Soybean is one of the most important legumes of the world. Soybean plants are affected by several biotic and abiotic factors as well as insect pests and diseases which lower the quality and production of the crop. In order to overcome these biotic and abiotic challenges, a systematic crop improvement plan has to be followed in order to enhance crop production which involves the use of new technologies and developing new cultivars with desirable qualities. With the completion of the soybean genome sequencing project, it is anticipated that access to desirable gene sequences will advance soybean improvement efforts. Two general approaches for in vitro plant regeneration are used; somatic embryogenesis from immature embryos and organogenesis from mature parts of the plant and seeds. In vitro regeneration in soybean depends upon several physical, biochemical and genetic factors. Different genotypes respond differently to the method of regeneration used. Pyramid soybean is used in several breeding and mapping projects but does not have a regeneration procedure worked out. The goal of our project was to develop an in vitro regeneration procedure for soybean cv. Pyramid that would be amenable to genetic manipulations. We excised cotyledons and embryos from germinating seeds and induced callus with various concentrations of 2,4-D and NAA, used alone or in combination. 2,4-D at 3-21 M concentrations in the culture media produced 100% callus induction from cotyledons. After callus formation we transferred them to BAP and Kinetin containing culture media and obtained roots and shoots; 5 M BAP was the most effective for that purpose. Fully developed plants were transplanted to the pots in less than three months where they produced healthy seeds in July.
Barren soil borders, weed border treatments, and caged barren soil were evaluated for their effect on movement of the twospotted spider mite, Tetranychus urticae Koch, into peanut (Arachis hypogaea L.) fields. In field cage tests when a 3, 4.5, or 6 m strip of barren soil separated a source of mite-infestation from initially mite-free peanut, mite damage to peanut was inversely related to the distance of barren soil crossed. In uncaged field tests, similar barren soil borders did not prevent mite movement into peanut fields, however, the number of mites were inversely related to the distance from the field border. There were no significant differences among weed border treatments and total numbers of mites entering peanut fields over time. There were, however, differences among weed border treatments on early mite movement and establishment trends into peanut fields. Mowing weed borders significantly increased the number of aerially dispersing twospotted spider mites within the adjacent peanut field.
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