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Desiccation tolerance is an important characteristic of rice seed quality during seed drying. In this study, two varieties of Oryza sativa L. subsp. japonica (Jiucaiqing and Wuyunjing 7) were used to investigate the dynamic changes in rice seeds that are associated with desiccation tolerance (germination traits produced by dried seeds), grain mass (GW), moisture content (MC), and electrical conductivity (EC) during seed development (18 to 42 days after heading (DAH)). Changes in the levels of malondialdehyde (MDA) and hydrogen peroxide ([H.sub.2][O.sub.2]) in fresh, dry, and imbibed states, and antioxidant enzyme activity (superoxide dismutase (SOD); catalase (CAT); and glutathione reductase (GR)) in fresh and imbibed seeds were also evaluated during seed development. The results showed that seeds started to acquire desiccation tolerance at 26 DAH and reached the highest levels at 38 DAH. The increase in GW and decline in MC coincided with the acquisition of desiccation tolerance. MDA and [H.sub.2][O.sub.2] levels, and SOD, CAT, and GR activities in fresh and imbibed seeds rapidly decreased during the early developmental stages (18-30 DAH), and then their levels gradually stabilized (30-42 DAH). Regression analyses indicated that [H.sub.2][O.sub.2] levels in fresh seeds was negatively correlated with seed germination, whereas SOD activity in imbibed seeds was positively correlated with seed germination. [H.sub.2][O.sub.2] and SOD are, therefore, good parameters for assessing desiccation tolerance during rice seed development. Keywords: rice, desiccation tolerance, hydrogen peroxide, antioxidant enzymes. La tolerance a la deshydratation constitue une caracteristique importante des semences de qualite durant leur sechage. Dans cette etude, deux varietes de Oryza sativa L. subsp. japonica (Jiucaiqing et Wuyunjing 7) ont ete utilisees afin d'examiner les changements dynamiques dans la tolerance a la deshydratation (traits de germination produits par les semences seches), le poids du grain (PG), la teneur en eau (TE) et la conductivite electrique (CE) durant le developpement de la semence (18 a 42 jours apres l'epiaison, JAE). Les changements des niveaux de malonaldehyde (MDA), de la concentration de peroxyde d'hydrogene ([H.sub.2][O.sub.2]) dans les semences a l'etat frais, sec et imbibe, et l'activite des enzymes antioxydantes (superoxyde dismutase (SOD); catalase (CAT); glutathion reductase (GR)) dans les semences a l'etat frais et imbibe ont aussi ete evalues durant le developpement des semences. Les resultats ont montre que les semences commencaient a acquerir une tolerance a la deshydratation au JAE 26 et que cette tolerance atteignait un plateau au JAE 38. L'augmentation du PG et la diminution de la TE co'incidaient avec l'acquisition de la tolerance a la deshydratation. Les concentrations de MDA et de [H.sub.2][O.sub.2], et l'activite de la SOD, de la CAT et de la GR dans les semences fraiches et imbibees diminuaient rapidement durant les stades precoces du developpement (JAE 18 a 30), pour se stabiliser graduellement (JAE 30 a 42). L'analyse de regression a indique que la concentration de [H.sub.2][O.sub.2] des semences fraiches etait en correlation negative avec la germination des semences alors que l'activite de la SOD des semences imbibees etait en correlation positive avec la germination des semences. Le [H.sub.2][O.sub.2] et la SOD constituaient ainsi de bon parametres devaluation de la tolerance a la deshydratation durant le developpement de la semence de riz. [Traduit par la Redaction] Mots-cles: riz, tolerance a la deshydratation, peroxyde d'hydrogene, enzymes antioxydantes., Introduction Seed quality is one of the most important factors influencing yield potential (Eskandari 2012). Seeds must be grown, harvested, and processed correctly for the best quality. Harvest management is [...]

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. doi: 10.2135/cropsci2009.05.0235

Understanding how defoliation affects soybean [Glycine max (L.) Merr.] yield during the seed-filling period will aid in making management recommendations for control of stresses that reduce yield through defoliation. Because previous research has studied defoliation effects at only one or two specific stages of seed filling, our objective was to gain a greater understanding of the mechanisms for yield reduction with defoliation at weekly intervals across the seed-filling period. Defoliations were conducted from the bottom of the canopy upward to mimic the progress of soybean rust. Two experiments, one in Kentucky (38[degrees] N lat) and the other in Louisiana (30[degrees]N lat), were conducted in randomized complete block designs in split-split plot arrangements with four replications. Main plots were two cultivars, split plots were defoliation timings at weekly intervals during seed filling, and split-split plots were defoliation levels of 0, 33, 66, and 100% leaf removal. Data were obtained on yield and several growth dynamic and yield component factors. Defoliation-induced yield losses corresponded more closely with percentage of light interception reductions than percentage of leaf area reductions. During the R5 to R6 period, defoliation levels sufficient to reduce light interception by 18 to 23% were required to cause yield loss. Yield losses from total defoliation were greatest at early seed filling (78%) but gradually diminished as seed filling progressed. Each 0.1 delay in developmental stage resulted in a 5% decline in yield loss. doi: 10.2135/cropsci2009.03.0128

Lack of adequate soil moisture during seed filling limits seed size in soybean [Glycine max (L.) Merr.], generally by shortening the duration of seed fill. Seed growth rate typically remains largely unaffected. The smaller seeds often have increased seed protein concentration due to less detrimental effect on final protein accumulation relative to other major seed components. Such changes in seed composition despite stable rates of seed filling suggest compensation may occur among component accumulation rates or the duration of accumulation of individual seed components is affected differentially by water stress. We examined these possibilities by evaluating the rates and durations of protein, oil, and residual accumulation in two soybean lines subjected to limited soil moisture during seed filling. Results indicated that both responses (rate and duration of accumulation) to water deficit can occur. The rates of accumulation of the different seed components often compensated, resulting in a constant seed growth rate, typically favoring protein accumulation. To our knowledge, this is the first demonstration of a differential response among rates and durations of seed component accumulation when soil moisture becomes limiting. The relative stability of protein accumulation likely reflects the availability of remobilizable N late in seed filling and the dependence of oil accumulation on current photosynthesis. doi: 10.2135/cropsci2009.05.0240

