Plants were grown in nutrient solution under conditions of deficiency of N, P, K, S, B, Cu or Zn till the stage of tillering. An attempt was then made to ascertain the extent of correction of the deficiencies by supplying the element lacking in the substrate either in the nutrient solution or through foliar application, The results of the corrective tratments are presented in Table 15 in which yield data are given as percentage of those obtained with the non deficient plants.