Selection of Traits and Physio-Metabolic Perspective of Source-Sink Mechanisms under Drought and Low-N Stress

Crop yield is the manifestation of the net photosynthesis of the whole plant over the growing season. Source organs are responsible for all biomass production through the process of photosynthesis, similarly, sink tissues are the net importers of assimilates which includes rapidly growing meristems, juvenile leaves, roots, tubers, and seeds. Recent climate changes have resulted in frequent droughts, heavy floods, temperature fluctuations, and nitrogen deficiency. Maize, being the C4 crop, grows in wide range of environmental conditions. Although to achieve high productivity it required large amount of water and nitrogen fertilizer. Therefore, drought and low nitrogen stress are major threats to maize productivity worldwide. Drought and N deficiency impact many physio-biochemical processes, hinder plant growth and development, and thus alter the source-sink balance. In drought and low-N stress, selection of traits that balance the source-sink mechanism plays crucial role and helps to improve the grain yield. The metabolic prospective of source and sink mechanism in drought and low-N stress induces the expression of various metabolites, providing the information on the complex regulatory systems behind stress tolerance. Therefore, yield can be improved by selecting the genotypes that shows optimized carbon and nitrogen metabolism under drought and low-nitrogen stress conditions. This review will help future researchers better understand the source-sink process for crop development in the context of changing climatic conditions.