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Light Interception and Plant Growth Light Interception and Plant Growth

Light Interception and Plant Growth - PDF document

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Uploaded On 2016-06-16

Light Interception and Plant Growth - PPT Presentation

Photo courtesy of BA Stewart ID: 364053

Photo courtesy B.A. Stewart

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Light Interception and Plant Growth Photo courtesy of B.A. Stewart •D.A. Charles-Edwards (Academic Press, 1982)–“The acquisition of knowledge of the potential yield of –“Mathematical models allow us to formalize –In order to understand plant/environment interactions, •Determinants of Growth–Determinants are elements that identify or •Light Interception•Light Use Efficiency•Dry Matter Production & Loss•Duration of Growth•Dry Matter Partitioning •Single layer of leaves -0°Sun Angle With no overlapping leaves, light interception by a plant in a day (LI) is a function of plant’s leaf area (LA) and the daily light intensity (S) as follows: SLA LI •As layers of leaves are added, shading occurs Still just one plant with sun straight overhead •Now we have interplant and intraplantshading as well as •Since leaf area distribution is complicated, )cmor (m above measured it was area Land)cmor (m area Leaf LAI2222Example: What is the LAI when 4500 cm2of leaf area was measured from 6 plants cut from 1 meter of row from soybeans grown in 0.5 m rows. 0.9 cm 10000m 1 x m 0.5 x m 1cm 4500222 •What is the relationship between LAI and light –Linear, quadratic, or a plateau? 0123456LAILight Inteception (%)Critical LAI? •How are LI and leaf growth and development 0.20.40.60.81.21.41.6152535455565Time (days) LI Leaf Wt (t/ha) •Crop growth rates are a function of:–Photosynthetic rates (–Respiration losses by existing tissue (–Leaf area intercepting light•As a result, net canopy photosynthesis (LUE) PS LUEPS = Photosynthesis R = Respiration Rice4.2Corn3.4Sunflower2.6Cotton2.5Clover1.6Soybean1.3 Reason for species differences? •Daily accumulated light interception and the light = daily dry matter production (g/m2)= Light use efficiency constant (g/MJ)LI= Light energy intercepted by the crop (MJ/m2) •For seasonal dry matter production, we simply sum the = daily dry matter production (g/mcy constant (g/MJ)= Light energy intercepted by the crop (MJ/m Now daily crop growth rate (LUEx LI) and duration of Daily Dry Matter 020406080100120Days After PlantingDry Matter (g dayLAI Daily DM Rate LAI •Dry Matter Distribution change as the plant develops. LeavesStemRootGrainEmergence to GPD0.600.030.370.0GPD to Silking0.470.380.080.0Grain fill0.00.00.01.00 Derived from CERES-Maize •Daily DM accumulation is:•LI is a function of Leaf area:•Daily change in DM is:= daily dry matter production (g/mency constant (g/MJ)LI = Light energy intercepted by the crop (MJ/m= specific leaf area (m= leaf weight (g)S = Daily light integral (MJ/m = leaf senescence factor (%)= Daily leaf loss (g) Water Stress and DM Non-Stressed –Plant population–Row spacing–Plant height–Planting configurations Plant Density and LAIPlant Density and LAI 150002000025000300003500040000Plant Denstiy (plts/a)Corn LA I 050000100000150000200000250000300000Plant Denstiy (plts/a)Soybean LAI Light and Row Light and Row SpacingsSpacings 30 in Light InterceptionLight Interception 0.10.20.30.40.50.60.77/27/127/228/18/118/218/319/10Light Interception (%) 20 in 40 in 60 in Clump Planting Photo courtesy of B.A. Stewart •Crop growth can be defined by five physiological –Light Interception, Light use ef•Light interception can be modeled based on plant LAI in •Light use efficiency is a function of plant species.•Dry matter production is a function of light interception •We can influence light interception by our choice of •The amount of time that a leaf is exposed –Varies based on daylength(day of year)•Total number of hours of daylight is called a –Influence by location on the earth (latitude) •The irradiance or illuminancefalling on a •The relationship is E At a 45°incidence angle, the