Scatter-hoarding rodents play an important dispersal role for many large-seeded plants. Seed traits affect their foraging behavior; however, it is difficult to isolate their effects because of the covariance among traits. Here, we used artificial seeds to partition the effects of seed size, tannin content, and nutrient content on scatter-hoarding rodents in a natural pine forest in Northwest Yunnan, China. Apodemus, a common genus of Old World rodents, consistently consumed small seeds in situ but removed medium-sized seeds (1.2-2.5 cm in diameter) and transported bigger seeds farther. Seed nutrient and tannin contents also significantly influenced rodents' behavior, but response varied substantially between years. Rodent behavior did involve some aspects of multivariate optimization. Our results strongly indicate that seed size is a decisive factor for scatter-hoarding rodents in the choice between seed predation and dispersal, while nutrient and tannin content played a less consistent role, possibly responding to confounding factors in the community. This result also has important implications for seed production by trees, which can improve the probability of long-distance dispersal of high-quality offspring by simply making them larger. The ability to tease apart the relative influence of different seed traits on the behavior of predators provides powerful insight into this important coevolutionary dynamic. Key words: Apodemus; artificial seed; condensed tannin; foraging behavior; hydrolyzable tannin; nutrient content; scatter-hoarding; seed dispersal; seed predation; seed size.

Ricinus communis (also know as the castor bean piano whose forbears escaped from suburban gardens or commercial cultivation grow wild in many countries. In temperate and tropical climates seeds will develop to maturity, and plants may be perennial. In Australia these plants have become widespread and are regarded as noxious weeds in many localities. The seeds of R. communis contain ricin, a protein toxin which can easily be extracted into an aqueous solution. Ricin is toxic by ingestion, inhalation, and injection. The history of terrorist and anarchist interest in the use of seeds from R. communis has driven the development of strategies for determination of cultivar and geographic location of the source of an extract of wild-grown castor bean seed. This forensic information is of considerable interest to law enforcement and intelligence organizations. During forensic studies of both the metabolome and proteome of extracts from eight specimens of six different cultivars of R. communis ('zanzibariensis' collected from Kenya and Tanzania, 'gibsonii', 'impala', 'dehradun', 'carmencita', and 'sanguineus' collected from Spain and Tanzania), three peptide biomarkers (designated Ricinus communis biomarkers, or RCB) were identified in both the MALDI and electrospray LC-MS spectra. Two of these peptides (RCB-1 and RCB-2) were present in varying amounts in all cultivars, while RCB-3 was present only in the 'carmencita' cultivar. The amino acid sequences of RCB-1 to -3 were determined using LC-M[S.sup.n] fragmentation and de novo sequencing on both the intact and the carbamidomethyl modified peptides. The connectivity of the two disulfide bonds that were present in all three RCB were determined using a strategy of partial reduction and differential alkylation using tris(2-carboxyethyl)phosphine with N-ethylmaleimide to reduce and alkylate the most accessible disulfide bond, followed by reduction and alkylation of the remaining disulfide bond with dithiolthreitol and iodoacetamide. The possible functional role of RCB-1 to -3 in R. communis seeds is also discussed.

Grain legumes could serve as a low cost nitrogen (N) and energy source for animal production in the southern Great Plains (SGP). This study evaluated the yield and nutritive value of grains of tropical annual legumes novel to the SGP. Included were cultivars of pigeon pea [Cajanus cajan (L.) Millsp.] (cv. GA-2), guar [Cyamopsis tetragonoloba (L.) Taub.] (cv. Kinman), cowpea [Vigna unguiculata (L). Walp.] (cv. Chinese red), mung bean [Vigna radiata (L.) Wilcz.] (cv. Berkins), and the grain soybean [Glycine max (L.) Merr.] (cv. Hutcheson) as a control. Seeds were inoculated and planted (60-cm row spacing) annually in mid-June 2004 through 2006. Seeding rates were varied to achieve 10 seeds [m.sup.-1] row length. Grain was harvested at the end of growing seasons (90-120 d since planting), and grain samples were ground (1.0 mm) and analyzed for N concentration and in vitro digestible dry matter (IVDDM). Significant (P < 0.05) year x legume interactions were recorded for all characteristics, with variable legume responses among years. Guar produced both the highest (2730 kg [ha.sup.-1] in 2004) and lowest (897 kg [h.sup.-1] in 2005) grain yields. Nitrogen concentrations were the highest in soybean grain (60.2-60.7 g [kg.sup.-1]) and consistently the lowest in pigeon pea (33.3-34.9 g [kg-.sup.-1]). Soybean grain had the highest IVDDM (968-969 g [kg.sup.-1]), while pigeon pea had the consistently lowest digestibility (890-894 g [kg.sup.-1]). The four novel legumes produced grains that meet the nutritional requirements for all classes of stocker or feeder cattle.

Seed size, a key quality determinant in the marketing of the cool-season food legume chickpea (Cicer arietinum L.), can be reduced under terminal drought. Sucrose synthase and invertase, important enzymes in sugar metabolism, play an important role in seed filling. This study aimed to determine whether these enzymes in the developing cotyledons are associated with the final seed size of chickpea by following their level of activity during seed filling in large- and small-seeded chickpea genotypes. The level of invertase in the cotyledons was unchanged during seed filling, but sucrose synthase reached a maximum about 500 to 600 growing degree days (GDD) after flowering when cell numbers were no longer increasing, but the cotyledons were increasing rapidly in dry weight. In a range of genotypes differing in seed size, the level of sucrose synthase activity in the developing cotyledons at 500 to 600 GDD was correlated with the final seed size at maturity when measured at a rainfed site in two different years. The level of activity of sucrose synthase at the same stage of development in [F.sub.2], [F.sub.3], and [F.sub.7] populations of crosses between a large-seeded cultivar and two small-seeded genotypes was also correlated with final seed size. It is concluded that sucrose synthase, but not invertase, in developing cotyledons is the key enzyme influencing seed size in chickpea.

