Seed Production Characteristics Research Articles

Spring nitrogen and plant growth regulator effects on seed yield of orchardgrass

AbstractOrchardgrass (Dactylis glomerata L.) is an important forage seed crop, but unlike other cool‐season grasses, seed yields have not increased over time. Seed yield increases in orchardgrass may be possible with plant growth regulators (PGRs) such as trinexapac‐ethyl (TE) and chlormequat chloride (CCC). Field trials were conducted at Hyslop Experimental Farm near Corvallis, Oregon, over three crop years (2017–2019) to examine the effects of spring nitrogen (N) and PGRs on seed production characteristics in orchardgrass. Spring N treatments included 0, 112, 157, and 202 kg N ha−1 and PGR applications were timed using the BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) scale. Four PGR treatments included an untreated control, 210 g TE ha−1 at BBCH 32, 210 g TE ha−1 at BBCH 51, and 105 g TE ha−1 + 1500 g CCC ha−1 at BBCH 32. An interaction of spring N and PGR increased seed yields in 2 years, while spring N and PGR increased seed yield independently in the other year. The combination of TE and CCC PGRs did not increase seed yield over TE alone. Seed yield increases from spring N were due to an increase in seed number m−2, while increases in seed yield attributable to PGRs were the result of increased seed number m−2 and harvest index. This study suggests that the combination of 112 kg ha−1 spring N and 210 g ha−1 TE PGR is the best practice to maximize seed yield in orchardgrass.

Rice: Seed Systems, Production Characteristics, and Fungal Infections of Stored Grains in Major Production Zones of Liberia

The inadequacy of information on rice farmers' situations, particularly their access to propagation materials and grain storage and the impact thereof on Liberia's food security scenario, curtails the development of strategies and interventions meant to optimize rice production. This study investigated the rice seed systems, storage methods of the harvested rice grains, and degree of fungal contamination of stored rice seeds in the major rice-producing counties of Liberia: Lofa, Bong, Montserrado, and Nimba. A mixed data collection method, comprising interviews and focus group discussions (FGDs) was adopted. Five hundred (500) farmers were purposefully selected for one-on-one interviews, and 12 FGDs were held (three in each county). The results indicated that 94.7% of farmers source seeds through informal channels. Grain for use as seed in the subsequent farming season is mainly stored in kitchen attics, a practice reported by 83.8% of the farmers, while 7.8%, 3.8%, and 4.6% of farmers stored seeds in plastic containers, nylon sacks, and jute bags, respectively. Land size was identified as the primary factor determining rice yield across the studied counties, R2 = 0.944, p = 0.001. Farmers in high-rainfall regions had a high likelihood of experiencing fungal infections on their stored grains; however, only 19.6% of farmers were aware of the health implications of consuming affected grains. Therefore, policies and support frameworks should be directed towards actualizing modern seed channels and extension services and creating awareness of the different nodes of the rice value chain.

Research and utilization of mixed seed production technology for two-line hybrid wheat

<p indent="0mm">China’s Two-line Hybrid Wheat Technology System is an important achievement resulting from novel domestic use of sterile lines to realize agroindustrial application of hybrid wheat. However, compared with hybrid rice and maize, the industrial application level of hybrid wheat is still in its early stage. The unstable production of hybrids, as well as their high cost and the large sowing amount of seeds required for their cultivation, have always limited the rapid industrialization of two-line hybrid wheat. Two-line hybrid wheat research and cultivation show that high-efficiency seed production is the core key technology for the successful industrialization of hybrid wheat. Moreover, the outcrossing performance of wheat photo-thermo sensitive sterile lines is the key to the success of seed production. Wheat photo-thermo sensitive sterile lines can change from selfing to outcrossing under seed production conditions, and their seed production characteristics are affected by various factors of both sterile lines and restorer lines. Breeding sterile lines and restorer lines with high combining ability and excellent outcrossing traits can effectively improve the seed setting rate and yield of outcrossing in seed production and also greatly reduce the cost of wheat hybrid seed production. In our study, the influencing factors and results of the seed production process were assessed based on related seed production experiments with two-line hybrid wheat conducted from 2016 to 2020. Outcrossing traits, such as female bloom traits of floret opening size and stigma exposure rate and male fertility traits of pollen dispersal distance, anther size, anther exposure rate, and pollen amount were significantly correlated with outcrossing performance. In the pollination stage, larger pollen amounts, shorter pollen dispersal distances, longer pollination durations of the restorer line, higher stigma exposure rates, and larger floret opening angles of the sterile line can greatly improve the outcrossing seed setting rate, production yield, and quality of the sterile line. The flowering period of male parents was 2–3 days later than that of female parents, which could be utilized to realize the effective preparation of temporal-spatial and physiological synergy. With the male parent comprising 5% of a mixed population, the yield of mixed seed production was significantly increased by 28.2% compared with even row ratio seed production. From 2019 to 2021, large-scale mixed seed production in the Nanyang area has achieved excellent results with large-scale seed production of BS1453/JS1 reaching 5273.4 kg/hm². The establishment of a simple, scientific, safe, and efficient technology system for large-scale mixed seed production has solved the technical bottleneck of large-scale seed production of two-line hybrid wheat, providing theoretical and technical support for the popularization and widespread application of two-line hybrid wheat.

