No abstract

Two mail surveys were carried out in Denmark and the Eastern Corn Belt, USA in 2002. Questionnaires were sent to 580 farmers who had used precision agriculture (PA) and 198 responses were received. The surveys focused on the current status of use of PA in both countries, including: PA practices, equipment and software, Internet and e-mail use, information sources for PA, satisfaction level from service providers, data handling, interpretation, storage and ownership, value of data for decision making, changes in management practices, desired information and services, and the next planned step in the practice of PA. The survey results showed more similarities in practicing PA between the two countries than differences. Time requirement and high cost of data handling were cited as the main problems. Survey respondents found soil maps to be more valuable than yield maps in management decisions. About 80% of the respondents would like to store the PA data themselves. The majority of the respondents indicated that they have changed their management practices due to PA, but not substantially. Some 90% of the respondents used the Internet and e-mail for agricultural purposes, but only a small number for PA websites.

No abstract

The objective of this study was to determine the allocation of testing resources that would provide the greatest genetic improvement for fatty acid composition in soybean [Glycine max (L.) Merr.] oil. Twenty random lines of maturity groups I to IIl were evaluated in two replications at seven environments in Iowa and Puerto Rico. The percentages of palmitic, stearic, oleic, linoleic, and linolenic acid were determined for two consecutive injections (analyses) of oil into a gas chromatograph from two 20-seed samples from each of two plants per plot. Heritability estimate averages across fatty acids were 49% on a seed-sample basis, 55% for plants, 63% for plots, and 93% for entry means. Two consecutive analyses were of little or no value for increasing the heritability of the five fatty acids compared with one analysis of an oil sample. The heritabilities for individual plant evaluation were effectively increased by analyzing more than one seed sample per plant. Evaluation of one sample from multiple plants in a plot was more effective than multiple samples from one plant when evaluating a pure line. Plot-to-plot variation was so small that evaluation of multiple plants in one plot was as effective as evaluation of multiple replications. The use of multiple environments was effective for increasing the heritabilities of the five fatty acids.

The objective of this study was to determine the influence of genotype X environment interaction on selection for fatty acid composition among soybean [Glycine max (L.) Merr.] lines adapted to the northern United States when grown in tropical environments. Twenty lines of maturity groups I to IIl were grown in three environments in Iowa and four environments in Puerto Rico. Seeds from two replications in each environment were analyzed for the percentages of palmitic, stearic, oleic, linoleic, and linolenic acids. The line X environment interactions were significant for all fatty acids; however, the phenotypic and rank correlation coefficients for the average performance of lines between Iowa and Puerto Rico were all highly significant. The lines with the lowest average percentage of palmitic, stearic, linoleic, or linolenic acid were the same at both locations. The lines with the highest percentages of the fatty acids in Iowa were ranked within the three highest lines in Puerto Rico. The results indicate that selection for fatty acid composition in tropical environments should be effective for genetic improvement of lines adapted to the northern United States.