Rice plants alter their yield component parameters based on their tolerance to low temperatures determined by a non-invasive method during the vegetative stage

The first rice phenological stages are commonly subjected to low temperatures (LT) in temperate crop areas. Here, plants of rice genotypes were analyzed according to their LT tolerance at seedling stage, using a realistic experimental temperatures range, and measuring quantitative and operator-independent parameters, fast-obtainable by non-invasive techniques. The ratios between values of these parameters determined in plants under LT condition with respect to the control condition were statistically analyzed. We have found a discriminant formula based on two parameters that allowed to differentiate between genotypes previously described as tolerant and sensitive to LT, with a very low general classification error. The application of the discriminant formula to score plants under LT, using all genotypes from the Rice Diversity Panel 1 which comprehensively represents the genetic variability of the O. sativa species, resulted in LT tolerance levels of its subspecies and subpopulations consistent with previous reports. In turn, a strong association between the LT tolerance score at the seedling stage and the panicle weight in plants under field LT during the vegetative stage, suggested that this scoring could be used as an indirect selection factor of genotypes with good yield traits and suited to LT prone environments.