No description available.

No description available.

Hard red duplex soils (HRDS) cannot sustain economically productive vineyards without careful management. An experiment was conducted at Rosbercon Vineyard, Picola from 1995 to 1998 in a vineyard block of Chardonnay on Ramsey rootstock planted in 1972. The hypotheses tested were: a) transient waterlogging decreases root growth and grapevine performance, and b) hardening of soil decreases root growth and grapevine performance. (For complete summary open document)

No description available.

Mature trees help to offset urban area problems caused by impervious pavement. Trees in paved areas remain unhealthy due to a poor root zone environment. The objective of this experiment was to test if soil under pervious concrete, with greater water and gas infiltration, would be more beneficial to existing mature trees during urban development. Root activity, root growth and soil chemistry of American sweetgum under standard concrete, pervious concrete and no concrete were measured. Soil CO2 efflux rates and soil CO2 concentrations were extremely high under both concrete treatments. Soil under standard concrete had lower oxygen concentrations than soil under pervious concrete and control treatments, particularly under wet conditions. There was no pavement effect on soil water content or soil chemistry. Under control treatment standing live root length was greater than under both concrete treatments. There were no major differences in soil conditions between impervious and pervious concrete treatments. The soil under the plots, a Ships clay, with very low permeability may have prevented soil water infiltration. Likely this overrode any potential treatment effects due to porosity of the concrete. To obtain root zone benefits out of pervious concrete, a different base soil with a higher permeability would be a better alternative.

The phenology of plants in northern ecosystems is currently changing. Roots have a key role in these ecosystems, though the phenology of roots is still poorly understood. The aim of this report was to investigate if above- and belowground phenology of the circumpolar sedge Eriophorum vaginatum was synchronized in a subarctic peatland underlain by permafrost, and to investigate which abiotic factors are limiting root growth. Additionally, the length of the belowground growing season was examined. The study was performed with a non-destructive in situ method (minirhizotrons and NDVI measurements) in the northernmost part of Sweden. Both above- and belowground phenology was measured biweekly during the whole growing season in 2016. The depth of the active layer, air temperature, soil temperature and soil moisture were measured to investigate the determinants of root growth. Root growth and aboveground activity was asynchronous, as peak in root growth occurred on average 21 days before maximum NDVI was reached. Soil temperature and thaw depth seem to be important factors regulating root growth in this peatland. The result highlight that solely studying the aboveground parts of plants can give a misleading interpretation about the phenology of the entire plant and thus during which time periods important ecosystem processes take place. Hence, to more accurate forecast ecosystem responses to global warming, both aboveground and belowground phenology should be considered.

Temperature is a major factor affecting plant growth and development at all stages. The objectives of this study were to investigate the temperature effects on all aspects of soybean growth and development. Five experiments were conducted at a wide range of temperatures under optimum water and nutrient conditions at specific growth stages. Two cultivars, Asgrow AG5332 (AG) and Progeny P5333RY (PR) from MG V with different growth habits, were used. All studies except the seed germination were conducted in sunlit plant growth chambers under optimum water and nutrient conditions. The seed germination experiment was conducted in a temperature-controlled incubator. Germination traits were measured during seed germination studies. In other experiments, plant growth, developmental rates, gas exchange parameters, and seed yield and quality were measured. Cultivars did not differ for seed germination and emergence traits. Quadratic functions best described time to 50% germination seed germination and emergence rates. The three cardinal temperatures for seed germination were 8.56°C (base) 27. 96°C (optimum) and 46.92°C (maximum). The base and optimum temperature for seed emergence were 10.6 and 36.7°C, respectively. During the early-season, 0-21 days, root and shoot growth parameters responded similar temperature responses, the root traits have a lower optimum (29.91°C) than the shoot parameters (36.56°C). Cultivars varied in their response to temperature during vegetative development, particularly for growth parameters, and the temperature optimums for various parameters. Node addition rate was not different among the cultivars but increased with increase in temperature. The flowering time (R1) from emergence showed quadratic trends with an increase in temperature up to 28°C and increased slightly at the higher temperatures. The PR cultivar, on an average, took 15 additional days to reach flowering compared AG cultivar across temperatures. Pod and seed yield and individual seed weight and harvest indices showed quadratic trends with maximum values at 25.82 °C for AG and 23.36 °C for PR. The functional algorithms could be helpful for management and in improving crop models.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Jason Griffin / The Midwest and southern Great Plains regions of the United States are known for historic and severe droughts. However, short-term recurring drought events are more common and can limit tree survival in landscape and production settings. The pressure of environmental stress combined with numerous diseases and pests are decimating existing Pinus L. spp. (pine) plantings and driving the effort to identify alternative species. Four species of conifer were grown in a pine bark substrate and subjected to recurring moderate to severe drought in a controlled environment glass greenhouse as well as field planted to observe root and shoot growth during the initial 12 months after transplant. The species utilized were Abies nordmanniana (nordmann fir), Cupressus arizonica (Arizona cypress), Picea engelmannii (engelmann spruce), and Thuja x ‘Green Giant’ (‘Green Giant’ arborvitae). Results indicate that C. arizonica exhibited extraordinary growth after establishment and was able to maintain growth and photosynthesis following several drought cycles. Thuja x ‘Green Giant’ exhibited significant increase in root and shoot growth after transplant. Under conditions of moderate and severe drought, only minimal reductions in height and shoot dry weight were observed while root growth and photosynthesis were unchanged. Abies nordmanniana experienced minimal increases in root and shoot growth throughout the growing season and was unaffected by drought. In contrast, P. engelmannii had only modest increases in root dry weight after transplant, while shoot growth was non-existent. Under conditions of severe drought, photosynthesis was reduced. Cupressus arizonica, a known drought tolerant species, with its ability to establish quickly and endure drought may have an advantage when establishing in harsh climates such as the Midwest and southern Great Plains. Thuja x ‘Green Giant’ is known to be a rapid grower, however, it established slowly during the current study and may require additional time before resuming rapid growth and maximum drought tolerance. Slow establishing species such as A. nordmanniana and P. engelmannii may require greater attention to season of planting to coincide with rapid root growth. However, P. engelmannii may not be a suitable choice for the Midwest due to the inability to maintain photosynthesis during periods of drought.

