ETa

PEM = protein energy malnutrition ppm = parts per million pr = proportion of plant available soil water which a crop can use without ETa becoming less than ETm

14. Saving seeds for planting 1991

W = amount of water needed to bring the soil in the root zone to field capacity (liters/m2 or mm of depth; see Chapter 17 to convert English measures to metric); pr = the proportion of plant available soil water which a particular crop can actually use without ETa becoming less than ETm, that is without experiencing water deficit-estimated at 0.5;

5. How plants live and grow 1991

A plant experiences water stress or water deficit when actual evapotranspiration (ETa) falls below ETm, that is, its requirements for water are not met (section 5.5).

5. How plants live and grow 1991