increased. The heaviest onion bulbs, 57.2 g, were from plants derived from 40-day-old transplants, and the lightest, 26.1 g, were from plants developed from 70-day-old transplants. Plants developed from 20- to 40-day-old transplants produced the highest yields. The results indicate that using 20- to 40-day-old transplants will give optimal bulb yields.
ABSTRACT A 2-year experiment was conducted to determine the potential for crisphead lettuce production on mineral soils compared to the production on organic soils of Quebec, during the warmest period of the season when quality often decreases. For each soil type, there were three experimental sites and two planting dates. For each soil type by site by planting date combination, three varieties, ‘Ithaca’, ‘Emperor’ and ‘Salinas 88’ were tested within four blocks. Transplanting occurred from 11 to 28 June 1999, and from 11 June to 5 July 2000, and harvest was from 21 July to 5 August 1999, and from 27 July to 10 August 2000. Lettuce on organic soils matured 4 to 7 days earlier and generally produced larger and heavier, firmer and more uniform heads. Soil type did not affect percentage of heads with the physiological disorders rib blight and tipburn. ‘Ithaca’ produced large, heavy and very firm heads, particularly on organic soil. Although this variety showed tolerance to bolting, it was susceptible to rib ...
ABSTRACT Soil type and management practices can affect Allium growth and quality. This study investigated the effects of water-deficit stress and soil type on tissue water content, plant growth and dry-matter production of spring onion (Allium cepa L.) cv. White Lisbon. Seedlings were grown in a glasshouse in pots containing clay (Alluvial Gley) or sandy loam (Brown Earth). Irrigation treatments were watering to near field capacity (−0.01 MPa), or re-watering to near field capacity when the available soil moisture level was depleted to either ≤ 50% (−0.80 MPa) or ≤ 25% (−1.19 MPa). Watering to field capacity significantly (P < 0.05) increased relative water content and water potential of leaf tissue. Periodic water-deficit stress increased leaf number, but reduced leaf length. At −0.01 MPa, plant fresh weight and dry-matter content were increased, especially for plants grown on clay as compared with the −0.80 or −1.19 MPa treatments. Irrigation to near field capacity improved growth and dry-matter product...
ABSTRACT Pod stripper combines have become the predominant method of harvesting green peas for processing in the Mid-Atlantic region. A two-year investigation consisting of seventy-one field tests was conducted to evaluate the effectiveness of these combines for pea harvesting in a wide range of field conditions. Trash content in the harvested product ranged from 4 to 33.7% by weight with an overall average of 15.2%. Total field loss for all tests conducted ranged from 24 to 1408 kg/ha (21 to 1239 lbs/acre) and averaged 555 kg/ha (488 lbs/acre) over the two-year test period. This corresponded to a range of loss from 0.5 to 34% of the pea yield with an average loss of 10.4%. The majority of field losses for the seven varieties and four combine models evaluated was at the head of the combine averaging 70.3% of the total field loss. The variety ‘Quantum’ exhibited significantly higher total field loss than did other varieties tested. There were no significant differences at the 5% level in total loss or head...
ABSTRACT The effect of fruit maturity at harvest from a tomato field plot without detectable silverleaf whiteflies (SLWF) on subsequent internal white tissue (IWT) and external tomato irregular ripening (TIR) was assessed. SLWF damage has been documented as the primary cause of IWT and external TIR, but some symptoms are observed in the absence of detectable whiteflies. Tomato fruit were harvested at either the red-ripe or mature-green stages from four different rows of a field treated with imidacloprid to control SLWF. The mature-green fruit were placed in a ripening room (20°C) for seven days. The fruit harvested at the red-ripe stage had a mean external TIR of 5.0%, and the fruit harvested at the mature-green stage and ripened at 20°C had a mean external TIR of 8.9%. The mean percentage of vine- and ripening-room ripened fruit with IWT was 8.3% and 8.9%, respectively. There were no differences in degree of external or internal symptoms for vine- and ripening-room ripened tomato fruit. The reasons for t...
ABSTRACT Hot peppers (Capsicum frutescens) are among the major vegetable crops grown in Mississippi for fresh and processed markets. While chemicals have been used to suppress purple nutsedge (Cyperus rotundus) and other weeds which cause significant reductions in yield, alternative controls that are safe to human health and the environment are needed. Four synthetic mulching materials (Miracle Mulch®, 6-mil black plastic, Weed Barrier®, and Ground Cover®) and an organic mulching material (pine needle) were evaluated for their efficacy in controlling purple nutsedge in field-grown ‘Long Pod Cayenne’ hot peppers. Pine needle mulch, Miracle Mulch, black plastic and Weed Barrier generally favored Cayenne hot pepper growth more than Ground Cover and the control. In 1992 all mulches controlled nutsedge, compared to the control. Nonmarketable yield was reduced by pine needle mulch, while the remaining treatments had no effect. Marketable and total yield were not affected by any of the treatments. In 1993 all mu...
