CONVERGENT-DIVERGENT SELECTION FOR SEED PRODUCTION AND FORAGE TRAITS IN ORCHARDGRASS .3. CORRELATED RESPONSES FOR FORAGE TRAITS

Most orchardgrass (Dactylis glomerata L.) cultivars are developed in a two-stage selection protocol. Stage 1 involves selection for agronomi c traits among spaced plants and Stage 2 involves selecting among a li mited number of clones based on their polycross progeny performance, u sually in sward plots. The objective of this study was to quantify gen etic progress in sward-plot forage yield and related traits of four or chardgrass populations subjected to two cycles of recurrent phenotypic selection for agronomic traits of spaced plants, Selection was conduc ted at four locations, using either a regional approach (convergent-di vergent) or selection for local adaptation at one location. Selection criteria varied among locations, depending on the local environment an d each breeder's goals. Convergent-divergent selection led to a 7 and 8% increase in forage yield of the MO2 and WO11 populations, respectiv ely, averaged over all evaluation locations. Local selection did not l ead to forage yield improvement for any population. Both selection met hods led to decreased rust reaction in at least two of the four popula tions and later maturity in all four populations. The improvements in forage yield appeared to be due partly to populational buffering among progeny of plants selected at different Locations, a phenomenon not p ossible within the local populations because of single-location select ion. These results indicate that selection for agronomic traits of spa ced plants in orchardgrass can lead to improved sward-plot forage yiel d across a wide range of environments when multiple-location selection is applied to some germplasms.