Journal of Scientific Research and Reports

Aims: To study the influence of weather parameters on rust (Puccinia arachidis) incidence in groundnut (Arachis hypogaea L.) varieties under different sowing environments and to develop forewarning models.

Study Design: A field experiment was conducted in a split-plot design with three replications at a site with medium-deep, well-drained soil suitable for groundnut cultivation. Main plot treatments included four groundnut varieties (JL-501, RHRG-6083 (Phule Unnati), TAG-24, and JL-776 (Phule Bharati)), while sub-plot treatments consisted of four sowing windows (25^th to 28^th meteorological weeks).

Place and Duration of Study: Department of Agricultural Meteorology Farm, College of Agriculture, Pune, MPKV, Rahuri, Maharashtra, India, during kharif seasons of 2017 and 2018.

Methodology: Daily weather parameters (temperature, rainfall, rainy days, humidity, evaporation, sunshine hours, and wind speed) were recorded to assess their impact on crop growth and rust incidence. Rust (Puccinia arachidis) incidence was recorded at 7-day intervals starting 30 days after sowing. Percentage disease incidence (PDI) was calculated.  Disease intensity (%) was assessed using a 1–9 scale. Correlation and multiple regression analyses were applied to study the relationship between weather parameters and rust incidence. Weather parameters including maximum and minimum temperature, morning and afternoon humidity, and bright sunshine hours were used to develop multiple linear regression models for prediction of percent disease intensity of rust in different varieties across sowing windows.

Results: Correlation analysis between PDI of rust incidence and weather parameters revealed that, maximum temperature, morning relative humidity, rainfall, and bright sunshine hours were positively correlated with rust development, whereas afternoon relative humidity and wind speed consistently showed negative correlations. Minimum temperature suppressed disease intensity. Forewarning models developed for each variety and sowing window explained a high degree of variability (R² = 0.84–0.97). Maximum temperature emerged as the most consistent positive predictor of rust, while minimum temperature strongly suppressed disease. Morning humidity sometimes enhanced rust development, though its effect was weaker, while afternoon humidity generally reduced incidence. Bright sunshine hours consistently played a suppressive role across all models. These models demonstrated strong predictive ability and can serve as reliable tools for disease forecasting.

Conclusion: From a practical perspective, adopting later sowing windows during 27^th to 28^th MW along with cultivation of moderate resistant varieties such as RHRG-6083 and JL-776 could significantly reduce the severity of rust disease in groundnut under field conditions. Among the tested varieties, TAG-24 was highly susceptible; JL-501 was susceptible to rust, whereas RHRG-6083 and JL-776 showed moderate resistant to rust with lower disease intensity.