Drum priming enhances seed performance without the waste and additional materials associated with conventional osmotic or matric priming techniques. Sweet corn (Zea mays L.) se (`White D' Lite') and sh2 (`WSS-4948') endosperm seeds were hydrated using drum priming at 25 °C for 6 hours. During each cycle, 125-g seed samples were exposed to 1.6, 3.2, 4.8, or 6.0 mL of distilled water and then rotated in a drum for 1 hour to ensure uniform uptake. At the end of this period, samples of 100 seeds (each) were removed and moisture content was determined. Drum priming hydrated all seedlots gradually, with increasing time required at reduced water levels for individual seedlots to achieve the desired moisture content (25% to 30%). Drum priming may provide a better alternative to conventional systems of priming.
Jabe E. Warren and Mark A. Bennett
Samuel Contreras, David Tay and Mark A. Bennett
Among the factors affecting germinability of a seed lot are the environmental conditions under which the seeds are produced. The objective of this study was to determine the effects of temperature during seed development on seed quality of two Asteraceae species. Seeds of lettuce cv. Tango and Helianthus debilis cv. Vanilla Ice and sp. cucumerifolius were produced in a greenhouse under one of two treatments: i) hot (27, 40, and 20 °C temperatures average, max, and min, respectively), and ii) cool (23, 33, and 18 °C temperatures average, max, and min, respectively). In both species, heavier seeds were produced under the cool conditions and no differences were observed in standard germination. In lettuce, germination percentage and rate were both affected by increased levels of exogenous ABA concentrations and reduced water potential (PEG solutions), and, in both cases, seeds from cool treatments were more affected. Germination at 30 °C and constant light was higher for seeds from the hot treatment. Lettuce seed showed a strong light requirement for germination. However, seeds from the hot treatment gave better dark germination at 13 and 19 °C. Seeds of H. debilis did not required light for germination, and the germination percentage and rates were evaluated at 13, 21, and 29 °C. For both lines, seeds from each treatment behave similarly; however, the germination of H. debilis cv. Vanilla Ice at 29 °C was higher when seeds were produced in the hot conditions. The results showed that temperature during seed development affected aspects of seed quality that are not detectable by the standard germination, but by germination at suboptimal conditions. Within the Asteraceae family, differences varied among and within species.
William B. Evans and Mark A. Bennett
A significant portion of the Great Lakes region's processing tomato crop is used to make whole fruit and diced products, where fruit color and textural uniformity are important. Soil and fertilizer studies were undertaken to better understand the role of soil fertility and potassium application on the color disorder known as internal white tissue (IWT) under this region's conditions and in area soils. During 2 years of replicated potassium rate trials in Ohio, tomato yield was not significantly altered by broadcast potassium applications. Potassium application rate was inversely correlated with frequency and severity of IWT in each season, and positively correlated with titratable acidity. The ability of split applications to influence IWT severity was not significantly different than that of preplant applications. IWT symptom frequency and severity was correlated with elemental concentrations in the fruit, leaves, and soil. In 1998, severity of IWT symptoms was positively correlated with shoulder tissue calcium and sodium concentrations, and negatively correlated with concentrations of phosphorus, magnesium, and nitrogen. Correlations for other nutrients, including potassium, were less clear. A companion study of six grower fields during the second year, using grid sampling techniques and the IWT-susceptible Peto 696 cultivar, found significant variability of IWT symptoms within and among fields. Variability within fields was correlated with soil nutrient concentrations. These data indicate researchers may be able to develop recommendations for field mapping and precision management strategies that can reduce the levels of IWT for area growers.
Mark A. Bennett and Elaine M. Grassbaugh
Processing tomato (Lycopersicon esculentum Mill.) producers in the Great Lakes region have expressed interest in cutting crop establishment costs and improving profitability by reducing plant populations. This study compared plant development, fruit set, fruit size and yields using a range of single and twin-row plant populations (14,800 to 44,500 plants/ha) and four commercially important processing tomato cultivars (`OH8245', `H9036', `PS696', and `H7135') with differing vine types and maturities. The 3-year study was conducted at Fremont, Ohio, on a Colwood fine sandy loam, using raised beds and other standard cultural practices. Six- to seven-week-old transplants (288 cell size) were mechanically planted in middle to late May. Once-over harvest was timed to achieve 80%–90% red fruit, using a Johnson tomato harvester. Plant population had a significant effect on 1995 fruit yields for all cultivars tested. Optimum red fruit yields were observed at 37,100 plants/ha in twin-rows for `OH8245', which was similar to 1994 results. Optimum fruit yields for `PS696' were obtained at twin-row populations of 29,600-44,500 plants/ha in 1995. Three year results for `OH8245' (medium-sized vine) indicate no significant differences due to plant population or arrangement. Mean red fruit yields varied considerably by year in this field research (62.7, 95.2, and 44.8 MT/ha in 1993, 1994, 1995 respectively), but twin-row spacing of `OH8245' provided significant yield gains in 2 of 3 years for populations of 29,600 plants/ha or greater.
