Estimating Genotype × Environment Interaction for and Genetic Correlations among Drought Tolerance Traits in Maize via Factor Analytic Multiplicative Mixed Models

Abstract

Water deficit is one of the most common causes of severe crop‐production losses worldwide in maize (Zea mays L.). The main goal of this study was to infer about genotype × environment interaction (G × E) and to estimate genetic correlations between drought tolerance traits in maize using factor analytic (FA) multiplicative mixed models in the context of multi‐environment trial (MET) and multi‐trait multi‐environment trial (MTMET) analyses. The traits measured were: grain yield (GY), ears per plot (EPP), anthesis‐silking interval (ASI), female flowering time (FFT), and male flowering time (MFT). Three‐hundred and eight hybrids were evaluated in a total of eight trials conducted under water‐stressed (WS) and well‐watered (WW) conditions across 2 yr and two locations in Brazil. For most of the traits (GY, ASI, and FFT), the magnitude of the genetic variances differed across WS and WW conditions. Genetic correlations between water conditions for FFT and MFT were 0.81 and 0.82, respectively, indicating that it might be unnecessary to measure these traits in both water conditions. Grain yield and EPP showed moderate to high G × E, with genetic correlations of 0.57 and 0.39 between WS and WW conditions, respectively, which suggested that gene expression was not consistent across different water regimes. Therefore, it is necessary to evaluate these traits under both water conditions. Genetic correlations between pairs of traits, in general, were higher under WS conditions compared with WW conditions. Grain yield exhibited moderate correlations with EPP (r = 0.62) and FFT (r = −0.42) under WS conditions. The FA models can be a useful tool for MET and MTMET analyses in maize breeding programs for drought tolerance.

Can Genetic Progress for Drought Tolerance in Popcorn Be Achieved by Indirect Selection?

“…Drought, considered the most limiting abiotic factor for plant growth and development, compared to other stress types, has a strong effect on grain yield, limiting maize production in both tropical and subtropical regions [3,[5][6][7][8][9][10]. In the South-Center and Southeast region of Brazil, corn production is concentrated in the second growing season, from February to June [11]. During this season, water limitations caused by heavy rainfall variations can drastically reduce grain yield, implying the importance of using drought-tolerant maize genotypes [11,12].…”

“…In the South-Center and Southeast region of Brazil, corn production is concentrated in the second growing season, from February to June [11]. During this season, water limitations caused by heavy rainfall variations can drastically reduce grain yield, implying the importance of using drought-tolerant maize genotypes [11,12]. These effects are influenced by sensitivity levels of the genotypes, stress intensity and duration and the plant development stage during drought stress [9].…”

“…Stress caused by drought at the pre-anthesis phenological stage causes harmful effects on the meiotic stage of reproductive cells, affecting the subsequent development of the male gametophyte, inducing pollen sterility [14], reflecting in fewer grains [9]. For the evaluation of germplasm with a view to drought tolerance, we consider the traits associated with grain yield under stress, and at reproductive structures, i.e., shorter interval between male and female anthesis [11,15,16], late leaf senescence [15,17], increased prolificacy [11,15,18], and lower number of tassel branches [6,15]. More recently, physiological traits were highlighted, namely: (i) canopy temperature [9,10]; (ii) estimate green biomass by remote sensing tools based on the use of irradiation [3,9]; (iii) green leaf color index (SPAD) [9]; and, (iv) root morphology and depth [19].…”

“…More recently, physiological traits were highlighted, namely: (i) canopy temperature [9,10]; (ii) estimate green biomass by remote sensing tools based on the use of irradiation [3,9]; (iii) green leaf color index (SPAD) [9]; and, (iv) root morphology and depth [19]. The phenological stage of male pre-anthesis is the most recommended period for the evaluation of more productive genotypes under dry conditions [8][9][10][11], and the pre-anthesis period coincides with the moment of shortage of rainfall in corn crops in Brazil [11]. Meiosis-related processes, which include pollen viability, in addition to zygote formation and initiation of grain filling, are biological processes highly sensitive to water stress [20].…”

Combined Dominance and Additive Gene Effects in Trait Inheritance of Drought-Stressed and Full Irrigated Popcorn

“…In response to the severe effects of this abiotic stress on plant growth and development, breeding is an effective tool to reduce the vulnerability of crops [5]. Breeders have developed studies to understand the morphological, physiological, and agronomic responses of water-stressed plants, as well as to select higher-yield genotypes of the major crops under water stress [1,2,[6][7][8] with a view to mitigating the effects of climate change, mainly perceptible in the poor temporal and spatial distribution of rainfall.…”