Relationships between roots, the stay‐green phenotype, and agronomic performance in barley and wheat grown in semi‐arid conditions

• Published in: Plant phenome journal Vol. 5; no. 1
• Main Authors: Williams, Jessica L., Sherman, Jamie D., Lamb, Peggy, Cook, Jason, Lachowiec, Jennifer A., Bourgault, Maryse
• Format: Journal Article
• Language: English
• Published: Guilford John Wiley & Sons, Inc 2022; Wiley
• Subjects: Adaptation; Agricultural production; Arid environments; Barley; Crop improvement; Crop yield; Crops; Drought; Gene loci; Genotype & phenotype; Genotypes; Hordeum vulgare; Nitrates; Phenotypes; Proxies; Seedlings; Semiarid environments; Senescence; Sorghum; Triticum aestivum; Wheat; United States > US; North Dakota; Montana
• ISSN: 2578-2703; 2578-2703
• DOI: 10.1002/ppj2.20050

Stay‐green is a phenotype that crop breeders could use to improve drought adaptation. It increases the duration of grain fill in several species including barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.), maintaining yield in semi‐arid conditions. Evidence from controlled environment experiments suggests a connection between stay‐green and root systems. These belowground structures are understudied and thus represent opportunity for crop improvement if relationships to agronomics can be understood. Minirhizotrons facilitate study of these relationships by allowing repeated nondestructive root measurements in field conditions. However, this is time‐consuming, and proxies would be useful for increasing throughput capacity of root research. Here we present results from field trials with minirhizotrons in a semi‐arid environment, as well as greenhouse seedling assays conducted on stay‐green and non‐stay‐green barley and wheat lines. In barley, stay‐green and greater yield were primarily associated with greater deep root length and delayed root senescence, whereas in wheat, yield was most strongly correlated with total root length, and root system differences for stay‐green were not as apparent. We speculate that the physiology of stay‐green is different between these two species, and that barley may use a more efficient root system to withstand drought whereas wheat relies on a larger one. Several seedling traits related consistently to field root traits, but correlation directions were often opposite between barley and wheat. The connections between traits presented here could be useful for breeders seeking to improve crop adaptation to drought, but more genotypes and environments will need to be tested.
Core Ideas
In‐field minirhizotrons revealed a connection between the stay‐green phenotype and deep roots in barley.
Yield was most strongly positively correlated with deep root length in barley and total root length in wheat.
There were positive correlations with percent deep root length for both grain yield and grain protein in wheat.
Seminal root angle and deep rooting were negatively correlated in wheat but positively correlated in barley.