H. Yacouba et al., DAILY WATER-STRESS DURATION AND SOYBEAN G RAIN-YIELD (GLYCINE L MAX), Comptes rendus de l'Academie des sciences. Serie 3, Sciences de la vie, 317(9), 1994, pp. 841-846
An infrared thermometry study of a soybean crop showed that the hour o
f appearance of water stress correlated well with the duration of the
water stress for that day. This water stress duration is a better indi
cation than a measurement made only at the solar mid-day and strongly
correlates with the soybean yield.