Screening of Submergence Tolerant Rice under Artificial Condition Based on Multiple Selection Indices

Flooding often occurs during the vegetative stage in freshwater swamps and rainfed lowlands, and therefore submergence tolerant rice varieties are needed. This study was aimed at evaluating rice lines to submergence stress. The experiments were conducted at Indonesian Center for Rice Research (ICRR) experimental station in Sukamandi, Subang, West Java, each in different environmental conditions: (1) submergence condition, which was conducted in a submergence pool and (2) optimal condition, which was conducted in the irrigation field. Ninety-five lines and four check varieties, namely Inpari 30 Ciherang Sub1, IR42, Limboto, and IR20 were used. An augmented design with five blocks was followed in each environment. Three selection methods were used: (1) selection based on survival rate and vigor, (2) selection based on productivity under submergence and sensitivity index on productivity character, (3) selection based on the weighted selection index using sensitivity index variables of morphological and agronomic characters. The clustergram analysis with heatmaps method was used to compile of three previous selection methods to facilitate scientist in clarifying tolerant and sensitive lines. There were eighteen lines selected as tolerant to submergence stress, i.e., line no. 9, 15, 34, 46, 47, 48, 49, 50, 53, 55, 56, 57, 59, 60, 61, 62, 89, and 90. These lines are considered promising for breeding improved rice varieties tolerant to submergence.