An Evaluation of Herbicides for Broadleaf-Weed Control in Rapeseed: Efficacy, Phytotoxicity, and Soil Persistence Studies

At the recommended rates (1.0 lb/A for trifluralin, ethalfluralin, EL5261; 0.75 lb/A for dinitramine; 1.2 lb/A for nitrofen), none of the herbicides we evaluated in these studies reduced rapeseed stands, yields, or test weights. However, at higher rates (1. 5, 3.0 lb A), dinitramine reduced rapeseed stands, but this did not result in decreased yields. None of the other herbicides reduced rapeseed stand, yield, or test weights when applied at up to four times the recommended rate. No trifluralin residues were detected in rapeseed whole-plant or seed samples. All of the herbicides provided adequate control of common lambsquarters (Chenopodium album L.). Corn spurry (Spergula arvensis L.) was controlled by trifluralin. ethalfluralin. EL-5261, and nitrofen. All of the herbicides except nitrofen controlled chickweed [Stellaria media (L.) Cyrillo]. In 1979, 51 per cent of the trifluralin applied remained at the end of the growing season in one study while 26 per cent remained in another study. The rate of degradation at three sites in 1979 were as follows (greatest to least); Delta Junction, Matanuska Valley, Fairbanks. Degradation rates of trifluralin were not significantly different in three soil types or at two different application rates. Trifluralin showed no signs of leaching through the soil profile. In 1981, 25 per cent of the trifluralin, 8 per cent of the ethalfluralin, and 24 per cent of the EL-5261 applied remained at the end of the growing season. Despite the relatively long persistence of these preplant, incorporated herbicides, yields and test weights of barley planted in succeeding years were not reduced. A benefit of these persistent residues was control of broadleaf weeds in the succeeding barley crop

Performance of Agronomic Crop Varieties in Alaska 1978 –2002

There is no such thing as the perfect variety for Alaska. Some varieties are adapted to a wide range of climatic and geographic locations, while others are more specific in their adaptation. The change in elevation of a few hundred feet or a move of a few miles can have a considerable effect on the performance of any variety. Also, cultural practices such as tillage, fertilizer rates, planting date, seeding rate, pest control, and a multitude of other factors can also influence crop yields. This is especially noticeable in northern environments such as Alaska. For example, date-of-planting studies done by F.J. Wooding (1973) and C.W. Knight (1989) found that any date after the middle of May for planting an agronomic crop can result in delayed maturity, low yields, and low quality grain, even for the best adapted varieties for Alaska

Circular 82

The development of improved plant cultivars is accomplished through comprehensive plant breeding programs. Such programs: 1) evaluate genetically-diverse germplasm in order to identify superior-performing genotypes; 2) create new genetic recombinations from crosses or other means using selected parental genotypes; 3) evaluate segregating progeny from these families while exerting selection pressure for desirable characteristics; and 4) identify superior-performing genotypes in yield trials conducted in multiple environments. This circular documents the current status of research in cultivar development associated with the Alaska barley breeding program

Circular 85

The development of improved plant cultivars is accomplished through comprehensive plant breeding programs. Such programs: 1) evaluate promising germplasm to identify superior-performing genotypes for use as parents; 2) create new genetic recombinations from these selected parental genotypes using crossing or other means; 3) evaluate segregating progeny from the resulting families while exerting selection pressure for desirable characteristics; and 4) identify superior-performing cultivars in yield trials conducted across multiple environments. This circular documents the current status of research in cultivar development associated with the Alaska barley breeding program

Circular 92

The development of improved plant cultivars is accomplished through comprehensive plant breeding programs. Such programs: 1) evaluate promising germplasm to identify superior-performing genotypes for use as parents; 2) create new genetic recombinations from these selected parental genotypes using crossing or other means; 3) evaluate segregating progeny from the resulting families while exerting selection pressure for desirable characteristics; and 4) identify superior-performing cultivars in yield trials conducted across multiple environments. This circular documents the current status of research in cultivar development associated with the Alaska barley breeding program

Fate of fertilizer nitrogen in a subarctic agricultural soil

Thesis (Ph.D.) University of Alaska Fairbanks, 1988A nitrogen balance approach was taken to determine the fate of fertilizer nitrogen in a subarctic agricultural soil. Urea and calcium nitrate fertilizers were compared in a three-year spring barley recrop field study. Methods of N application included incorporating the N fertilizer into the soil during spring tillage versus broadcasting it on the soil surface after planting. \sp{15}N labeled urea was applied on one-meter square subplots within the main fertilizer plots. Nitrogen transformations and movement were monitored with ammonia volatilization traps, suction cup lysimeters, deep soil cores, plant tissue samples, and grain samples. Environmental data including precipitation, soil temperatures and soil moisture tensions were collected. Fertilizer N loss by ammonia volatilization was negligible, amounting to only a few grams N/ha/day. Rate of urea hydrolysis was rapid in the cool soil and was not considered to be a limiting factor affecting N availability to the crop. There appeared to be a little nitrate leaching during the growing season, but some may have occurred between cropping seasons. Only 16 percent of the fertilizer N could not be detected when the crop was physiologically mature, and that loss was accredited mostly to denitrification. Fertilizer N use efficiency, determined by the Difference Method, was 73 and 60 percent for calcium nitrate and urea, respectively. When the crop was physiologically mature, average fertilizer N recovery rates determined by the Isotope Dilution Method were: 40 percent in the plants, 43 percent immobilized in the soil, 1 percent available in the soil, and 16 percent unrecovered. Barley yields were not significantly affected by N source, but plants took up more N where nitrate had been applied. Position of N placement had little effect on either N loss or barley yield, but the surface application of N resulted in delayed barley maturity when spring rains were deficient

Why are African American Males Dropping out of High School? A Case Study

When hearing the question; why are African American males dropping out of high school? A number of things can come to mind as to what may or may not be some of the reasons. What I have done in this capstone, is set out with the objective of narrowing down the list of possible answers to the research question. To the most poignant research based issues currently afflicting African American male youth, and contributing to the rise in the dropout rate of African American male youth

Next Generation Teaching and Learning ??? Technologies and Trends

The landscape of teaching and learning has been radically shifted in the last 15 years by the advent of web technologies, which enabled the emergence of Learning Management Systems (LMS). These systems changed the educational paradigm by extending the classroom borders, capturing and persisting course content and giving instructors more flexibility and access to students and other resources. However, they also constrained and limited the evolution of teaching and learning by imposing a traditional, instructional framework. With the advent of Web 2.0 technologies, participation and collaboration have become predominant experiences on the Web. The teaching and learning community, as a whole, has been late to capitalize on these technologies in the classroom. Part of this trend is due to constraints in the technology (LMS), and part is due to the fact that participatory media tools require an additional shift in educational paradigms, from instructional, on-the-pulpit type of teaching, to a student-centered, adaptive environment where students can contribute to the course material and learn from one another. This panel will discuss the next generation of teaching and learning, involving more lightweight, modular systems to empower instructors to be flexible, explore new student-centered paradigms, and plug and play tools as needed. We will also discuss how the iSchools are and should be increasingly involved in studying these new forms, formulating best practices and supporting the needs of teachers as they move toward more collaborative learning environments