Response of different lines and cultivars of rice subjected to low temperatures under controlled conditions

Abstract

Rice (Oryza sativa L.) is the most important food crop in the world and primary source of food for more than a third of the population. The low temperatures are among the main abiotic stresses that affect the yield of this cereal. The objective of this work was to determinate the response of different lines and cultivars of rice in seedling state to low temperature stress under controlled conditions. 172 lines and cultivars were studied. It were subjected to 5 0C for 24 hours, when the plants were about three to four leaves. The evaluations were conducted by measured of chlorophyll fluorescence and visually. A wide range of response was obtained, which indicated a high allelic diversity for the low temperatures sensitivity in the studied germplasm. A group of 30 cultivars responded more favorably to the cold and the most prominent cultivars showed Fv/Fm values between 0.80 and 0.89. A significant relationship between visual evaluation and chlorophyll fluorescence was found. The correlation coefficient revealed a moderately strong relationship between both variables. Tolerant plant materials were more consistently identified. However, the dispersion between methods increased to more susceptible cultivars. Keywords: cold tolerance, chlorophyll fluorescence, Oryza sativa, visual evaluation