Forage production and longevity of alfalfa (Medicago sativa L.) are reduced by the effect of the fungus Phytophthora megasperma Drechs. in irrigated alfalfa fields located in Central Mexico. There are no resistant alfalfa cultivars adapted to this region. Phytophthora root rot was found in irrigated fields at elevations between 1600 to 2000 m. Strains of this fungus isolated from soil collected in Mexico were more virulent than one strain from Arizona. Four alfalfa cultivars of Mexican origin, Certified Hayden, and Hayden PX-III, an experimental cultivar resistant to strains of P. megasperma from Arizona, were susceptible to P. megasperma Bajio strain collected in Central Mexico. Following two cycles of phenotypic current selection, the level of resistance to Phytophthora root rot was increased from 5.6% to 22.8% in the new population originating from the cultivar INIA-76, and from 12.8% to 30.6% in the new population originating from the cultivar Hayden PX-III.

Mounted ill. / Bibliography: leaves 263-265 / 265 leaves [1] leaf of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agriculture, 1984

Bibliography: leaves 200-225 / xxiii, 225 leaves, [39] leaves of plates : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1984

El presente estudio de pre-factibilidad está orientado a la instalación de una planta productora de pellets de heno de alfalfa, localizada en la ciudad de Lima-Perú. Éste estudio es relevante como proyecto de investigación en ingeniería industrial porque integra y relaciona todos los elementos que constituyen un sistema o proceso: personas, tecnología, máquinas, materiales e información, con el fin de optimizar tanto el rendimiento como la calidad de producción del sector industrial de alimentos balanceados para animales pecuarios. Ello permitirá reducir sus costos de producción respetando los factores medioambientales para de un adecuado desarrollo sostenible. / Trabajo de investigación

Forage crops grown in many parts of the Appalachian region are restricted in yields as a consequence of shallow soils, low levels of essential nutrients, toxic levels of aluminum, and low pH. Therefore, the successful growth of alfalfa in these regions is dependent on either changing existing edaphic conditions or modifying the plant physiologically so as to improve nutrient acquisition and utilization. The purpose of the present study was to determine if chemicals reported to possess growth regulatory properties affect nutrient uptake and utilization and how such effects are manifested in the plant. In the first series of experiments, foliar sprays containing 10 mM CaCl₂ with or without tetracosanoic acid (C-24), hexacosanoic acid (C-26), triacontanoic acid (C-30), or dipalmitoyl phosphatidic acid (DPA) were ineffective (p=0.05) in enhancing alfalfa (Medicago sativa, Arc) shoot or root biomass when applied to 21 and 28 day-old plants. DPA treatments also had no effect (p=0.05) on the leakage of Ca²⁺, K⁺, Mg²⁺, and PO₄³⁻ from foliar leaf discs. Foliar treatments containing either 10 mM CaCl₂ + DPA or 10 mM CaC1₂ were effective in increasing shoot biomass in plants grown in solution culture containing suboptimal levels of calcium and phosphate. The increased biomass, however, was attributed to calcium supplementation rather than the effect due to DPA. The second series of experiments evaluated the effect of seed treatments with the growth retardant XE-1019 ((p-chlorophenyl)-4,4-dimethyl-2(1,2.4-triazol-1-yl)-1-penten-3-ol) on alfalfa growth, chlorophyll concentration, ionic leakage, nutrient uptake, and root nodulation. Seed treatments resulted in plants with significantly reduced (p=0.05) shoot and root biomass and thicker greener leaves. Quantitation of leaf chlorophyll indicated that the seed treatments caused significant increases (p=0.05) in both chlorophyll a and b concentrations at initial growth stages. After six weeks, no significant differences in chlorophyll concentrations were detected. XE-1019 had no apparent effect on leaf membrane permeability or transport since no significant differences (p=0.05) were detected in the leakage of Ca²⁺, K⁺, Mg²⁺, and PO₄³⁻ from foliar leaf discs. However, whole plants treated with XE-1019 depleted significantly (p=0.05) higher amounts Ca²⁺, K⁺, Mg²⁺, and PO₄³⁻ from hydroponic solutions on a per centimeter root basis. On a per plant basis, untreated plants absorbed greater quantities of the assayed nutrients. The presence of XE-1019 in the rhizosphere was not deleterious (p=0.05) to the inoculation of the root with Rhizobium meliloti and the subsequent formation of root nodules. Seed treatments with XE-1019 also had no effect on the cultured growth of Rhizobium meliloti strains 102F34a, l02F51a, 102F66d, and 102F77b. / Master of Science

Three sampling methods for estimating abundance of alfalfa weevil (AW) larvae (Hypera postica Gyllenhal) were evaluated for both accuracy and precision. Calibration equations were developed to convert intensity estimates of AW larvae among sampling methods. Greenhouse experiments evaluating the interaction of moisture stress and defoliation by AW larvae indicated that yield response of alfalfa to AW feeding is dependent on moisture stress levels. Field studies on the influence of AW feeding on alfalfa confirmed the importance of moisture stress in alfalfa tolerance to weevil feeding. Quadratic regression models are presented to predict yield loss and changes in stem density as a function of weevil intensity. A sequential sampling plan was developed and validated for use in pest management decision making. Validation of the plan indicated an average error rate of 1.8%, with the number of samples needed reduced by 55% in 1980, 53% in 1981, and 28% in 1982. A net benefit analysis the Virginia Alfalfa IPM program indicated that growers participating in the program during 1981-84 realized an estimated average increase in net revenue of $8.80 per hectare from the alfalfa weevil scouting program, and $28.13 per hectare from the potato leafhopper scouting program. / Ph. D. / incomplete_metadata

Call number: LD2668 .T4 1932 B43

Call number: LD2668 .T4 1948 S65 / Master of Science

Call number: LD2668 .T4 1956 B76 / Master of Science

Call number: LD2668 .T4 1958 S79