WHILE growing oats at different temperatures in water of different 18O and deuterium (D) abundances, we noticed that oats grown in Antarctic water in which is depleted in 18O and D by -49??? and -400???, relative to standard mean ocean water (SMOW used as a comparative reference in hydrogen and oxygen isotope studies), showed initial growth 1-2 weeks sooner than did oats grown in water containing greater 18O and D concentrations. The oats seemed to grow better in water which was most depleted in the stable isotopes throughout the growth period. ?? 1975 Nature Publishing Group.