Texas, USA 2010 - International Herbage Seed Group

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Seeds(%)Seeds (%)Seeds (%)Seed germination percentage (%)1008060402001 2 3 4 5 6 7 8 9 10 11 12 13 14 28Days (d)WP WOP RRP RCP WP+F WOP+F RRP+F RCP+FFigure 1. Cumulative germination of Zygophyllum xanthoxylum seeds subjected to differentphysical treatments (WP, seeds with pericarp; WOP, seeds without pericarp; RRP, seeds ofpericarp near radical removed; RCP, seeds of pericarp near cotyledon removed; F, flush with tapwater for 24hours)Effect of pericarp and seed burial on seed persistence in the fieldField germination was significantly influenced by pericarp, burial depth and burial time (Figure2.). Seeds without pericarp germinated earlier compared to seeds with pericarp, and as burialdepth increased, seed germination increased early in the season (from February to June ) but nodifference was observed between 2 and 5cm burial depths late in the season (from August toOctober). Most buried seeds (at 2 and 5 cm) with or without a pericarp germinated during theAugust to October period. However, nearly all seeds exposed on the soil surface failed togerminate at any time of the year. A significantly higher proportion of decayed seed wasobserved in treatments without a pericarp compared to seeds with a pericarp, regardless of burialdepth, and increased over time.100806040Field germination40302010Decayed seeds10080604020Pericarp imposed dormancyWOP+0WOP+2WOP+5WP+0WP+2WP+5200Dec-07 Feb-08 Apr-08 Jun-08 Aug-08 Oct-080Dec-07 Feb-08 Apr-08 Jun-08 Aug-08 Oct-08Date0Dec-07 Feb-08 Apr-08 Jun-08 Aug-08 Oct-08DateFigure 2. Status of seeds recovered over time in the burial experiment, expressed as a proportionof field germination (%), decayed seeds (%) and pericarp imposed dormancy (%). WOP+0, 2 or5 are seeds without pericarp buried at 0, 2 or 5 cm depth; WP+0, 2 or 5 are seeds with pericarpburied at 0, 2 or 5 cm depth.DiscussionThis study clearly shows that pericarp is responsible for seed dormancy in Z. xanthoxylumbecause the pericarp almost completely inhibits seed germination and removal of the pericarp101
increases germination to its potential percentage (Figure.1). Also the pericarp seems to not affectgas exchange because removal of the pericarp near cotyledon (RCP) did not increase seedgermination significantly, but interesting, removal of the pericarp near radical (RRP) largelyimproves seed germination, this implies that a mechanical resistance on radical protrusion isimposed by the pericarp. Further, the pericarp mechanical resistance just partly explains pericarpimposed seed dormancy because RRP germinated to 44% only which indicate other factors areinvolved in the dormancy of the remaining seeds. In the present study, water flushingsignificantly increased germination percentage of seeds with pericarp or with a part of pericarp,and this result is consistent with previous research (Clrak, et al., 2007) and implies a germinationinhibitor existed or generated by the pericarp. Based on this, we suggest that pericarp imposeddormancy in Z. xanthoxylum seed is a combination of mechanical resistance and chemicalinhibition generated by pericarp.Seed dormancy has an important role in determining the time and place of seed germination inthe field to spread the risk of germination failure, and thus may help ensure long-term seedsurvival, especially for wild species growing in harsh environments (Baskin & Baskin, 1998). Itis clear from the current field experiment that pericarp imposed dormancy is responsible for thelack of germination from December 2007 to June 2008. During this period seeds with pericarpdo not germinate even when returned to optimum conditions for germination (Figure. 2), and thisis consistent with previous research in other species (Hu et al., 2009b). Seeds without a pericarpcan germinate readily at any time of the season depending on environmental conditions. Hu et al.(2009a) also reported that seeds with a pericarp exhibited a lower germination but higherseedling establishment compared to seeds without a pericarp because most seedlings from nakedseeds had a greater spread of germination time and many died from subsequent droughtconditions.Seed decay is another factor affecting seed persistence in addition to changes in dormancy.Present experiment clearly showed that the presence of a pericarp significantly reduced thenumber of decayed seeds regardless of burial depth and burial time. Low levels of seed decayearly in the season may be a consequence of low soil moisture at the experimental site (similarlyslowing the process of seed aging). When soil moisture rapidly increases late in the season,environmental conditions become optimum for seed germination and most seeds germinaterather than lose viability and decay. In addition, more than 90% of the variance in terms of seeddecay could be explained by the pericarp, suggesting that the presence of the pericarp plays adeterment role in limiting seed decay across a range of conditions.AcknowledgementsThe study was funded by the National Key Basic Research Special Foundation Project of China(2007CB108904).References102
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Proceedings of the 7th Internationa
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Table of ContentsORAL PRESENTATIONS
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Seed yield components and yield per
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International Herbage Seed Conferen
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16:15 - 16:30 Reliability of salini
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Hotel expense is covered for night
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40,000 were slaves (McDonald, 2007)
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Fig. 1. Texas AgriLife Research and
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$7 billion for cattle, $3 billion f
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principle and encourages both AgriL
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eceived by growers, the above perce
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seed conditioning plants are locate
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Table 4.Hectares of open-field burn
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system, a seed crop is produced fro
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Fig. 1. Land resource areas of Texa
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y land owners. Seed yields are low
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The influence of planting density o
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Simple correlation and regression a
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Variation in seed shattering in a g
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Seed retention (SR) was calculated
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mm160120Precipitation8040020Km h -1
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Young, B. A. (1986). A Source of Re
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Several methods are commonly used f
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Table 3. Effect of the length of ha
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Alfalfa seed production in semi-hum
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Rather near the meteorological stat