Domesticating native grasses in New Zealand

AbstractNew Zealand produces no commercial seed of any native grass species. All grasses used in agriculture and turf have evolved on other continents, and most natives fail to compete in mown turf or grazed pasture. Is this simply because of a lack of research or the lack of native grazing animals, or is there something fundamentally different about the New Zealand flora? New Zealand has many indigenous species within genera containing known turf species such as Festuca, Poa, Agrostis, Deschampsia, and Zoysia, but most are rare in the modern landscape. After collecting and screening over 50 native species for potential use in turf or pasture, it was apparent that most lacked vigor; were unable to form a turf; had slow establishment, extended flowering periods, poor seed yields, seeds with long awns, or seed that shattered readily; or had other difficulties with harvesting. One of the native grasses that showed promise was Poa imbecilla Spreng., which formed a very fine turf and had seed production characteristics suitable for development as a commercial species. It established readily but was usually dominated by introduced species within a few years. A cultivar was developed from local material, ‘Stewarts’, which is suitable for fine turf and for native grass revegetation and is now in limited commercial production.

The Conservation and Restoration of Riparian Forests along Caribbean Riverbanks Using Legume Trees

In the actual context of global change and biodiversity depletion, soil bioengineering represents an important tool for riparian ecosystem restoration and species conservation. Various techniques have already been implemented, but their adaptation still must be carried out in Caribbean Islands biodiversity hotspots, where suitable species remains unknown. Nitrogen-fixing legumes are particularly relevant for ecological restoration and the diversity of native Caribbean legume trees is promising in the search for suitable species for soil bioengineering. We hypothesized that Caribbean legume tree species present a growth performance and set of biotechnical traits compatible with their use in soil bioengineering. We selected five native legume trees, adapted to riparian environments, in different ecosystems (swamp forest, evergreen seasonal forest, rainforest) based on their ecology, resistance to disturbance and seed production characteristics. We measured root traits relevant for soil bioengineering on nursery grown 3-month-old seedlings. Despite their differences in sensitivity to herbivory and in growth strategies, the selected species have a high potential for use in soil bioengineering, with high seed production, high germination rates—from 88 to 100%—, and 100% survival rates, and are therefore compatible with large scale plant material production. We provided practical guidance tools for their integration into soil bioengineering techniques.

Urochloa spp. multivariate performance: Similarities and divergences among intra‐ and interspecific populations

AbstractMultivariate analysis is a tool that breeders can use to compare populations and select genotypes for specific purposes. This study used principal component analysis to compare three intraspecific and three interspecific populations of Urochloa spp. based on insect resistance, agronomic, and seed production characteristics. This multivariate strategy exposed completely different profiles and important differences among these populations despite their close genomic ancestry. In general, interspecific populations had greater variability than intraspecific populations for agronomic traits, seed production, and spittlebug resistance. Consequently, crosses among different species, whenever possible, are a better option to obtain new Urochloa breeding populations. However, the breeding of intraspecific populations is also an excellent option to improve specific traits related to each species, which can then be used to speed the breeding in the interspecific programs. Multivariate analysis demonstrated substantial variability within progenies of the interspecific Urochloa populations that can be used to improve insect resistance and productivity of tropical pastures.