Samuel Contreras, Mark A. Bennett and David Tay
Lettuce (Lactuca sativa) is an important vegetable crop worldwide, and its seed is commercially produced mainly under irrigation in arid and semiarid regions. The objective of this study was to determine how water availability during seed development affects lettuce seed productivity and quality. Three experiments were performed in the greenhouse and growth chambers using lettuce (cv. Tango) cultivated in pots. When watering volume was restricted (dry treatment) from bolting to seed harvest to 54% of the well-watered control (wet treatment), plants were shorter, had reduced dry weight, and produced fewer and heavier seeds. Water productivity (seed yield/watering volume) was nearly 50% higher in the dry treatment. Seeds from the dry treatment had a modest improvement in seed vigor (assessed by seedling growth) and decreased germinability (higher sensitivity to exogenous abscisic acid and water potential) compared with the wet treatment. In another experiment, water stress was applied abruptly to well-hydrated lettuce plants with developing seeds. Seeds that were at one-third and two-thirds of physiological maturity when water was withheld had lower germinability and greater storability than seeds with no water restriction. These results provide information that may be used for improvement of irrigation practices for lettuce seed production.
Nancy G. Creamer and Mark. A. Bennett
A mixture of rye, hairy vetch, barley, and crimson clover was seeded on raised beds at two locations in Ohio in August, 1992. The following May, the mixture was killed with an undercutter and left on the surface as a mulch. Processing tomatoes (OH 8245) were planted into the killed cover crop mulch immediately following undercutting. Four systems of production were evaluated including: conventional (without cover crop mulch), integrated (with reduced chemical input), organic, and no additional input. At the Columbus site, above ground biomass (AGB) was 9,465 kg ha-1 with 207 kg ha-1 N in to AGB. In Fremont, the AGB was 14,087 kg ha-1 with 382 kg ha-1 N in the AGB. Annual weeds were suppressed by the killed cover crop mulch, and no additional weed control for the annual weeds was necessary. Weed suppression by the mulch was equivalent to weed suppression by the herbicides used in the conventional system. Other data that will be reported include soil moistures and temperatures; impact on insects end diseases; and, tomato growth, development, and yield.
Elaine M. Grassbaugh, Mark A. Bennett, Thom Harker and Mark Schmittgen
The specialty vegetable market is a rapidly expanding niche in the produce industry. One popular sector of this market is focused on heirloom tomatoes. Heirloom varieties, mostly open-pollinated, are often favored for their taste and unique shapes and colors. Older, traditional varieties have been maintained mostly by home gardeners, seed saver organizations, and government germplasm centers, but are becoming increasingly popular with commercial growers, consumers, and seed companies. Special growing techniques and attention to postharvest handling is also necessary with heirloom tomatoes because most do not have an extended shelf life. For growers willing to develop special harvesting and handling techniques, specialty tomatoes offer colors, shapes, and flavors that are an important part of today's cuisine. Performance of a given cultivar will vary from year to year depending on several factors: planting date, irrigation, disease pressure, staking practices, and climatic conditions during the growing season. Fourteen heirloom tomato cultivars have been researched at Ohio State Univ. (OSU) since 1995. Data collected on yield, fruit characteristics, market outlets, cultural information, special harvesting and handling requirements, and disease pressure for heirloom cultivars will be presented.
Elaine M. Grassbaugh, Mark A. Bennett, Mark Schmittgen and Brad Bergefurd
Specialty vegetables are defined as crops that are different in color, size, shape or nutrient content for that particular crop, those not normally grown in a specific area, or crops grown out of season. Knowing the clientele and what they demand is the first step in successfully marketing these less common crops. Due to market demand, “uncommon” crops are more frequently requested by produce buyers and the public. What is in demand one year may not be marketable the next. Our attempts to produce >25 specialty crops under Ohio growing conditions over the past 3 years resulted in successes and failures. Regardless of the outcome, our findings were important to vegetable growers who are interested in producing these crops. Crops tested from 1994 to 1996 included globe artichokes, luffa gourds, chili peppers, habanero peppers, okra, tomatillos, baby corn, and several specialty tomato varieties. Crops produced successfully in Ohio were marketed through several farm markets, food terminals, and produce brokers. A summary of cultural practices, production tips, and marketing opportunities on these less common vegetable crops based on our research in Ohio will be presented.
Mark A. Bennett, Nancy W. Callan and Vincent A. Fritz
Disease management is an important step in any crop establishment system. Emergence of field-seeded crops may take several weeks for many species and represents a vulnerable stage of plant growth. This paper considers various biological, chemical, and physical seed treatments for improved seed performance. The role of seed quality and cultural practices in seedling establishment also is reviewed. Multidisciplinary approaches to improving horticultural crop establishment are promising.