CHARACTERIZATION OF ENVIRONMENTAL FACTORS CONDUCIVE FOR BROWN RUST DEVELOPMENT IN WHEAT (Triticum aestivum L.)

Abstract

Wheat (Triticum aestivum L.) is one of the world's most important cereal crop in terms of cultivated area and quantity of grain produced. It is the most communal staple food in Pakistan, followed by rice and maize. Wheat is susceptible to a wide range of biotic and abiotic stressors, which can lead to severe yield reductions. Rusts are economically the most significant biotic factor of wheat crop. Leaf rust, commonly known as brown rust, is a severe wheat disease in Pakistan that results in production losses ranging from 10% to 40%. In the present study, the experiment was conducted in MNS-University of agriculture Multan, in which screening of wheat breeding lines against the natural inoculum of brown rust and the relationship of leaf rust with different environmental parameters was done in two years of data. The disease severity (DS), Coefficient of infection (CI) and average coefficient of infection (ACI) was recorded by using Modified Cobb’s scale. During 2020-2021, among 100 breeding lines, 16 breeding lines revealed an immune response, 14 exhibited moderately resistant response, 5 showed a susceptible response and the remaining were moderately resistant-moderately susceptible response. In season 2021-22, 19 breeding lines were immune, 19 showed a moderately resistant response, 4 breeding lines were susceptible and the remaining were moderately resistant-moderately susceptible. Correlation clearly demonstrated the response of disease development to environmental factors. Maximum temperature, minimum temperature, wind speed and sunshine hours showed a positive relationship with leaf rust severity while a negative relationship was evident in relative humidity and disease severity during both year study. This study provided evidence that there is a strong relationship between environmental factors and leaf rust severity. The environmental conditions were not ideal during the early stage of the host plant that help them to withstand the building inoculum during March-April. Therefore, the breeding lines exhibiting immune and moderately resistant response could be utilized in future breeding programs to develop leaf rust resistant varieties/ cultivars to combat this menace.