Soybean [Glycine max (L.) Merr.] seeds accumulate sucrose, raffinose family oligosaccharides (RFO), phytin, and small amounts of galactopinitols and fagopyritols during normal seed maturation. RFO and phytin are indigestible by non-ruminant animals and contribute to decreased feed efficiency, reduced mineral adsorption, and phosphorous pollution in manure. Low raffinose, stachyose, and phytin seed may have imbibitional chilling sensitivity and reduced field emergence. The objective was to characterize the profiles of soluble carbohydrates in cotyledons, axis, and seed coats of low raffinose and stachyose (LRS) seeds expressing the mutant stc1 phenotype; in low raffinose, stachyose, and phytin (LRSP1, LRSP2) seeds expressing the mutant mips phenotype; and in normal raffinose, stachyose, and phytin (CHECK) seeds expressing the Stc1 and Mips phenotype during 17 stages of soybean seed development, maturation, and desiccation. Seventy percent of RFO accumulated after maximum seed dry weight during seed desiccation. LRS, LRSP1, and LRSP2 seeds had low RFO, but LRS seeds accumulated higher galactinol and di- and tri-galactosides of myo-inositol, D-chiro-inositol, and D-pinitoI earlier during seed maturation than CHECK, LRSP1, and LRSP2. LRSP1 and LRSP2 seed had low RFO and low galactosyl cyclitols during maturation and were reported to have imbibitional chilling sensitivity and reduced field emergence.

Phytate is an important antinutritional component of legume seeds, which chelates minerals that are essential to the human diet such as iron and zinc. Phytate levels are often correlated with total seed phosphorus (P). The objective of this research was to evaluate quantitative trait loci (QTL) for seed P and phytate content in an inter-gene pool (G2333 x G19839) recombinant inbred line population of common bean (Phaseolus vulgaris L.) planted at medium and high levels of soil P in randomized complete block experiments. Seed P and phytate content were quantified with spectrophotometric methods based on acid digestion with molybdenum blue and Wade reagents, respectively, and net seed P and net phytate content were calculated on a per-seed basis using seed weights for each experiment. Total seed P varied from 2.8 to 6.1 g [kg.sup.-1] and phytates varied from 0.29 to 1.78% across fertilization levels. A total of six QTL were found for total or net seed P, while three were found for percentage or net seed phytates. The QTL for seed P and percent phytates were located independently on linkage groups B2 and B11 vs. B6, respectively. Meanwhile, the QTL for net seed P or phytate content were related to seed weight QTL on linkage groups B6, B7, and B10, with one additional net phytate QTL on B5. The results suggest that bean plants can adapt to different initial supplies of P and that seed P and phytate levels in common bean can be modified through plant breeding.

To investigate the genetic factors underlying a major quantitative trait locus (QTL) contributing to low seed stachyose content in two separate populations derived from soybean [Glycine max (L.) Merr.] line PI200508, the recently released 'Williams 82' whole genome shotgun (WGS) sequence was exploited for candidate gene discovery. The physical interval containing a low stachyose QTL from PI200508 was identified in the WGS, and screened for areas that could be exploited for linkage mapping purposes. Microsatellite sequences designed in these areas were used to develop new markers, creating tighter linkage with the QTL. Examination of the Williams 82 sequence in this interval and the corresponding glyma0.1b gene model, available through the Phytozome website (http://www.phytozome.org), revealed one candidate gene with significant homology to previously characterized galactosyltransferase genes from Arabidopsis, pea, and cucumber. Sequencing of the annotated coding region for this gene revealed a single unique sequence polymorphism between PI200508, and lines exhibiting wild-type expression of stachyose content. The mutant phenotype appears to have arisen from a 3 bp deletion, and is easily distinguished from the wild-type allele via a marker presented in this study. This mutation-specific marker explained 88 to 94% of the phenotypic variation for seed stachyose content, and 76% for seed sucrose content, traits that exhibited a strong negative correlation in this study (p < 0.01).

The low-phytate (LP) trait in plant seeds offers important nutritional and environmental benefits for food and feed uses. Mutants with reduced phytate content are commonly produced by chemical mutagenesis, as is the case for soybean [Glycine max (L.) Merr.] line CX1834. Quantitative trait loci (QTL) for LP in CX1834 have previously been reported, however the genetic basis for this trait has not been identified. In this study, we examined several possible chromosomal map locations for the LP mutation in CX1834. After eliminating the myo-inositol phosphate synthase (MIPS) gene family as the location of the LP mutations based on mapping studies, we focused on candidate genes in regions of known low-phytate QTL on linkage groups (LGs) L and N. Using the soybean whole-genome sequence, we identified genes encoding two putative multidrug resistance-associated proteins (MRPs). The sequence of a segment of the CX1834 MRP gene on LG N was compared with sequences from 16 other soybean lines with normal phytate content. A single nucleotide mutation from A to T, resulting in substitution of a stop codon for an Arg residue, was detected in the MRP gene on LG N of the low phytate line, but not in the normal counterparts. Further comparative sequence analysis of normal and LP progeny from a cross of CX1834 with V99-3337 (normal phytate) also indicated the A to T substitution in LP individuals, suggesting a mutation in an MRP gene as the possible cause of the low-phytate phenotype.

Many native grasses display seed shattering and other seed production problems. Basin wildrye [Leymus cinereus (Scribn. & Merr.) A. Love] and creeping wildrye [L. triticoides (Buckley) Pilg.] are perennial Triticeae grasses native to western North America. In this study, variation in the number of florets per inflorescence, percent seed set, seed mass, seed shattering, and seed dormancy was measured in clonally replicated multiyear field evaluations of 164 progeny derived from a backcross between a creeping x basin wildrye hybrid and a true creeping wildrye tester. Genomewide quantitative trait locus (QTL) scans detected independent gene effects for all five traits and one pleiotropic QTL, located on Triticeae homeologous chromosome group 6, associated with major seed shattering (43.1% [R.sup.2], 26,9 log of odds likelihood ratio [LOD]) and seed dormancy (24.1% [R.sup.2], 10.6 LOD) effects. We hypothesize that a dominant basin wildrye gene creates an abscission that promotes seed disarticulation but hinders seed development and seed ripening in the creeping wildrye backcross family. Alignments of Leymus chromosome 6 expressed sequence tag markers to the rice (Oryza) genome reveal well-defined correspondence of Leymus wildrye and American wildrice (Zizania palustris L.) seed shatter QTLs.

