Evaluation submergence tolerance of KDML105 backcross introgression lines under simulated flood condition

Abstract

Flash flooding is one of the major problems for rainfed lowland rice in northeast, Thailand.Approximately 1.86 million rai of this rainfed lowland rice area of 29.76 million rai was reported to be damagedevery year during 2002-2006. Thus, submergence tolerance is an objective of rainfed lowland rice breeding programfor northeast Thailand. Khao Dok Mali 105 backcross (KDML105-BC) for flood tolerance have been developedusing marker-assisted selection (MAS) by BIOTEC (Thailand). In order to evaluate for their performance underflood condition, an experiment was conducted under simulated flood condition in 2006 at Kasetsart University,KamPhaeng Saen campus, Nakhon Pathom. The 13 KDML-BC lines which have been selected by MAS for beingtolerance to flood together with 4 check lines (KDML105, HPSL1 Prajeenburi 2, Ayuthaya 1, and Fang Loy) wereevaluated. Flood condition was imposed at 30 days after transplanting with the depth of 120 cm. Flood stress wasmaintained for 12 days then it was drained out. Rice plants were kept to maturity to observe for grain yield.The results showed that all 13 lines of KDML105-BC were much better tolerant, recovery and produced highergrain yield than KDML105 (recipient) and other check varieties. Less percentage of death tiller after draining offlood-water which indicated tolerance to flood was observed in all KDML-BC lines compared with checkvarieties. Higher increasing percentage of tiller number at 30 days after flood stress was removed was also observedin KDML-BC lines which indicated better recovery after flooding than check varieties. Grain yield of KDML105-BC lines was higher (343-581 g/m2) than KDML105 (132 g/m2). There was significant positive relationshipbetween number of tillers after flooding and grain yield which suggested that lines with better tolerance and recoveryfrom flood stress could produce higher grain yield than susceptible lines. Grain physical and chemical qualities of allKDML-BC lines were similar to KDML105.