Dispersion statistics and sequential sampling plan for rice blast disease

摘要

Spatial dispersion of rice blast lesions in the field was studied by using Iwao's patchiness regression technique, The estimates of dispersion parameters revealed that the basic components of the lesion in a population were aggregates and these were contagiously distributed in the rice field. A sequential sampling plan was devised with the help of the dispersion parameters estimated from the pooled regression analysis, with a preliminary economic threshold of one lesion leaf~(-1), alongwith the student's t-test for an error level of 0.01 at infinite degree of freedom. This plan calls for a minimum of 10 samples and a maximum of 58 samples to determine if the mean number of lesions leaf~(-1) in a field is significantly different from 1 and to decideon the necessity of initiating control measures.