Search Results

Windbreaks reduce wind speed and modify the microclimate in sheltered areas. Many producers use wind barriers in their production systems, but few producers recognize all of the benefits available or understand the principles involved in windbreak function and design. Wind has direct and indirect effects on plant growth and development. Direct effects include soil abrasion, increased transpiration, and lodging. Indirect effects are based on changes in the crop microclimate, which influence plant growth and yield. Windbreaks increase soil and air temperatures and can extend the growing season in sheltered areas, resulting in increased crop development, earlier crop maturity, and market advantage. Plant-water relations and irrigation efficiency are improved by shelter. Overall, modifications to the microclimate in sheltered areas contribute to 5% to 50% higher crop yields. Winds in excess of about 5 m·s⁻¹ (1.0 m·s⁻¹ = 2.25 miles/h; miles/h × 0.447 = m·s⁻¹) result in wind erosion and soil abrasion and may cause a loss of crop stand. Wind speeds below 5 m·s⁻¹ may have an equally adverse impact on crop quality and marketable yield. In both cases, wind-breaks can reduce damage effectively in sheltered areas. Wind protection reduces certain problems associated with plasticulture under windy conditions.

Experiments were conducted during summer seasons from 1991 to 1994 to find out the effect of winds on early growth of muskmelon. A randomized complete-block design with sheltered and exposed areas as treatments was used. Sensors for air temperature and relative humidity (model HMP35C or model XN217, Campbell Scientific) were placed at canopy height and 3-cup anemometers (model 12102, R.M. Young, Traverse City, Mich.) were 50 cm aboveground. All sensors were connected to CR10 automatic data loggers and recorded hourly average data. Using regression analysis, we found that the accumulative windspeed frequency below threshold (<4 m^–s^–1) can be used to predict both accumulative hourly heat units of air temperature (GDHT) with R2's more than 0.85 and total muskmelon fresh and dry weight and leaf area index at early growth. Predicted models using accumulative hourly windspeed frequency have R2's >0.80 in sheltered areas. Adding vapor pressure deficit to the model improves the prediction of muskmelon early growth, especially in exposed areas.

Field experiments were conducted in 1991, 1992, and 1993 to evaluate the effects of antitranspirant (Folicote, Aquatrol Inc.) and polyacrylamide gel (Supersorb, Aquatrol Inc.) on early growth of muskmelon. A RCBD with split plot arrangement was used with sheltered and exposed areas as the main treatments and seven combinations of antitranspirant spray and gel dip applications as subtreatments. Two greenhouse experiments were also conducted to simulate field research. A RCBD with seven treatments described as subtreatments in the field research was used in the greenhouse studies. Based on destructive harvests in the field, treatments and subtreatments did not affect dry weight or leaf area index. Specific contrasts, how ever, showed that gel application significantly increased dry weight and leaf area index whereas the spray application tended to reduce these factors during the first three weeks after transplanting. Significant differences between dip and spray subtreatments disappeared by five weeks after transplanting. In both greenhouse experiments, gel dip application increased dry weight and leaf area index of muskmelon at all observations from 2 weeks to five weeks after transplanting. We conclude that gel application generally will provide more benefit during early muskmelon growth compared to the use of antitranspirant spray.

Field experiments were conducted over 4 years to evaluate the effects of antitranspirant (Folicote, Aquatrol Inc., Paulsboro, N.J.) and polyacrylamide gel (SuperSorb, Aquatrol Inc., Paulsboro, N.J.) on early growth of transplanted muskmelon grown either protected by tree windbreaks or exposed to seasonal winds. A randomized complete block design (RCBD) with split plot arrangement was used with wind protection (sheltered and exposed) areas as the main treatment and use of an antitranspirant spray or gel dip as subtreatments. Based on destructive harvests in the field, treatments and subtreatments did not affect dry weight or leaf area index in the first 2 years. Specific contrasts, however, showed that gel application significantly increased fresh weight, dry weight, and leaf area index over that of the untreated transplants whereas the spray application tended to reduce these factors during the first 3 weeks after transplanting. Significant differences between gel and spray subtreatments disappeared by 5 weeks after transplanting. Shelterbelts ameliorated crop microclimate thereby enhancing plant growth. Significantly, wind velocity at canopy height was reduced 40% on average and soil temperatures were about 4% warmer in the sheltered plots compared to the exposed plots during the first 5 weeks post-transplant. Muskmelon plants in the sheltered areas grew significantly faster than the plants in the exposed areas in 2 of the 3 years reported, with the 3-year average fresh weight increased by 168% due to wind protection. Overall transplanting success and early growth were enhanced the most by wind protection, followed by the polyacrylamide gel root dip, and least by the antitranspirant foliar spray. We conclude that microclimate modification by wind speed reduction can increase early muskmelon plant growth more consistently than the use of polyacrylamide gel as a root dip at transplanting or the use of an antitranspirant spray. A polyacrylamide gel root dip generally will provide more benefit during early muskmelon growth than the use of an antitranspirant spray.

