Typescript (photocopy). / Digitized by Kansas Correctional Industries

It is surprising to know the small amount of work that has been done on alternate freezing and thawing of seeds. Many experiments, however, have been conducted to see the effect of very low temperatures on seeds and to notice the effect it had on their vitality. Some experimenters subjected seeds to temperatures as low as liquid hydrogen with very interesting results but in very few cases, if any, was the effect of alternate freezing and thawing studied. The work that follows deals directly with the effects of alternate freezing and thawing on impermeable seeds of alfalfa and of dodder. It is known that this seed does not germinate readily; therefore it often lays over winter in the soil. Does this natural freezing and thawing aid or hinder this impermeable seed in it's later germination? this has been the main question kept in mind throughout this experiment.

Alfalfa, Medicago sativa L., cultivars, breeding lines and germplasm releases (populations) and Rhizobium meliloti L. strains that exhibit nitrogen fixation efficiency and tolerance to salinity and drought stresses should enhance seedling establishment, increase yields, reduce nitrogen dependency on petroleum-based nitrogen fertilizers, and allow wider use of irrigated lands in semiarid and a rid regions. In vitro experiments were conducted to determine relative salt (sodium chloride -- NaCl) tolerance: l) during germination and early seedling growth of 229 alfalfa populations from North Africa, the Middle East and the United States, 2) survival and growth of 92 rhizobial strains obtained from different laboratories in the United States or isolated from host plants growing in saline and arid regions of the Intermountain west, 3) compatibility, nodulation and nitrogen fixation efficiency of the most salt-tolerant alfalfa populations and rhizobial strains, and 4) survival, nodulation and nitrogen fixation efficiency of the most salt-tolerant alfalfa populations and rhizobial strain tested under drought conditions. Results from screening of alfalfa at salinity levels of 0 to 3.2 S m-1 (0.1 S m-1 = 640 mg L-1 = 10 mM NaCl at 25° C) indicated 29 populations exhibited salt tolerance at 2.8 S m-1. At salinity levels of 0 to 7.2 S m-1, 14 rhizobial strains exhibited salt tolerance at 6.4 s m-1. Compatibility, nodulation and nitrogen fixation efficiency in the 29 alfalfa populations and the 14 rhizobial strains under controlled conditions showed that four of the rhizobial strains were highly compatible with all 29 populations. These 29 populations and four strains were then exposed to 0 to 1.6 S m-1 NaCl, with the result that nitrogen was fixed with highly compatible symbionts at 1.6 S m-1 NaCl. From these results, the six most highly compatible alfalfa populations and the best overall rhizobial strain were combined and tested under simulated drought stress. These populations were able to fix more nitrogen under drought stress (-0.76 MPa) (0.088 nmol seedling-1 s-1) than they did under salt stress (1.6 S m-1) (0.066 nmol seedling-1 s-1). The in vitro screening technique for acetylene reduction appears to be a useful tool for detecting physiological changes due to salinity and water stresses and for measuring seedling nitrogen fixation efficiency. Breeding for drought and salinity tolerance in conjunction with high nitrogen fix ing potential may be more realistic than breeding strictly for nitrogen fixation without regard for environmental adaptation.

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.

Alfalfa is a major cash crop in the western United States, where fields that are infested with the alfalfa stem nematode (Ditylenchus dipsaci) can be found. With no nematicides available to control alfalfa stem nematode spread, growers can use nematode resistant varieties of alfalfa to manage nematode populations in a field. A deterministic, discrete-time, host-parasite model is presented that describes the spread of alfalfa stem nematodes on resistant hosts that was fit to experimental data obtained in Weber County, Utah. Numerical results obtained from simulations with the model are used to compare how varying levels of resistance can affect harvest yield. Resistant varieties can also affect the invasion speeds of epidemics in crops. A continuous time, spatial model is presented that describes how these resistant varieties affect invasion speeds in general crop systems. Speeds of traveling wave fronts are determined for simple epidemics in crops that contain a mixture of resistant and non-resistant hosts. For the model, it was found that the wave speeds will slow down as highly nematode resistant varieties of alfalfa are used. The speed of invasion for the alfalfa stem nematode can be determined by using a mathematical relationship that is know as the contact distribution. We present a spatial model for the spread of alfalfa stem nematodes that uses a Gaussian distribution as the contact distribution of the alfalfa stem nematodes, which was determined by experimental data. Using this contact distribution we are able to approximate the speed of nematode invasive fronts in absence of advection, i.e. without nematode trans-port through flood irrigation. The contact distribution is then used to calculate front speeds when resistant varieties of alfalfa are introduced. We found that, unsurprisingly, invasive speeds are relatively low and cannot support the rapid dispersal of the disease among fields as seen in practice. However, this result leads to conjecture that changing current irrigation practices, from flood to sprinkle irrigation, could effectively contribute to control the spread of alfalfa stem nematodes. Resistant varieties of alfalfa can be used to effectively control the spread of the alfalfa stem nematode. In this work we have shown that using resistant varieties of alfalfa can increase yield up to 83%, they can slow down invasion speeds of nematodes, and switching from flood to sprinkler irrigation could effectively contribute to the control of the alfalfa stem nematode.

The establishment of alfalfa is expensive and good initial stands permit the farmer to secure high yields and spread establishment costs over several years, Of the factors involved: seedbed preparation, fertilization, seed viability, method of planting, and water application are controlled by the farmer, On the other hand, beneficial and detrimental microflora are not so easily controlled because practices aimed at controlling the detrimental microflora may also destroy the beneficial.