Inland saltgrass [Distichlis spicata var. stricta (L.) Greene], native to the western United States, has potential for use as a turfgrass and a revegetation species on saline sites. This study was conducted (i) to evaluate the effect of seeding date, seeding rate, and seed treatments on saltgrass establishment; and (ii) to determine the required accumulative growing degree days (GDD) for saltgrass to establish adequate cover ([greater than or equal to] 80%) after seeding. Seeding dates were 15 May, 15 June, and 15 July in 2006. Machine scarification and stratification broke saltgrass seed dormancy equally well. Saltgrass seeded in May established adequate coverage ([greater than or equal to] 80%) in September even using the lowest seeding rate (74 kg [ha.sup.-1]). For plots seeded in June, only the higher seeding rates (123 and 170 kg [ha.sup.-1]) established adequate coverage ([greater than or equal to] 80%) by the end of growing season. For plots seeded in July, however, even the highest seeding rate failed to establish adequate coverage in September. The accumulated GDD to achieve adequate coverage was 1748, 1663, and 1435 for 74, 123, and 172 kg [ha.sup.-1] seeding rates, respectively.

Soybean [Glycine max (L.) Merrill] seed with low raffinose, stachyose, and phytin is desired for feeding nonruminant animals to improve feed efficiency, increase mineral uptake, and reduce flatulence, but may have reduced agronomic quality. Composition of soluble carbohydrates in seed parts and sensitivity of mature seed to imbibitional chilling were determined for low raffinose and stachyose (LRS) seed; low raffinose, stachyose, and phytin (LRSP1, LRSP2) seed; and normal raffinose, stachyose, and phytin (CHECK) seed. Cotyledons and axes of seed from the three modified lines had low raffinose, stachyose, and verbascose compared to the CHECK. Cotyledons from LRS seed had significantly higher concentrations of galactinol and the di- and tri-[alpha]-galactoside derivatives of myo-inositol, D-pinitol, and D-chiro-inositol than cotyledons from LRSP1 and LRSP2 seed. Seed coats of all four lines were similar in soluble carbohydrate composition indicating the modifications were expressed in embryo tissues. Mature seed of LRS and CHECK was tolerant to imbibitional chilling, but LRSP1 and LRSP2 seed were sensitive to imbibitional chilling. The higher accumulation of cyclitol [alpha]-galactosides in embryos (cotyledons) of LRS seed (90% cotyledons, 2% axis, 8% seed coat) may have contributed to imbibitional chilling tolerance.

Stearic acid (18:0) is typically a minor component of soybean [Glycine max (L.) Merr.] oil, accounting for only 2 to 4% of the total fatty acid content. Increasing stearic acid levels of soybean oil would lead to enhanced oxidative stability, potentially reducing the need for hydrogenation, a process leading to the formation of undesirable trans fatty acids. Although mutagenesis strategies have been successful in developing soybean germplasm with elevated 18:0 levels in the seed oil, the specific gene mutations responsible for this phenotype were not known. We report a newly identified soybean gene, designated SACPD-C, that encodes a unique isoform of [[DELTA].sup.9]-stearoyl-ACP-desaturase, the enzyme responsible for converting stearic acid to oleic acid (18:1). High levels of SACPD-C transcript were only detected in developing seed tissue, suggesting that the encoded desaturase functions to enhance oleic acid biosynthetic capacity as the immature seed is actively engaged in triacylglycerol production and storage. The participation of SACPD-C in storage triacylglycerol synthesis is further supported by the observation of mutations in this gene in two independent sources of elevated 18:0 soybean germplasm, A6 (30% 18:0) and FAM94-41 (9% 18:0). A molecular marker diagnostic for the FAM94-41 SACPD-C gene mutation strictly associates with the elevated 18:0 phenotype in a segregating population, and could thus serve as a useful tool in the development of cultivars with oils possessing enhanced oxidative stability.

Soybean [Glycine max (L.) Merr.] seeds contain a high concentration of the isoflavones daidzein and genistein, which are considered to be compounds beneficial to human health. Our objective was to determine the influence of breeding and selection for yield on the isoflavone concentration of short-season cultivars. A collection of 14 historical cultivars released from 1934 to 1992 was grown at Ottawa for 12 yr under identical cultural conditions. Seed samples, taken at harvest, were examined using near-infrared reflectance in conjunction with traditional chemical methods to measure the concentration of daidzein, genistein, and total isoflavones (TIF). A linear regression equation developed based on the changes across time of cultivar release was used to determine the improvement rates for various soybean parameters. Across the 58 yr of breeding history, yield and oil concentration increased by 0.43 and 0.24% per year, respectively, while protein concentration decreased by 0.15% per year. Across the same time period daidzein, genistein, and TIF increased by 1.04, 1.47, and 0.98% per year, respectively. Moderate broad sense heritabilities of 43, 45, and 44% were calculated for the aforementioned isoflavones. Genotype main effects + genotype x environment interaction biplots revealed that recent cultivars with high isoflavone concentration were more prone to environmental influence than older cultivars. In the short-season region, plant breeders should be aware that selecting for higher yield may indirectly select for higher isoflavone concentration.

