Three cycles of recurrent restricted phenotypic selection (RRPS) were carried out on two cultivars each of timothy (Phleum pratense L.) and orchardgrass (Dactylis glomerata L.). The selections were conducted at the E. A. Lods Agronomy Research Center of Macdonald Campus of McGill University from 1984 to 1988. Individual plant selections were based on dry matter yields of 25 plants. Within each of 16 grids, the five highest yielding genotypes were selected (i.e. 80 genotypes overall) and allowed to interpollinate. Equal weights of seeds from each of the 80 selected plants were mixed in each cycle. Evaluation trials were carried out in both sward and spaced stand from 1989 to 1993 to assess the effectiveness of selection in improving dry matter yield. Several other morphological and physiological characteristics of cycles were recorded to find possible associated changes. / Three cycles of RRPS were not effective in increasing forage dry matter yields. The lack of response may be due to a narrow genetic base in the source populations and/or the population size under selection may have been too small, resulting in inbreeding depression. Another explanation for the ineffective selection may be non-random pollination among selected plants. The selection for forage yield produced some minor changes in other characteristics. There was a tendency towards increased plant height and circumference in orchardgrass; however, for timothy, height and circumference were reduced by selection. Cycle 3 of Avon orchardgrass was one day later in maturity and there was also a tendency for later maturity for timothy.

No description available.

An optical weed sensing sprayer (WeedSeeker) was evaluated for making postemergence glyphosate herbicide applications in a Yuma, AZ lemon orchard. In addition, mechanical (disk and Perfecta cultivator) and chemical weed control strategies were compared. Results were fairly similar; however, the use of the WeedSeeker units combined with a preemergence herbicide (H1) increased weed control three fold compared to disking (D) and perfecta (P1). Additionally, when the WeedSeeker units were used in conjunction with preemergence herbicides, spray volume was reduced by 66% compared to a conventional sprayer and by 57% when used for postemergence applications only. There was a relationship between weed ground cover and the area sprayed by the WeedSeeker units indicating that maximum postemergence herbicide savings will occur at low weed densities or less than 10% groundcover. The use of a sprayer with an improved suspension system allowed for faster spraying speeds than were possible with the tractor mounted sprayer. Weed control was similar for the conventional and the WeedSeeker sprayer. However, yields were variable for both years. Future investigations will include efforts to develop crop budgets based on experimental operations

No description available.

Master of Agribusiness / Department of Agricultural Economics / Mykel Taylor / Choosing a viable long-run crop investment can be risky and time consuming for farmers. The high establishment costs and risk for perennial tree crops like cherries require producers to conduct careful analysis prior to investing. Farmers must not only look to prices today but to the long term price trends that are likely affect the investment profitability. This thesis is an investment analysis on planting twenty-five acres of Sweetheart cherries in Washington State. The purpose is to calculate the total net present value over the commercially productive life of the cherry trees. Prices received by growers for sweet cherry production can fluctuate. Sweet cherries are also susceptible to yield volatility. Therefore, a sensitivity analysis was calculated that shows the changes in price and yield and its effect on net present value. Sweet cherry production for fresh market is also labor intensive. Changes in labor supply and minimum wage can affect a farmers profit margins. This thesis evaluates the risk of a wage shock to the total net present value of the investment. The net present value calculated was found to be positive, making planting Sweetheart cherries a viable option for Hillslide Orchards. The internal rate of return was favorable at 12.30% return. Yield risk was relatively low in this model showing positive net present values at 60% over base yield and still positive at 40% below base yields. The price risk was found to be slightly higher with negative net present values below $1.00 or 20% below the base price. It is important to note that this model represents planting a block of Sweetheart cherries within an existing operation. There are additional costs that would be incurred for other farm operations, not modeled here that could decrease the overall profitability under alternative planting scenarios.

Experiment Station Road is an original work of fiction serving as a collection of short stories set in Hayford, Oregon and Las Vegas in 1962-1972. Each story presents the point of view of a resident in Hayford. The stories are written to function independently, but when read as a collection present insight to cultural diversity, intricate relationships and the ignorance of prejudice.

