Assessment of spot blotch disease and terminal heat stress on the performance of spring wheat genotypes in eastern Indo-Gangetic plains of India

Spot blotch and terminal heat stress are the two major constraints of spring wheat (Triticum aestivum L.) in Eastern Indo-Gangetic Plains (EGP) of South Asia, causing severe yield losses. The present study has assessed various morphological traits with spot blotch and terminal heat stress on wheat. A total of 55 wheat genotypes were evaluated in two sets of growing conditions (GC); GC-1 (timely sown + protected from spot blotch) and GC-2 (late sown + inoculated with spot blotch). Differential responses of high temperature and spot blotch have been realized as significantly reducing the mean performance of traits under GC-2. The present study observed a yield loss of 57%, on a mean basis, from GC-1 to GC-2. This study also emphasized that area under SPAD (Soil Plant Analysis Development) decline curve, i.e., AUSDC and areas under NDVI (Normalized Difference Vegetation Index) decline curve, i.e., AUNDC becomes more responsive in deciding the performance of a crop and positively influence most of the yield contributing traits under stress conditions. Regression analysis revealed that AUSDC and days to maturity (DM) were major predictor variables when plants faced high temperature and spot blotch disease stress (GC-2). The present study identified six wheat genotypes CRPW-16, CRPW-53, CRPW-11, CRPW-35, CRPW-9 and CRPW-40 as resistant to spot blotch, tolerant to terminal heat with high yield potential. These promising genotypes would serve as breeding material to develop stress-tolerant wheat varieties more especifically for EGP of India.