Soybean [Glycine max (L.) Merr.] seed produced in high-temperature, high-humidity production environments is prone to have substandard germination. Hardseededness, wrinkled seed coats, and infection by Phomopsis Iongicolla Hobbs are all known to affect soybean seed germinability. Ancestors of modern U.S. soybean cultivars may lack the necessary variability to impart high germinability to new cultivars without the introgression of new genetic diversity. The purpose of this research was to identify soybean germplasm possessing positive traits affecting high seed germinability for seed produced under high-temperature environments, such as in the early soybean production system (ESPS) of the midsouthern United States. Seed was produced in the ESPS for 486 U.S. plant introductions (PI), 25 ancestral lines of U.S. cultivars, and four U.S. cultivars at Stoneville, MS, in 2002 and 2003. Standard and accelerated-aging germination percentages, hardseededness, seed coat wrinkling, and incidence of P. longicolla were estimated for each line. Based on the 2002 and 2003 field data, 42 PIs were selected for further testing, along with three cultivars, in two greenhouse temperature regimes (36[degrees] and 42[degrees]C) at Stoneville, MS, in 2005. Standard field germinations for the 25 ancestral lines ranged from 26 to 82%. Sixty-three accessions were identified as having a mean standard field germination of [greater than or equal to] 90%,

The fatty acid composition of soybean [Glycine max (L.) Merr.] seed affects the flavor, nutritional value, and stability of the oil. Increasing oleic acid content in soybean oil would reduce the need for hydrogenation, a process that creates unhealthy trans fatty acids. The objective of this study was to map and confirm the areas of the soybean genome associated with oleic acid content from the soybean line N00-3350 (~583 g [kg.sup.-1] oleic acid) using simple sequence repeat (SSR) markers. An [F.sub.2:3] population of 259 lines from the cross of G99-G725 x N00-3350 was used as a mapping population, and an [F.sub.2:3] population of 231 lines from the cross of G99-G3438 x N00-3350 was used for confirmation. Using single-factor analysis of variance, interval mapping, and composite interval mapping, six quantitative trait loci (QTLs) for oleic acid content were found on linkage groups LG-A1 (Satt211, [R.sup.2] = 4%), LG-D2 (Satt389, [R.sup.2] = 6%), LG-G (Satt394, [R.sup.2] = 13%), LG-G (Satt191, [R.sup.2] = 7%), LG-L (Satt418, [R.sup.2] = 9%), and LG-L (Satt561, [R.sup.2] = 25%) in the G99-G725 x N00-3350 population. All six QTLs for oleic acid were confirmed in the G99-3438 x N00-3350 population. The designations cqOle-001, cqOle-002, cqOle-003, cqOle-004, cqOle-005, and cqOle-006 have been assigned to these confirmed QTLs by the Soybean Genetics Committee. The identification of SSR markers linked to the oleic acid QTLs will facilitate the use of marker-assisted selection (MAS) in soybean breeding programs to increase the oleic acid content in soybean seed.

Dry, windy weather conditions during harvest can lead to very low seed-moisture content and severe soybean [Glycine max (L.) Merr.] seed germination problems. Some low-moisture content seed lots have particularly low and highly variable standard germination test results, presumably caused by imbibitional injury. The objectives of this study were to evaluate the influence of seed moisture content and seed composition on germination in the laboratory and field, and to evaluate standard germination test protocols for testing low-moisture content soybean seeds. Commercial seed lots of different seed composition were equilibrated to 0.07, 0.08, and 0.12 g [H.sub.2]O/g fw. Four official testing media were used in the experiments: rolled paper towels (T), crepe cellulose paper (C), crepe cellulose paper covered with sand (CS), and sand germination (S). Soybean germination and emergence were affected by maturity group, seed composition, and field conditions at planting. The testing medium and seed moisture content also influenced germination in the laboratory, but seed moisture content did not affect field emergence. These results suggest that soybean imbibitional injury caused by low-moisture seed lots occurs primarily in the laboratory. Seed analysts must consider soybean seed composition, moisture content, and their interaction with testing media when testing low-moisture content soybeans in the laboratory.

Soybean [Glycine max (L.) Merr.] lines have been developed with the ol allele for elevated oleate from the mutant line M23 and alleles for reduced linolenate as a means of increasing stability of the oil. The purpose of this study was to evaluate the influence of elevated oleate content on agronomic and seed traits. From each of three segregating populations, 27 low-linolenate lines with a mean oleate content >500 g [kg.sup.-1] and 27 low-linolenate lines with a mean oleate content

Vitamin A deficiency affects approximately 250 million people in semiarid regions of Africa and Asia, where sorghum (Sorghum bicolor Moench) is a major staple crop. Yellow endosperm sorghums contain carotenoids, some of which can be transformed by humans into vitamin A. Our objective was to study the genetic basis of variation in carotenoid levels in sorghum endosperm by mapping quantitative trait loci (QTL) associated with carotenoid content and endosperm color, as a putative predictor of carotenoid concentration. A recombinant inbred line population developed from a yellow ('KS115') by a white endosperm ('Macia') parental cross was evaluated in two locations in 2005. A genetic map was generated using 112 molecular markers including nine carotenoid candidate genes. Lutein, zeaxanthin, and B-carotene were the major carotenoids identified. Several QTL were detected for each compound as well as for color and total carotenoids. Color was significantly correlated with the levels of all compounds, and color QTL co-localized with carotenoid QTL. For [beta]-carotene (provitamin A), five QTL were localized on chromosomes 1, 2, and 10. One of them, on chromosome 2, was stable across both environments, had positive additive effects (1.179 and 1.379), explained large proportions of the phenotypic variance (11.6% and 15.15%), and was associated with a new phytoene synthase gene (Psy3). This first report of QTL for carotenoid content in sorghum grain provides a starting point for breeding high-provitamin A sorghums.

A well-known, but largely untested, prediction in plant reproductive ecology is that dioecious taxa should produce larger, more, higher-quality, or better-defended seeds than cosexual taxa. Using a data set composed of 972 species in 104 families, representing the flora of the Tambopata Wildlife Reserve (Madre de Dios, Peru), we evaluated the first component of this prediction, examining ecological and evolutionary relationships between breeding system and mean seed size with two kinds of tests. First, we conducted cross-species analyses to determine whether species with different breeding systems differed significantly with respect to mean individual seed size. Second, we used a hypothesized phylogeny to identify pairs of the most closely related taxa or clades within the Tambopata community that differed with respect to breeding system. Comparing pair members allowed us to determine whether evolutionary divergence in breeding system (between taxa with unisexual vs. cosexual individuals) was consistently associated with evolutionary change in seed size. In both analyses, we controlled for potentially confounding effects of growth form by examining these relationships within woody and nonwoody taxa. Cross-species analyses revealed that dioecious species produced larger seeds than cosexual species among woody species, shrubs, lianas (each growth form analyzed separately), and all species pooled, but not among trees. Phylogenetically independent contrasts upheld the significant association between breeding system and seed size among woody taxa, lianas, and all taxa pooled, but not among shrubs. We discuss the implications of our findings for evolutionary hypotheses regarding associations between dioecy and seed size. Key words: angiosperms, breeding system, dioecy; monoecy; plant growth forms; rain forest; seed size.

