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With continued development of new and better herbicides for chemical weed control in soybeans, the potential exists for growing soybeans in very narrow rows (17 cm) without cultivation. The objective of this research was to examine the potential yield of soybeans [Glycine max(L.) Merr.] in 17‐cm rows under weed free conditions and also to determine the optimum seeding rate and relative yield of this row width compared to greater row widths. Up to nine cultivars were grown in three different row widths and at five different populations in field plots in central Illinois over a period of 6 years. When seeding rate was low enough to prevent lodging, yield advantages of 10 to 20% (3 to 6 q/ha) were obtained from planting in 17‐cm rows compared to 50‐ or 75‐cm rows. Earlier maturing cultivars tended to be more responsive to 17‐cm rows, and under high yield conditions and irrigation, 30 to 40% (9 to 12 q/ha) yield responses were observed with one of the more responsive cultivars. The combination of early cultivars in 17‐cm rows provided the highest absolute yields. A seeding rate of 37.5 viable seeds per m2 was near optimum for most cultivars and for all three row widths tested. These results suggest that if an effective weed control program can be developed to control weeds in soybeans without cultivation, there would be a significant yield advantage from planting soybeans in 17‐cm rows.

Some determinate soybean [Glycine max(L.) Merr.] cultivars developed for the northern USA yield as well as the conventional indeterminate cultivars. The principal objective of this research was to compare morphological and physiological traits of the determinate cultivar ‘Elf’ with the indeterminate cultivar ‘Williams’ and a determinate isoline of the cultivar ‘Clark.’ Field experiments were conducted at Urbana, IL in 1976 on a Flanagan silt loam (fine, montmorillonitic, mesic Acquic Argiudoll) and at Wooster, OH in 1981on a Wooster silt loam (fine‐loamy, mixed, mesic Typic Fragiudolf). Plants from weekly samples taken from the 5th week after emergence until R7 were separated into leaflets, petioles, main stems, branches, pods from main stems, and pods from branches. Patterns of dry weight accumulation for the plant parts were estimated using regression techniques. Estimates of seed yield components were obtained from an adjacent set of experiments. The genotypes accumulated leaf, petiole, and total dry weight in a similar fashion. Williams accumulated more main stem dry weight than the determinate genotypes. However, the difference in main stem dry weight was partially compensated by a greater branch dry weight of the determinate genotypes. Although Williams produced more main stem nodes, the determinate genotypes set as many pods on the main stems as Williams. The determinate genotypes produced a greater number of pods and more seed weight from branches than Williams. In 1976, Elf accumulated reproductive dry weight at a greater rate than Williams or Clark (dt1). The apparent harvest index of Elf was greater than the other genotypes during both years. Seed yields did not differ in 1976, whereas the determinate genotypes yielded slightly less than Williams in 1981.

Four segregating soybean [Glycine max(L.) Merr.] populations were used to evaluate the effectiveness and efficiency of three selection procedures in isolating highyielding lines; early‐generation yield testing (EGT), pedigree selection (PS), and single‐seed‐descent selection (SSD). Lines were obtained from the PS procedure in the F4generation and from the EGT and SSD procedures in the F5generation. These lines were yield‐tested and selected in either the F6or F7generation in each procedure. In the F8generation of each cross the selected lines in each procedure were compared. The means of all selected lines, the means of the five highest‐yielding lines, and the highest‐yielding line from each population showed no consistent differences in procedures. The lines from the EGT procedure were consistently later in maturity than the lines from the other two procedures. This was attributed to the yield‐testing in unbordered plots in the early generations by the EGT procedure. The SSD procedure emerged as the most efficient procedure, because it required less selection effort than the EGT and PS procedures, allows a rapid advance of the early‐generation segregating populations, and did not use expensive yield‐testing until later generations, when yield‐testing is more efficient.

A soybean [Glycine max(L.) Merr.] breeding program which emphasized short stature was carried out to alleviate the effect of lodging in reducing seed yields. The primary approach taken was to cross high yielding indeterminate (Dt1) Cultivars grown in the northern United States with high yielding determinate (dt1) cultivars grown in the southern U.S. with selection in the resultant progeny for high yielding determinate plant types adapted to the Midwest. From 150 crosses each year determinate, short‐statured progeny were selected in the F2and subsequent generations and evaluated for yield, using an early‐generation testing procedure. Short‐statured selections with adaptation to high yield environments were developed that exceeded the yield of broadly adapted “universal” cultivars when grown in their specific area of adaptation. The determinate gene (dt1) and other genes which complement dt1from southern U.S cultivars were most useful in producing the high yielding short‐statuted types. Introducing the dt1gene from determinate isolines of indeterminate cultivars produced short‐statured progeny, but high productivity was not obtained. The addition of the E1gene in combination with dt1was also ineffective in producing high yielding short‐statured types. The short‐statured lines were more responsive to narrow rows and high seeding rates than indeterminate cultivars. Narrow row spacing (17‐cm) at a seeding rate of 75 seeds/m2produced maximum yields. The short‐statured lines, because of their determinate growth type, were less able to compensate for early season moisture streess than standard‐height cultivars. Thus the short‐statured types selected produced very high yields in good environments, but with some loss in yield in poor environments.

