B. RAVINDRA REDDY*, V. MEENA KUMARI, G. MOHAN NAIDU, P.N. HARATHI AND M. MAHESH KUMAR

Department of Statistics and Mathematics,

ABSTRACT

This paper presents the rice Bacterial Leaf Blight (BLB) severity and the influence of climatic factors in rice growing in SPSR Nellore district of Andhra Pradesh. The data analysis on BLB incidence with the climate factors in standard weeks of rice growing seasons from 2003 to 2013 revealed that the rainfall distribution varied greatly within rice growing seasons and also over years. The average minimum temperature 23°C, average maximum temperature 29°C, morning relative humidity (81 – 97%) and evening relative humidity (66-90%) observed during crop seasons over years. The BLB severity during the years 2003, 2004, 2005 and 2008 was mild to moderate and during 2009 and 2011 was high. Analysis of 11 years (2003-2013) weather data revealed that the days with RH > 91%, temperature (20°C-31°C) and weekly rainfall are the most critical factors in the development of BLB incidence. The correlation studies revealed that, among the climate variables minimum temperature exhibits negative correlation. Rainfall, maximum temperature, morning relative humidity and evening relative humidity were positively correlated while wind velocity imparted significant positive correlation with bacterial leaf blight infestation. The different combinations of climate factors are found to be useful in the prediction of rice blast through MLR and Logistic regression models. The ANOVA carried out for testing the significance between standard weeks/varieties with respect to BLB incidence.

KEYWORDS:

ANOVA, Bacterial leaf blight, Climate factors, Logistic regression, MLR models, S.V. Agricultural College, Tirupati-517 502, Andhra Pradesh, India