Abstract

An experiment was conducted to study the genetic variability for seedling thermo-tolerance in the Indian mustard germplasm. 165 genotypes of Indian mustard were sown in two seasons (2011 and 2012) in the early conditions when the soil temperature is in the range of 40 to 42°C. The same set of genotypes were screened in the controlled growth chamber using a screening protocol that simulates the temperature fluctuations experienced during the seedling stage of Indian mustard in many of the mustard growing areas of the country. Analysis of the data revealed significant variation for seedling thermo-tolerance. There was a high consistency in the tolerant and susceptible genotypes identified between the two screening procedures. The phytotron screening protocol was effective in differentiating and identifying high temperature tolerant and susceptible genotypes; and for the further studies, field screening can be replaced with phytotron screening. Re-evaluation of selected thermo-tolerant and thermo-susceptible genotypes in the controlled growth chamber revealed significant differences between the two groups regarding the specific leaf area and in the extent of lipid peroxidation, indicating that these two parameters can be used as selection criterion for seedling thermo-tolerance in Indian mustard.

Key words: Lipid peroxidation, screening, seedling thermo-tolerance index (STI), thermo-tolerance.