Standardisation of Temperature Induction Response Technique: A Promising Method for Screening of Maize Genotypes for Thermotolerance at Seed Level

Climate change adversely affects global agriculture. Heat stress is a major problem for crop production, which detrimentally affects plant growth and development. Maize is a diverse crop widely used as food, feed and fodder. Heat stress affects maize growth and development significantly, reducing the yield and quality of the crop. Crop improvement is critical for heat stress. With the advancement in omics technologies, developing tolerant genotypes has become a great option. The crop improvement involves screening and evaluation of the diverse maize genotypes, which is laborious and time-consuming. The temperature induction response technique (TIR) is one of the reliable and robust techniques that can be used for screening a large population of genotypes. It is based on the concept of acquired thermotolerance and lethal dose 50, but it is crop-specific. Hence, the present study standardized the TIR technique in maize at the seed level. The Lethal temperature standardised for maize seeds was 50°C for three hours, while the induction or sublethal temperature standardised was gradual exposure of maize seeds to 32-50°C for 4.5 hours. After a recovery period of 24 hours under room conditions, the seeds were tested for germination and recovery growth was measured as a means of thermotolerance. The standardized TIR in maize can be a reliable and robust technique for evaluating and screening the maize genotypes for thermotolerance at the seed stage itself.