A major problem in irrigated agriculture in the Western U.S. is the gradual accumulation of salinity in the plant root zone. These nonuniformly saline soils contain increasing amounts of salinity with depth, and salt accumulation is accelerated in situations where leaching is minimized. Root growth and thus plant yield is limited in these soils due to decreased water uptake. We studied the root growth of two subpopulations of alfalfa differing in their ability to produce fibrous roots to determine if altering root morphology would increase plant yield and water extraction, in an irrigated saline soil. Soil profiles for a control and three treatments with increasing salinity were packed in to PVC cylinders fitted with a flat window down one side for root measurements. A single alfalfa plant was grown from seed in each cylinder, and irrigated with water enriched primarily in sulfate salts. Alfalfa plants were grown for five successive harvests in a greenhouse, and water extraction was measured in the control and high Salinity treatment by time-domain reflectometry. Final electrical conductivities of the soil ranged from 3.0 to 23 dS m-1. The yield of the high fibrous root subpopulation was not reduced by the soil salinity by the fifth harvest, while that of the low fibrous subpopulation was reduced 22%. Root growth of the high fibrous subpopulation was significantly increased by as much as 54% in the upper 30 cm of the root zone, compared to that of the low fibrous subpopulation. Water extraction was higher in the upper, least saline portion of the root zone for the high fibrous root subpopulation. The results of this study support the use of alfalfa with increased fibrous root production under saline irrigation with minimal leaching.

Surface mining is a major industry in eastern Tennessee that removes much of the native forest. To restore the forest, reclamation practices are used. These include planting a ground cover species with native hardwoods. Competition between the ground cover and tree species for soil resources could hinder growth and decrease survival of the trees. Northern red oak (Quercus rubra) was used for this study to examine the possible effects of this competition and the relationships between root growth and soil moisture through a field and a greenhouse experiment. A field experiment was designed using four different ground cover treatments (Soldiago nemoralis, Medicago sativa, Panicum virgatum, and bare ground) with four different hardwood species. Northern red oak was measured for this study. The results showed that the site physical factors (slope position, soil temperature, and soil moisture) were not related to each other. Soil moisture varied by depth with the lower depths (46 cm to 76 cm) was much higher than the upper depths (0 to 46 cm). Root growth did not differ by treatment or percent cover. Both soil temperature and ground cover percentage increased over the growing season. Root growth showed a relationship with depth with the upper depths of soil having more roots than the lower depths. Annual rye was used as well as switchgrass, alfalfa, and bare ground treatments for a green house study. Two-year-old Northern red oak seedlings were first planted in pots and then ground covers were established and grown for 9 weeks. Then water stress was imposed over two dry down periods during which transpiration and soil moisture were measured. Root growth was measured after harvest. The results showed a relationship between transpiration and soil moisture. Soil moisture was highest in the bare ground treatment and lowest in the annual rye treatment. Fine root development of trees was greatest in the bare and alfalfa and lowest in the annual rye. Switchgrass had the second highest soil moisture and third highest fine root development. Root growth was related to both soil moisture and transpiration.