Threshing wheat (Triticum aestivum LO at high speeds is the main reason behind abnormal seedlings and vigor reduction of the seeds. This problem is expected to be severe in headstripper combines with successive impact Ioaclings of stripping and threshing units. The airo of this study was to simulate the effects of impact velocities (IV), number of impact loadings (NL), and seed moisture content (MC) on percentage of physical damage (PPD) and percentage of Ioss in germination (PLG) to wheat seeds. Modeling the correlation between dependent ancI independent variables was performed using mathematical and artificial neural networks (ANN). The result showed that all the three independent variables significantly influenced PPD and PLG (P = 0.01). Increasing the IV from 5 to 30 m [s.sup.-1] caused an increase in PPD and PLG from 0.17 to 35.8% and from 0.37 to 19.9%, respectively. It was found that the seeds with higher MC could better withstand physical and physiological damage than those with Iower MC. With an increase in NL from 1 to 3 times, the mean values of PPD and PLG were increased by 2.9 and 2.6 times, respectively. An ANN model with two hidden layers, trained with a back-propagation algorithm, successfully learned the relationship between the input and output variables. In comparison with regression models, ANN performecI better when predicting PPD and PLG to wheat seeds.

Soybean [Glycine max (L.) Merr.] seeds with undesirable texture cause processing complications in soyfood production. Seed hardness is an important quality attribute for food-grade soybeans. The objective of this study was to identify quantitative trait Ioci (QTLs) associated with seed hardness in soybean. Three generations of [F.sub.2]-derived lines (159 [F.sub.2:3], [F.sub.2:4,] and [F.sub.2:5] lines) from a soft ('SS-516') x hard ('Camp') soybean cross were grown in a replicated test in Fayetteville, AR, in 2003, 2004, and 2005. Pressure-cooked samples from each line were tested for seed hardness using a texture analyzer. A total of 874 simple sequence repeat (SSR) markers were used to screen the parents; 177 out of 236 polymorphic markers between the parents showed polymorphism in the [F.sub.2:3] lines. A linkage map for seed hardness was established using 148 SSR markers, 15 of which were new and added to the current public soybean genetic linkage map. AII identified markers were placed on 19 linkage groups (LGs) and covered 1363.7 cM of the soybean genome with an average distance of 9.6 cM between markers. Broad-sense heritability was estimated to be 0.56 for seed hardness. Two stable QTLs across environments (Ha1 and Ha2, p < 0.00001) were identified near Satt229 on LG L and Satt531 on LG D1a, respectively, for the average seed hardness over 3 yr. Ha1 had a Iogarithmic odds score of 6.17 with [R.sup.2] = 12.7%; Ha2 had a score of 5.08 with [R.sup.2] = 36.1%. A dominance-by-dominance interaction was detected between Ha1 and Ha2, explaining 7.9% of the phenotypic variance. Research is under way to confirm the identified QTLs for soybean seed hardness in multiple populations with different genetic backgrounds.

Relative growth rate (RGR) is currently the most commonly used method for measuring and comparing species' intrinsic growth potential. Comparative studies have, for example, revealed that small-seeded species have higher RGR, leading to the common belief that small-seeded species possess physiological adaptations for rapid growth that would allow them to outgrow large-seeded species, given sufficient time. We show that, because RGR declines as individual plants grow, it is heavily biased by initial size and does not measure the size-corrected growth potential that determines the outcome of competition in the long term. We develop a daily growth model that includes a simple mechanistic representation of aboveground and belowground growth and its dependency on plant size and environmental factors. Intrinsic growth potential is encapsulated by the size-independent growth coefficient, G. We parameterized the model using repeated-harvest data from 1724 plants of nine species growing in contrasting nutrient and temperature regimes. Using information-theoretic criteria, we found evidence for interspecific differences in only three of nine model parameters: G, aboveground allocation, and frost damage. With other parameters shared between species, the model accurately reproduced above- and belowground biomass trajectories for all nine species in each set of environmental conditions. In contrast to conventional wisdom, the relationship between G and seed size was positive, despite a strong negative correlation between seed size and average RGR, meaning that large-seeded rather than small-seeded species have higher size-corrected growth potential. Further, we found a significant positive correlation between G and frost damage that, according to simulations, causes rank reversals in final biomass under daily temperature changes of [+ or -] 5[degrees]C. We recommend the wider use of this new kind of plant growth analysis as a better way of understanding underlying differences in species' physiology: but we recognize that RGR is still a useful metric if considering the potential rate of population increase in empty habitats. Key words: coexistence; community ecology; ecophysiology; European sand-dune annual species; exponential vs. linear growth; likelihood; neutral theory; relative growth rate (RGR); storage effect; trade

Seed color is an important trait affecting flour yield and quality in wheat. Seed color also is either tightly linked to or pleiotropically controls seed dormancy in wheat, because most of the red-seeded wheats are tolerant to preharvest sprouting in comparison to white-seeded wheats. Seed color in hexaploid wheat is controlled by the dominant red seed color genes R-A1, R-B1, and R-D1 located in orthologous positions on chromosome arms 3AL, 3BL, and 3DL, respectively. By using wheat ESTs and synteny with rice, we identified one STS marker and one EST marker flanking R-A1 in a 4.4-cM interval by using an RIL and [F.sub.2] populations of L angdon (LDN)/LDN-DIC3A (disomic substitution of T. turgidum subsp, dicoccoides chromosome 3A for 3A of LDN). Physical mapping of the R-A1 gene using tightly linked markers on a set of deletion lines specific to the long arms of group-3 chromosomes indicated that the red seed color genes are located in the distal region (less than 10% of the chromosome arm 3/), which is a high-recombination, generich region in wheat. Comparative genomic analysis indicated that, except for a very minor rearrangement of gene sequences in wheat relative to rice, macrocolinearity is well conserved between the consensus distal deletion bin of wheat 3L-0.80-1.00 and rice chromosome arm 1L. The R-A1 gene of wheat was targeted into a single PAC of rice using colinear flanking markers.

