Search Results
Abstract
Nine conifer species, including 3 selections of Scotch pine, were exposed to SO2 dosages of 1310 µg/m3 (0.5 ppm) for 5 hours, 2620 µg/m3 (1.0 ppm) for 4 hours, or 5240 µg/m3 (2.0 ppm) for 2 hours. Seedlings in the cotyledon and primary needle stages were utilized throughout the study. Significant injury occurred only at the highest concentration. Pine species (Pinus spp) were more susceptible to SO2 than were spruce (Picea spp.), fir (Abies spp.) or Douglas-fir (Pseudotsuga sp.). The 3 Scotch pine selections and ponderosa pine were more susceptible than Austrian pine species. Balsam fir, Douglas-fir, Fraser fir, white fir, blue spruce, and white spruce were not injured.
Two studies were conducted to evaluate recycled newspaper mulch for landscape plantings. In the first study, two paper products (pellets and crumble) were tested at three depths. Application of either 25 or 50 mm provided excellent control of prostrate spurge. Of the four annuals grown, ageratum exhibited severe stunting of roots and shoots. In the second study, three annual species were mulched with the two recycled paper products applied at 25 mm each and adjusted with P at 0, 3.75, or 7.5 ppm to bind excess Al. When no P was added, ageratum growth was about half that of the control plants. Addition of P at either rate resulted in similar growth compared to control plants. Marigold and geranium were less affected by recycled paper mulch; however, when P was added growth was always similar to nonmulched control plants.
Excessive moisture is a problem in evaluating recycled paper products as mulch to replace other common mulch materials and in landscape and container uses. To isolate the water associated with soil and/or media, two recycled paper products, pellets or crumble, were used as mulches in trade gallon containers in a greenhouse. Pine bark, pellets, and crumble needed to obtain standard mulch depth were enclosed in plastic mesh. These mulches were placed in containers that contained 1 kg of a 7 pine bark : 1 sand media. All containers were saturated with tap water for 24 hours. Mulches were placed on each container and allowed to drain for 1 hour. Weights of media, mulch, and media and mulch were obtained every 24 hours for a total of 312 hours. Water content of the media was not influenced by any of the mulch treatments. Water content of the paper products was increased by a factor of two. Pine bark mulch water content was zero 96 hours after an initial dry down cycle began, while the water content of pellet and crumble were 100 and 90 cm of water. Total water content of the media plus the mulch was increased by 30% to 35% when compared to pine bark mulch alone. However, the increase was associated with the water content of the waste paper mulch.
Abstract
The objective of our research is to understand the genetic basis of embryogenesis. Somatic embryogenesis from carrot culture was chosen as the experimental system because of its simplicity and the ease with which it lends itself to obtaining a large number of embryos for genetic and biochemical experiments. Our general philosophy is to avoid media manipulation and to focus on gene expression during embryogenesis. One approach is to isolate genes preferentially expressed at specific stages of embryogenesis, and then to study the role of these genes in development.
Abstract
Thermal blast peeling yielded products of comparable quality to freeze–heat-peeled tomatoes (Lycopersicon esculentum Mill.). Both methods resulted in higher peeled yields and firmer fruit than did caustic, steam-peeling, or peeling by scalding. Thermal blast peeling may thus be a practical alternative to traditional methods.
Abstract
Roots of sweet potato [Ipomoea batatas (L.) Lam.] and beet (Beta vulgaris L.) peeled with superheated steam, had higher peel and trim yields than did those peeled with saturated steam at the same pressure. Product recovery was greater with all steam-peeling methods than with caustic peeling. Direct injection of cold water into the partially pressurized steam atmosphere of the peeler also increased product recovery. Better color retention in processed beets was obtained from steam-peeled roots than from caustic-peeled roots.
Diploid plums (Prunus L. sp.) and their progenitor species were characterized for randomly amplified polymorphic DNA polymorphisms. Bootstrap analysis indicated the variance of genetic similarities differed little when the sample size was >80 markers. Two species from China (Prunus salicina Lindl. and P. simonii Carr.) and one species from Europe (P. cerasifera Ehrh.) contributed the bulk (72% to 90%) of the genetic background to the cultivated diploid plum. The southeastern plum gene pool was more diverse than those from California, Florida, or South Africa because of the greater contribution of P. cerasifera and P. angustifolia Marsh. to its genetic background.
Abstract
Seven fertilizer treatments and a pruning treatment were evaluated for their effect on reducing symptom expression of B toxicity on spring growth of Rhododendron catawbiense Michx. ‘Lees Dark Purple’. Pruning of tissue showing B toxicity was the best treatment based on the first growth flush; treatment with CuS04 + limewater was the best treatment based on the second growth flush.
Abstract
In a collaborative study at 5 North American locations, treatment with 12% CO2 and 3 to 5% O2 for 2 weeks at 0° to 3°C at the beginning of controlled atmosphere (CA) storage significantly delayed softening of ‘McIntosh’ apples (Malus domestica Borkh.). Softening was retarded further when treatment time and CO2 concentration were increased, and when fruit was harvested less mature. The effect was diminished by treatment at 0°, and was nullified by delayed treatment and slow cooling during treatment. Softening response to CO2 was not influenced by O2 concentration or storage humidification during treatment. CO2 treatment reduced the rates of CO2 and ethylene evolution from the fruit, even after 4 to 5 months of subsequent CA storage, but affected neither soluble solids nor titratable acidity of fruit after storage. When taste panelists could distinguish CO2-treated from nontreated CA apples, they preferred the treated fruit.
These beneficial results were usually accompanied by external CO2 injury, and occasionally by internal CO2 injury; 30 to 50% of the fruit were injured in some tests. Treatment in a non-humidified room reduced CO2 injury without also reducing treatment benefits. We conclude that for ‘McIntosh’, the potential for injury outweighs the benefits obtained from CO2 pre-treatment in CA storage.