Texas, USA 2010 - International Herbage Seed Group

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Seed yield components and their potential interaction in grasses - to whatextend does seed weight influence yield?B. Boelt & R. GislumFaculty of Agricultural SciencesAarhus UniversityDenmarkE-mail: Birte.Boelt@agrsci.dkAbstractIn a first-year seed crop of red fescue (Festuca rubra L.) the degree of lodging was controlled bythe use of Moddus (Trinexapac-ethyl). Seed weight was found to increase by the decreasingdegree of lodging prior to harvest. The higher seed weights were accompanied by higher yieldseven though the number of reproductive tillers and floret site utilization (FSU) were unaffectedby the treatments.Seed yield is affected by several yield components and reflects the interaction between the seedyield potential (e.g. number of reproductive tillers, number of spikelets and florets/spikelet perreproductive tiller), the utilization of the potential (e.g. seed set, seed weight) and the realizationof the seed yield potential, defined as the number of florets forming a saleable seed. Therealization of the seed yield potential is affected by seed retention, seed weight and other traitsassociated with yield loss during the harvest and post-harvest processes.IntroductionThe number of reproductive tillers per unit area is an important component in establishing theseed yield potential; however, its importance varies among grass species. In slow-establishingspecies or species with a high vernalization requirement tiller number and tiller size in autumnare important factors in maintaining a high yield potential in first-year seed crops. Tillerdevelopment influences transition rate from vegetative to reproductive growth with large tillersbeing more successful than smaller tillers (Boelt 1999; Meijer 1987).The total number of spikelets and florets per inflorescence depends on the number of primarybranches and on the number of florets produced per primary branch. It is believed that thenumber of primary branches increases with apex size (Colvill and Marshall 1984). Thereforeautumn-produced tillers usually have more spikelets per tiller and in addition, they are also foundto have more florets per spikelet (Ryle 1964). This is in agreement with a more recent study ofYamada et al. (2004), who found a positive correlation between plant height, tiller size, spikelength and the number of spikelets per spike.109
The seed set is of major importance for grass seed production. Elgersma (1991) distinguishedbetween the biological floret site utilization (FSU), which is the percentage of florets present atanthesis resulting in a viable seed and the economic FSU, which is the percentage of floretspresent at anthesis resulting in a cleaned pure seed. Different studies are reporting largevariations in biological FSU, but on average 20-50% of the florets are biologically unproductivewith losses occurring during pollination, fertilization and seed development.Seed development depends on the position of the seed within the inflorescence. Seed weightdecreased from the basal to the distal spikelets and with an even steeper gradient within thespikelet (Anslow 1964). From a glasshouse experiment with spaced plants of perennial ryegrass,Warringa et al. (1998) concluded that the amount of carbon assimilates in flowering tillers doesnot limit seed growth. Reducing light intensity by 75% had only minor effects on seed dryweight.Information on how seed weight is influenced by seed crop management is very limited, andoften it is confounded with variation in other seed yield components such as reproductive tillernumber.Materials and methodsA field experiment was conducted in 2007 and 2008 at Aarhus University, Research CentreFlakkebjerg where the growth regulator Moddus (Trinexapac-ethyl) was evaluated in differentdoses in a first-year seed crop of red fescue (Festuca rubra L.) cv. Maxima. In the seedproduction year one plant sample per plot was cut within an area of 0.25 m 2 prior to seed harvestand the number of reproductive tillers was registered. The number of florets per spikelet atflowering and the number of seeds per spikelet prior to harvest were registered in 30reproductive tillers in selected treatments in each of four replicates. Lodging was assessed atflowering and prior to harvest using a scale where 0 equals „all reproductive tillers erect‟ and 100equals „all reproductive tillers completely lodged‟. Before shedding, 8 m x 2.5 m area per plotwas harvested directly with a trial combine harvester, and seeds were air-dried to 12% moisturebefore determining seed yield. After seed drying and cleaning, one sample from each replicatewas analyzed for purity, and seed yield expressed as 100% clean seed was calculated. Thousandseed weight was calculated on basis of eight individual counts of 100 seeds in each plot.ResultsVariation in the degree of lodging at harvest was recorded in response to growing season and theapplied dose of Trinexapac-ethyl. In the harvest year 2007 lodging ranged from 71-88; whereasthe responses in 2008 were 0-41. Seed weight ranged from 0,94 to 1,08 mg seed -1 , the lowestseed weight obtained when lodging at harvest was registered at 71 and highest when lodging wasregistered at 11 (figure 1).110
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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
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Perennial ryegrass (Lolium perenne
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Relative Seed Yieldsingle composite
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Flowers, M.D.; Hart, J.M.; Young II
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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 and 112: The seeds were collected from the A
Page 113 and 114: increases germination to its potent
Page 115 and 116: Light, lodging and flag leaves-what
Page 117 and 118: Relative seed yieldSeed yield (kg/h
Page 119: Hampton, J.G.; Clemence, T.G.A.; He
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
Page 163 and 164: Seed yield components and yield per
Page 165 and 166: ResultsVariation among populations
Page 167 and 168: Table 2. Means of total seeds per p
Page 169 and 170: Ryle, G. J. (1970). Partition of As
Page 171 and 172:
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
Page 255 and 256:
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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