ABSTRACT Fresh sawdust from particleboard glued with urea formaldehyde was applied as a possible replacement for ammonium nitrate (NH4NO3) fertilization in sweet corn (Zea mays L.) production. The treatments consisted of two combinations of sawdust and NH4NO3 combinations (25% sawdust:75% NH4NO3; 50% sawdust:50% NH4NO3); 100% sawdust; a standard NH4NO3 application (296 kg·ha−1); and a control treatment that consisted of preplant NH4NO3 only. Total N applied for all treatments was 139 kg·ha−1 of N except for the control with 101 kg·ha−1 of N. The elemental composition of the fresh sawdust had a high N composite (32.1 g·kg−1) and alow C: N ratio (15:1), making it favorable for direct use as an organic nitrogen fertilizer. Results indicated that the 25% and 50% sawdust treatments were similar to the standard NH4NO3 treatment in chlorophyll content at V6 and R1 stages, R1 plant height, and marketable yield. When the amount of NH4NO3 was increased, as is the case of the 25% sawdust, all measured responses were...
ABSTRACT Yellow crookneck ‘Dixie’ hybrid summer squash, Cucurbita pepo L. var. melopepo Alef., was evaluated at E. V. Smith Research Center, Shorter, Alabama. Treatments were: (1) black plastic mulch (BPM), (2) yellow painted plastic mulch (YPM), (3) white plastic mulch (WPM), (4) bare soil (BS), (5) aluminum painted plastic mulch (APM) and (6) bare soil with diazinon insecticide (BSI). Summer squash planted in APM, WPM and BPM produced 96%, 98%, 75% and 21%, respectively, more than did that planted on bare soil (control). Aphid traps caught more aphids in BS or BPM plots than from APM plots. A higher percentage of green squash (virus infected) was produced from plants grown over BPM (72%), BSI (68%), BS (59%), YPM (57%) or WPM (57%) than from APM (39%). The onset of mosaic disease incidence of squash infected with zucchini yellows mosaic virus and cucumber mosaic virus was delayed by as much as three weeks on APM when compared to BSI or BS.
Broccoli, Brussels sprouts, cabbage, cauliflower and kale are rich sources of antioxidant phytochemicals and significant amounts of dietary fiber. This study was conducted to estimate the variability of some important antioxidants and minerals between, and within, the crucifer accessions in edible portions of plants. Significant variations for protein, carbohydrate, fiber, β-carotene, ascorbic acid and mineral content were observed between, and within, the crucifers. Total carbohydrate content ranged between 2.54 to 4.03 g/100 g, whereas, protein content ranged from 0.41 to 3.57 g/100 g of fresh weight. Mean fiber content ranged from 0.60 to 3.62 g/100 g. Vitamin C content ranged from 22.16 to 82.14 mg/100 g and β-carotene ranged from 1.56 to 9.09 mg/100 g on fresh weight basis. In general kale, broccoli and Brussels sprouts contained significantly higher amounts of vitamin C and β-carotene as compared to cabbage and cauliflower. The total nitrogen ranged from 1.36 to 4.6% and phosphorous from 0.39 to 0.8...
ABSTRACT A good balance in pre-plant and in-season nitrogen (N) application is important for optimal production of high quality potato (Solanum tuberosum L.) tubers in coarse texture soils, to improve N uptake efficiency, and minimize N losses. Field experiments were conducted in a Quincy fine sand (mixed, mesic Xeric Torripsamments) in the Columbia Basin region in the Pacific Northwest under center pivot irrigation. In the first year (2000), ‘Russet Burbank’ and ‘Umatilla Russet’ cultivars were grown with 112 kg·ha− of N as pre-plant soil application. In-season fertigation was done with 224 kg·ha− of N in either 2, 5, 10, or 20 doses starting three weeks after emergence. In-season N frequency had no significant effects on the tuber yield (60 Mg-ha−) or quality of both the cultivars. The second year (2001) ‘Ranger Russet’ and ‘Umatilla Russet’ cultivars were grown with either 56, 112, or 168 kg·ha− pre-plant N treatment (including the soil residual N content). The total N over the entire growing period wa...
ABSTRACT Field studies were conducted during 1998 and 1999 to determine the effect of different color plastic mulches and row covers on total and marketable yield and US grades of three varieties of potatoes, ‘Kueka Gold’, ‘AF1437-1’ and ‘Dark Red Norland’. Although there was an observed increase in the rate of emergence and growth of the potato plants with row covers, there was no significant effect on yield of any of the varieties. In both years all mulch treatments significantly increased marketable yields compared to no mulch. In 1998, yields of ‘Dark Red Norland’ showed a statistically significant difference between mulch color, with metallized silver and red being higher than black. In 1999, both total and marketable yields of ‘Dark Red Norland’ were significantly higher with the use of metallized silver rather than black mulch. For ‘AF1437-1’ total yield, with the use of metallized silver, was significantly higher than that of red mulch, and for marketable yield only metallized silver was significa...