Development of Seed Production Technology of CIMMYT Tropical Single Cross Maize Hybrids

Medium and small seed companies require information on maize parental seed production to make rational choices on what germplasm to introduce into their seed and breeding pipelines. The objective of this study was to generate public data on the appropriate hybrid seed production information of five female lines (T21, T26, T28, T33 and T38) and one line (T10) as a male hybrid parent. The effect of female and male sowing date and sowing density on hybrid seed production characteristics including flowering time, flowering duration, distance between tassel and stigmas and effective seed yield was determined. Recommendations to stagger male and female sowing to achieve flowering synchrony for the hybrid parents were complemented with data of seedling growth stages. The results were similar for T21, T26, T28, and T38; sowing the female and T10 on a row proportion of 4 females:1 male, and on a second date, when the coleoptiles of the female plants are halfway to emerge, sowing the missing male row to complete the 4:2 ratio. T33 is a late flowering line, therefore it is desirable to sow T33 first and T10 five days later, or when the T33 coleoptile begins to emerge. Plant densities did not cause differences in most plant characteristics. Line T21 showed good female parental traits. While this study provides a knowledge framework for seed production technology for these single cross hybrids, data specific to seed production regions need to be generated by seed companies to define the best regimes for hybrid production.

Comparison of the possibility for naturalization between Sesbania cannabina and S. rostrata based on seed production characteristics

Comparison of the possibility for naturalization between <i>Sesbania cannabina</i> and <i>S. rostrata</i> based on seed production characteristics

Genetic divergence among interspecific Paspalum hybrids based on seed production traits

ABSTRACT The use of genetic divergence as a basis for identifying superior individuals, with greater heterozygosity, is important in view of the difficulty when selecting of dissimilar genotypes exhibiting high average for interest traits. The aim of this study was to evaluate the genetic divergence and the expression of seed production traits in seventeen apomictic Paspalum plicatulum × Paspalum guenoarum hybrids and two male parents (P. guenoarum). A randomized block design was used, with genotypes individually arranged into ten blocks. The following traits were assessed: total number of tillers/plant (TT), reproductive tiller/plant (RT), number of racemes per inflorescence (NRI), reproductive tiller height (RTH), inflorescence rachis length (IRL), number of seeds/inflorescence (NSI), weight of a thousand seeds (WTS) and seed production (SP). Genetic divergence among the genotypes was estimated using the Tocher method and UPGMA clustering, based on the generalized Mahalanobis distance (D2 ii’). The Tocher and UPGMA optimization methods showed high concordance. The traits that most contributed to genetic divergence were RTH (23.59%), IRL (21.63%), WTS (16.67%) and SP (14.23%). The presence of genetic diversity made it possible to identify divergent genotypes and those with high means for the traits studied, allowing the selection of genotypes with significant breeding potential. Repeated cross-breeding of female superior plants with the genotypes Azulão and H20 can result in a high heterosis effect on seed production characteristics.

Tillage and establishment system effects on annual ryegrass seed crops

Annual ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] seed crops have been produced on some Oregon farms continuously for decades without rotation of crops or farming practices. The objective of the study was to determine the effects of tillage and establishment systems on ‘Gulf’ annual ryegrass seed crops over a 9-year period. Six systems were employed: (i) continuous conventional tillage (CT), (ii) continuous no-till (NT), (iii) NT/CT cycle alternate year tillage (NT/CT), (iv) volunteer/CT cycle alternate year tillage (Vol/CT), (v) burn and NT/CT cycle alternate year tillage (Burn+NT/CT), and (vi) volunteer/NT/CT cycle with tillage every 3rd year (Vol/NT/CT). Environment×system interaction effects governed seed production characteristics. Three seed yield environments were observed during the 9 years: high, intermediate, and low. High yield environments had higher temperatures (+1.2°C) and lower precipitation (−48mm) in April–June than in low yield environments. Across environments, yields were greatest with Burn+NT/CT, CT, and Vol/NT/CT and lowest with NT. Stability analysis revealed that Burn+NT/CT, CT, and Vol/NT/CT systems produced up to 40% greater yields than the mean of all systems in low yield environments. Yield variation among systems was high in low yield environments. Increasing tillage frequency from zero in NT to once every other year in NT/CT boosted yields so that they were equivalent to CT. Yield differences among systems were attributable to seed number. Moderate tillage frequency and occasional residue removal are required to produce the best long-term seed yields in annual ryegrass.

