Abstract
Abstract: The objective of this work was to evaluate different traits of four corn (Zea mays) genotypes with contrasting responses to drought and to determine the main traits associated to such responses. The experiment was carried out in a greenhouse. The plants were grown in pots subjected to full irrigation. Drought was imposed to plants at 54 days after sowing and kept constant for 12 consecutive days; however, a group of plants remained under full irrigation. Traits related to leaf gas exchange, photochemical apparatus, growth, and yield were assessed, and data were subjected to hierarchical agglomerative clustering and principal component analysis. DKB 390 distinguishes from the other genotypes for growth and yield traits, while 2B-707 and DKB 390 discriminate from 'BRS 1030' and 'BRS 1010' for physiological traits. Ear length, kernel number per ear, above-ground dry matter, shoot dry matter, and plant height are the most important growth and yield traits to discriminate genotype-dependent drought tolerance. Among the physiological traits, the most important are: chlorophyll content, absorptivity, leaf temperature, maximum fluorescence in the dark-adapted state, minimum fluorescence in the dark-adapted state, water-use efficiency, and intercellular CO2 concentration.
Highlights
Drought tolerance in plants is a complex phenomenon, which is strongly influenced by morphological, physiological, and biochemical traits, as well as by environmental factors and their interactions (Farooq et al, 2009; Jaleel et al, 2009; Obidiegwu et al, 2015; Khan et al, 2018; Sahebi et al, 2018)
The main reason for the failure can be attributed to the complexity of drought stress, as there is not a universal trait that works for all drought situations at any stage of the plant (Tardieu, 2012)
In order to simplify the cluster analysis of physiological traits, only the two major clusters formed under both control (Figure 2 A) and drought (Figure 2 B) were taken into account
Summary
Drought tolerance in plants is a complex phenomenon, which is strongly influenced by morphological, physiological, and biochemical traits, as well as by environmental factors and their interactions (Farooq et al, 2009; Jaleel et al, 2009; Obidiegwu et al, 2015; Khan et al, 2018; Sahebi et al, 2018). Drought stress can reach the plant at any stage of the cycle Because of this fact, a specific trait may be more important than others for plants to better resist stress (Tardieu, 2012). Several secondary traits, known as physiological traits (Silva et al, 2007; Masuka et al, 2012), have been used to select drought-tolerant plants. Most uses of these traits showed little, or no success, in breeding programs, for which the most important trait is yield (Obidiegwu et al, 2015; Sahebi et al, 2018). Tolerance to vegetative drought stress does not necessarily confer tolerance in the reproductive stage
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