Identification of submergence-tolerant rice genotypes: a comprehensive analysis of survival and growth parameters in germination stage

This study aimed to screen and identify submergence-tolerant rice genotypes from the Fedearroz germplasm bank in Colombia by evaluating their survival rates and growth parameters, with the goal of considering them as potential parents in plant breeding programs. In a preliminary experiment, 368 genotypes were subjected to submergence stress for 21 d during germination. Four genotypes (FL11338, FL17927, FL17938, and FL17813) had survival rates above 70%, suggesting seed and seedling tolerance. In the second experiment, the tolerant genotypes chosen in the previous test, along with tolerant (Khao Hlan On) and susceptible (IR-42) controls, were further evaluated for survival rate, seedling growth, and morpho-agronomic, industrial, and culinary traits. The stressed genotype/control genotype (S/C) ratio showed that submergence stress negatively affected the genotype IR-42, which showed the greatest negative difference in survival percentage (SP) (-1.33) compared to the other genotypes [Khao Hlan On (-0.31), FL11338 (-0.42), FL17927 (-0.28), FL17938 (-0.4), and FL17813 (-0.33)]. The recovery capacity of tolerant genotypes was notable, as they completed their life cycle with no differences in morpho-agronomic traits, yield components, or culinary characteristics compared with the controls. Survival rate and plant height were identified as key physiological attributes for assessing submergence tolerance during germination in rice breeding programs. This study provides valuable insights into the response of rice genotypes to submergence stress in Colombia and Latin America during the germination phase, as it identifies promising tolerant genotypes for use in breeding programs to develop direct-seeded rice cultivars adapted to excessive water availability during the germination phase.