Simultaneous improvement of forage traits and seed yield in orchardgrass (Dactylis glomerata L.) has been problematic because of geographic separation of forage and seed production locations. Most attempts to simultaneously improve both forage and seed traits have relied on a single location. The objective of this study was to conduct and evaluate two cycles of convergent‐divergent (C/D) and local selection for panicle seed weight (PSW) and forage traits. Selection was conducted at four locations (Ames, IA; Mount Vernon, MO; Rock Springs, PA; and Arlington, WI) in four base populations (I79DT, MO2, PLS4, and WO11). Phenotypic selection on a spaced‐plant basis was applied at a 0.25 selection intensity for forage traits, followed by a 0.25 selection intensity for PSW. All populations were evaluated as spaced plants at the Iowa and Pennsylvania locations in 1990 and 1991. Both selection methods were equally effective at increasing PSW, with responses averaging 1.0 to 18.2% cycle−1. Realized heritabilities for PSW were highly variable among the four populations (mean of 0.03–0.23) and were lower for Cycle 2 than for Cycle 1 (mean of 0.02 vs. 0.16). For C/D selection, IA, MO, PA, and WI selection locations increased PSW by 25, 39, 94, and 33 mg panicle−1 respectively. Three of the four populations had significant genetic changes of 2 to 4 d later heading, despite no direct selection pressure for heading dale. There were very few significant and biologically meaningful genotype × location interactions for any trait. Therefore, neither selection method resulted in plants with differential adaptation when evaluated as spaced plants.
More than 90% of U.S. production of orchardgrass (Dactylis glomerata L.) seed occurs in the U.S. Pacific Northwest. However, breeders in forage‐producing regions are unable to effectively select for Pacific Northwest seed yield by direct selection in their environment. This study was undertaken to determine if selection for broad adaptation for seed yield within forage‐producing regions could maintain commercially adequate seed production when grown in the U.S. Pacific Northwest. Two cycles of convergent‐divergent (C/D) selection were conducted and the resulting populations were evaluated for 2 yr in Oregon. The experiment was a randomized complete block design with three replicates grown in the field on a Woodburn silt loam (fine silty, mixed, mesic Aquultic Argixeroll, on 0–3% slopes) soil. Panicle seed weight (PSW) was the selection criterion for seed production. Except for the WO11 population, PSW remained unchanged when the selected and original populations were grown in Oregon. Both C/D and local selection methods resulted in decreased PSW in WO11. However, total seed yield (TSY) increased 163 and 111 kg ha−1 cycle−1 for the MO2 and WO11 populations, respectively, from C/D selection. Populational buffering for TSY appeared to be present in these two populations because single‐location selection at each of four sites was ineffective in increasing TSY as measured in Oregon. Total seed yield of 179DT and PLS4 was not changed by either C/D or local selection. A shift toward later maturity occurred in three of the four populations as a result of either C/D or local selection. A population selected from WO11 was both as late maturing and as high yielding as the latest‐maturing and highest‐yielding cultivars tested. Multiple‐location selection, such as C/D selection, can effectively accumulate genes for broad adaptation making it possible to achieve high seed yields concomitantly with later maturity.
Forage yield and quality can be improved by breeding only if genetic variance exists within the population. This study was conducted to determine the genetic variability within a population of plants selected at random from a seed lot of ‘Cllmax’ timothy (Phleum pratense L.), to predict the possibility of improving several traits, and to investigate associations among traits. Progeny from diallel crosses of seven sets of six clones each were used to establish field plots. Forage yields were recorded and forage quality characteristics determined for forage from each plot. Significant general combining ability variances were observed for most traits, while specific combining ability variances were significant only for Ca/P ratio and percentage dry matter and Ca. Year ✕ general combining ability variances were significant for some traits, but year ✕ specific combining ability variances were of little or no importance. Narrow sense heritabilities ranged from 0.08 (Pb) to 0.85 (Ca). The genotypicorrelation between forage yield and percentage dry matter was significant and positive. Genotypic correlations between forage yield (and percentage dry matter) and IVDMD, protein, P, and K were negative. The genotypic correlations among IVDMD, protein, P, and K were positive. Most of the other genotypic correlations studied were near zero. Calculated compositions of mixtures of timothy and alfalfa forages are shown graphically. Moderately producing dairy cattle require higher concentrations of most minerals than those contained in timothy forage. Breeding programs making use of general combining ability, such as polycross progeny test, should be used when attempting to improve forage yield and quality of timothy; however, breeding programs should start with a broader based population than found in Climax.
The purpose of this research was to ascertain the genetic control of reproductive tiller production in orchardgrass (Dactylis glomerata L.) and to determine whether sparse panicle production affects.forage yield and quality. We postulated that sparse‐flowering synthetic would retain forage quality longer than normal cultivars as reproductive tillers mature in late spring and early summer. In the greenhouse, up to 12 weeks of cool, short days were required before some orchardgrass plants would flower under long‐day conditions. The response of progeny from three crosses to floral induction treatments suggested that a complex interaction of genetic and environmental factors controls the onset and rate of reproductive tiller production. Reciprocal differences were not observed. Syn 2 generation of synthetics, that produced relatively few flowering tillers when grown in the northeastern USA, flowered and produced satisfactory seed yields at Prosser, Wash.In the field under a hay management cutting system, the most sparse‐flowering synthetic had slightly lower first harvest forage yield in June. than the check cultivars, possibly because dry matter was produced rapidly by the flowering culms of the cultivars. The absence of significant differences among entries for in vitro dry matter disappearance or lignin concentration suggests that the synthetics and cultivars were similar in forage quality. Thus, the experimental strains exhibited no apparent improvement in forage production or quality.
Nonstructural carbohydrates are sources of readily available energy that enhance rumen microbial activity and forage utilization. Experiments were conducted in Pennsylvania and West Virginia to determine the effect of maturity on total nonstructural carbohydrate (TNC) concentrations in spring herbage of eight grass species and determine TNC concentrations in herbage at immature and mature growth stages on a given day. The grasses were fertilized early each spring and summer with 0, 60, 120, or 240 kg N/ha.Determinations for TNC were made using the Smith takadiastase technique. Mean TNC concentration in the spring herbage of ‘Masshardy’ orchardgrass (Dactylis glomerata L.), ‘Climax’ timothy (Phleum pratense L.), and ‘Sac’ smooth bromegrass (Bromus inermis Leyss.) decreased seven or more percentage units with maturation from vegetative to full bloom stage, but decreased less than four percentage units in ‘Fawn’ tall fescue (Festuca arundinacea Schreb.), ‘Kenblue’ Kentucky bluegrass (Poa pratensis L.), and redtop (Agrostis alba L.). Mean TNC concentration was 50% higher in ‘Pennfine’ perennial ryegrass (Lolinm perenne L.) than in Kenblue Kentucky bluegrass or redtop. Concentration of TNC was inversely related to maximum air and soil temperatures and was affected much more by harvest date than by maturation of the herbage. Concentration of TNC was usually lower in N‐fertilized herbage than in unfertilized controls at early growth stages, but N had little effect on TNC concentration of herbage at full bloom.Maximum yields of TNC were obtained at the stem elongation stage with ryegrass, at flower‐head emergence with Pennmead orchardgrass and ‘Ky. 31’ tall rescue, and at full bloom with other grasses. N fertilization increased TNC yield of orchardgrass, tall rescue, and reed canarygrass; decreased TNC yield of smooth bromegrass and redtop; and had little effect on TNC yield of ryegrass and timothy.
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