00323nam a2200109Ia 4500008004100000082002600041245005700067260003000124650002000154650002200174650001700196220204s9999    xx            000 0 und d  a581.1:631.524.84bJOH 0aPhysiological processes limiting plant productivity.  aLondonbButterworthc1981  aCrop physiology  aNitrogen fixation  aWater stress