Estimating Genetic Effects of Rapid Tillering Rate and Rhizome Formation in Tall Fescue (Lolium arundinaceum (Schreb.) Darby.) Using Polycross.

A polycross mating design is an efficient method to inter-pollinate perennial grass species and to evaluate quantitative genetic information. A polycross mating design was used to evaluate genotype’s combining ability for growth habit in tall fescue. Different types of growth habit (bunch type, rapid tillering type and rhizomatous type) were reported in tall fescue. Bunch types predominantly produce vertical tillers and limited lateral spread; rapid tillering types produce lateral tillers and cover more ground surface than bunch types; and rhizome types produce rhizomes with limited number of tillers in tall fescue. Fourteen genotypes were selected based on their growth habits and two clones from each genotype were grouped together in a polycross block to allow inter-pollination in isolation. Twenty four progenies from each clone of every genotype were planted in a mowed spaced-plant in a completely randomized block design and four replications. Three clones of each genotype in each replication were planted in the trial. The rhizome formation (number of rhizomes per plant), rapid tillering (number of tillers per 7.62 cm plug size) and ground coverage (average of length and breadth (cm)) were measured on each individual plant in the summer 2012 and 2013. Collected data was analyzed for the analysis of variance, narrow sense heritability, general combining ability of each parent, and predicted gain from selection based on the half-sib progeny testing. Significant positive GCA estimates were found for rhizome formation, rapid tillering and ground coverage in tall fescue. A low narrow sense heritability (0.24 ± 0.04) was estimated for rhizome formation, whereas moderate (0.51 ± 0.098) to moderately high (0.57 ± 0.08 (2011); 0.62 ± 0.08 (2012)) narrow sense heritability was estimated for rapid tillering rate and ground coverage, respectively. Significant negative correlation coefficient was found between rapid tillering rate and rhizome formation and between rhizome formation and ground coverage. Tall fescue showed genetic variation in growth habits which would aid in development of superior tall fescue cultivars and it’s utility to different environments.