The PCR method has proved to be an invaluable tool for the specific and sensitive detection of genetically modified material (e.g., Roundup Ready Soybean and Bt-176 "Maximizer" Maize) in foodstuffs. The first step in the procedure, namely the purification of nucleic acids from the sample, is often the deciding factor in the production of meaningful results. In this study, we present two procedures that enable an efficient isolation of trace amounts of genetic material from both raw and highly processed foodstuffs. We show that for optimal, PCR-ready DNA purification from highly processed foodstuffs and PCR inhibitor-rich substances--such as cocoa-containing products--adapted protocols for the QIAGEN QIAamp DNA Stool Mini Kit can be utilized. For complete DNA isolation from raw foodstuffs, a protocol using the DNeasy Plant Mini Kit is presented.

Wide variation in soybean [Glycine max (L.) Merrill] seed quality is often observed by seedsmen. This investigation was conducted to determine the effect of the date of harvest maturity (first time the seed moisture declined to less than 14%) on seed germination, seed vigor, and infection of seed by fungi. Cultivars varying in maturity from Group II to V were planted in a Maury silt loam soil (Typic Paleudalfs, fine, mixed, mesic) during three periods (mid‐May, mid‐June, and early July) for 4 years (1976 to 1979). Seed were hand harvested at harvest maturity and evaluated for germination, vigor, and seedborne fungi. A wide range in seed quality was observed across the 4 years, with approximately 25% of the 54 cultivar‐planting date combinations having unacceptable seed germination and vigor at harvest maturity. Seed infection by Phomopsis sp. was the major factor influencing seed quality and was negatively correlated (r = −0.88) with seed germination. Phomopsis sp. seed infection decreased and standard germination increased with later dates of harvest maturity. Seed vigor also increased as harvest maturity was delayed, but was not closely correlated with the incidence of Phomopsis sp. seed infection. Later maturing cultivars (‘Kent’ and ‘York’) produced seed of the highest quality regardless of planting date. Delaying the planting date of early and mid‐season cultivars (‘Beeson’, ‘Williams’, and ‘Cutler 71’) delayed harvest maturity which improved seed germination and vigor and reduced the levels of seed infection by Phomopsis sp. Differences in seed quality and seed infection by Phomopsis sp. between two genotypes of nearly identical maturity (OX‐303 and Beeson) grown in similar environmental conditions provided evidence of genetic variability for improving seed quality.

A visual indicator of physiological maturity (maximum dry seed weight) in soybean [Glycine max (L.) Merrill] would be useful to researchers and soybean producers. Experiments were conducted utilizing two cultivars in the greenhouse and six cultivars in the field to characterize the color of soybean seeds and pods at physiological maturity. In greenhouse experiments where plants were exposed to 14CO2 as they neared maturity, it was found that the 14C content of the seed decreased as the yellow coloration of the seed coat increased. Practically no 14CO2 was recovered from yellow seeds, regardless of the color of the pod, suggesting that the seed stops importing assimilates and is physiologically mature when it is completely yellow (free of green color). Normally, yellow seeds were found only in yellow or brown pods. The respiration rate of seed, measured as CO2 evolution, declined rapidly as the seedcoat began to turn yellow and reached a low level when the seed were completely yellow at a seed moisture content of 55 to 60%. Physiological maturity of an entire plant, estimated from dry seed weight data in the field, occurred when 26% of the seed were yellow and 35% of the pods were yellow or brown. The seed moisture content ranged from 54 to 62%. The date of physiological maturity estimated in the field was slightly early in comparison to complete physiological maturity (all seed completely yellow) due to the sampling variation associated with estimating dry seed weight and the variation in pod maturity on an individual plant. The data suggest that the occurrence on the main stem of one normally colored mature pod per plant represents a useful and acceptable indicator of physiological maturity, even though all the pods or seed were not completely yellow at this stage of development.

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Prohexadione-Ca (BAS 12511W or Apogee™ Plant Growth Regulator) acts within a plant by blocking the biosynthesis of growth-active gibberellin. The result is decreased cell and shoot elongation; thus, vegetative growth in apple trees can be reduced. Air blast applications of prohexadione calcium were made in the Spring 1998 in commercial orchards. Application rate was 125 ppm a.i. applied twice beginning at 5 to 12 cm of new shoot growth. Reduction of shoot growth averaged 45% across locations. As a result of reduced vegetative growth, dormant pruning was reduced. In total, significant benefits to the grower included reduced pruning costs in addition to other positive effects such as improved light penetration and enhanced resistance to some pathogens. Research will continue with the effect of prohexadione-Ca on pruning in multiple year studies.