Shattering during harvest is a major problem in seed production of Vicia cracca (L.). The aim of this study was to evaluate a simple empirical relationship and determine optimum harvest time by simultaneously analyzing pod and seed morphological and physiological properties, as well as seed quality. Pods were harvested at three-day intervals from peak anthesis until shattering. Pod and seed sizes from 36 to 42 d after peak anthesis (DAPA) were significantly smaller than at other sampling dates after reaching maximum size. Pods and seeds lost their green color and turned light brown and black, respectively from 36 to 42 DAPA. Seed dry weight (DWT) reached maximum values, and seed moisture content (SMC) reached the minimum and suitable values, respectively from 36 to 42 DAPA. Seeds reached maximum percent germination and germination rate at about 36 DAPA. Thus, V. cracca can be harvested six days before shattering (shattering begins at 42 DAPA) without affecting yield.

Genetic control and environmental modulation of seed size operate through their influences on rate and duration of seed filling, and their interaction. To account for this interaction, here we advance an allometric model centered on the scaling exponent [alpha] calculated as the slope of the linear regression between duration and rate of grain filling in a log-log scale. The scaling exponent allows for three types of responses: seed size is stable as a result of full compensation between rate and duration ([alpha] = -1), seed size is variable as a result of rate ([alpha] > -1), or duration-dominated growth ([alpha] < -1). The concept was tested with 45 data sets from the literature involving nine crop species, and sources of variation including genotype, environment, and their interaction. Relative variation in seed size ranged from 5 to 274%, and the scaling exponent was strongly concentrated in the range from 0 (large, rate-driven seed size range) to -1 (narrow seed size range due to mutually cancelled effects of rate and duration). The range of seed size declined when the scaling exponent declined from approximately 0 to -1. An [alpha] [approximately equal to] -1(rate and duration effects cancel each other) is necessary and sufficient for small variation in seed size, whereas [alpha] [approximately equal to] 0 is necessary but not sufficient for large seed size variation. The magnitude of seed size variation is dependent on the variation in the rate of seed growth when [alpha] [approximately equal to] 0. This double condition for seed size variability is summarized in a multiple regression model with [alpha] and range of rate of grain filling as independent variables, which accounted for 73% of the variation in range of seed size.

The effectiveness of a frugivore as a disperser of a plant is greatly determined by how fruits and seeds are handled in its mouth and its digestive tract. Although a number of studies have investigated the effect of avian ingestion on germination, we still know very little about the modifications to seeds during ingestion and the specific consequences on plant fitness. Here we investigate for the first time the different mechanisms by which germination patterns of seeds are modified following ingestion by frugivores. Specifically, we examine changes in seed mass, water content, permeability, seed coat thickness, texture, and resistance in two common Mediterranean fleshy-fruited plants, Phillyrea angustifolia and Myrtus communis, after ingestion by Eurasian Blackbirds, Turdus merula. We found a number of differences between the plant species: Phillyrea seeds lost mass, mainly due to water loss, and had thinner coats after gut passage, but Myrtus seeds did not. Seeds of both species showed increased permeability, while Myrtus seeds in particular became less resistant to breakage. No quantifiable changes in seed coat texture were detected in either species, although this trait was partly associated with differences in germination rate in Phillyrea. High intraspecific plant variation was found for most seed traits measured. Seed passage through birds' guts sped up germination in both species, especially in Myrtus. Increased permeability in seeds of both species following ingestion resulted in a higher germination rate. Moreover, seeds with thick coats (and in the case of Phillyrea, harder coats) germinated at a slower rate and produced seedlings that also grew more slowly, indicating a cost of coat thickness and/or hardness for seedling emergence. Results obtained here contribute to explaining the great heterogeneity in germination responses among and within plant species and the large variety of factors, both intrinsic and extrinsic to the plants, that influence such responses. Key words: avian digestive tract; endozoochory; fruit dispersers; mediterranean fleshy fruits; Myrtus communis; Phillyrea angustifolia; seed germination; seed traits; seedling growth; Turdus merula.

Postharvest seed coat darkening is a significant problem in pinto beans (Phaseolus vulgaris L.), resulting in product that is undesirable to consumers and that is discounted in the marketplace. There is a range in the rate and extent of darkening among pinto germplasm and recently, slow-darkening (SD) lines have been identified. Line 1533-15, an SD line from the University of Saskatchewan, was crossed to CDC Pintium, a regular darkening pinto, and seed of [F.sub.1] and [F.sub.2] individuals and [F.sub.5:6] recombinant inbred lines were assessed for their darkening phenotype. Segregation data indicated that there is a single, recessive gene that controls the SD phenotype. All [F.sub.2] individuals from a cross between 1533-15 and Pinto Saltillo, another SD line, were slow-darkening suggesting that the phenotype is controlled by the same gene in both lines. The simple genetics of this trait should facilitate the introduction of this trait into breeding programs, thereby increasing the quality of pinto beans being developed.

Seed production may be limited because flowers do not get enough suitable pollen or because plants lack the resources to make seeds. We used replicated plantings to test factors that influence effects of bumblebee behavior on pollen limitation, as measured by the difference in seed set between hand- and naturally pollinated flowers, of Penstemon digitalis in patches of four to 41 flowering individuals. Seed set per flower was 376% higher in the largest as compared with the smallest Penstemon patches. This positive density dependence reflects activity of long-tongued bees, which (1) have higher effective density as patch size increases, (2) visit greater proportions of plants as patch size increases, and (3) visit smaller proportions of flowers per visited plant as patch size increases. Our results suggest that economics of flight and maneuverability of large, long-tongued bumblebees lead them to transfer more pollen between than within Penstemon plants in large patches. Density of smaller, short-tongued bumblebees was not positively associated with Penstemon seed set, but these bees may be important pollinators at low plant densities. Our experimental system indicates a clear positive relationship between activity of effective pollinators and seed set in a species capable of pollinating itself. Key words: bumblebee behavior; long-tongued bees; Penstemon; pollen limitation; positive density-dependent pollination; protandry; self-compatibility; short-tongued bees.

