COLD TOLERANT MECHANISM OF RICE CULTIVARS BASED ON PHYSIO-MORPHOLOGICAL CHARACTERISTICS

Abstract

A filed experiment was carried out to investigate the physio-morphological characteristics of nine rice seedlings for screening cold survival during low temperature in Northwest of Bangladesh. The test rice varieties were V1, Bashful; V2, Poshurshail; V3, Gochi; V4, Taipee; V5, Bogra; V6, Lafaya; V7, Banglamoti (BRRIdhan-50); V8, Jotapari and V9, BRRIdhan-28, respectively. The leaf proline synthesis, chlorophyll content, relative water content (RWC), seedling shoot and root length, total biomass, seed germination and mortality rate were investigated. The V2 (Poshurshail) and V9 (BRRIdhan-28) seedling synthesized the highest proline at low temperature. The highest chlorophyll ‘a’ content was obtained in V1 (Bashful) local cultivar (1.75 mg g’') and statiscally similar to V2 (Poshurshail). The highest percentage of RWC in rice leaf (95%) was found in V5 cultivar. The highest shoot length (11.8 at 35 DAG) was found in V5 and the lowest shoot length was found in V8 cultivar. The V8 plant showed significantly greater root dry weight and root length while the lowest was in V6 plant for both cases. Root weight, length as well as root volume markedly decreased during cold stressed condition. The number of root number plant’ was found statistically significant among the varieties. The V2 and V9 cultivars produced higher root and shoot weight, higher germination percentage and lower mortality rate. This study reveals that V2 (Poshurshail) and V9 (BRRIdhan-28) varieties showed the better survival potentiality during cold temperature by over-synthesizing proline, chlorophyll and other physio-morphological parameters.