Assessing vineyard water status using the reflectance based Water Index

▶ Contrasting water supply promotes changes in both stomatal conductance and WI. ▶ WI closely follows diurnal changes in stomatal conductance at the leaf level. ▶ Predawn water potential indicates moderate to severe water stress in field grown vines. ▶ WI relates to the midday canopy to air temperature difference in field grown vines. ▶ WI tracks variation in canopy transpiration under moderate to severe water stress.