A greenhouse study was conducted to determine the effects of deposition from static rocket test fires on corn and alfalfa. Seeds were germinated in a wide concentration range of depositional material, called test fire soil (TFS). Additionally, the impact of chloride and aluminum, two major components of test fire soil, on germination was also evaluated. Furthermore, plants were grown in packed columns and exposed to test fire soil, either in the root zone or on foliage. Tissue was weighed and analyzed to compare biomass production and plant composition. Corn and alfalfa exposed to test fire soil in the root zone produced less biomass than controls, but foliar treatment had no effect on biomass production. No kernels were produced by corn exposed to test fire soil in the root zone. Leaves of plants exposed to test fire soil in the root zone accumulated more metals and nutrients than controls, whereas plant tissue treated with test fire soil on the leaves contained only elevated levels of aluminum, although levels were still within reasonable concentrations for plants. Germination of seeds was not affected below 1% test fire soil in soil; however higher concentrations of test fire soil decreased percent germination. Addition of chloride to soil also inhibits germination, but addition of aluminum has no effect on germination percentage. Corn germination was restored in test fire soil leached with 200 mm artificial rainwater. The results of this research contribute information regarding the potential impact of test fire soil from static test fires on crop production. Test fire soil inhibits germination and growth if deposited in the root zone, and even foliar application alters tissue composition. However, plant composition is not altered significantly in terms of feed criteria, and germination can be restored by irrigating the TFS. The effects of test fire soil are attributed to high levels of chloride that induce salt stress. Crop damage may be avoided by conducting static test fires after crops are harvested or providing extra irrigation to soil impacted with the TFS.

A field experiment was conducted at two locations in Utah, one at Erda in Tooele County and the other at Minersville in Beaver County. Each experiment was designed as a randomized block design with five treatments and four replication s for each treatment. The test crop was alfalfa. Three cuttings were taken from each location to estimate the yield. Soil samples from the first 12 inches and subsoil samples from 12-24 inches were taken to determine the available NaHCO3-P in the soils. Plant samples were taken to determine the P content of the crop. The results showed that with 5 ppm soil-test P, P content in crop was above the critical level. There was no increase in yield resulting from adding different levels of P to the soil. This conclusion suggests that the criteria used at the soil -testing laboratory at Utah Stat e University should be modified. The criteria used had heen based on samples from the first 6 inches of the soil and from previous investigations. The limit used for low P status for the soil s was 8 ppm.

Third-cutting alfalfa hay harvested at bud stage in each of 2 yrs, treated with a live bacterial incoulant, packed in polyethylene-bonded bags and allowed to ensile. In both years, treated haylage had a lower pH, and a period effect was found for pH and mold count, regardless of treatment. In year 1, there was a period effect found for acid detergent fiber. In year 2, mean lactic-acid-producing bacteria numbers (log 10) were significantly higher for treated haylage (9.69 and 10.36) for control and treated haylage, respectively). Regardless of treatment, lactic-acid-producing bacteria numbers and water soluble carbohydrates significantly declined through time. For both years, treated haylage was fed to early-lactating dairy cows at 60% of the ration dry matter. In year 1, lactating cows were fed treated haylage for a 10-wk period, and no differences were observed in milk production performance or dry matter intake over cows fed untreated haylage. In year 2, cows were fed for a 6-wk period, and no differences were detected between treatments for milk production, milk composition, or dry matter intake.

Orbital ATK tests horizontally restrained solid rocket motors (SRMs) in Promontory, Utah, USA. During SRMs tests, an estimated 1.5 million kg (~3.3 million lbs.) of entrained soil and combustion products (mainly aluminum oxide, gaseous hydrogen chloride, and water) are deposited over a wide area. Local farmers have expressed concerns regarding the deposition of this material, referred to as Test Fire Soil (TFS), on crops surrounding the test site. Greenhouse studies of mature corn and alfalfa (54 days to harvest) exposed to a worse case TFS deposition density to soil (3200-g/m2) resulted in reductions in germination and plant growth. Application of TFS only on leaves caused visual changes in leaf appearance (e.g. “burning”) but did not impact on growth. The visual damage to the leaves was thought to be caused by the high chloride in the TFS. The pH (measured from 2-10 in the field) of the TFS was also thought to be a potential cause of the visual damage. Follow-up studies were conducted using younger corn, alfalfa and winter wheat (12-54 days from emergence), to evaluate the impact of a more typical TFS deposition density and application scenario. The relationship between deposition amount and the crop impact was also examined. Impact was evaluated by comparing the growth, tissue composition (focusing on chloride and aluminum) and chlorophyll content of controls relative to the treatments. The individual effects of chloride and pH on corn leaves were determined by monitoring visual appearance and chlorophyll content. Leaves exposed to a typical TFS deposition loading (70-g/m2) did not contain elevated chloride or aluminum levels relative to the controls. Higher TFS loadings (700-g/m2 and 3200-g/m2) resulted in significantly elevated chloride content in corn leaves at 29 days from emergence. Corn leaves treated with TFS at the 700-g/m2 loading 12 days from emergence had comparable chloride levels to controls. High and low pH and chloride solutions visually impacted corn leaves and reduced leaf chlorophyll. This study indicated SRMs testing can be conducted under typical conditions during the juvenile growth stages of field corn, alfalfa, and winter wheat without adverse impact on crop yield and plant tissue composition.