ON RELATION OF SOIL MOISTURE TO DEVELOPMENT OF RICE BLAST DISEASE WITH SPECIAL REFERENCE TO RESULTS OF INOCULATION EXPERIMENTS ON SEEDLINGS AND PEDICELS OF SPIKES OF PLANTS GROWN IN SOILS DIFFERING IN TIME AND DURATION OF DRYING AND IRRIGATION. PART B
ARMY BIOLOGICAL LABS FREDERICK MD
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The paper deals with the results of inoculation experiments on seedlings and spike pedicels of rice plants grown on soils differing in moisture for the same or different duration of time during different stages of growth of the plant. It was found that the susceptibility of the seedlings as well as the spike pedicels of the rice plant to the blast disease increased proportionally with the length of duration of a dry condition, and that it decreased similarly with a humid state of the soil. The rate of increase or decrease of susceptibility to the disease seemed to vary with the stage of growth of the host plant at which a certain condition occurred. The results of inoculation experiments on seedlings showed that the highest percentage of infection occurred in the lot in which the soil was continuously dry throughout the entire growth period. This was followed in percentage by the lot in which the soil was dry during the first half of the growth and well irrigated during the latter half of the growth period. The lot in which the soil was irrigated for the first half and allowed to dry out for the second half was third in rate of infection, while there was least infection in the lot which was constantly irrigated throughout the entire period of growth.
- Anatomy and Physiology