土壌水分応答を通じたダイズ品種「美里在来」の子実生産特性の解明．

土壌水分応答を通じたダイズ品種「美里在来」の子実生産特性の解明．

The characteristics of seed production in an Adonis multiflora (Ranunculaceae) population

A natural population of Adonis multiflora , a spring ephemeral herb growing in temperate deciduous forests, was studied to determine the seed production characteristics. Plant size, flowering time, and seed number were monitored from Feb ruary 2009 to May 2011 in main growing season (i.e., from March through May). The biomass rates of the shoot and the root in the A. multiflora population were 22-24% and 76-78%, respectively, and the biomass of the root was proportional to that of the shoot. The flowering rate was 60 % in the plants with 1 to 2 g of shoot biomass, and 100% in the plants with >2 g of shoot biomass. In the plants with root biomass between 4 and 6 g, the flowering rate was 43 % and, in the plants with the root biomass over 8 g, it was 100%. The shoot biomass was a better predictor of the flower production probability than the root biomass. The number of flowers and seeds was closely correlated to shoot biomass at 1 % significance level. The size of the plant that produced seed excessively instead of the shoot biomass in one year typically decreased in the next year and vice versa. The flowering time and its duration were closely related to the number of faithful seeds but not to that of total seeds. The number of faithful seeds was proportionate to flowering duration and inversely proportionate to flowering time (year day, YD). In a plant, the number of faithful seeds noticeably decreased with the inflorescence (i.e., order of flower in a plant), and this difference between the two successive flowers was significant at the 1 % level between the first and the third flower in 2009 and 2011 but not between the third and the fourth. However, the number of total seeds was mostly similar in the first through the fourth flower for all three years.

Spring‐Applied Nitrogen and Trinexapac‐ethyl Effects on Seed Yield in Perennial Ryegrass and Tall Fescue

Trinexapac‐ethyl (TE) [4‐(cyclopropyl‐α‐hydroxymethylene)‐3,5‐dioxo‐cyclohexanecarboxylic acid ethylester] is a widely used plant growth regulator (PGR) for lodging control and seed yield enhancement in perennial ryegrass (Lolium perenne L.) and tall fescue [Schedonorus phoenix (Scop.) Holub], but little information is available on interaction of this PGR with spring‐applied N. The objective of this study was to determine how spring‐applied N and TE influenced seed production in perennial ryegrass (180 kg N ha−1) and tall fescue (135 kg N ha−1). Field trials were conducted over three harvest years in both crops. Interaction of spring‐applied N and TE were evident for seed yield in all 3 yr in perennial ryegrass and in 2 yr in tall fescue. The combination of spring‐applied N and TE produced the greatest yields among the treatments tested. Averaged over years, the combination of spring‐applied N and TE PGR increased yield over the untreated control (no spring‐applied N and no TE) by 859 kg ha−1 (126%) in perennial ryegrass and by 538 kg ha−1 (75%) in tall fescue. Responses of other seed production characteristics to spring‐applied N and TE were independent of one another. Spring‐applied N consistently increased aboveground dry weight and seed weight of both seed crops. Other characteristics were inconsistently affected or not affected by N or by TE. Spring‐applied N × TE interaction effects in increasing yield were best explained by an increase in seed number per unit area. Perennial ryegrass and tall fescue seed yield is best enhanced by the lodging control agent TE with recommended rates of spring‐applied N.

Seed Production Characteristics of Three Fine Fescue Species in Residue Management Systems

Field‐burning based residue management is an important but controversial tool in seed production of three fine fescue species: Chewings fescue (CF) [Festuca rubra L. subsp. fallax (Thuill.) Nyman], strong creeping red fescue (strong CRF) (F. rubra L. subsp. rubra), and slender creeping red fescue (slender CRF) [F. rubra L. var. littoralis (Vasey)]. The objective of this study was to characterize seed productivity responses of fine fescue species to residue management in on‐farm and experiment station trials. Three cultivars each of CF and strong CRF were subjected to five postharvest residue management treatments at six on‐farm sites in two different environments in Oregon, while four cultivars of CF and strong CRF, and two slender CRF cultivars were treated with two postharvest residue management treatments in experiment station trials at one location. Seed yield responses to residue management was similar among production environments. Removal of residue by several methods improved seed yields, whereas yield declined after the second year of the stand in all three species. In second year stands, burning increased seed yields in all strong CRF cultivars, but caused mixed responses in CF and slender CRF cultivars. Burning increased seed yield in third year stands in all CF and strong CRF cultivars, but reduced yield by 9% in slender CRF. Burning increased yield over nonthermal treatment in strong CRF by 32% and by 84%, in second and third year stands, respectively. Beneficial effects of burning increased with stand age, resulting in greater seed yields in fine fescue species except slender CRF.

