Duration of low temperature changes physiological and biochemical attributes of rice seedling.

The low temperature (LT) is detrimental to growth of rice seedling during boro season in Bangladesh. An experiment was conducted in growth chamber during June to October, 2021 using BRRI dhan29 as planting material. The aim of this experiment was to determine the effect of variable duration of LT on growth, physiological and biochemical traits of rice seedling and to determine the age of seedling that can tolerate cold effect. In this experiment 5, 10, 15 and 20 days old seedling (DOS) were exposed to 6 °C for 1, 2, 3 and 4 days. Seedlings were also grown under room temperature (25 °C, RT) which consider as control treatment. Seedlings were grown in plastic trays filled with mixture of soil and cowdung. The experiment was conducted following completely randomized design with 3 replications. Data on shoot length and weight, root length and weight, chlorophyll (Chl), carotenoids, malondialdehyde (MDA) and proline contain were determined after 5 days of temperature sock. The results revealed that the LT was injurious to younger rice seedling when they were exposed to LT for 1 to 2 days. The shoot and root length as well as their dry weight were reduced under low temperature. Further, the Chl and carotenoid content of younger rice seedlings degraded within 2 days of LT exposure. On the contrary, the proline and MDA content of rice seedlings increased to reduce the harmful effect of under LT. It could be concluded that the rice seedlings could tolerate the detrimental effect of LT when they attain at least 15 days. [ABSTRACT FROM AUTHOR]