Search Results

You are looking at 1 - 10 of 12 items for :

  • Author or Editor: J. A. Taylor x
  • HortScience x
Clear All Modify Search
Authors: and

Abstract

Imbibed nonviable lettuce (Lactuca sativa L.) seeds have been shown to have lower density than imbibed control seeds. The purpose of this study was to investigate density differences associated with seed death. The relationship between endosperm integrity and the volume, density, and leakage of imbibed control and heat-killed ‘Montello’ lettuce seeds was studied. After an 8-hr soak, heat-killed seeds imbibed 23% more water than control seeds. The percentage of heat-killed seeds with density of 1.08 g·cm-3 was 2%, compared to 90% for the control. Mean electrical conductivity of the steep water was similar for heat-killed and control seeds. Seeds were punctured to rupture the endosperm layer surrounding the embryo. Puncturing the heat-killed seeds decreased total water uptake, as measured by decreased swelling, and increased density compared to intact heat-killed seeds. Leachate from punctured heat-killed seed had a 41% higher mean conductivity than that from punctured control seed. These data suggest that the undamaged endosperm restricted leakage of electrolytes from the embryo to the soak water. We speculate that the endosperm caused osmotically active solutes to accumulate in the extra-embryonic fluid of heat-killed seeds. This accumulation of solutes decreases the water potential inside the embryonic pouch, resulting in a greater uptake of water from the environment. The additional water uptake by heat-killed seeds would increase seed swelling and decrease seed density relative to control seeds.

Open Access

Abstract

Greenhouse-grown root, foliage, fruit, and seed crops were exposed to peroxyacetyl nitrate (PAN) at 0, 5, 10, 20, and 40 ppb, 4 hours per day, twice per week, from germination to maturity of harvestable product. A response of PAN dose and growth or yield parameters was significant only for lettuce (Lactuca sativa L. cv. Empire) and Swiss chard (Beta vulgaris L. var. cicla, cv. Fordhook). Leaf fresh weight was reduced by 13% in ‘Empire’ lettuce and by 23% in chard in the 40 ppb PAN treatments relative to 0 ppb PAN controls. Peroxyacetyl nitrate at 10 ppb appeared to stimulate the growth of most crops. The threshold for inhibition of growth by PAN, under conditions of 2 exposures per week, appeared to be between 10 and 20 ppb. These results suggest that PAN, at concentrations below the threshold for visible injury, can alter the growth of plants, but that significant reductions in growth or yield may occur only in highly susceptible cultivars of leafy crops.

Open Access

Abstract

Seed of germinated celery, Apium graveolens L. (Dulce group) and pepper, Capsicum annuum L. were separated from ungerminated seed by density differences in a sucrose and water solution. The top (floating) fraction in both species had the highest percentage germination and percent and rate of emergence compared to either the bottom fraction or unseparated seed.

Open Access

The Ellis-Roberts seed viability equation is used to predict seed survival after storage at specified temperatures and moisture contents. Seed priming, which can break dormancy and accelerate germination, can also reduce seed storage life. Because primed seeds were not used in developing the Ellis-Roberts equation, the reciprocal nature of specific seed moisture content (MC, fresh weight basis) and temperatures that applies to nonprimed lettuce (Lactuca sativa L.) seeds may not apply to primed seeds. To determine how priming affects lettuce seeds in relation to the viability equation, an experiment was conducted using two cultivars, ‘Big Ben’ and ‘Parris Island Cos’. Seeds primed in polyethylene glycol 8000 (–1.45 MPa, 24 h at 15 °C) and nonprimed seeds were first adjusted to 6% and 9% moisture contents and then stored at 48 and 38 °C for up to 30 days, respectively. These storage conditions (6% MC and 48 °C; 9% MC and 38 °C) were predicted by the viability equation to result in equal longevities. Subsequent viability assays at 20 °C revealed that nonprimed seeds in both storage environments exhibited similar losses in viability over time, thus validating the Ellis-Roberts equation and the use of these conditions to apply different but equal aging stress. Primed seeds of both cultivars deteriorated faster than nonprimed seeds as expected. However, primed seeds did exhibit different rates of deterioration between the storage environments. Primed seeds stored at 9% MC and 38 °C deteriorated faster than primed seeds stored at 6% MC and 48 °C. The rate of decline in probit viability percentage was three times greater in primed ‘Big Ben’ seeds stored at 9% MC and 38 °C than for those stored at 6% MC and 48 °C (–1.34 versus –0.26 probits per day, respectively). ‘Parris Island Cos’ seeds stored at 9% MC and 38 °C had twice the rate of deterioration that those stored at 6% MC and 48 °C (–1.19 and –0.49 probits per day, respectively). The results indicate that primed lettuce seeds were more sensitive to the adverse effects of higher seed MC than were nonprimed seeds during storage at elevated temperatures.