Abstract: We analyzed effects of seed-hoarding by rodents on the variation in seed mass and seed success for a perennial forest undergrowth plant--Symplocarpus renifolius Schott ex Miquel--in Hokkaido, northern Japan. [...]

To investigate the existence of coordinated sets of seedling traits adapted to contrasting establishment conditions, we examined evolutionary convergence in seedling traits for 299 French Guianan woody plant species and the stress response in a shadehouse of species representing seed size gradients within five major cotyledon morphology types. The French Guianan woody plant community has larger seeds than other tropical forest communities and the largest proportion of hypogeal cotyledon type (59.2%) reported for tropical forests. Yet the community includes many species with intermediate size seeds that produce seedlings with different cotyledonal morphologies. A split-plot factorial design with two light levels (0.8% and 16.1% PAR) and four damage treatments (control, seed damage, leaf damage, stem damage) was used in the shadehouse experiment. Although larger-seeded species had higher survival and slower growth, these patterns were better explained by cotyledon type than by seed mass. Even larger-seeded species with foliar cotyledons grew faster than species with reserve-type cotyledons, and survival after stem grazing was five times higher in seedlings with hypogeal cotyledons than with epigeal cotyledons. Thus, to predict seedling performance using seed size, seedling morphology must also be considered. Key words: cotyledons; French Guiana; functional morphology; herbivory; life history; phylogeny; regeneration strategy; shade tolerance.

Unlike pollen and seed size, the extent and causes of variation in ovule size remain unexplored. Based on 45 angiosperm species, we assessed whether intra- and interspecific variation in ovule size is consistent with cost minimization during ovule production or allows maternal plants to dominate conflict with their seeds concerning resource investment. Despite considerable intraspecific variation in ovule volume (mean CV = 0.356), ovule production by few species was subject to a size--number tradeoff. Among the sampled species, ovule volume varied two orders of magnitude, whereas seed volume varied four orders of magnitude. Ovule volume varied positively among species with flower mass and negatively with ovule number. Tenuinucellate ovules were generally larger that crassinucellate ovules, and species with apical placentation (which mostly have uniovulate ovaries) had smaller ovules than those with other placentation types. Seed volume varied positively among species with fruit mass and seed development time, but negatively with seed number. Seeds grew a median 93-fold larger than the ovules from which they originated. Our results provide equivocal evidence that selection minimizes ovule size to allow efficient resource allocation after fertilization, but stronger evidence that ovule size affords maternal plants an advantage in parent-offspring conflict. Key words: integument; nucellus; ovule; parent-offspring conflict; placentation; resource allocation; seed; size-number trade-off.

Identifying ecological factors that affect seed number and seed size is key to understanding the persistence of large seed mass variation in some plant species. Pathogens may increase seed mass variation by increasing resource demand over the growing season such that late fruits experience higher resource competition than early fruits. We tested whether Fusarium sp. and Rhizoctonia sp., soil fungi that cause wilt, contributed to seasonal decline in flower size, seed number, or seed mass in Hydrophyllum appendiculatum and H. canadense. A third species not infected by these soil fungi, H. virginianum, was studied to determine how seasonal decline in floral traits and seed mass variation varies within this genus. Flower size declined seasonally for all species, but was greatest for H. appendiculatum, a monocarpic biennial with indeterminate inflorescences. Seed number decreased between first and last inflorescences in H. appendiculatum, but not in H. canadense or H. virginianum, perennials with determinate inflorescences. Seed mass varied most in H. appendiculatum and H. canadense (4-20-fold in 50% of individuals) and least in H. virginianum (4-8-fold in > 30% of individuals). Fungal infection increased seed mass variation among diseased plants in H. canadense and H. appendiculatum. However, within plants fungal infection only increased seasonal decline in flower size, seed number, and seed mass in H. appendiculatum when flowers received supplemental pollination. Key words: fungal pathogens; Fusarium; Hydrophyllum; life history; offspring size; Rhizoctonia; seed mass; seed number.

As they descend, the autorotating seeds of maples and some other trees generate unexpectedly high lift, but how they attain this elevated performance is unknown. To elucidate the mechanisms responsible, we measured the three-dimensional flow around dynamically scaled models of maple and hornbeam seeds. Our results indicate that these seeds attain high lift by generating a stable reading-edge vortex (LEV) as they descend. The compact LEV, which we verified on real specimens, allows maple seeds to remain in the air more effectively than do a variety of nonautorotating seeds. LEVs also explain the high lift generated by hovering insects, bats, and possibly birds, suggesting that the use of LEVs represents a convergent aerodynamic solution in the evolution of flight performance in both animals and plants.

1 The trade-off between seed mass and the number of seeds a plant can make for a given amount of energy underpins our understanding of seed ecology. However, there is little information on the magnitude of the fecundity advantage of small-seeded species over an entire plant lifetime. 2 We compiled data from the literature to quantify the relationships between: (i) seed mass and plant size (because the photosynthetic area of a plant determines how much energy is available for allocation to seed production); (ii) seed mass and plant reproductive lifetime (the number of years a plant has to produce seeds); and (iii) seed mass and the number of seeds produced per individual per year, and per lifetime. 3 Seed mass was positively related to all measures of plant size (canopy area, plant height, stem diameter, plant mass and canopy volume). There were also positive correlations between seed mass and time to first reproduction, plant life span, and reproductive life span. Thus, although small-seeded species produce more seeds per unit canopy area per year than large-seeded species, large-seeded species tend to have larger canopies and more reproductive years. 4 These patterns accord well with independently gathered data on annual and lifetime seed production. The negative relationship between seed mass and the number of seeds produced per year was much shallower on a per individual basis than on a per unit canopy basis. Seed mass was not significantly related to the total number of seeds produced by an individual plant throughout its lifetime. 5 Our previous understanding of seed mass as a spectrum from production of many small seeds, each with low establishment probability, to a few large seeds each with higher establishment probability, was missing some important elements. To understand the forces shaping the evolution of seed mass, we will need to consider plant size and longevity, as well as seedling survival rates and the number of seeds that can be produced for a given amount of energy.

Comparison of physiochemical properties of seeds from garden orach (Atriplex hortensis) and sweet quinoa seeds with those of bitter quinoa is described.