Seasonal patterns of stomatal activity, plant-temperature-based drought stress indices, growth and grain yield of two pearl millet (Pennisetum americanum (L.) Leeke) parental lines and their F₁ hybrid were studied under a sprinkler irrigation gradient system in 1985 and 1986 in Tucson, Arizona. Physiological and morphological measurements of stressed and nonstressed plants were made periodically starting at the panicle initiation stage. Well-defined trends in stomatal conductance (Cg), transpiration (Tr), and photosynthetic (Pn) rates of nonstressed plants were observed over the seasons. Tr increased from 5ug H₂O cm⁻²s⁻¹ at early panicle development stage to a peak of up to 30 ug cm⁻²s⁻¹ at flowering and declined to 10 ug cm⁻²s⁻¹ at maturity. Pn of well-irrigated plants was highest (26 uMoles CO₂ m⁻²s⁻¹) at early flag leaf appearance stage and declined slowly to 14 uMoles m⁻²s⁻¹ at maturity. In extremely stressed plants, Cg, Tr and Pn were highest early in the seasons, lowest in the middle of the seasons, and slightly increased towards the end of the seasons. The seasonal trends in stomatal response depended on the stage of plant growth and vapor pressure deficit of the air. Transpiration efficiency was highest at partial stomatal closure. Morphologically, the F₁ hybrid was more like its male than its female parent. The female parent produced less dry matter, had thinner leaves and greater ratio of leaf to stem dry matter, and yielded less grain than the other genotypes. The results indicated that leaf:stem ratio can be a useful selection criterion of drought avoiding genotypes. Plants that develop stems and heads rapidly (low leaf:stem ratio) are more desirable under stress than plants that tend to become leafy. Decreases in Tr, Pn, dry matter and grain yield due to stress could be assessed with canopy or leaf temperature, canopy minus air or leaf minus air temperature, and crop (CWSI) or leaf (LWSI) water stress indices. CWSI and LWSI were more desirable in assessing stress than the other indices. CWSI is effective in assessing the magnitude of stress in a crop stand, while LWSI may be useful in situations where use of the infrared thermometer is difficult.

A survey of leaf mineral concentration of cultivated jojoba was conducted by selecting male and female plants of varying sizes. Mineral concentrations in jojoba were within the expected range for most cultivated plants. Nitrogen, P and Zn were higher in young leaves but K, Ca, Mg, Na and Mn were higher in old leaves. Iron and Cu were similar in old and young leaves. The order of jojoba leaf concentration was: N>K>Ca>Mg>Na>P and Fe>Mn>Zn>Cu. Soil macronutrients, Mn and Cu were adequate for jojoba growth but zinc and Fe were lower than accepted critical values for most crops. For a better understanding of jojoba mineral nutrition, a second experiment was conducted in greenhouse sand culture. Levels of 0, 4, 10, 50, and 100 ppm N in solution culture were evaluated on growth, N and P leaf concentration. Fifty ppm of solution N was adequate for optimum vegetative growth, shoot dry weight production and shoot N concentration (1.96 %) of jojoba plants. Nitrogen was higher in young (2.52%) than old leaves (1.52%) and increased with increments of N rates, as did shoot dry weight, shoot N and shoot P concentrations. Root dry weight did not change with N treatment levels but root N concentration increased with rate. Jojoba plants under field conditions are subjected to water stress and little information is available regarding the effect on leaf mineral concentration. Therefore, a greenhouse sand culture experiment was conducted to study irrigation fequencies of 3 min once every: 1) 2 hr for 10 hr/day, 2) day, 3) other day and 4) 4 days on growth of two clones and foliar, shoot and root N and P concentrations. Also, leaf water potentials were monitored. Vegetative growth increments were similar among treatments but treatment 3 resulted in statistically greater shoot and root dry weight. Leaf N concentration was similar among treatments but root N increased with greater moisture stress. Shoot P concentrations decreased with increasing water stress but root P did not show any pattern. The threshold leaf water potentials for jojoba growth cessation was in the range of -3.0 to -3.5 Mpa.

No description available.

No description available.

This study evaluated relative responses of two grain sorghum (Sorghum bicolor (L.) Moench) hybrids to moisture stress treatments imposed during the seedling, early boot, flowering and grain-filling stages. The two hybrids, T.E. Y77 and FUNK HW6125, are high and low yielding respectively, having similar maturity periods. Twelve phenological characters were measured. The height to upper leaf collar, peduncle exsertion, panicle length, total plant height and total leaf area showed significant differences between the hybrids. Early boot stage stress was most sensitive to vegetative characters. T.E. Y77 produced more heads/m², grains, panicle, 500 grain weight (seed size), and grain yield/ha than FUNK HW 6125 across all treatments. Seed size was the most important determinant of grain yield in both hybrids. Moisture stress during the seedling and early boot stages enhanced grain yield, whereas during the grain-filling stage it was detrimental to grain yield in both hybrids.

