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High temperature during reproductive stage of winter crops causes sterility of pollen grains and reduced yield. It is essential to find the genotypes with higher pollen viability, as it is most sensitive to temperature extremes. A field study was conducted with wheat (Triticum aestivum L.) genotypes to understand the effect of high temperature on pollen viability and grain yield for 2 years under timely (TS) and late sown (LS) conditions. A strong correlation was observed between higher pollen viability and higher grain yield under heat stress condition. Genotypes like K7903, HD2932, WH730 and RAJ3765 showed higher pollen viability, whereas DBW17, HUW468, RAJ4014 and UP2425 had lower pollen viability under LS condition. Further, the quantification of antioxidant enzymes activity mainly, Super oxide dismutase (SOD), Catalase (CAT), Peroxidase (POD) and Glutathione peroxidase (GPX) has showed significant variation among study genotypes. Thus, the identified high pollen viability genotypes can serve as a potential source for trait based breeding under heat stress in wheat. The present study is a first of its kind to assess more number of wheat genotypes for pollen viability and antioxidants activity under field condition. It also confirms that pollen viability can be used as a potential trait to screen genotypes for heat stress tolerance in wheat.

Wheat is produced worldwide over six continents with the European Union, China, India, Russia, and the United States as major producer countries. The productivity was recorded 749 million tons by harvesting from 220-million-hectare land. It is the need of the hour to develop stress-tolerant wheat varieties to enhance the productivity by 60% to provide food security to 9.6 billion-world population by 2050. Although the genotypes have been identified for heat, drought and salt tolerance, their underlying mechanism for tolerance is poorly understood. The detailed understanding of the mechanism and identification of critical factors participating in multiple abiotic stress tolerance is essential. In the present study, the contrasting wheat genotypes were intensely characterized and assessed for the expression of different stress responsive genes under lab conditions. The expression analysis revealed that SHN1, DREB6, NHX2 and AVP1 were found to be highly induced under heat, salt and drought stresses in wheat. Thus, these genes can be used as signature genes to identify the multiple stress-tolerant varieties in the breeding program. The novel variants of these genes can be targeted through breeding or genetic engineering or genome editing strategies to develop multiple abiotic stress tolerant wheat varieties.

Wheat ( Triticum aestivum L.), being a principal staple cereal crop for about 36% of the world population is of prime importance. However, due to its wide agro ecological adaptations it is subjected to various climatic vagaries and hence prone to yield losses. Hence, it is an exigency to explore novel ways to mitigate the drought stress. One such approach is the exogenous application of plant growth regulators and other biochemical compounds which are identified to be involved in plant growth regulating activities. Melatonin (N-acetyI-5-methoxytryptamine) is a ubiquitous growth regulator suggested as a promising molecule involved in abiotic stress tolerance. The experiment was conducted at ICAR-Indian Institute of Wheat and Barley Research, Karnal during crop season 2017-18 under controlled condition. Six wheat genotypes namely, C306, NI5439, HD3086, RW5, DBW136, WH147 were sown in two sets with three replications in the germination tray under drought stress condition. Melatonin treatment was given to one set of genotypes at GS 14, GS 22 growth stages according to Zadok’s scale and the second set of genotypes was kept untreated. Data was recorded for Chlorophyll content (SPAD), Normalized Difference Vegetation Index (NDVI) and Chlorophyll fluorescence (CFL) along with seedling growth related traits like shoot fresh weight, shoot dry weight, root fresh weight, root length on per plant basis. The results highlighted that melatonin application improved seedling vigor, and other morpho-physiological traits along with overall plant performance as compared to the non-treated set of wheat seedlings under drought stress.The research findings entail that melatonin can enhance drought stress tolerance and could be considered as a potential growth regulator for yield improvement in arid and semi arid areas.

Wheat is produced worldwide over six continents with the European Union, China, India, Russia, and the United States as major producer countries. The productivity was recorded 749 million tons by harvesting from 220-million-hectare land. It is the need of the hour to develop stress-tolerant wheat varieties to enhance the productivity by 60% to provide food security to 9.6 billion-world population by 2050. Although the genotypes have been identified for heat, drought and salt tolerance, their underlying mechanism for tolerance is poorly understood. The detailed understanding of the mechanism and identification of critical factors participating in multiple abiotic stress tolerance is essential. In the present study, the contrasting wheat genotypes were intensely characterized and assessed for the expression of different stress responsive genes under lab conditions. The expression analysis revealed that SHN1, DREB6, NHX2 and AVP1 were found to be highly induced under heat, salt and drought stresses in wheat. Thus, these genes can be used as signature genes to identify the multiple stress-tolerant varieties in the breeding program. The novel variants of these genes can be targeted through breeding or genetic engineering or genome editing strategies to develop multiple abiotic stress tolerant wheat varieties.