Seed Production Characteristics of Prairie Junegrass Germplasm Accessions

Prairie junegrass [Koeleria macrantha (Ledeb.) Shult.] is a perennial, short‐grass prairie species distributed throughout the northern hemisphere. This species is known to require fewer inputs than other cool‐season turfgrasses and it demonstrates tolerance to many environmental stresses found in Minnesota. In June 2007, 48 K. macrantha accessions from the U.S. National Plant Germplasm System (NPGS) were grown and evaluated for seed production characteristics in 2 locations (St. Paul, MN, and Becker, MN). Significant variation was found among accessions for several seed production traits including harvest date, plant height, seedhead number, and seed yield. A significant correlation between seedhead number and seed yield was found, which can be utilized for indirect selection in the production nursery. Plant growth and seed yield were highest at the Becker location, demonstrating the species' preference for well‐drained soils. Flowering times were significantly different between the locations; however, there were no significant differences in the duration from seedhead emergence to harvest between the locations. Multivariate analysis did not reveal clustering of accessions based on geographic origin, suggesting a diversity of material within collection regions.

Crimson Clover Seed Production and Volunteer Reseeding at Various Grazing Termination Dates

Crimson clover (Trifolium incarnatum L.) is a widely used cool‐season annual clover in the southeastern USA, but is not considered a dependable reseeder. Grazing termination dates (GTD) of 2‐wk intervals from 1 April to 15 May for 3 yr were used on small plots of seven crimson cultivars. Seed production characteristics, seed germination after seed harvest, remaining hard seed percentage after 90 d heat treatment, and volunteer reseeding were determined. There was a general decline in flower density, seed weight flower−1 and seed yield as GTD was delayed. There was variability among cultivars for flower density and seed weight flower−1, but in only 1 out of 3 yr for seed production. Percentage germination, soft seed, and hard seed after seed harvest were not influenced by GTD. Cultivars did differ for percentage germination and hard seed in 2 of 3 yr. Cultivar ranking was not consistent among years except for Columbus that always had high germination and low hard seed percentages. ‘Auburn’ and ‘Flame’ maintained the best hard seed percentage after the 90 d heat treatment. Volunteer seedling densities of 100 m−2 or higher occurred if grazing was terminated by mid‐April except for Columbus. The poor reseeding of crimson clover is due to the initial low hard seed production and decline of hard seed percentage during the summer.

A List of Germplasm Releases from the University of Wisconsin Onion Breeding Program, 1957–1993

The table beet (Beta vulgaris L.) breeding program at the Univ. of Wisconsin‐Madison, initiated by W.H. Gabelman in 1949, was geared toward assessing the feasibility of F 1 hybrids. This attempt required an understanding of pollen sterility, inbreeding potential, and seed production characteristics. The primary breeding objectives of the beet program focused on sterile and maintainer lines for the production of hybrids, disease resistance, round to globe-shaped roots, improved color and sweetness, multigerm and monogerm seed, and enhancement of combining ability. Hybrids and inbred lines were released by Gabelman in cooperation with the Wisconsin State Agricultural Experiment Station during 1964‐92. Gabelman took advantage of useful genes found in sugar beet (also Beta vulgaris L.) in improving table beet germplasm. The sf allele, which conditions self-fertility, was introduced from a sugar beet breeding line obtained from V.F. and H. Savitsky, emigres from Russia working with F.V. Owen, U.S. Dept. of Agriculture‐Agricultural Research Service, Fort Collins, Colo. The sf allele allowed for inbreeding individual plants, a technique that was not previously possible in beet because of its self-incompatibility. Inbreeding enabled the development of more homogenous populations and ultimately resulted in uniform inbred lines. Similarly, the x and z alleles, conditioning sterility at the nuclear restorer locus (in homozygous recessive condition), were introduced from sugar beet breeding lines obtained from F.V. Owen. These alleles, in combination with the sterile cytoplasm obtained from Owen, allowed for the development of pollen-sterile breeding lines and their maintainer lines. The B allele conditioning annual flowering habit also was obtained from sugar beet breeding material from V.F. Savitsky. The B allele allowed for efficient development of sterile inbred lines since spring-sown plants carrying Bb flower in Madison, Wis., by midAugust. A cross of the constitution SxxsfsfBb x N__sf_bb will give rise to 50% annual ( Bb) progeny, which, because they are flowering, can be classified for sterility in the field. These annual sterile plants can then be decapitated,

The Relationship Between Progeny Seed Yield in Drilled Plots and Maternal Spaced‐Plant Traits in Perennial Ryegrass (Lolium perenne L.)