Renewable energy technologies are infrequently evaluated with regard to water use for electricity generation; however traditional thermoelectric power generation uses approximately 50% of the water withdrawn in the US. To address problems of this water-energy nexus, we explore the replacement of existing electricity generation plants by renewable technologies, and the effect of this replacement on water use. Using a binary mixed integer linear programing model, we explore how the replacement of traditional thermoelectric generation with renewable solar and wind technologies can reduce future water demands for power generation. Three case study scenarios focusing on the replacement of the J.T. Deely station, a retiring coal thermoelectric generation plant in Texas, demonstrate a significant decrease in water requirements. In each case study, we replace the generation capacity of the retiring thermoelectric plant with three potential alternative technologies: solar photovoltaic (PV) panels, concentrated solar power (CSP), and horizontal axis wind turbines (HAWT). The first case study, which was performed with no limits on the land area available for new renewable energy installations, demonstrated the water savings potential of a range of different technology portfolios. Our second case study examined the replacement while constrained by finite available land area for new installations. This demonstrated the trade-off between land-use efficient technologies with water-use efficiency. Results from our third case study, which explored the replacement of a gas-fired plant with a capacity equivalent to the J. T. Deely station, demonstrated that more water efficient thermoelectric generation technologies produce lower percentages of water savings, and in two scenarios the proposed portfolios require more water than the replaced plant. Comparison of multiple aspects of our model results with those from existing models shows comparable values for land-use per unit of electricity generation and proposed plant size. An evaluation of the estimated hourly generation of our model’s proposed solution suggests the need for a trade-off between the intermittency of a technology and the required water use. As we estimate the “costs� of alternative energy, our results suggest the need to include in the expression the resulting water savings.

Digitized by Kansas Correctional Industries

Typescript. / Digitized by Kansas Correctional Industries

No-tillage winter wheat (Triticum aestivum L.) grown in a wheat-fallow cropping system has consistently produced lower grain yields than conventionally tilled soils in the semiarid Pacific Northwest. A 2-year study was conducted in a long-term tillage trial at Moro, OR to determine factors responsible for differences in wheat growth and yield as affected by moldboard plow, stubble mulch, and no-tillage fallow method. Soil water, soil mineral N, plant N uptake, soil temperature, above-ground dry matter accumulation, and yield components were measured. The highest fallow efficiency during both years was achieved by stubble mulch tillage, followed by the plow and no-tillage systems. Accelerated water loss from no-tillage fallow occurred during the hot, dry summer due to uninterrupted capillary flow. The main yield limitations to no-tillage technology in this study were: (1) diminished seedzone water at planting time in the fall which resulted in reduced germination and stand establishment; (2) cooler spring soil temperatures which slowed crop development and dry matter accumulation, and; (3) production of fewer spikes per unit area. The second objective of this study was to determine if late season seedzone water loss from fallow could be reduced by altering the physical characteristics of the dust mulch. Loss of seedzone water appears to accelerate in late August and September because of increased diurnal heat flux. Compacting the soil surface with a roller in mid-August increased surface bulk density and volumetric water content to depths as great as 10 cm. Evaporative water loss from compacted plots, however, occurred at a faster rate than from control plots and, by mid-September, there were no differences in seedzone water content among treatments. Increased soil thermal conductivity appeared to be the reason for accelerated water loss in compacted treatments. Although water loss occurred at a faster rate in compacted treatments, compacting fallow soils with a roller immediately prior to fall seeding may increase winter wheat germination, emergence, and stand establishment during years of marginal seedzone water. / Graduation date: 1992

The Linear Voltage Differential Transformer (LVDT) is an accurate sensor for stem diameter measurements. Based on the results of this dissertation it was found that stem diameter [mm] was related to water content [grams] of the cotton crop by the following equation: W(D) = 0.114(D)³ˑ¹⁸² Also the ratio of stem diameter contraction rate to the rate of water loss in cotton was experimentally determined to be: (dW/dt)/(dD/dt) = (0.166 [g min⁻¹])/(0.535 [μm min⁻¹]) = (.0469% per minute)/(.0039% per minute). Similarly the cellular water potential was derived to be a non linear function of stem diameter in cotton: ψ(t) - ψₒ = 2 ε ln (D(t)/ Dₒ) + πₒDₒ² [(1/D²(t)) – (1/Dₒ²)]. Based on this work, the grower can estimate the water content, transpiration rate and water potential of the cotton crops via stem diameter measurements. Moreover, a computer system can be implemented to remotely keep track of the water status of the field, and control the irrigation system. A general model was proposed to quantify the nature of input-output relation of the cotton crop. A proposed simplified model based on stem diameter is also introduced. The stem diameter measurements can be used as an index for estimation of cotton's water content, transpiration rate, and water potential. These three parameters and the proposed simplified model established a plant based predictive irrigation scheduling technique. The electrical output of the LVDT was quite noisy. To remove the noise and demodulate the data, two cascade circuits were designed and implemented. First, the external output circuit removed the noise and isolated the LVDT. Second, the LVDT signal conditioner demodulated the phase information from the secondary windings which were produced by the movement of the rod. By the implementation of these circuits, 1 m of the rod displacement resulted in 1.14 mv of dc voltage changes in the output.