Conventional and Advance Breeding Approaches for Developing Abiotic Stress Tolerant Maize

Conventional breeding approaches in crops continue to deliver improved genotypes to farmers since long back; however, the ever-increasing population is a great challenge for the researchers to produce sufficient food from available land in the increasing adverse effects of changing climate. In the era of climate change, several abiotic and biotic stresses are prevalent and affecting maize production worldwide. Among abiotic stresses, drought, water logging and heat stresses are important yield restraining factors in maize, which are adversely affecting its growth and development. They affect the maize biomass production, grains formation and development by intervening in plant physiological, morphological, and anatomical and biochemical mechanisms. Therefore, it is the major concern of all maize breeders to develop the climate resilient genotypes that ensure the global food security threatened by the climate. There are several in built mechanisms in tolerant plant which help in their osmotic adjustment, leaf canopy temperature regulation, stomata conductance, deep root systems development, availability of soluble sugar, and aerenchyma formation etc., under various abiotic stresses conditions. Breeding for abiotic stress tolerance includes selection and utilization of resistant/tolerant germplasm, use of molecular markers, utilization of secondary traits through different breeding techniques. Wide or distant related germplasm like teosinte provides useful source germplasm for drought and water logging tolerance. In addition to the conventional breeding approaches, recent advances in molecular breeding and biotechnology have provided powerful tools to accelerate breeding gains and stress adaptation. Marker assisted selection (MAS), genome editing and genomic selection are the important innovative techniques which can increase and speed up the genetic gain in any of the maize improvement programme. Many Quantitative Trait Loci (QTLs) have been mapped for the drought, water-logging and heat in maize which can be integrated in breeding programme. In the era of molecular biology, "omics" has proved its potential in detail study of genes and transcriptional factors which play significant roles in abiotic stresses tolerance regulation in maize. Biotechnological approaches can only be utilized as supplement to the conventional breeding approaches and alone they may not be able to invent the potential genotypes which can survive under abiotic stresses.