Windbreaks can increase crop growth and improve crop quality. The effects of shelter on vegetable production varies with crop, location, and farming practices. While the advantages of minimizing wind stress on vegetable production is well-known, little research documents the specific response of vegetables to microclimate modification through the use of shelterbelts.

During the summer, 1991, a preliminary experiment was conducted on the effects of tree windbreaks (shelterbelts) on muskmelon plant growth, yield, and fruit quality. A split-plot design was used with shelter and exposed areas as main treatments with 3 replications. Subtreatments were 7 combinations of anti-transpirant and time of application. Leaf growth was measured 4 and 6 weeks after planting. Muskmelon fruit were harvested over a 6 week period at 2 day intervals. Muskmelon yield, fruit and cavity diameter, fruit color, and total sugar content were obtained.

The use of anti-transpirant did not significantly affect total yield, fruit or cavity diameter, total sugar content, or early leaf growth. The effect of shelter varied with the measured variable.

Producers in the central United States are showing considerable interest in growing alternative crops such as specialty forest products for food, herbal medicinal, decorative floral and craft markets. Crops showing particular promise are shrubs and trees that produce decorative woody stems such as curly willow (Salix matsudana), scarlet curls willow (S. matsudana `Scarlet Curls'), french `Scarlet Curls'), french pussy willow (S. caprea), red twig dogwood (Cornus sericea), and branches of flowering trees and shrubs, including apple (Malus spp.), cherry (spp.), cherry (Prunus spp.), and forsythia (Forsythia spp.). spp.). The objectives of this study were to 1) determine yields and performance of 10 woody plant cultivars used in the floral industry, and planted in an alley-cropping configuration, and 2) quantify wholesale prices, establishment and maintenance costs, management and harvest labor inputs, and financial returns by cultivar. Production and performance data are derived from a 40-acre (16.2-ha) alleycropping trial in Nebraska containing 10 species or cultivars of shrubs that produce woody florals. Results are based on two harvests that commenced two and three growing seasons after establishment. Harvested woody stem size and quality were measured and determined, and sold to wholesale florists to determine prices and identify buyer requirements. Annual gross financial returns ranged from a high of $24.94/plant for scarlet curls willow to a low of $0.63/plant for bloodtwig dogwood (C. sanguinea var. atrosanguinea), while net returns per plant for these species ranged from a positive $17.46 to a loss of $1.30. Financial returns varied among species and cultivars due to the combined effects of annual marketable stem production, harvesting and processing labor requirements, and price/stem. Stem production increased over time due to subsequent coppicing of harvested plants. Overall findings indicate that commercial production of selected cultivars of woody florals in an alleycropping arrangement can be a profitable alternative to using conventional woody species.

The effects of wind protection on growth and total and marketable yields of snap bean (Phaseolus vulgaris L.) planted at 2-week intervals through the 1994 and 1995 growing seasons were examined. Research was conducted under nonirrigated conditions at the Shelterbelt Research Area, Univ. of Nebraska Agricultural Research and Development Center (ARDC) near Mead. `Strike' (white-seeded) and `Rushmore' (dark-seeded) were planted in locations sheltered from wind stress by tree windbreaks (shelterbelts) and in locations exposed to normal winds using a randomized complete-block design with a split-split plot arrangement of treatments. Air temperature, soil temperature, humidity, wind speed, and wind direction were monitored. Detailed microclimate conditions at bean canopy level in sheltered and exposed plots are provided in the text. Wind speed in sheltered areas averaged 36% of open field wind speed in 1994 and 43% of open wind speed in 1995. Soil temperatures were higher in sheltered areas than in exposed areas. Microclimate changes due to shelter had no effect on the percent seedling emergence or number of days to emergence. Plants in shelter had significantly higher total dry weight and leaf area index and greater total internode length than exposed plants. Both total and marketable yields were increased significantly by production under sheltered conditions each year. Planting date and cultivar also had a significant impact on average pod yields. No interactions between shelter and planting date, or shelter and cultivar, were found in either year. The results suggest that wind protection provided by shelterbelts (tree windbreaks) can increase pod yields of snap bean both early and late in the season. This may result in greater profit for the grower due to a tendency for higher prices at these times.

