Table 1.

Some basic meteorological and plant factors affecting water uptake of plants.

Meteorological factors
Solar radiation (K↓)	Atmospheric water demand increases with K↓. 1 to 5% of the intercepted K↓ by plants is used for photosynthesis;
Atmospheric temperature (Ta)	The water amount in atmospheric increases with Ta. For every 10°C rise in atmospheric temperature, atmospheric can hold twice as much water as it can at a 10°C lower temperature.
Wind velocity (Va)	Transpiration increases with Va. Higher wind speeds reduce the boundary layer thickness. In the boundary layer RH is 100%. A high RH decreases the water potential gradient hence decreasing transpiration.
Relative humidity (RH)	High atmospheric RH results in a less steep water potential gradient (less transpiration). Transpiration increases with decreasing RH;
Plant factors
Rooting depth	Plants with deep roots have more potential to find soil water since they are able to reach the groundwater table.
Leaf amount and Leaf Are Index (LAI)	a The larger the leaf surface area the higher the transpiration flux. LAI is the ratio of plant leaf area to leaf area projected on the field.
Stomatal conductance	Light and moisture levels affect stomatal conductance most prominently. Leaf moisture content affects turgor pressure in the guard cells of stomata. Water stress (even under normal field conditions) results in a loss of turgor in the guard cells and hence induces leaf wilting.
Leaf enrolling folding and reflection	Typically maize and bluegrass reduce the exposed leaf area under water stress. The silver skin of soybean leaves reflects more K↓ when enrolled