Evaluation of root morphology of selected rice varieties under anaerobic and aerobic conditions in Sri Lanka

Abstract

Rice (Oryza sativa L.) is the staple food in Sri Lanka. With the increasing population and the changing climatic conditions, there is a need to grow rice with increased yielding potential and tolerance to several biotic and abiotic stresses. Around 99 % of the total paddy production area of the country is cultivated with newly improved varieties, while the remaining area is adopted with low-yielding traditional rice varieties [1]. Since rice is a semi-aquatic plant, it is usually grown under anaerobic conditions as long as water is available. According to recent studies, the annual mean rainfall in Sri Lanka has decreased throughout the country. In 2013, about 35 % of rain-fed rice farmers in Dry and Intermediate zones had given up their cultivation during the Yala season compared to the Maha, primarily due to insufficient water availability [2]. Further, the rice production of Yala 2019 had decreased approximately by 1.5 million metric tons than Yala 2018 season, owing to the drought situation and pest damages experienced in the primary rice-producing districts [3]. The root architecture critically influences the the yield of the crops, and improved root characteristics help farmers grow crops tolerant to multiple stresses and with high yield. There is an urgent need to identify and develop drought stress adaptable rice genotypes for rain-fed and drought-prone areas. Therefore, the objectives of this study were to screen three locally available rice varieties for their root morphology under aerobic and anaerobic conditions and to identify best-performing varieties with improved root traits to withstand drought.