INHERITANCE OF COLD TOLERANCE IN ST. AUGUSTINEGRASS

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a popul ar southern turfgrass with poor cold tolerance. The objective of this study was to evaluate the inheritance of cold tolerance in St. Augusti negrass, Eight diploid genotypes were chosen as parents for a complete diallel mating with reciprocals. Three replications of each single cr oss and the parents were planted in a field trial at Mississippi State , MS, and winter survival was evaluated from 1994 to 1996. Differentia l thermal analysis was used to predict lethal low temperatures for par ents and single cross progenies. Lethal temperatures of parental genot ypes ranged from -3.65 to -5.25 degrees C. Combining ability analysis revealed that general combining ability was the largest source of vari ation for lethal temperature and winter survival. Specific combining a bility was significant only for winter survival in 1996. Reciprocal ef fects were significant for winter survival each year. Estimated narrow sense heritability was 0.58 for lethal temperature and ranged from 0. 70 to 0.98 for winter survival. Lethal temperatures were significantly correlated to winter survival of each year.