A citricultura mundial enfrenta novos desafios, principalmente, em função do surgimento de doenças, encurtamento da vida útil dos pomares e maiores exigências sócio-ambientais por parte dos consumidores. Neste contexto, práticas como diversificação de porta-enxertos, irrigação e adensamento dos pomares são relevantes. Avaliou-se o desempenho da limeira ácida Tahiti cultivada com e sem irrigação. Em cada condição foram estudados 12 porta-enxertos e um interenxerto. As parcelas foram distribuídas seguindo o delineamento aleatorizado em blocos, com quatro repetições e uma planta por parcela. Os porta-enxertos influenciaram no vigor das plantas, especialmente, o trifoliata Flying Dragon que apresentou sua altura diminuída em aproximadamente 47%, em relação ao limão Cravo. As plantas sobre os porta-enxertos mais vigorosos apresentaram alta produtividade e maior receita quando cultivadas sem irrigação, destacando-se especialmente a citradia 1646 e o citrange Morton. As plantas sobre os portaenxertos menos vigorosos apresentaram melhor desempenho, em termos de produtividade e receita bruta, quando irrigadas, destacando-se o citrange Carrizo tetraplóide, citrange Troyer tetraplóide, citrumelo Swingle, trifoliata Davis A e trifoliata Flying Dragon. As plantas sobre o citradia 1708 apresentaram alta produtividade e receita bruta em ambas as condições (com ou sem irrigação). O efeito do interenxerto sobre o vigor das plantas foi dependente do porta-enxerto. Plantas interenxertadas sobre trifoliata Davis A foram maiores àquelas sem interenxerto, enquanto plantas interenxertadas sobre limão Volkameriano Catania 2 foram menores em relação àquelas sem interenxerto. / The citrus industry worldwide is facing new challenges mainly due the outbreak of diseases, shortening of orchard life and larger social and environmental demands from consumers. In this context, practices such as diversification of rootstocks, irrigation and high density planting are relevant. The performance of Tahiti lime under irrigated and non-irrigated conditions was evaluated. In each condition, 12 rootstocks and one interstock were studied. The plots were distributed in randomized complete blocks design with four replications and one plant per plot. Rootstocks influenced the plant vigor, particularly the Flying Dragon trifoliate which plant height was reduced by approximately 47% compared to Rangpur lime. Trees on more vigorous rootstocks showed high yield and increased gross income when grown without irrigation, stood out especially 1646 citradia and Morton citrange. The plants on less vigorous rootstocks showed better performance in terms of yield and gross income, when irrigated, the highlights were the Carrizo citrange tetraploid, Troyer citrange tetraploid, Swingle citrumelo, Davis A trifoliate and Flying Dragon trifoliate. Plants on citradia 1708 showed high yield and income in both conditions (with or without irrigation). The effect of interstock on plant vigor was dependent of rootstock. Interstocked plants on Davis A trifoliate were higher than those without interstock. On the other hand, interstocked plants on Volkamer Catania 2 lemon were less vigorous than those without interstock.

