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Physiological responses to environmental stress in eucalyptus cloeziana and eucalyptus argophloia /Ngugi, Michael R. January 2004 (has links) (PDF)
Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliography.
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Evapotranspiration and drainage from a snap bean cropBlack, Thomas Andrew. January 1969 (has links)
Thesis--University of Wisconsin. / Supported in part by Environmental Science Services Administration, grant E-287-68(G).
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The effect of intercepted rainfall on evapotranspiration rates over a mixed hardwood forest in southern Quebec /Singh, Bhawan January 1976 (has links)
No description available.
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Effect of water stress and light on the activities of certain enzymes in corn.Bardzik, John Michael 01 January 1969 (has links) (PDF)
No description available.
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Temporal and spatial relationships of canopy spectral measurementsBamatraf, Abdurhman Mohamed. January 1986 (has links)
Ground-based, remotely sensed reflectance and temperature data were collected over differentially irrigated, developing cotton and sorghum canopies in order to investigate interrelations of these parameters; to monitor their temporal changes ; to understand their spatial structure ; and to estimate crop coefficient (KO from canopy reflectance. Spectral reflectance and derived vegetation indices showed ability to significantly discriminate among differential irrigation levels of sorghum canopies, starting the fourth week of growth. All vegetation indices increased as a result of crop development, with the perpendicular vegetation index (PVI ) demonstrating the greatest potential for assessing water stress conditions, whereas, soil indices behaved independently of crop development and water stress. Canopy temperature and derived water stress indices, on the other hand, were in high concordance and were able to detect crop water stress with variable degrees of sensitivity. Experimental variograms revealed that cotton reflectance and temperature were not spatially dependent when all water treatments were included. For the moisture stress treatments, only canopy temperature exhibited spatial dependence early in the period of stress. Sorghum canopy reflectance and temperature demonstrated some spatial structure; however, a drift was suspected due to regularity in the data spatial distribution. Normalized difference (ND), normalized perpendicular vegetation index (NPVI) and normalized green vegetation index (NGVI), for fifty days covering the period from planting to heading, were fitted with a complementary error function equation with minor adjustment. Both NPVI and NGVI displayed a 1:1 relation with interpolated tabular values of basal Kc, whereas ND deviated from the 1:1 relation for the period beyond 30 days after planting. The model was also found to be valid for estimating K(c) for moderately deficit irrigation conditions.
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Effect of water stress on the physiology, growth, and morphology of three pearl millet genotypesOsman, Mohammed A. January 1988 (has links)
A pearl millet hybrid (Pennisetum americanum (L.) Leeke) and its two parents were evaluated for their photosynthetic rates, diffusive resistance, canopy temperature, transpiration rates, stomatal aperture and frequency, and growth responses to various irrigation levels. The experiments were conducted on Brazito sandy loam soil at The University of Arizona Campus Agricultural Center, Tucson, AZ in 1985 and 1986. A sprinkler was used to create water treatments. Photosynthetic rates were not significantly different among genotypes at each water level. Transpiration rate, diffusive resistance, canopy minus ambient temperature, and photosynthetic rate were all significantly related to water treatments with correlation coefficients .ranging from 0.91 to 0.98. Under water stress, the female transpired more, exhibited lower diffusive resistance and had a cooler canopy compared to the hybrid and male parent. Based on these characteristics, the female seemed to expend more energy on heat dissipation than yield improvement. Water stress reduced stomatal aperture but increased stomata! frequency. The hybrid had significantly higher stomatal frequency at all water levels and smaller aperture between 63 and 125 mm irrigation levels. Dry matter, leaf area, leaf area index, and plant height were also reduced by water stress. In general, the hybrid and the male parent produced significantly more dry matter and were significantly taller than the female. The female parent had significantly higher leaf area and leaf area index late in 1986. Grain yield was reduced by water stress. Both years, the female grown under optimum moisture conditions had approximately half the grain yield as compared to the male and the hybrid. The major components contributing to the higher grain yield of the hybrid and male were larger panicles and more productive tillers.
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Hydrological consequences of two native shrubs in semi-arid Senegal : patterns, processes, concepts and methodsKizito, Fred 02 December 2005 (has links)
Water availability is a critical limiting element in semi-arid ecosystem productivity and
presents particular challenges in Sahelian countries such as Senegal. The landscapes are
characterized by the presence of two common semi-arid shrubs (Piliostigma reticulatum
and Guiera senegalensis), both of which may be important hydraulic regulators in these
water-limited ecosystems. Dry season observations revealed higher moisture levels in soil
surrounding the shrub shallower roots relative to bare soil. This observation led us to
hypothesize that these shrubs may participate in a natural irrigation phenomenon termed
as "hydraulic redistribution" (HR). This dissertation reports on three studies performed to
ascertain the existence of and investigate the characteristics of this hypothesized
phenomenon. The first study investigated seasonal variability in soil water and shrub root
patterns. Soil moisture content declined steadily in the 0.9-1.2 m depth range and
increased in the 0.2-0.4 m depth range, which supports the HR hypothesis. The second
study quantified plot scale water balance fluxes. Notably, shrub water uptake from the
water table served as a crucial contribution to the system water balance. The third study
investigated the magnitude and dynamics of HR during the dry season. Crop-shrub
associations were evaluated from measurements of soil moisture and potential, root sap
flow and plant physiological measurements. This study proved the existence of HR and
quantified the HR magnitude (~0.1 mm d⁻¹). For shrubs and annual crops in close
association with shrubs, HR clearly provides a mechanism for drought-stress avoidance
and maintenance of plant physiological functions. At the landscape scale, the interplay
between shrub root morphology and HR may play a vital role in ecosystem function with
practical implications for nutrient cycling and water balance in arid ecosystems. / Graduation date: 2006
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Stable carbon isotopes as indicators of increased water-use efficiency and biomass production in white spruce (Picea glauca (Moench) voss) seedlings grown under different water and nitrogen regimesSun, Zongjia 26 August 2015 (has links)
Graduate
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EFFECTS OF HIGH AND LOW IRRIGATION ON SYMBIOTIC NITROGEN FIXATION ON COWPEA (VIGNA UNGUICULATA (L.) WALP.)Mohamed, Ibrahim Elbashir January 1982 (has links)
No description available.
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The germination of certain introduced African grasses as influenced by different temperature and moisture stressesAsare, Ebenezer Okae, 1931- January 1963 (has links)
No description available.
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