Screening Rice Lines Tolerant to Low Temperature at the Germination Stage Using Thermogradient bar

Sri Dalimunthe, Luthfi Aziz Siregar, T. Nisa and Aris Hairmansis

Background and Objective: Breeding for superior rice varieties for upland drylands requires parent lines that tolerate low temperatures. Thermogradient bar can be used to screen plant tolerance to temperature during the germination stage. This study aimed to evaluate several tolerance variables to low-temperature stress during the germination stage and select hybrid rice lines tolerant to low temperatures using a Thermogradient bar device. Materials and Methods: The experiment was conducted at the Biology Research Center Laboratory, Indonesian Institute of Sciences (LIPI), Cibinong, Bogor. It used a Complete Randomized Block Design with five replications. Rice tolerance to low temperatures during the generative phase was tested in the highlands in the KP. Tongkoh, Karo (1430 m above sea level and 19°C temperature). A total of 10 promising lines and five control varieties were used in the test. The control varieties used were Ciherang, Stubagendit, Mekongga as sensitive comparative varieties and Sigambiri Merah and Sigambiri Putih as tolerant comparative varieties. Thermogradient bar was used for testing tolerance to low temperatures at several temperature levels, namely 13, 16, 18 and 28°C. Results: The rice genotypes tested had better responses than the sensitive comparative varieties. However, the responses differed from the comparative tolerant Sigambiri under low-temperature stress conditions. The Karo 121 DHP line is a sensitive genotype at <18°C, and the Karo 122 DHP line is the most tolerant. Conclusion: Rice selection using Thermogradient bar can be a rapid test method for low-temperature stresses in the germination phase.

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