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ReferencesBolaños-Aguilar E.D., Hu
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ased bioenergy conversion plants wa
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Table 1. Average distances required
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Figure 1. Optimized locations for 1
Page 61 and 62: Perennial ryegrass (Lolium perenne
Page 63 and 64: Relative Seed Yieldsingle composite
Page 65 and 66: Flowers, M.D.; Hart, J.M.; Young II
Page 67 and 68: Thus, similar to tissue tests, remo
Page 69 and 70: Conclusion:Perhaps our most importa
Page 71 and 72: Modelling critical NDVI curves in p
Page 73 and 74: The five spectral reflectance measu
Page 75 and 76: Harvest loss in ryegrass seed crops
Page 77 and 78: Larger than expected harvest losses
Page 79 and 80: Rolston, P.; Trethewey, J.; McCloy,
Page 81 and 82: Optical sensors have the potential
Page 83 and 84: Figure 2. Seed yield response to ap
Page 85 and 86: Flowers, M. D., Hart, J.M., Young I
Page 87 and 88: In 2010, France has launched the fo
Page 89 and 90: Yield (% maximum)ConclusionThe resu
Page 91 and 92: Plant N uptakeN unavailableSoil nit
Page 93 and 94: Stresses associated with germinatio
Page 95 and 96: correspond to electrical conductivi
Page 97 and 98: applied later in the fall was more
Page 99 and 100: Figure 2. Establishment of five ove
Page 101 and 102: The seed vigour testing was perform
Page 103 and 104: Table 1. Germination index (GI) for
Page 105 and 106: Reliability of salinity screening L
Page 107 and 108: AcknowledgmentThis research was sup
Page 109 and 110: Table 2. Greenhouse salinity screen
Page 111: The seeds were collected from the A
Page 115 and 116: Light, lodging and flag leaves-what
Page 117 and 118: Relative seed yieldSeed yield (kg/h
Page 119 and 120: Hampton, J.G.; Clemence, T.G.A.; He
Page 121 and 122: The seed set is of major importance
Page 123 and 124: In grass species with poor seed ret
Page 125 and 126: support system to optimize fungicid
Page 127 and 128: weather stations in grass seed fiel
Page 129 and 130: ust resistance loci in Lolium peren
Page 131 and 132: Seed yield variation in a red clove
Page 133 and 134: 100Seed yield plant -1 (g)806040200
Page 135 and 136: Marden, J. H. 1984. Remote percepti
Page 137 and 138: Crimson clover seed production in t
Page 139 and 140: Piper, C.V. 1935. Forage plants and
Page 141 and 142: deal of investigation into the caus
Page 143 and 144: genes and subsequent ability to pro
Page 145 and 146: Gatenby, W.A., S.C. Munday-Finch, A
Page 147 and 148: Control of Vulpia myuros in red fes
Page 149 and 150: The strip design provides an opport
Page 151 and 152: The pot experiments did not reveale
Page 153 and 154: CharacterWeed abundance1 A few plan
Page 155 and 156: Jensen, P. K. (2010) Longevity of s
Page 157 and 158: Effects of intraspecific competitio
Page 159 and 160: flowering, Gangi accumulated a high
Page 161 and 162: The seed yield of Gangi was, on ave
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Seed yield components and yield per
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ResultsVariation among populations
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Table 2. Means of total seeds per p
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Ryle, G. J. (1970). Partition of As
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Control of Apion trifolii in red cl
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Number of seeds /inflorescencesimil
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population. However, in spite of th
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Corvallis where they were debearded
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Table 1. Effect of Palisade growth
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Variations on potential and harvest
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Determination of optimum desiccatio
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Relative seed yield (%)Flowers/m225
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Harvesting too soon after peak flow
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Annual ryegrass seed production in
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seed yield, kg/haExtractable Al, mg
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ReferencesHaby, V.A. (1995). Soil m
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Kentucky bluegrass (Poa pratensis L
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urn residue management (Fig. 1 and
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Comparing herbicide selectivity in
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Development of new tetraploid Chlor
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Following 4 (or 5) cycles of select
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Loch, D.S., Rethman, N.F.G. & van N
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KBGcocksfootHykorLofatimothymeadowf
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Figure 2 Relative seed yield (%) se
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and GA 4 . In consequence this inac
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Table 1 The effect of trinexapac-et
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Silberstein, T.B., Young, W.C. III,
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inflorescece number and seed yield
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Germination of Lolium multiflorum g
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Effect of sowing density on seed yi
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y-products of this grass seed crop
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Table 2. Effect of PGR on seed yiel
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Further culm length measurements ga
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chlorophyllometer. Measurements wer
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Table 2. Photosynthesis rate of fla
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Organization of grass seed research
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Path Coefficient and Ridge Regressi
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through y4 (0.133). Increasing y 1
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Newell G.J., Lee B. (1981)Ridge reg
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Relative humidity, seed moisture co
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Ergovaline contents in grasses from
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11.8 % (Central East) to 40.0% (Nor
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ReferencesBony, S. & Delatour, P. (
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Long-term Evaluation of Annual Ryeg
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seed yield. All systems of establis
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Preliminary results after four year
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Casals, Marie-LaureFNAMSImpasse du
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Mao, PeishengForage Seed LabChina A
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Vanasche, DavidVanasche Farm36130 N
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Texas, USA 2010 - International Herbage Seed Group

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