V. AMARVADH, B. RAVINDRA REDDY*, P. SUMATHI, G. MOHAN NAIDU AND I. BHAVANI DEVI

Department of Statistics and Mathematics, S.V. Agricultural College, ANGRAU, Tirupati – 517 502,Chittoor Dt., Andhra Pradesh

ABSTRACT

This paper presents the groundnut leafhopper incidence and the influence of climatic factors in groundnut growing areas of Chittoor district of Andhra Pradesh. The data analysis on leafhopper incidence and its correlation with the climate factors in standard weeks of groundnut growing seasons from 2007 to 2016 revealed that the rainfall distribution varied greatly within groundnut growing seasons over years. The average minimum temperatures ranged from 12.8°C – 32.5°C, average maximum temperatures ranged from 25.7°C – 41.9°C, morning relative humidity ranged from 36.8 – 95% and evening relative humidity ranged from 21.5 – 91.5%. The results revealed that the days with RH > 78 per cent, temperature ranging from 13°C – 42°C and rainfall ranging from 0.00 to 297 mm are most critical factors for incidence of leafhopper. Correlation coefficients were com-puted to ascertain the pattern of relationship between leafhopper and climate factors over years (2007-2016). The results re-vealed that there was a positive relationship between the leafhopper incidence and rainfall, evening relative humidity and sun-shine hours. The MLR models for within year and between years found to be useful in the prediction of leafhopper incidence. The logistic models were found to be useful in the prediction of probabilities for occurrence and non-occurrence of leafhopper incidence of groundnut. The markov chain models revealed that there was significant change in occurrence of leafhopper in consecutive days.

KEYWORDS:

Leafhopper, climate factors, logistic regression, MLR models, Markov chain models.