The effects of windbreak shelter on growth, total, and marketable yield of snapbeans were evaluated during 1994 and 1995. Plantings of `Strike' and `Rushmore' were made at roughly 2-week intervals in exposed plots and plots protected by tree windbreaks. Air and soil temperature, relative humidity, wind speed and direction were monitored continuously and averaged hourly. Wind speed in shelter was 36% and 43% that of open field wind speed in 1994 and 1995 respectively. Air and soil temperatures were higher in sheltered areas. Sheltered plants had significantly higher total dry weight and leaf area index, and significantly greater total internode lengths than exposed plants. For each year, sheltered plant means for both total and marketable seasonal yields were significantly higher compared to exposed plants. Mean pod yields were significantly affected by planting date and cultivar. `Rushmore' produced significantly higher total and marketable yields than `Strike'. The two cultivars responded similarly to sheltered and exposed production environments. Shelterbelts can increase total and marketable yields, with greatest increases early and late in the growing season, an additional advantage since market prices tend to be higher at these times.

The relationships between shelterbelt (tree windbreak)-induced microclimate and muskmelon (Cucumis melo L.) growth and development were investigated at the Univ. of Nebraska-Lincoln Agricultural Research and Development Center near Mead, Nebr., during the 1992 and 1993 growing seasons. Wind speed, wind direction, air and soil temperatures, relative humidity, and soil moisture were monitored in both sheltered and nonsheltered areas. Plant growth parameters (plant height, vine length, plant dry weight, and leaf area) were measured at various stages of development. Shelterbelts provided improved growing conditions for muskmelon transplants. Direct wind damage and duration of higher wind speeds were reduced 47% to 56% in sheltered areas. Air temperatures in sheltered areas were slightly higher during daytime and slightly lower at night, and significantly so early in the growing season. Relative humidity was increased significantly in sheltered areas in 1992 and, while higher in 1993, the difference was nonsignificant. Soil moisture content was not affected significantly by wind protection. Sheltered plants exhibited earlier development and faster growth. The first female flower appeared 2 days earlier in sheltered areas in both years. The first fruit set, as indicated by fruit swelling and retention on the vine, occurred 6 days earlier and matured 5 and 6 days earlier in sheltered areas in 1992 and 1993, respectively. Leaf areas and dry-matter accumulation of sheltered plants were greater than those of exposed plants. The shoot relative growth rate of sheltered plants increased earlier in the growing season, but decreased slightly later in the growing season. The earlier development and faster growth of sheltered plants were related mainly to the reduction of wind speed, higher total accumulated air temperatures during the daylight hours (sum of daily average daytime air temperatures based on hourly averages), and higher soil temperature in sheltered areas. Total yields were not affected significantly in either year; however, early yields were significantly greater in sheltered areas in 1993. If earlier maturity and increased yield are possible in large sheltered fields, this practice would provide an economic benefit to producers.

Nontimber forest products (food, herbal medicinals, and woody floral and handicraft products) produced in forest, agroforestry, and horticultural systems can be important sources of income to landowners. White-tailed deer (Odocoileus virginianus) can reduce the quality, quantity, and profitability of forest products by browsing twigs and rubbing stems, resulting in direct and indirect losses to production enterprises. We evaluated deer damage (frequency and intensity of browsing and rubbing) sustained by 26 species of trees and shrubs, the relationships among morphological features of trees and shrubs to damage levels, and the economic impacts of deer damage on the production of nontimber forest products. Levels of browsing were high (frequency >93% and intensity >50%) in most species of trees and shrubs, with the highest intensity (>60%) occurring in chinese chestnut (Castanea mollisima) and dogwood (Cornus spp.), and the lowest (<20%) in ginkgo (Ginkgo biloba), curly willow (Salix matsudana), ‘Scarlet Curls’ curly willow, smooth sumac (Rhus glabra), and pussy willow (Salix caprea). Species of trees or shrubs with one or a few stout stems unprotected by dense branching [e.g., american elderberry (Sambucus canadensis), smooth sumac, and curly willow] sustained the most damage by rubbing. Trees and shrubs with many small diameter stems or with dense tangled branching [e.g. redozier dogwood (Cornus sericea), forsythia (Forsythia suspensa), ‘Flame’ willow (Salix alba), and ‘Streamco’ basket willow (Salix purpurea)] were damaged the least by rubbing. Annual economic costs of deer damage to producers of nontimber forest products can range from $26/acre for pussy willow to $1595/acre for curly willow.