Variation in Varietal Reaction to Rice Tungro Disease: Possible Causes

摘要

Variation in varietal reaction to rice tungro disease is encountered among locations and over time, particularly in field tests. The variation may be due to mechanical errors wherein a variety shows a reaction in the field but is noted differently in a notebook or publication, or to different reactions of rice varieties in the field. The former could be caused by negligence in handling test materials, misidentification of the disease, difference in level of ability to score the reaction, and insufficient replicates; the latter, by existence of different biotypes of tungro vectors or tungro strains among locations or tests, and variation in tungro disease pressure to the variety in the tests. Except for variation caused by biotypes and strains which is under investigation by a Rice Tungro Virus Collaborative Project, the possible causes are discussed with suggestions on minimizing or reducing the errors.