We set out to document events and relationships among key traits throughout cabbage head formation, particularly in early stages, in order to help develop and implement efficient strategies to increase crop yield and quality. Head traits used as indicators of horticultural maturity and crop quality were documented at five stages of development in 3 commercial fresh market/slaw and processing cabbage cultivars grown in 2001 and 2002 at The Ohio State University, Ohio Agricultural and Development Center in Wooster, Ohio. Seedlings containing 2–4 true leaves were planted in June of both years. Trait measurement began 35 days prior to the estimated market maturity date for each cultivar and continued weekly for five weeks. Harvest timing affected all head traits evaluated. Head weight, diameter, volume, and density and core volume generally increased with harvest date, while the ratio of head polar to equatorial diameter and the percent of head volume occupied by the core decreased. A strong curvilinear relat...
ABSTRACT The extent of onion (Allium cepa L.) bulb and seed production varies with different production management practices. Field experiments were conducted during the 2000–2001 and 2001–2002 growing seasons to evaluate bolting and yield in onion grown with blue, red or white mulch in comparison to those grown with manual cultivation or chemical weed control treatment without mulch. The role of low temperature at the post-juvenile growth stage in bolting induction was also examined. Bolting was sometimes higher under mulch as compared to plots receiving manual hoeing or herbicide treatments. No particular mulch color appeared to consistently favor bolting. There was an inverse relationship between bolting and yield. Treatments did not affect germination of harvested seeds. Onion plants which were exposed to low temperature after attaining the critical growth stage for vernalization produced more inflorescences.
ABSTRACT The genetic analysis of crop yield potential includes three main components that are controlled by groups of genes: (i) genes that control yield/plant, which are selected by the entry mean of individual plant yields; (ii) genes that confer tolerance to the biotic and abiotic stresses, which are defined by the CV of individual plant yields; and (iii) genes that control responsiveness to inputs, which are defined by the progeny standardized selection differential (SSD). This paper evaluates the efficiency of a breeding program applied to improve the stability, the yield and the product uniformity of a snap bean cultivar following these three components. The selection was based on the following criteria: (i) comparisons on the basis of whole-genome phenotypic evaluation should expand among progeny lines and among individual plants within lines; (ii) selection should be applied across the target area of adaptation from the earliest generations and during all stages of the breeding program; (iii) honeycomb designs should be used to sample effectively for environmental diversity and exploit the genotype-by-environment inter-action for the development of “homeostatic cultivars.” The changes in the three components through the honeycomb pedigree selection showed: (i) the entry mean of earliness increased by 54.1–79.8%, while the entry mean of yield followed stabilizing trends, which means improvement in early harvest; (ii) the CV of earliness and yield decreased by 49.2–65.9% and 27.5–35%, respectively, which means improvement in performance stability; and (iii) the SSD of earliness and yield followed different trends in the different offsprings, i.e., the responsiveness to inputs was family dependent. The breeding program provides the possibility of incorporating desirable genes in improved cultivars of green bean.
ABSTRACT Aerial dispersal of inoculum is considered to be an important factor in the epidemiology of many plant diseases. Discarding of untreated onion (Allium cepa L.) bulbs infected with the pathogen Botrytis allii Munn (Syn. B. aclada Fres) can increase the inoculum pressure and infect healthy plants in neighboring fields. A technique to suppress fungal development is needed. Doses of gamma radiation from 1 to 5 kGy were tested on the survival these conidia and mycelial development under laboratory conditions. Conidia were placed on water agar after exposure in closed Petri dishes for 24 h. Results showed that germinability of conidia exposed to gamma irradiation was reduced up to 99% at 5kGy, whereas, germinability of conidia that were not exposed did not decrease significantly. Mycelia exposed to gamma radiation had significantly decreased growth of up to 98% at 4 kGy. Gamma irradiation might be exploited in the treatment of infested onion residues to decrease the inoculum load in the environment.
ABSTRACT Rock phosphate (RP) is being considered as a phosphorus (P) source for reversing soil fertility depletion in Sub-Saharan Africa. We conducted research to evaluate organic or inorganic materials to be combined with RP to enhance P availability. Field trials were conducted at the Institute of Agricultural Research and Training, Moor Plantation, Ibadan in 2001 and 2002 to evaluate the comparative effects of urea (U) and poultry manure (PM) on solubilization of rock phosphate and on the growth and yield of okra (Abelmoschus esculentus (L.) Moench). Okra growth and yield were significantly enhanced by the addition of the treatments. The combined use of RP with either PM and to a lesser degree U, significantly improved the growth and yield of okra compared to when the materials were used individually. Application of RP + U and RP + PM increased available soil P of between 112 and 115% and 144 and 153%, respectively, in both years.
