Damião Inácio Clemente
Abstract:
World demand for food has been growing steadily over the years. United Nations (UN) estimates indicate that by 2050 global demand could grow by 60% compared to 2015. This is due to the population growth estimated to reach 9.2 billion in this century (MUTEIA, 2015). Given this reality, concerns about the increase in food production become even greater due to the advent of climate. In order to overcome the difficulties arising from population growth and estimates of world food demand, climate change, linked to water scarcity, leads the agricultural sector to seek the adoption of new technologies, as well as the optimization of water use and selection of cultivars more efficient in water use. This scenario brings new challenges to plant breeding programs for the development of cultivars more adapted to adverse conditions (HAO et al., 2010). Due to the high production potential, its wide geographical distribution and its high genetic variability, maize (Zea mays L.) is a species that has great adaptive potential for these conditions, which justifies the cereal being the most cultivated in the world. In Brazil, maize is the main cereal produced, being cultivated on about 15.96 million hectares, with an average yield of 5.2 tons ha-1 (CONAB, 2016). Nevertheless, maize is highly sensitive to abiotic stresses, especially water stress, which is the main factor responsible for crop yield losses over the years. Water stress significantly affects maize in almost all of its developmental phases, being more emphatic during the reproductive phase. Water deficit during this period may compromise ovule fertilization, carbohydrate production and grain formation, as well as promote a lower accumulation of dry matter in the grains and consequently a reduction in final production. The good productive performance of maize, as well as its stability in the face of climatic oscillations during the cropping periods are correlated to several morphophysiological factors, which interact with each other to express adaptability characteristics and tolerance to stress levels. However, little is known about the interaction between these mechanisms and the agronomic characteristics associated with drought tolerance. Local varieties and populations adapted to diverse environments are potential sources of genes in the search for tolerance and or efficiency in relation to the various levels of abiotic stress (MACHADO et al., 2011). Such genotypes may contribute to the development of more efficient cultivars when grown under stress. Therefore, the exploitation of the genetic diversity existing in maize crop is a valuable alternative to increase the natural capacity to respond to climate change to new genotypes. Along those lines, the identification and characterization of morphophysiological descriptors, as well as the elucidation of agronomic traits responsible for the differential behavior of genotypes under stress conditions can help in the selection of superior populations, as well as contributing to the development of selection techniques that may assist in the selection identification of genetic sources of tolerance to water stress. So, the goal of this work was to study the effect of water stress on the interaction between morphophysiological and agronomic traits in maize (Zea mays L.) populations and to identify populations with higher potential for use in breeding programs aiming at stress tolerance water.
