Theme 2: Forage--Oral Sessions

Description

Warm-season (C4) perennial grasses are grown over millions of hectares in the Southeastern United States. These grasses produce optimal growth at 30 to 38°C diurnal temperature. Bermudagrass (Cynodon sp.) has been adopted as the preferred forage for many livestock and hay producers. Compared to other native and introduced warm-season perennial grass species, improved bermudagrass varieties produce high biomass with enhanced digestibility for ruminant grazing or feed. Until the 1930’s pastures in the region consisted of unimproved ‘common’ bermudagrass (Cynodon dactylon (L.) Pers.) that had been introduced earlier. However, in the early 20th century, new germplasm, including stargrass (C nlemfuënsis Vanderyst) was collected, primarily from Africa. This germplasm provided a source for major improvements in yield and digestibility. Unfortunately, stargrass is not cold tolerant, limiting it to regions between 30°N and 30°S. Intercrossing of C. nlemfuënsis with C. dactylon has produced highly successful cultivars, such as Tifton 85, which can survive at northern latitudes of at least 35°. However, there has been a desire to extend adaptation further north into the warm-season/cool-season grass transition zone. This would require a combination of breeding to improve cold tolerance in clonally-propagated varieties and development of seeded varieties that could be re-seeded following extremely cold winters. Earlier work at Oklahoma State University indicated that some cultivars had significantly different tolerance to freeze. Screening the Tifton, GA, USA core collection of 175 accessions in a northern, high-altitude location, has identified germplasm with promising cold tolerance. A breeding line (Tifton 79-16) had significantly higher yields at the northern Georgia location than the cold tolerant cultivar (Tifton 44). A number of plant introductions had higher yields as well.

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Moving Warm-Season Forage Bermudagrass (Cynodon sp.) into Temperate Regions of North America

Warm-season (C4) perennial grasses are grown over millions of hectares in the Southeastern United States. These grasses produce optimal growth at 30 to 38°C diurnal temperature. Bermudagrass (Cynodon sp.) has been adopted as the preferred forage for many livestock and hay producers. Compared to other native and introduced warm-season perennial grass species, improved bermudagrass varieties produce high biomass with enhanced digestibility for ruminant grazing or feed. Until the 1930’s pastures in the region consisted of unimproved ‘common’ bermudagrass (Cynodon dactylon (L.) Pers.) that had been introduced earlier. However, in the early 20th century, new germplasm, including stargrass (C nlemfuënsis Vanderyst) was collected, primarily from Africa. This germplasm provided a source for major improvements in yield and digestibility. Unfortunately, stargrass is not cold tolerant, limiting it to regions between 30°N and 30°S. Intercrossing of C. nlemfuënsis with C. dactylon has produced highly successful cultivars, such as Tifton 85, which can survive at northern latitudes of at least 35°. However, there has been a desire to extend adaptation further north into the warm-season/cool-season grass transition zone. This would require a combination of breeding to improve cold tolerance in clonally-propagated varieties and development of seeded varieties that could be re-seeded following extremely cold winters. Earlier work at Oklahoma State University indicated that some cultivars had significantly different tolerance to freeze. Screening the Tifton, GA, USA core collection of 175 accessions in a northern, high-altitude location, has identified germplasm with promising cold tolerance. A breeding line (Tifton 79-16) had significantly higher yields at the northern Georgia location than the cold tolerant cultivar (Tifton 44). A number of plant introductions had higher yields as well.