To obtain additional information on the effectiveness of recurrent selection for specific combining ability in maize (Zea mays L.), we evaluated seven cycles of selection for combining ability with the single‐cross tester F44 ✕ F6. Grain yield, lodging resistance, and low ear height were the main selection criteria.Seed of the selected population from each cycle was stored and later evaluated for combining ability with the original tester, F44 ✕ F6, and with an unrelated synthetic. The evaluation with F44 ✕ F6 indicated that the seven cycles of selection resulted in 18% more grain yield, 9% lower ear height, and 35% less lodging. Performance was similar when the same selected populations were crossed with an unrelated synthetic. This suggests that gains for all traits resulted from increasing the frequency of genes with additive effects.These results and others previously reported for inbred testers suggest that narrow‐base testers are effective for improving general as well as specific combining ability, and that it is possible to change such testers in a recurrent selection program with little loss in accumulated improvement.

Inbred testers have been used successfully for the improvement of general combining ability (GCA) in maize (Zea mays L.), but they are not generally accepted as being equal to testers with a broad genetic base for this purpose. The objective of this study was to compare estimates of GCA obtained by use of the two tester types. Ten parents (nine S2 lines and the original population) from one population were crossed in a factorial design with a like set of parents from another population, and the resulting 100 crosses (10 involving each parent) were. tested at two locations. Significant estimates of GCA effects were obtained in both populations for grain yield, ear height, husk rating, and percentage erect plants at harvest. Specific combining ability (SCA) effect estimates were significant, but much smaller than those for GCA. Crossbred performance values for parents (testers) were compared by correlation analyses with predicted values based on GCA estimates for both parents. Correlation coefficients for the 18 inbred parents were similar to those for the two broad‐base populations, which suggests that the former were in general as effective as the latter for ranking parents for GCA. These results provide further evidence that inbred testers can be used successfully for improving GCA as well as SCA in maize.

The stabilities of four peanut (Arachis hypogaea L.) multiline populations plus their component lines were determined over a 4‐year period, 1980‐1983, at two locations in Florida. The study was undertaken to provide information concerning the stability of both yield and market quality factors of multiline cultivars vs. the component lines which form them. Each multiline was obtained from a different cross, and was formed by compositing in equal proportions the seed from four early generation, phenotypically similar sib‐lines. The interactions of genotype (population) with environments was highly significant (P = < 0.01) for pod yield and five quality factors (percentage fancy pod, shelling percentage, weight per 100 seeds, percentage of extra large kernels and sound mature kernel yield) studied. Large differences in yield and market quality traits were not found between sib‐lines. However, differences were found in stability estimated from regression coefficients and deviation from regression of multilines compared to their component lines, possibly due to the buffering action resulting from greater genetic variability. Multilines did not have greater stability in all cases, but the difference between the multiline and its least stable component line was generally greater than the difference between the multiline and its most stable component line. This research indicates that the chance of improving the yield stability and market acceptibility of peanut cultivars is increased when the multiline approach is used.

Creeping bluestem (Schizachyrium stoloniferum Nash.) is a rhi-were reported by Lewis (1975). In April forage averaged 10.2% zomatous native grass that is the dominant species on many Flor-protein and 54.0% IVDMD, but declined to 3.2% protein and ida rangelands. To evaluate its grazing potential, dry matter yield, 34.0% IVDMD by October. in vitro organic matter digestibility (IVOMD), crude protein, neu-In order to evaluate the potential of creeping bluestem, additral detergent fiber (NDF), acid detergent fiber (ADF), and acid tional information is needed about its seasonal yield and quality. detergent lignin (ADL), were measured in plants cut at 10 and 20 This investigation was designed to determine the dry matter yield, cm stubble heights during 70-day-intervals from June to October in vitro organic matter digestibility (IVOMD), crude protein, neu-(summer), August to December (summer-fall), and October to tral detergent fiber (NDF), acid detergent fiber (ADF), and acid February (winter). Winter yields were significantly greater (2,090 detergent lignin (ADL) in plants cut at 10 and 20 cm above the soil kg/ha) than summer yields (1,600 kg/ha) with summer-fall yields during 70-day intervals from June to October, August to intermediate (1,860 kg/ha). After 3 years there was a significant December, and October to February. decline in dry matter in plants cut at 10 cm, but yield was sustained in plants cut at 20 cm. Herbage regrowth in July to August was Materials and Methods high in IVOMD (37.8%). Crude protein and IVOMD percentages were also greater in November to December regrowth (7.5 and Experimental work was conducted at the University of Florida's 36%, respectively) and January to February regrowth (6.8 and Ona Agricultural Research Center which is 27" 55'N and 81" 55'W.

Florida's soils are low in nutrients, which is reflected in the low mineral content of range forages. This investigation was designed to determine the contents of P, K, Ca, Mg, Fe, Mn, Zn, and Cu and the Ca: P ratio in creeping bluestem (Schizachyrium stoloniferum