Free access

Container-grown plants require large amounts of water and nutrients during their production cycle. This results in substantial runoff that is contaminated with nitrogen and phosphorus. At our study site, nutrients were delivered through incorporation in the potting media as timed-release prills and through liquid feeding by injection into irrigation water. Mitigation of nutrients in runoff water was dealt with proactively by the container nursery with construction of 3.77 ha of planted wetlands to receive runoff from a 48.6-ha drainage basin and excess water diverted from adjacent watersheds. Water flowed though drains between wetland cells and eventually into stilling ponds before it was allowed to exit the property. Water flow through the wetlands ranged from 1.1 to 3.1 million liters per day over the period. Three years of monitoring data indicate some seasonal differences in nitrogen removal efficiencies. Nitrogen removal between March and November averaged ≥95% while removal during winter (December through February) averaged ≥72%. Nitrogen (as nitrate) varied from 4.28 ppm to ≤0.01 ppm in wetland discharge, well below drinking water quality standards, but occasionally above levels that may cause downstream eutrophication. Orthophosphate phosphorus removal was highly variable with greatest removal occurring during late spring, late fall, and winter. There was a significant net export of phosphorus during some summer months for years 2 and 3. Phosphorus levels in wetland discharge ranged between 0.84 and 2.75 ppm. While there is currently no legal water quality standard for phosphorus, these levels were above the generally accepted level for preventing downstream eutrophication.

Free access

Abstract

Cabbage seed (Brassica oleracea L. Capitata group cv. Golden Acre) germinated in aerated water went through a pre- and post-radicle emergence separation by specific gravity to separate germinated from nongerminated seed. The desired specific gravity solutions were made with maltrin 250 and water. The percent germinated seed after separation was 99.3; recovery of germinated seed was 95.1%. A metering system was developed to precision plant the germinated seed. Metering rates of 0.5 and 2.0 seed/second were tested in the laboratory and greenhouse. Laboratory tests resulted in 5.7% doubles and 4.9% skips at 2.0 seed/second. Greenhouse test seedling emergence test resulted in 8% doubles and 15.6% skips at the fast rate. Spacing uniformity was acceptable for all tests.

Open Access

Abstract

Seeds of tomato (Lycopersicon esculentum Mill.) were sown in the greenhouse in a field soil prone to crusting, and at the same time a stable foam was generated and placed over the seed furrow in a 4 x 0.5 cm band. The foam withstood a simulated rain and offered little (0.03 MPa) mechanical resistance to seedling emergence. The percentage of seedling emergence was increased by the foam microenvironment. The foam strip remained over the seed furrow for 3 weeks and was not observed to be phytotoxic to seedling growth.

Open Access

Abstract

There are 2 corrections in the article “Development of a Foam Microenvironment for Enhanced Seedling Establishment“ by A.G. Taylor, T.J. Kenny, E.P. Carney, and G.H. Gibbs (HortScience 18:696–697, Oct. 1983)

Open Access

Abstract

‘Majestic’ peach {Prunus persica (L.) Batsch) was released by the Louisiana Agricultural Experiment Station to provide a large, excellent quality freestone fruit in the ripening sequence between ‘Harvester’ and ‘Red Globe’ or from June 22 to July 1 in north Louisiana (1).

Open Access

Abstract

‘Ruston Red’ peach [Prunus persica (L.) Batsch] was released by the Louisiana Agricultural Experiment Station (LAES) to provide a high quality, large freestone fruit that ripens about 5 days before ‘Elberta’ or about July 20 in north Louisiana. ‘Ruston Red’ has exhibited high resistance to bacterial leaf spot [Xanthomonas Campestris pv. pruni (Smith 1903) Dye 1978] even when grown in orchards next to trees that were severely infested with the bacterium.

Open Access