A citricultura mundial enfrenta novos desafios, principalmente, em função do surgimento de doenças, encurtamento da vida útil dos pomares e maiores exigências sócio-ambientais por parte dos consumidores. Neste contexto, práticas como diversificação de porta-enxertos, irrigação e adensamento dos pomares são relevantes. Avaliou-se o desempenho da limeira ácida Tahiti cultivada com e sem irrigação. Em cada condição foram estudados 12 porta-enxertos e um interenxerto. As parcelas foram distribuídas seguindo o delineamento aleatorizado em blocos, com quatro repetições e uma planta por parcela. Os porta-enxertos influenciaram no vigor das plantas, especialmente, o trifoliata Flying Dragon que apresentou sua altura diminuída em aproximadamente 47%, em relação ao limão Cravo. As plantas sobre os porta-enxertos mais vigorosos apresentaram alta produtividade e maior receita quando cultivadas sem irrigação, destacando-se especialmente a citradia 1646 e o citrange Morton. As plantas sobre os portaenxertos menos vigorosos apresentaram melhor desempenho, em termos de produtividade e receita bruta, quando irrigadas, destacando-se o citrange Carrizo tetraplóide, citrange Troyer tetraplóide, citrumelo Swingle, trifoliata Davis A e trifoliata Flying Dragon. As plantas sobre o citradia 1708 apresentaram alta produtividade e receita bruta em ambas as condições (com ou sem irrigação). O efeito do interenxerto sobre o vigor das plantas foi dependente do porta-enxerto. Plantas interenxertadas sobre trifoliata Davis A foram maiores àquelas sem interenxerto, enquanto plantas interenxertadas sobre limão Volkameriano Catania 2 foram menores em relação àquelas sem interenxerto. / The citrus industry worldwide is facing new challenges mainly due the outbreak of diseases, shortening of orchard life and larger social and environmental demands from consumers. In this context, practices such as diversification of rootstocks, irrigation and high density planting are relevant. The performance of Tahiti lime under irrigated and non-irrigated conditions was evaluated. In each condition, 12 rootstocks and one interstock were studied. The plots were distributed in randomized complete blocks design with four replications and one plant per plot. Rootstocks influenced the plant vigor, particularly the Flying Dragon trifoliate which plant height was reduced by approximately 47% compared to Rangpur lime. Trees on more vigorous rootstocks showed high yield and increased gross income when grown without irrigation, stood out especially 1646 citradia and Morton citrange. The plants on less vigorous rootstocks showed better performance in terms of yield and gross income, when irrigated, the highlights were the Carrizo citrange tetraploid, Troyer citrange tetraploid, Swingle citrumelo, Davis A trifoliate and Flying Dragon trifoliate. Plants on citradia 1708 showed high yield and income in both conditions (with or without irrigation). The effect of interstock on plant vigor was dependent of rootstock. Interstocked plants on Davis A trifoliate were higher than those without interstock. On the other hand, interstocked plants on Volkamer Catania 2 lemon were less vigorous than those without interstock.

The results of the 3-year project successfully indicated that petroleum-derived spray oils can be used for effective control of a range of citrus pests including citrus leafminer, Asiatic citrus psyllid, chaff scale, red scale, citrus red mite. The results suggested that it should be possible, through use of horticultural and agricultural mineral oils and enhanced natural enemy activity, to reduce the number of pesticide sprays applied annually in China from 14-16 sprays to significantly fewer sprays in most regions. The results are also valuable as references for the implementation of citrus integrated pest management programs in Australia and other citrus-growing countries. However, despite extensive use of PDSOs in citrus and other crops since the late 1800s, few studies have been undertaken to determine their disruptive effects on orchard ecosystems or to compare their effects with those of synthetic pesticides, and these studies are limited in their sc / Doctor of Philosophy (PhD)

This study focuses on the soil- and water-borne plant pathogen Phytophthora cinnamomi Rands and the phenomenon of P. cinnamomi suppressive soil. In particular, this thesis reports on the outcome of field surveys and glasshouse assays undertaken to locate P. cinnamomi suppressive soils and to confirm the involvement of biological processes in suppression. The potential role of cellulase and laminarinase in suppression was investigated and a molecular technique known as length heterogeneity PCR (LH-PCR) was used to analyse the structure and diversity of bacterial and fungal communities in avocado orchard soils that were suppressive and conducive to P. cinnamomi. Four avocado orchards with P. cinnamomi suppressive soils were identified and soils were ã-irradiated to destroy their suppressive capacity, thus confirming biological suppression. Suppression was also partially transferred to ã-irradiated and conducive soils by mixing with 10% suppressive avocado soils. Cellulase and laminarinase activities measured in avocado orchard soils inoculated with P. cinnamomi were not associated with disease severity in lupin seedlings during glasshouse assays involving the same soil samples. Minor shifts in bacterial and fungal community structure were observed in response to mixing conducive and irradiated soils with suppressive soils. This was associated with decreased disease severity in avocado seedlings in these treatments. The shift in bacterial community structure was partially determined by the appearance and increased abundance of several bacterial 16S rDNA sequences, which were unique to the suppressive soils, in the mixed soil treatments. It is suggested that the bacteria and fungi from which these sequences originated may be involved in suppression and further work should be undertaken to determine their identity and confirm their potential role in the development and maintenance of P. cinnamomi suppressive soils. / Doctor of Philosophy (PhD)