Maize: Impacts and Management of Abiotic Stresses

Abstract

Maize is an important staple cereal crop grown for food, feed, and biofuel production owing to its multipurpose use, different types, and wider adaptability. To meet the increasing demand for animal and human consumption, maize production should be doubled, particularly in developing countries. Maize productivity in African and Asian countries including India is very low because it is mainly cultivated in arid and semi-arid regions as a rainfed crop. Maize production across the globe is mainly threatened by an increased incidence of severe droughts, waterlogging conditions during times of excess rainfalls, extreme temperatures (heat and cold), salinity, and nutrient stress. The effects of these stresses on maize are prevalent from seed germination to maturity and cause drastic yield losses. Drought is one of the major constrain in tropical maize growing areas and often it causes up to 100% yield loss if it occurs prior to and post reproduction phase. Recently waterlogging, becoming a major problem, and even one- or two-day continuous waterlogging may cause up to 30-40% yield losses. Further, frequent occurrences of extreme temperatures (heat and cold/chilling) affect plant growth and physiological process mainly photosynthesis, pollination, and grain filling. Salinity is reported to occur mainly in arid or semi-arid regions which are further aggravated by waterlogging and high temperature and impacts largely germination and seedling growth. Nitrogen (N) stress is also considered abiotic stress since maize growth and phenology is very sensitive to varying levels of N supply and thus influences yield attributing traits. In recent years most tropical countries experienced the simultaneous occurrence of different abiotic stresses and are more destructive to crop production than occurring separately. The combined strategies of crop improvement and production are the way forward for the development of abiotic stress tolerance. Crop production strategies include judicious use of water and other resources and the development of input-saving agronomic practices. While crop improvement involves pre-breeding, identification, and introgression of traits/genes/QTLs associated abiotic stress tolerance through marker-assisted and genomic selection. This approach demands understanding the complex mechanisms associated with abiotic stress tolerance. Further, the use of nutrients, soil amendments, bio-regulators, phytohormones, microbes also enhances abiotic tolerance level to some extent. Hence, adopting suitable and efficient strategies will help to mitigate and manage different abiotic stresses in maize