Recurrent phenotypic selection for increased winter productivity in annual ryegrass (Lolium multiflorum Lam.)
Type of Degreethesis
DepartmentAgronomy and Soils
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In the Southeastern USA, dry matter distribution of cool season annual and perennial grasses is concentrated more in spring months with relatively less production in late autumn and early winter. Annual cool season grasses have the tendency for earlier spring production than perennial grasses. Due to lower availability of forage of both types of cool season grasses in early winter, animals are typically fed stored forages in order to meet their nutritional requirement, which results in increased management costs. A preferable approach is to provide live forage for maximizing the forage intake by animals and minimizing feeding of stored forages and grains. Annual ryegrass (Lolium multiflorum Lam.) is a cool season annual crop that originated in Southern Europe. The growing season for annual ryegrass in the southeastern USA is from late summer to late spring with maximum dry matter production during the spring months. Phenotypic recurrent selection was used to increase early winter dry matter production. The base population (C0) was generated from a polycross nursery of an equal number of plants (50) from the five top performing cultivars in Alabama Annual Ryegrass Trials along with cv. Gulf. These plants were open pollinated and bulk harvested for two years to create a random mating population. Selection was carried for two cycles (C1 and C2).The objectives of this study were a) to select for increased winter production; b) to study correlated responses; c) to evaluate the first two cycles of phenotypic recurrent selection and d) to determine the relationship between dry matter yield and indirect responses. For the first objective, evaluation and selection with grid restriction followed by recombination was carried out for two years. Selection was done on the basis of individual plant dry matter yield, individual plant green matter yield, visual appearance, individual plant dry matter percentage, and a random selection. After two cycles of selection, correlated responses such as seed yield, maturity, plant erectness and disease incidence, were also collected. Seed of C0, C1 and C2 along with check cultivars was used for solid-seeded plot evaluation in five environments in Alabama in 2008/09. Correlated responses have shown remarkable change from C0 to C1 but remained constant from C1 to C2. Selection resulted in increased early winter dry matter production at three out of five evaluation locations. Indirect responses (green matter, visual appearance and percent dry matter) have shown insignificant differences from dry matter yield, the direct response.