Experiment setup and crop model calibration for assessing the impacts of haze on crop growth and yield. Weihong Luo Nanjing Agricultural University

Transcription

1 Experiment setup and crop model calibration for assessing the impacts of haze on crop growth and yield Weihong Luo Nanjing Agricultural University

2 Outline Impacts of haze on crop growth Model applications Experiment setup

3 Impacts of haze on crop growth Haze (atmospheric aerosols) Amount of radiation and that of PAR reaching the surface Fraction of diffused radiation Amount of leaf photosynthesis Impacts on growth Impacts on yield Dry matter allocated to grains PAR reached shaded leaves Total amount of canopy photosynthesis Overall impact on yield is + or -? It s quantity? It s causes? Impacts on growth+

4 采用三季试验对照实测总辐射值模拟结果 biomass produc ction in Nanjing Simulation result ts for wheat crop 总干重增加比例 (%) 总干重增加比例 (%) 20% 15% 10% 5% 0% 10% 8% 6% 4% 2% 0% SLA 增加 4% SLA 增加 5% SLA 增加 6% 假设总辐射比三季试验对照实测值降低 10% 模拟结果 k 降低 7% k 降低 12% k 降低 19% f(dif) 增加 64% f(dif) 增加 90% f(dif) 增加 147% PAR/Q 比例增加 5% PAR/Q 比例增加 5% PAR/Q 比例增加 5% SLA 增加 4% SLA 增加 5% SLA 增加 6% k 降低 7% k 降低 12% k 降低 19% f(dif) 增加 64% f(dif) 增加 90% f(dif) 增加 147% PAR/Q 比例增加 5% PAR/Q 比例增加 5% PAR/Q 比例增加 5%

5 Model calibrations

6 Structure of Crop Simulation Model Day length PAR, CO 2 temperature photosynthesis Maintenance respiration Shading and Changing k LAI Growth respiration Biomass production fraction of Q dif Dry matter partitioning leaf stem storage organ Yield Quality root Development stage Development rate

7 Leaf Photosynthesis Leaf photosynthesis rate P g [kg CO 2 ha -1 h -1 ]: P g =P g,max * [1-exp(-ε*PAR/ P g,max )] Under shading (more diffused radiation, ε will increase due to more chlorophylls in leaves P g P g,max ε PAR ε increase can compensate some reduction of P g caused by reduced PAR

8 Canopy Photosynthesis Canopy photosynthesis rate P c :Integrate P g over 0~LAI: P c = P g d(lai)= [P g,max (1-exp (-ε*par L / P g,max )]d(lai) PAR L = PAR o *exp(-k*lai L ) PAR o : the PAR above the canopy PAR L : the PAR at depth L (where LAI, accumulated from top to depth L, is LAI L ) inside the canopy k: the canopy light extinction coefficient Smaller for diffused radiation Q dif Larger for direct radiation Q dir more Q dif reaches lower leaves increase canopy RUE

9 Leaf area index Leaf area index growth rate: LAI/ t= =( WLV/ t)*sla SLA: specific leaf area (m 2 /kg WLV). SLA increases under shading (more diffused radiation) conditions. Promote the fast establishment of the canopy, hence increase canopy RUE

10 Yield Yield= biomass*hi HI: harvest index HI deceases under shanding conditions. Negative impact on yield

11 Model parameters need to be calibrated ε: initial light use efficiency of leaves k: canopy light extinction coefficient SLA: specific leaf area Fraction of dry matter allocated to different organs (leaves, stems and grains) HI: harvest index

12 Experiment design: Experiment setup Crop variety: use represent cultivar that has the largest sowing area in the exp region. Treatment: using PE plastic film as shading material to simulate the haze conditions. Films installed at a height of 2 m above ground on steel tube frames. The films are open in the morning after sunrise and closed in the afternoon near sunset every day except rain and overcast days, and should be closed when it is going to have rain during a day.

13 Treatment: Level of shading 20~25% reduction of global radiation using PE plastic film (3 layers) with global radiation transmittance of Under the films, the fraction of diffused radiation is about 2.6~2.8 times of CK at midday under clear weather conditions. Plot area 4 (south-north) 5 (east-west) = 20 m 2, 3 replicas for CK and each treatment. All plots are arranged with randomized block.

14 0.4 Fraction of diffused radiation at midday under clear weather condition CK T1 T2

15 江苏农科院试验整块地面积为 19* *19/2=855 m 2 T1-1,T1-2,T1-3 代表第一个处理 (6 号膜 ) 的 3 个重复 T2-1,T2-2,T2-3 代表第二个处理 (7 号膜 ) 的 3 个重复 randomized CK 为对照 CK1 15 m 南 西 东 北 3m T1-3 T2-1 3m 3m 路与钢架间隔 60cm CK3 T1-1 小路, 宽度 50cm, 地面以上高度 50-60cm 37.5m 3m 3m T2-2 T2-3 3m 3m 5m T1-2 4m CK2 3m 3m 19 m

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17 Measurements 1. Soil N, P, K (inorganic or available and total) contents before planting 2. Global and diffused radiation, PAR, net radiation*, air temperature at 1.5m above ground; canopy temperature* (after canopy closed) 3. Development stage observation (sowing or transplanting, tillering, jointing, booting, heading, milk filling, ripening, and harvest date)

18 Measurements 4. Non distractive measurements (1) At each development stage: number of stems (tillers) per unit area; k, plant height, number of leaves per main stem, number of tillers per plant. (2) After heading: number of spike per unit area. (3) At each development stage after treatment started: photosynthesis PAR response curves (LI-6400) and chlorophyll (SPAD-502) of fully open green leaves at top, middle and lower level of the canopy.

19 Measurements 5. Distractive measurements (1) At each development stage: sample 3 hills (for rice) or 10 plants for wheat per plot to measure total biomass, organ dry weight, LAI (LAI-2000), SLA, N content of organs. (2) At harvest: number of spike per plant, number of spikelet per spike, number of non fertilized spikelet per spike, number of grains per spike, grain weight (1000 grains), total biomass, harvest index, and yield.

20 Questions? Thank you for your attention!