AbstractSeed production in perennial ryegrass, Lolium perenne L., is low. Early selection for high seed yield carried out in spaced plants would be valuable for breeders, but only if this potential is also expressed in derived progenies sown later in drilled plots. Therefore, spaced‐plant traits assessed on clonal ramets of 31 genotypes in each of two perennial ryegrass varieties in four environments were related to seed production characteristics in drilled plots of open‐pollinated progenies of these plants.Significant differences were found among these half‐sib families for seed yield, thousand‐grain weight, spring performance and earliness. The number of spikelets per ear in the maternal plants was negatively correlated with the seed yield of the progenies, explaining 17 % of the variation for seed yield in the cv. ‘Barenza’ and 14 % in the cv. ‘Wendy’. Multiple regression analyses revealed that no combinations of plant traits consistently explained a major portion of the variation for seed yield of the progenies.The results indicate that in these varieties, spaced‐plant data are of limited value in predicting seed production. Direct selection for seed yield in drills of progenies in later stages of the breeding programme remains the best method for obtaining varieties with sufficient seed production.

Evaluation of pasture legumes sown into a prepared seedbed at Tamworth, New South Wales. 2. Seed production and seed reserves

Plots sown in 1983 were used to examine the seed production and reserves (residual hardseeds) of 15 annual legumes over 5 years at Tamworth in northern New South Wales. Seed production characteristics were measured in 1983 for these annuals, and for 6 perennial legumes. After the annuals had set seed in 1983, an area of the plots was sprayed to prevent flowering in subsequent years, and the rates of decline in seed reserves were compared with those from areas that seeded annually. Seed yields of the perennials were often significantly lower than those of the annuals except Trifolium glomeratum. Seed yields of T. subterraneum var. subterraneum cvv. Seaton Park and Woogenellup were significantly higher than those of cv. Nungarin and T. subterrarzeum var. brachycalycinum cv. Clare. Seed numbers were lowest for Medicago scutellata cv. Sava among the annual medics, and for Nungarin among subterranean clovers. There was little relationship between the mean number of seeds produced from 1983-86 and maturity grading, and between seed numbers and relative dry matter yield. Seed reserves decreased over 5 years by more than 90% in the sprayed treatments of all species. This decrease was not continuous, with the largest declines occurring from December 1983 to August 1984. In the sprayed treatments of Seaton Park, Woogenellup, and Clare, and in both treatments of Astragalus hamosus cv. Ioman, Vicia dasycarpa var. villosa cv. Namoi, and T. hirtum cv. Hykon, none of the original 1983 seed was recovered in 1987. For the annual medics and Nungarin, the number of residual hardseeds in the sprayed treatments in 1987 was about 3-5% of the seed produced in 1983. From 1983 to 1987, seed numbers in the unsprayed treatments declined by 7040% for the annual medics and by 85-95% for Seaton Park, Woogenellup, and Clare. Long-term persistence of annual medics and Nungarin depended on seed production in most years and the maintenance of a high number of residual hardseeds in the soil. In contrast, the mid- and late-maturing subterranean clovers Woogenellup and Clare had low seed reserves and were dependent on seed production in most years for their continued regeneration.

Variability in habit, flowering and seed production within the Kangaroo Valley cultivar of Lolium perenne when grown in a range of environments

Diversity of flowering and seed production characteristics were measured within and between seven populations of Kangaroo Valley perennial ryegrass. The hypothesis that these characteristics would not change when grown in diverse environments was tested. The average time from seedling emergence to spike emergence was similar for each of three biotypes that represented early, intermediate and late flowering populations. This occurred in spite of variation in this character of 54 to 72 days between plants within each of these biotypes. When data from all seven populations were combined, they formed a normal distribution with respect to time of flowering. Distinctive components of seed production were found for the different populations. Early flowering populations had higher seed yields and more but shorter spikes than late flowering populations. Wide variation in habit occurred within populations but there was a high correlation between erect habit and early flowering. Spikes of erect plants emerged 27 days earlier than prostrate plants. The seed formation characteristics of an early flowering population were unaltered when grown for three generations in diverse environments. The spike emergence and anthesis times for each of the seven populations were not changed when grown in new environments. We conclude that seed production of Kangaroo Valley ryegrass in environments similar to those described in these experiments will not significantly alter the population characteristic. For changes in the character of the population to occur, the new environment would have to be so severe to (a) restrict growth and select out a proportion of the progeny or (b) cause a change in the time of seed harvest.