A larval antibiosis screening technique was applied to three soybean [Glycine max(L.) Merr.] populations to determine the inheritance of resistance to Mexican bean beetle [Epilachna varivestis(Mulsant)]. The F1, F2, and F3generations (five F3plants per F2plant) of crosses between ‘Williams’ (susceptible) and L76‐0049, L78‐608, and L76‐0328 (resistant) were screened along with the parents. Mean weight of surviving larvae after 10 d of feeding on detached leaves was used as the measure of antibiosis. The resistance of F1plants was intermediate to that of their parents. Data from the F1of Williams ✕ L76‐0049 and Williams ✕ L76‐0328 indicated a small degree of dominance for resistance. The distributions of F2and F3phenotypes were continuous and unimodal. Skewness toward susceptibility occurred in Williams ✕ L76‐0328, but symmetry was evident in the other crosses. Heritability estimates (single F2plant basis) ranged from 0.33 to 0.48 when calculated from F3data, and from 0.11 to 0.22 when calculated from the covariance of F2plants and their F3progeny. Estimates of heritability derived from F2and parental data were larger but had large standard errors. Gene number estimates by the method of moments, and frequency of recovery of parental phenotypes suggested that the number of segregating resistance loci was small. Provided selection was no more intense than 2.5%, expected genetic gain from selection among individual F2plants was greater if a large number of plants were screened with a single determination per plant than if one‐half or one‐third that number were screened with two or three determinations per plant, respectively.

Old constant estrous and young cycling control rats were injected with L-dopa, 200 mg/kg, for a period of 14 days. L-Dopa reinstated vaginal cycling in the old rats and it did not affect the vaginal cycling in young rats. Likewise, 200 mg/kg of L-tyrosine reinstated vaginal cycling. The effect of L-dopa on old rats was blocked by pimozide, by high doses of MK-486 and Ro 4-4602, and by fusaric acid. High doses of phenoxybenzamine or L-propranolol did not alter the L-dopa effect on old rats. A low dose of MK-486 or Ro 4-4602 increased the efficacy of L-dopa in reinstating vaginal cycling. These results suggest that L-dopa reinstates vaginal cycling in old rats by stimulating dopamine receptors. The possibility that a simultaneous stimulation of norepinephrine alpha and beta receptors and/or a decrease of central nervous system serotonin is necessary for this effect is discussed.

The Maturity Group II soybean [Glycine mar(L.) Merr.] cv. Corsoy often produces seed yields in central Illinois that are equal or greater than many full‐season, Maturity Group III cultivars. A field study was conducted during two growing seasons at Urbana, Ill. in order to gain a better understanding of the yield physiology of Corsoy. Dry matter accumulation patterns of various plant parts, leaf areas, seed yields, and seed yield components of Corsoy were compared with those of Maturity Group III cv. Williams. Corsoy accumulated seed dry weight more efficiently than Williams by producing seed yields as great as or greater than Williams with less leaf area and less total vegetative dry weight than Williams. Although Corsoy produced less leaf area than Williams, crop growth rates of Corsoy and Williams were similar. This suggested that Corsoy possessed a greater net assimilation rate than Williams. Although Corsoy reached harvest maturity (RS) 2 weeks earlier in the growing season than Williams, duration of the seed filling periods of Williams and Corsoy were similar. Differences in seed yield were attributed to differences in rates of seed dry weight accumulation per unit‐area. Corsoy accumulated reproductive (seed and pod wall) dry weight at a greater rate than Williams by setting a greater number of pods containing at least one seed. Corsoy initiated reproductive development earlier in the growing season than Williams which resulted in Corsoy accumulating less vegetative dry weight and leaf area than Williams. The results suggested that earlier reproductive development might enable the pod filling period to be lengthened without affecting the harvest maturity date.

Retinal nerve fibre layer (RNFL) photography is an established and integral tool in the management of ocular hypertensives and glaucoma suspects, and in assessing the management of glaucoma in an ophthalmic practice. When RNFL negatives are viewed for analysis, high-contrast negatives yield the most information. When positive prints are subsequently requested, the RNFL negatives are difficult to print. The use of an unsharp mask facilitates the transfer of all the high-contrast negative density range to the print. The use of an unsharp mask has been simplified so that it is quick and efficient and can be adapted for high-contrast negatives other than RNFL images.

Photosynthetic response curves to CO2concentration and light intensity were determined for the soybean varieties ‘Hark’ and ‘Chippewa‐64’. At light intensities above 5,380 lux, the photosynthetic rates of both varieties were limited by the CO2concentration of the surrounding atmosphere within the range investigated (270 to 1670 ppm). At normal atmospheric CO2concentration (300 ppm), photosynthesis of both varieties was light saturated at about 21,530 lux. At a CO2concentration of 1670 ppm, photosynthesis was not light saturated in either variety at the highest light intensity tested (75,350 lux). The photosynthetic rate of the variety Hark was higher than that of the variety Chippewa‐64 at 45 of the 48 combinations of light intensity and CO2 concentration tested.