Stay-Green and Associated Vegetative Indices to Breed Maize Adapted to Heat and Combined Heat-Drought Stresses

Abstract

Abstract:The objective of this study was to assess the importance of stay-green on grain yield under heat and combined heat and drought stress and to identify the associated vegetative indices allowing higher throughput in order to facilitate the identification of climate resilient germplasm. Hybrids of tropical and subtropical adaptation were evaluated under heat and combined heat and drought stress in 2014 and 2015. Five weekly measurements with an airplane mounted multispectral camera starting at anthesis were used to estimate the area under the curve (AUC) for vegetation indices during that period; the indices were compared to the AUC ( AUC SEN) for three visual senescence scores taken two, four, and six weeks after flowering and a novel stay-green trait (AUC for stay-green; AUC SG) derived from AUC SEN by correcting for the flowering date. Heat and combined heat and drought stress reduced grain yield by 53% and 82% (relative to non-stress trials reported elsewhere) for trials carried out in 2014 and 2015, respectively, going along with lower AUC SG in 2014. The AUC SG was consistently correlated with grain yield across trials and years, reaching correlation coefficients of 0.55 and 0.56 for 2014 and 2015, respectively. The AUC for different vegetative indices, AUC NDVI (r gGY = 0.62; r gAUCSG = 0.72), AUC HBSI (r gGY = 0.64; r gAUCSG = 0.71), AUC GRE (r gGY = 0.57; r gAUCSG = 0.61), and AUC CWMI (r gGY = 0.63; r gAUCSG = 0.75), were associated with grain yield and stay-green across experiments and years. Due to its good correlation with grain yield and stay-green across environments, we propose AUC NDVI for use as an indicator for stay-green and a long grain filling. The trait AUC NDVI can be used in addition to grain yield to identify climate-resilient germplasm in tropical and subtropical regions to increase food security in a changing climate.

Beat the stress: breeding for climate resilience in maize for the tropical rainfed environments

“…To support the development of climate-resilient varieties and through strategic partnership, the CIMMYT maize breeding program, has been developing and deploying various sensing-based tools/methods for improving phenotyping throughput and accuracy (Zaman-Allah et al 2015 ; Makanza et al 2018a ). These tools/methods have made it possible to quantitatively measure the key traits relevant to drought or heat stress tolerance like early vigour, canopy senescence, with comparable or higher accuracy at a lower cost compared to visual assessments (Cerrudo et al 2017 ; Makanza et al 2018a ). Similarly, digital imaging has been used to rapidly assess yield component traits that can provide insights about tolerance to abiotic stresses like drought or heat as well as tolerance to pests like Fall Armyworm (Makanza et al 2018b ).…”

Changes in Ecophysiology, Osmolytes, and Secondary Metabolites of the Medicinal Plants of Mentha piperita and Catharanthus roseus Subjected to Drought and Heat Stress

“…Drought and heat stress frequently co-occur, especially in arid and semi-arid regions of globe, and they result in significant decreases in plant growth and productivity [40,41]. Plants frequently survive these stress conditions by changing their metabolism to favor the synthesis of osmolytes and secondary metabolites that promote stress tolerance.…”

Genome-Wide Association Mapping for Heat Stress Responsive Traits in Field Pea

“…Pigments including chlorophylls, carotenoids, anthocyanins contribute to heat tolerance through heat dissipation and protection of vital plant components and processes [13,14]. Multi-environment studies on pea [10], and maize [15] revealed leaf color (greenness) as a trait linked to stress tolerance.…”

“…Chlorophyll represents pigment abundance and composition, and is used to drive photosynthesis, plant senescence, and yield potential [15,16]. Stay-green, a trait that delays plant senescence, is reported to be associated with improved yield under stress conditions [15]. Estimation of leaf chlorophyll concentration by the soil plant analysis development (SPAD) meter is reliable, and is strongly correlated with laboratory-based destructive methods [17].…”