NECK ROT INFECTION OF RICE: VARIETAL RESISTANCE, PANICLE PHENOLOGY AND YIELD REDUCTION

SUPAAD MOHD. AMIN

SUMMARY

Three rice varieties (Kadaria, Jaya and Sekencang) were inoculated with Pyricularia oryzae when 75%of the crops had headed. Disease severity was monitored from the time of inoculation until harvest, after which the grain yield was separately recorded for each variety. Kadaria was found to be resistant to neck rot. However, about 75% of the panicles in Jaya and Sekencang were infected. In both varieties, it was also observed that more than 45% of the panicles which exserted after the time of inoculation had secondary infections. Infection of neck node reduces grain yield. As much as 41% and 32% loss in yield was observed in Jaya and Sekencang respectively. Detailed observations on Jaya showed that early infections resulted in greater loss in yield. The grain yield of the lower zone of the panicle was most affected. Laboratory experiments indicated that panicles become less susceptible to infection as they mature.

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