Texas, USA 2010 - International Herbage Seed Group

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Predicting spring nitrogen for perennial ryegrass seed crops from NDVIR.J. Chynoweth 1 , M.P. Rolston 2 , J.A.K. Trethewey 2 , & B.L. McCloy 3 .1 Foundation for Arable Research, PO Box 80, Lincoln 7640, New Zealand2 AgResearch Lincoln Research Centre, Private Bag 4749, Christchurch 8140, New Zealand3 NZArable, PO Box 16-101, Christchurch, New ZealandEmail: chynowethr@far.org.nzAbstractNitrogen (N) fertiliser makes up approximately 15 % of the total cost of growing a perennialryegrass seed crop. Therefore accurate estimates of applied N fertiliser are important bothfinancially and environmentally. Optical sensors may have the ability to determine the nitrogenrequirements and the output expressed as normalized difference vegetation index (NDVI).In two experiments carried out in the 2008/09 season a treatment based on estimating nitrogenrequirements using NDVI calculations was implemented. Results were promising with NDVIreading increasing as N rate increased until a saturation level. The NDVI readings were thenconverted in to a nitrogen nutrition index (NNI) where resulting treatments ranked in the topstatistical seed yield group in both experiments. In each experiment this technique applied alower or equal amount of N fertiliser compared to standard best practice while achieving similarseed yields.If NDVI and NNI can be used to predict N requirement of perennial ryegrass this method couldprovide a tool for variable rate N applications based on crop variability within a field.IntroductionPerennial ryegrass (Lolium perenne L.) seed production is responsive to the application ofnitrogen (N) fertiliser, averaging 36% response above control treatments in 17 trials throughoutCanterbury (Rolston et al. 2008). The availability of nitrogen to the ryegrass seed crop is amajor determinant of seed yields. At various points throughout the growing season N contentvaries between 5 (possible in early spring) and 1.5% (typical at harvest) of herbage dry matter.Nitrogen influences dry matter production, tillering and therefore number of inflorescenceswhich develop to maturity. Currently best practice in New Zealand is to record soil mineral N inearly spring to determine the application rate of nitrogen for each field. Recent work by theauthors has identified that testing soil mineral N is a reliable indicator to the amount of applied Nrequired to achieve optimum seed yields in New Zealand. Currently application rates can beestimated by; 185 – measured soil mineral N (kg ha -1 ) (Rolston et al. 2008). However thisapproach relies on an average target application rate and may be excessive or insufficient in anygiven year. Therefore if a method exists of using ‟real time‟ data for crop N status (and alsobiomass production, growth rate, chlorophyll content etc) then profitablity could be improved.69
Optical sensors have the potential to determine stress in arable crops and therefore may have theability to determine the nitrogen requirements. The “Greenseeker” is an active type opticalsensor that measures canopy reflectance in the red (~650nm) and near infrared (770nm) wavebands. The output is then converted to normalized difference vegetation index (NDVI) ascalculated by. Normalized difference vegetation index has been used previously to provide anestimate of crop nitrogen (N) concentration in wheat (Flowers et al. 2003).With a lack of New Zealand data, results published by Flowers et al. 2007 were used to estimateN% and unpublished New Zealand data used for estimating dry matter per hectare based onNDVI values (FAR unpublished data 2008). From these data sets a nitrogen nutrition index(NNI) (Lemaire & Gastal 1997) was estimated with critical levels as described by Gislum andBoelt (2009). It was assumed that 40 kg N would raise plant N tissue by 0.5 % based on datapresented by Cookson (1999).Typically spring nitrogen is applied in two or three applications at 14 to 21 day intervals, to limitthe potential for leaching and/or volatilisation losses. The aim of this study was to investigatetools for determining the amount of additional nitrogen required after the first application.MethodsTwo trials, each with 22 treatments including applied N from 0 to 240 kg N ha -1 in 40 kgincrements, were undertaken within irrigated commercial seed crops at Greendale and Methven(Canterbury, New Zealand) with cv Grasslands Samson and cv Alto respectively. Plots were 10m long and 3.2 m wide with four replicates in a randomized block design. The crops weremanaged by the grower for all inputs except N. The soil N levels (Table 1) are based on analysisby Hills Laboratories 1 for samples collected in September before closing. The mineral N (MnN)is the combined NH 4+and NO 3 - levels. A “Greenseeker” NDVI assessment was made 21 daysafter the initial spring N application. Two treatments used NDVI values for making a decision ontotal spring N.At approximately 40% seed moisture content a 1.7 m swath was cut from the centre of all plotswith a modified plot windrower. <strong>Seed</strong> was then harvested at 12% seed moisture content with a plotcombine. <strong>Seed</strong> samples were machine dressed on a small-scale air-screen separator to achieve a 1 stGeneration seed purity standard and converted to a yield/ha.Results and DiscussionSoil Mineral NSoil mineral N levels were slightly below the long term average (41 kg ha -1 , range 10 – 122 kgha -1 ) (Rolston et al. 2008) at both sites (Table 1) indicating that winter leaching had removedmuch of the available N below the rooting zone.1 Hills Laboratories see www.hill-labs.co.nz70
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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
Page 29 and 30: Fig. 1. Land resource areas of Texa
Page 31 and 32: y land owners. Seed yields are low
Page 33 and 34: The influence of planting density o
Page 35 and 36: Simple correlation and regression a
Page 37 and 38: Variation in seed shattering in a g
Page 39 and 40: Seed retention (SR) was calculated
Page 41 and 42: mm160120Precipitation8040020Km h -1
Page 43 and 44: Young, B. A. (1986). A Source of Re
Page 45 and 46: Several methods are commonly used f
Page 47 and 48: Table 3. Effect of the length of ha
Page 49 and 50: Alfalfa seed production in semi-hum
Page 51 and 52: Rather near the meteorological stat
Page 53 and 54: ReferencesBolaños-Aguilar E.D., Hu
Page 55 and 56: ased bioenergy conversion plants wa
Page 57 and 58: Table 1. Average distances required
Page 59 and 60: 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: Rolston, P.; Trethewey, J.; McCloy,
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 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
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Seed yield variation in a red clove
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100Seed yield plant -1 (g)806040200
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Marden, J. H. 1984. Remote percepti
Page 137 and 138:
Crimson clover seed production in t
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Piper, C.V. 1935. Forage plants and
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deal of investigation into the caus
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genes and subsequent ability to pro
Page 145 and 146:
Gatenby, W.A., S.C. Munday-Finch, A
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Control of Vulpia myuros in red fes
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The strip design provides an opport
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The pot experiments did not reveale
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CharacterWeed abundance1 A few plan
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Jensen, P. K. (2010) Longevity of s
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Effects of intraspecific competitio
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flowering, Gangi accumulated a high
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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
Page 189 and 190:
Annual ryegrass seed production in
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seed yield, kg/haExtractable Al, mg
Page 193 and 194:
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
Page 239 and 240:
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
Page 257 and 258:
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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