Performance of Backcrosses Involving Transgressant Doubled Haploid Lines in Rice under Contrasting Moisture Regimes

Abstract

tomary statistical analyses are found to be inadequate in discerning the effects of different yield components Improvement of grain yield in the rainfed lowland rice (Oryza on yield (Zobel et al., 1989). Hence, studying grain yield sativa L.) ecosystem is important because that ecosystem covers a under varying moisture conditions and employing more considerable area. The objectives of this study were first to find relationship(s) among grain yield and its components, second to assess reliable statistical analyses may lead to better underthe influence of root morphological characters on grain yield, and standing of the influence of various traits on grain yield. finally to find the relationship of molecular marker heterozygosity Ample genetic variability for root morphological with heterosis-performance of yield related characters in rainfed lowtraits and other components (primary traits) of drought land rice. Nine backcrosses involving transgressants for maximum resistance has been documented over the past few deroot length in rice from a doubled haploid mapping population of cades. These studies have been conducted on specific IR64/Azucena along with parents were evaluated simultaneously for primary trait(s) of interest and its (their) contribution grain yield and related characters as well as root traits under conto drought resistance (Ludlow and Muchow, 1990; trasting moisture regimes. Grain yield showed maximum reduction Acevedo and Fereres, 1993; Sadiq et al., 1994; Hemaunder severe moisture stress conditions. Significant negative correlamalini et al., 2000). Even after several well designed tion between drought tolerance index and grain yield was observed in the well-watered conditions only. Multiple linear regression analysis

Genetic Basis of Drought Resistance at Reproductive Stage in Rice: Separation of Drought Tolerance From Drought Avoidance

“…Previous studies showed that the drought resistance index (relative yield) was often negatively correlated with potential yield and was also dependent on the actual developmental stage of the plants when stress treatment was applied (Price and Courtois 1999;Venuprasad et al 2002;Toorchi et al 2003). In an attempt to separate the components in the field experiments, several approaches have been adopted, including staggering the sowing date, installing a drip irrigation system in the plots, normalizing the data by statistical method, and utilizing advanced backcross lines (Blum 1988;Price and Courtois 1999;Robin et al 2003).…”

Genetic Advances in Adapting Rice to a Rapidly Changing Climate

“…, Toorchi et al. ). Lack of effective selection criteria for drought tolerance traits contributing to yield stability and low heritability of grain yield under stress are cited as the major reasons for the slow progress in enhancing drought tolerance in various breeding programs (Ouk et al.…”

Development of elite indica rice lines with wide spectrum of resistance to Thai blast isolates by pyramiding multiple resistance QTLs

“…Marker-assisted selection has been popularly exploited in modern breeding as it has many advantages, including easy selection for traits, which is difficult and expensive to evaluate e.g. salt tolerance, root length, blast resistance and bacterial resistance (Huang et al 1997, Hittalmani et al 2000, Toorchi et al 2003, Yamaguchi and Blumwald 2005. Moreover, it can be selecting donor chromosomal segments in a backcrossing scheme (Zhang et al 2006).…”