Little information is available regarding the relationships of alfalfa (Medicago sativa L.) forage yield with yield components in seed‐established stands grown under dryland conditions. Field experiments that included two cultivars and 15 seeding rates ranging from m 2.2 to 33.6 kg pure live seed ha−1 were established in 1985 at Brookings and Highmore, SD. The objective was to determine seeding rate effects on components of alfalfa forage yield and on plant morphology several years after establishment. In the seeding year, plant density increased linearly with seeding rate at both locations. Yield components were determined in 1988 and 1989. Mean alfalfa yield during 1988 and 1989 was optimum at the 13.4 kg pure live seed ha−1 rate at Brookings, but did not respond to seeding rate at Highmore. Plant density continued to be affected by seeding rate 4 yr after establishment, but greater mortality at high seeding rates caused the response to deviate from linearity. Shoots per plant were negatively correlated with plant density (r = –0.73, P = 0.01). Shoot weight did not respond to seeding rate at Brookings but declined linearly with seeding rate at Highmore. Nevertheless, path analysis suggested that shoot weight was the major influence on alfalfa yield at both locations. Leaf‐to‐stem ratio and shoot length were not affected by seeding rate. Alfalfa yield components are affected similarly by plant density in seed‐established and transplanted stands. Although yield may not be affected by plant density, shoot weight may be affected because of differences in plant competition.

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Red clover (Trifolium pratense L.) seed coats range in color from yellow to purple with the majority of populations having seeds with various proportions of both. Our objectives were to determine the extent of variability for seed color in red clover and evaluate the potential of a color classification scheme as a descriptor for red clover populations. Two to four replicates of 100 randomly selected seeds were classified for color for single seed lots of the National Plant Germplasm System (NPGS) red clover core collection and 15 cultivars. In addition, four 100‐seed samples of multiple (2– 5) seed lots of five cultivars were evaluated. Individual seeds from each sample were placed into 1 of 5 (1 = >95% yellow to 5 = >95% purple) different color classes. This allowed a color index (CX) to be calculated for each sample by the formula [∑(seeds per class × class number)]/(total number of seeds evaluated). Extensive variability was found among accessions within the core collection for CX, with a range of 4.4 for PI 207972 to 2.4 for PI 120105. A highly significant difference was observed among cultivars for CX; however, most had mean CXs between 3.0 and 3.3. Slight, but significant, differences were found among lots within ‘Arlington’ (range 3.3–3.5) and ‘Altaswede’ (range 2.5–2.8) for CX. However, the difference between Arlington and Altaswede mean CXs averaged across seed lots was more than three times larger than the greatest intracultivar seed lot difference. Frequencies of Classes 1 and 5 were relatively consistent across environments. From analysis of variance of five seed lots from each of Arlington and ‘Kenstar’, estimates of variance components associated with cultivar, seed lot within cultivar, and 100‐seed sample within seed lot indicated 94% of total variance of a randomly selected sample was due to differences between cultivars. Our data indicated CX used in conjunction with class frequencies, if necessary, could be a useful descriptor for red clover populations.

Little bluestem [Schizachyrium scoparium (Michx.) Nash] was the most important dominant species of uplands in the tallgrass prairie. Presently, it is a dominant species, most significantly on coarse‐textured soils, in the mixed‐grass prairie region of the United States and Canada. This wide geographical adaptation to dry soils suggests little bluestem has potential for biomass production in areas unsuitable for most other grass species in the North American steppe. Primary objectives of this research were to (i) describe the morphology and determine the distribution of biomass among main stem and axillary components of little bluestem, and (ii) determine genetic variation for morphology and biomass production in ‘Camper’ little bluestem. Morphological analysis was conducted on tillers collected from natural populations in South Dakota and Montana and from swards of Camper and ‘Badlands’ ecotype in eastern South Dakota. Sixteen genotypes of Camper were evaluated for three years at two locations for determination of genotypic variation for biomass and biomass components. Quadratic models explained relationships between phytomer position and leaf and internode lengths and mass of individual phytomers of natural and selected populations. Genotypic variation occurred for phytomers per tiller, tillers per plant, mass per tiller, axillary branches per tiller, and biomass (range: 102–387 g plant−1). However, the correlation between locations for biomass was not significant for genotypes due to genetic variation for phenotypic plasticity. High frequency of survival over two winters for all genotypes indicated Camper has adequate winter hardiness to serve as a source population for cultivar development for biomass in the northern Great Plains.

man, WA. Ninety-eight seeds from each accession were planted individually in 40 mm diameter by 205 mm long plastic Red clover (Trifolium pratense L.) is known for trifoliolate leaves cones in the greenhouse. No auxiliary light was used. Temperawith light marks (i.e., variegation) on the leaflets. However, red clover ture inside the greenhouse generally ranged from about 20ЊC plants without leaf marks occur in some wild and cultivated populaat night to as high as 30ЊC during the day, depending on tions. The no mark (NM) phenotype is due to a homozygous recessive ambient weather conditions. Seedlings were evaluated weekly genotype. This study was conducted to evaluate the core collection for leaf markings, and those that displayed leaf marks were of red clover for frequency of the recessive allele that imparts the counted and discarded. For some plants a leaf mark appeared NM phenotype. Ninety-eight seeds from 82 accessions in the core on the first trifoliolate leaf. If a plant had no marks on any collection and one selected population (Blankleaf, NSL 303023) were of its leaves from emergence to flowering, it was classified as planted in individual containers in the greenhouse. Seedlings were a NM phenotype. evaluated weekly for leaf markings. If a plant had no mark on any Sixty-two accessions and 'Blankleaf' were evaluated from of its leaves from emergence to flowering, it was classified as a NM mid-Feb. through mid-June 1999, and 24 accessions were evalphenotype. We assumed that all evaluated accessions were diploid uated from mid-Feb. through mid-June 2000. Space restricand in Hardy-Weinberg equilibrium for the leaf mark locus. Estimates