signaling. PGRs can be thought of as components of large signaling networks that communicate information from one part of a plant to another. By way of four examples including the communication of 1) root anaerobiosis—epinasty, 2) soil moisture status
Anish Malladi and Jacqueline K. Burns
Joan R. Davenport, Robert G. Stevens and Kelly M. Whitley
both sides of the row around each emitter selected and then averaged to best reflect drip water distribution in the soil. The data strongly suggest that spring soil moisture status reflects winter precipitation patterns rather than the end
Michael T. Deaton and David W. Williams
football season in Kentucky using the BTS three times per week, once each Monday, Wednesday, and Friday with no regard to soil moisture status or weather for the periods 10 Sept. to 29 Oct. 2007 and 12 Sept. to 14 Nov. 2008. Traffic treatments consisted of
Ben Faber, James Downer and Lori Yates
Soil moisture status can be measured using neutron probes, time domain reflectometry, tensiometers, gravimetric methods, and electrical resistance blocks. Most methods have limitations; they may be time-consuming (gravimetric), expensive (neutron probe, time domain), or fixed in place (tensiometer, gypsum block, and neutron probe) (Schmugge, 1980; Weems, 1991). Water management in droughty, urban areas of the country would benefit from identification of a portable, fast, and relatively inexpensive soil moisture measuring device suitable for use in urban lawns and gardens. In this study, we have identified an instrument that may be suitable for this purpose.
Marvin P. Pritts
Manipulating light, temperature, moisture, and nutrients to favor plant growth and productivity is an important component of horticulture. The technology required to achieve such manipulation ranges from inexpensive, basic practices to elaborate, costly approaches involving the latest engineering advances. For example, pruning and mulching are relatively low-tech methods for improving light interception and soil moisture status in small fruit plantings. At the opposite extreme are glass houses with supplemental lighting, CO2 enrichment, and nutrient film hydroponic systems Of greatest value to small fruit growers, however, is technology that ran be applied in field situations, such as the use of overhead irrigation for maintaining soil moisture status, frost protection, and evaporative cooling. One of the greatest challenges to small fruit growers and rcsearchers is integrating new technology into production systems. The introduction of a new technique for environmental modification usually has indirect effects on other aspects of management, which may require additional technology to compensate for adverse changes while maintaining the favorable change. In addition, unique macro- and microclimates demand and market opportunities, specific solutions, and the result is a dynamic, diverse collage of production systems used by growers throughout the world.
Grady L. Miller
The effects of several soil amendments, following a single filling of core aerification holes, on growth and transpiration of `Tifdwarf' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] were examined during drought stress. Soil amendments had variable effects on turf quality. In general, turf grown in ZeoPro®- and Profile®-amended sand had the highest quality. Data indicated that the evaluated soil amendments have the potential to influence soil water content, ultimately influencing transpirational response to drought stress. Amended sand contained 1% to 16% more transpirable water compared with non-amended sand. Turfgrass grown in Axis®- and Isolite®-amended sand required 0.4 to 1.4 days longer to reach the endpoint (transpiration rate of drought stressed plants <12% of well-watered plants) during a period of rapid water depletion. Data from this study suggest that the total volume these amendments occupied in the root zone, following a single filling of core aerification holes in sand, may positively influence soil moisture status, resulting in an increase in drought avoidance.
David C. Percival, J.T.A. Proctor and J.A. Sullivan
Field experiments including supplementary trickle irrigation (IR), IRT-76 plastic film (PF), and straw mulch (STR) treatments were conducted during 1993 and 1994 to determine the influence of root-zone temperature and soil moisture status on carbon assimilation and dry mass distribution, and soil and plant nutrient content, during the establishment of Rubus idaeus L. `Heritage' primocane-fruiting raspberries. The IR, PF, and STR treatments were reapplied after the 1993 establishment year to examine their effects on an established, hedgerow planting. Physical environment, vegetative and reproductive data were collected. PF increased root and shoot mass, total flower number, and total berries harvested. Maximum leaf net photosynthetic (Pn) rates were observed under cool air temperatures and root-zone temperature of 25 °C. Field Pn measurements indicated that there was no seasonal decline in Pn. Mulch treatments however, were not beneficial to the established (i.e., 2-year-old) hedgerow planting. The root system of the 2-year-old planting was largely confined to an area within the foliage wall and also at a greater depth from the mulch treatments. Therefore, beneficial effects of mulch management on the growth and development of raspberries may be limited to the establishment year.
Margaretha Blom-Zandstra and Klaas Metselaar
Strict legislation on the release of water and nutrients into the subsoil exists in the Netherlands. Therefore, on-line monitoring and control systems are being developed to tune the supply of water and nutrients to the plants' demand for optimal control of production and reduction of system losses. In this context sensors and control systems are important tools. For Chrysanthemum, however, the effect of reduced irrigation on crop production is not well understood and more data from adequate sensors are required to establish critical soil moisture levels for an optimal crop water status and growth. We studied the effect of different soil water levels and soil desiccation in a climate chamber and under changing light intensities in a greenhouse to assess the critical soil moisture status for optimal growth of Chrysanthemum plants. Moreover, we studied the efficacy of infrared (IR) thermometry as a useful tool for on-line monitoring and control under the conditions of Dutch greenhouse horticulture. It is shown in this study that under moderate climate conditions plants start to suffer from water shortage when soil moisture potential pF reaches values below –32 kPa. Water status of the plant can very well be monitored on-line in a greenhouse as changes in leaf temperature due to water shortage can be detected by IR thermometry, especially at summer radiation levels. In the climate chamber however, leaf temperature did not respond to changes in soil water status, suggesting that the environmental settings of the climate chamber are unsuitable for these kind of experiments. In two of the three experiments at different levels of global radiation a change in leaf temperature is explained by a change in water regime. We conclude that regression analysis of high frequency on-line IR monitoring may be a useful tool for expost analyses of irrigation regimes at high light intensities, and may lead to interesting insights in crop responses.
varieties in response to daily, 5-, 10-, and 15-day irrigation intervals by monitoring turfgrass quality, root weight, evapotranspiration, and soil moisture status. Variability was observed among the bermudagrass varieties tested. Results also indicate that
David W. Williams, Paul B. Burrus and Kenneth L. Cropper
fields. The severity of damage depends on factors such as the number of events per season, the size of the athletes, and the soil moisture status during use ( Powell, 2007 ). Traffic-stressed turf exhibits discoloration and bare areas that are unsightly