Genetic Diversity in Tall Fescue Ecotypes from Alabama I. Maturity, Morphological Traits, and Disease Reaction

Abstract

There is a large hectarage of tall fescue in Alabama. Recognition of the deleterious effects of the endophytic fungus Acremonium coenophialum has resulted in substantial acceptance of new endophytefree cultivars. Destruction of old pastures and the concomitant loss of potentially valuable adapted germplasm could be a valid cause for concern. The objectives of this study were to evaluate genetic variation for maturity and plant morphological traits, both among and within tall fescue cv. 'Kentucky 31' populations from 18 to 38 year-old pastures in Alabama. Ten populations of approximately 50 plants each were collected from old Alabama tall fescue pastures. Two pastures were sampled in each of five counties, representing the five major land use areas of the state. In 1990, spaced plants of all populations were evaluated at heading time for maturity, morphological, and disease traits at two locations in central Alabama. Endophyte infection level of the populations ranged from 2 to 100 %. Maturity was highly correlated with tiller length and flag leaf width and was used as a covariate for these traits in the analysis of variance. Leaf rust and net blotch ratings were negatively correlated. Significant variation among populations was observed for maturity and flag leaf dimensions, most variation being due to differences among source counties. Significant variation was observed within all populations for maturity and morphological traits, but only in seven populations for leaf rust. No within-population variation was detected for net blotch. The average precipitation for the month of May explained 81 % of the variation among populations for maturity. Age of the pasture sampled had a significant effect on tiller diameter (r^ = 0.55), and latitude of the pasture sampled was the best individual predictor of leaf width (r^ = 0.42). This study reveals that considerable genetic diversity, largely influenced by climatic conditions, exists among 'Kentucky 31' tall fescue ecotypes from Alabama.

Population Differentiation, Spatial Variation, and Sampling of Tall Fescue under Grazing

“…Maturity in Ky 31–derived populations generally fits these constraints. Eight out of 10 Ky 31–derived populations in a study by van Santen and Collins (1991) had broad‐sense heritabilities greater than or equal to 0.74.…”

“…Vaylay and van Santen (1999) observed significant genetic diversity among tall fescue populations derived from original seed lot, ungrazed survivors, and survivors of the same genetic background after two years of grazing for two experimental populations, but not in the old cultivar Ky 31. Because Ky 31 is an old cultivar, only two years of exposure to grazing is unlikely to cause drastic genetic shifts; however, considerable genetic diversity among Ky 31 ecotypes collected in Alabama from pastures with ages ranging from 18 to 38 years was reported by van Santen and Collins (1991) These differences among populations were largely attributed to climatic variables such as long‐term normal precipitation and temperature. The material used in the present study was Ky 31, which, although subjected to six years of different pasture management treatments, showed no significance among different management treatments.…”

Performance of Endophyte Infected Tall Fescue in Europe and North America

“…Thus, it is perfectly adapted to the climatic "transition zone" of the United States where summers are too hot and humid for most other perennial cool season grasses [ 28 , 45 ]. The adaptive capacity of KY-31 to variable environmental conditions might be related to considerable diversity detected among KY-31 genotypes that may partly be influenced by climatic conditions [ 46 ]. For example, in environments characterized by long and harsh winters, juvenile seedlings are prone to winterkill and some genotypes to poor performance.…”

Tall fescue in Australia and New Zealand

“…There remain large resources of untapped genetic variation in collections of tall fescue (de Araujo et al 1983;Burner et al 1988;van Santen & Collins 1991 for recent examples), and most tall fescue breeding pools in the world have probably been through very few generations of selection. The intriguing potential of hybridisation with Lolium still attracts, with new methods available (Scott & White 1988).…”