Exogenous melatonin improves seedling vigor and drought tolerance in wheat

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.