Stress
- stress_radiation(ra_24)
Computes the stress for plants when there is not sufficient radiation.
\[S_{r}=\frac{S^{\downarrow}}{\left(S^{\downarrow}+60\right)} \left(1+\frac{60}{500}\right)\]- Parameters
ra_24 (float) – daily solar radiation, \(S^{\downarrow}\) [Wm-2]
- Returns
stress_rad – stress factor for radiation, \(S_{r}\) [-]
- Return type
float
Examples
>>> import ETLook.stress as stress >>> stress.stress_radiation() 0.0 >>> stress.stress_radiation(500) 1.0 >>> stress.stress_radiation(700) 1.0 >>> stress.stress_radiation(250) 0.90322580645161288
- stress_moisture(se_root, tenacity=1.5)
Computes the stress for plants when there is not sufficient soil moisture in the root zone.
\[S_{m}=K_{sf} \cdot S_{e,root}-\frac{\sin\left(2\pi \cdot S_{e,root}\right)}{2\pi}\]The tenacity factor \(K_{sf}\) ranges from 1 for sensitive plants to 1.5 for moderately sensitive plants to 3 for insensitive (tenacious plants).
- Parameters
se_root (float) – effective saturation root zone moisture S_{e,root} [-]
tenacity (float) – tenacity factor K_{sf} [-]
- Returns
stress_moist – stress factor for root zone moisture, \(S_{m}\) [-]
- Return type
float
Examples
>>> import ETLook.stress as stress >>> stress.stress_moisture(0.5) 0.75 >>> stress.stress_moisture(0.5, tenacity = 1) 0.5 >>> stress.stress_moisture(0.5, tenacity = 3) 1.0
- stress_temperature(t_air_24, t_opt=25.0, t_min=0.0, t_max=50.0)
Computes the stress for plants when it is too cold or hot
\[f=\frac{T_{max}-T_{opt}}{T_{opt}-T_{min}}\]\[s_{T}=\frac{\left(T_{a}-T_{min}\right)\cdot\left(T_{max}-T_{a}\right)^{f}} {\left(T_{opt}-T_{min}\right)\cdot\left(T_{max}-T_{opt}\right)^{f}}\]- Parameters
t_air_24 (float) – daily air temperature, \(T_{a}\) [C]
t_opt (float) – optimum air temperature for plant growth, \(T_{opt}\) [C]
t_min (float) – minimum air temperature for plant growth, \(T_{min}\) [C]
t_max (float) – maximum air temperature for plant growth, \(T_{max}\) [C]
- Returns
stress_temp – stress factor for air temperature, \(S_{T}\) [-]
- Return type
float
Examples
>>> import ETLook.stress as stress >>> stress.stress_temperature(15) 0.83999999999999997 >>> stress.stress_temperature(15, t_opt =20) 0.9451080185178129 >>> stress.stress_temperature(15, t_opt =20, t_min=10) 0.79398148148148151 >>> stress.stress_temperature(15, t_opt =20, t_min=10, t_max=30) 0.75
- stress_vpd(vpd_24, vpd_slope=-0.3)
Computes the stress for plants if the vpd increases too much. With lower slopes the stress increases faster. The slope of the curve is between -0.3 and -0.7.
\[S_{v}=m \cdot \ln(0.1 \cdot \Delta_{e}+\frac{1}{2})+1\]- Parameters
vpd_24 (float) – daily vapour pressure deficit, \(\Delta_{e}\) [mbar]
vpd_slope (float) – vapour pressure stress curve slope, \(m\) [mbar-1]
- Returns
stress_vpd – stress factor for vapour pressure deficit, \(S_{v}\) [-]
- Return type
float
Examples
>>> import ETLook.stress as stress >>> stress.stress_vpd(15) 0.79205584583201638 >>> stress.stress_vpd(15, vpd_slope=-0.7) 0.51479697360803833 >>> stress.stress_vpd(15, vpd_slope=-0.3) 0.79205584583201638