Polymorphisms in cyanogenic glucoside and cyano‐amino acid content in natural accessions of common vetch (Vicia sativa L.) and selection for improved agronomic performance

Common vetch (Vicia sativa L.) is an important annual forage legume. It is used as a cover crop, green manure, pasture legume and for silage and hay production. Its seeds can be used as a source of highly digestible protein and minerals in animal diets. However, their utilization as a feedstuff for monogastric animals is hindered by the fact that the seeds contain cyanogenic antinutritional factors that reduce their palatability. An effective utilization of V. sativa seeds as a successful monogastric feed stuff requires selection for higher protein availability and minimization of the cyanogenic antinutritional factors content. In this study, we selected one natural accession named Mjez Ibeb, from a collection of 25 accessions and cultivars, based on its superior agronomic performance and its naturally occurring genetic variation for cyanogenic traits. We investigated the genetic variation that exists for the cyanogenesis trait in more detail and analysed the seeds of 133 lines derived from accession Mjez lbeb. Of these, 40 naturally polymorphic lines that showed deficiencies in cyanogenesis and cyano‐amino acid content, were subsequently selected for detailed chemical analysis. Cyanogenic glucosides and cyano‐amino acid concentrations varied widely in the 40 lines. Multivariate analysis was performed and three lines (L₁₆, L₂₁, L₁₈) with low content of cyanogenic compounds were identified.     

Chromosomal regions associated with barley yellow dwarf virus resistance in oat

Immature embryos of the spring barley variety GoldenPromise, were bombarded with three different particledelivery systems and both transient and stabletransformation examined. In addition, a range oftechniques for the preparation of the DNA coated goldparticles was examined. Fertile transgenic barleyplants were obtained using three particle preparationtechniques which differed in the amount of gold andDNA used for each bombardment. However, only one ofthe particle delivery systems, the PDS 1000/He device,appeared to be effective in yielding transformedbarley plants.     

Some laboratory investigations relevant to the possible use of new pyrethroids in control of mosquitoes and tsetse flies

Cypermethrin, fenvalerate, permethrin, (S)-α-cyano-3-phenoxybenzyl (1R,cis)-3-(2, 2-dibromovinyl)-2, 2-dimethylcyclopropanecarboxylate (NRDC 161) and (R,S)-α-cyano-3-phenoxybenzyl 2, 2,3, 3-tetramethylcyclopropanecarboxylate (S-3206; WL 41706) have been tested against adult mosquitoes (Anopheles stephensi) and tsetse flies (Glossina austeni). They possess many of the necessary characteristics such as high intrinsic toxicity, low volatility, and high stability but vary considerably in the contact action of their spray residues.     

Spatial scale influence on longterm temporal patterns of a semi-arid grassland

Longterm (45 years) temporal data were used to assess the influence of spatial scale on temporal patterns of a semi-arid west Texas grassland. Temporal basal area dynamics of common curlymesquite (Hilaria belangeri (Steud.) Nash) collected from permanent plots within two areas that were released from disturbance (longterm overgrazing and drought), were evaluated at two spatial scales (quadrat, site). Wiens (1989) proposed hypotheses to characterize the influence of scale on variability, predictability, and equilibrium. These hypotheses were tested for this grassland and temporal patterns observed were different for each spatial scale. The large scale (site) was characterized by low variation between units, high variation within units, high potential predictability, and possible movement toward a fluctuating but relatively stable or equilibrial state. At the small scale (quadrat), variation between units was high, predictability low, and there was no indication of movement toward a stable state; chaotic behavior may be expressed at this scale although the length of the temporal record may not be sufficient to evaluate this phenomenon.     

Farm labor contractors: The processors of new immigrant labor from Mexico for Californian agribusiness

The deteriorating living and working conditions suffered by California's farm workers and their families is associated with the escalating proportion of the agricultural labor market (ALM) provisioned by the state's farm labor contractors (FLCs). The increasing use of FLCs is the result of a restructuring strategy undertaken by Californian agribusiness to reduce the cost of labor, as well as responsibility for work place, labor, and immigration laws. The FLCs' rise to prominence as the bulwark between growers and workers within the state's ALM has been ensured by the internal dynamics of contractor firms. During almost three years of binational fieldwork in both California's San Joaquin Valley and rural Mexico I found that FLC management agents cultivate sociocultural practices and provide socioeconomic services that diffuse management-labor conflict within the agricultural sector. However, the existing literature concerning the FLCs focuses upon the firm, not its labor agents; therefore, FLC heterogeneity is emphasized, while ubiquitous management characteristics and practices are overlooked. As a result, recent legislation has had the unintended effect of augmenting the role played by management agents in processing an unending flow of new immigrant workers through the revolving door ALM, leading to the deterioration of conditions in rural California.Fred Krissman, an anthropologist, is currently writing a monograph on California's farm labor contractors as Researcher-in-residence at the Center for US-Mexican Studies at the University of California, San Diego. Fred has taught courses on issues related to immigration and rural development, and has published several articles on Californian farm workers, Mexican immigrants, and rural poverty. He will conduct comparative research on farm workers in Washington state's Yakima Valley and in San Diego County in 1996.     

Exophthalmia associated with paranasal sinus osteoma in a Quarterhorse mare.

An 11-year-old Quarterhorse mare developed a paranasal sinus osteoma that extended into the right orbit and led to ipsilateral exophthalmia. Although the tumor was radiographically evident in the paranasal sinuses, ultrasonography was used to demonstrate extension of the tumor into the retrobulbar space, and endoscopy was used to identify its extension into the nasopharynx. Biopsies were obtained using both fine-needle aspiration and paranasal sinus trephination. Despite numerous antemortem diagnostic tests, only postmortem histologic analysis of the mass afforded the diagnosis of osteoma.     

Calf and disease factors affecting growth in female holstein calves in Florida, USA

A prospective cohort study was undertaken to determine calf-level factors that affect performance (growth) between birth and 14 months of age in a convenience sample of approximately 3300 female Holstein calves born in 1991 on two large Florida dairy farms. Data collected on each calf at birth included farm of origin, birth date, weight, height at the pelvis, and serum total protein (a measure of colostral immunoglobulin absorption). Birth season was dichotomized into summer and winter using meteorological data collected by University of Florida Agricultural Research Stations. Data collected at approximately 6 and 14 months of age included age, weight, height at the pelvis, and height at the withers. Growth in weight and stature (height) was calculated for each growth period; growth period 1 (GP1) = birth to 6 months, and growth period 2 (GP2) = 6 to 14 months. Health data collected included date of initial treatment and number of treatments for the diseases diarrhea, omphalitis, septicemia, pneumonia and keratoconjunctivitis. After adjusting for disease occurrence, passive transfer of colostral immunoglobulins had no significant effect on body weight gain or pelvic height growth. Season of birth and occurrence of diarrhea, septicemia and respiratory disease were significant variables decreasing heifer growth (height and weight) in GP1. These variables plus farm, birth weight and exact age when ‘6 month’ data were collected explained 20% and 31% of the variation in body weight gain and pelvic height growth, respectively, in GP1. The number of days treated for pneumonia before 6 months of age significantly decreased average daily weight gain in GP2 (P < 0.025), but did not affect stature growth. Treatment for pneumonia after 6 months of age did not significantly affect weight or height gain after age 6 months. Neither omphalitis nor keratoconjunctivitis explained variability in growth in either of the growth periods.     

Waldshutz und Aufforstng in Brafilien

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