THE USE OF WATER BY WHEAT PLANTS WHEN INOCULATED WITH HELMINTHOSPORIUM SATIVUM

Abstract

The transpirational histories of wheat plants, inoculated with Belminthosporium sativum Param., King & Bakke to produce root rot, showed a marked reduction in water loss during the early stages of growth, when compared with uninoculated plants. This was accompanied by a corresponding reduction in the transpiring areas owing to reduced lengths and widths in the second, third, and fourth leaves to appear. As the plants entered into the early stages of elongation of the culm the transpirational story reflected a recovery in the inoculated plants. The later leaves to appear were longer with greater transpiring areas than in uninoculated plants. This fact combined with the death of the first three or four leaves resulted in greater transpirational and photosynthetic areas in the inoculated plants with consequent increased yields of dry matter. Probably similar recovery does not occur under competitive field conditions, where weeds and healthy wheat plants are present. Poor light conditions and low soil moistures were not conducive to recovery of inoculated plants. The water requirements of wheat did not appear to be affected significantly by inoculation. Of two varieties of spring wheat, Reward was more severely injured initially and recovered more rapidly than Marquis. Several possible explanations of the recovery recorded here are discussed.