Comparing phenotypic variation of root traits in Thai rice (Oryza sativa L.) across growing systems

Abstract

© 2018, ALÖKI Kft., Budapest, Hungary. Root systems have long been neglected in plant breeding due to their inaccessibility and the laborious nature of root studies. Over the past years, root scientists developed the classification system, methodologies and growing systems for high throughput measurements of root traits. We compared root traits obtained with three growing systems for eleven Thai rice varieties. We found considerable differences in the variation of root traits between the laboratory system with paper roll-up, a pot system in the greenhouse and a field system. The variation of root traits ranged from 1.31 folds in root cortical aerenchyma (RCA) to 4.20 folds in crown root growth angle in a roll-up system. Varieties also differed in root plasticity among the three growing environments. Principal components analysis indicated that root anatomical traits contributed 55% to the observed variation in the field. Hierarchical cluster analysis revealed that upland varieties clustered in a steep-angled group while lowland varieties clustered in a shallow-angled group. The observed clustering could be linked to the amount of RCA. Our results suggest that optimization of root growth angle could be an important strategy for improved adaptation of rice plants growing in flooded and non-flooded areas. We propose Thai rice varieties as donors in root trait driven breeding programs to enhance water and nutrient uptake.