Response to Early Generation Selection for Resistance to Rice Kernel Fissuring

Abstract

ABSTRACTThe value of milled rice (Oryza sativa L.) depends on the percent whole versus broken kernels after milling. Kernel fissures caused by pre‐ or postharvest stresses are the leading cause of breakage on milling. ‘Cypress’ is known to be more fissure resistant (FR) than most cultivars, but breeding success has been limited by a lack of ability to identify FR among F2 and F3 progeny. An induced‐fissuring method wherein small samples of seed are evaluated for fissure rates after controlled exposure to humid laboratory conditions can distinguish FR among pure‐breeding rice cultivars. To measure the efficacy of the induced‐fissuring system for evaluating FR among segregating breeding progeny, we applied divergent selection for FR and fissure susceptibility (FS) on seed harvested from ∼300 Cypress (FR) × ‘LaGrue’ (FS) F2 plants and evaluated selection success using seed from F2:3 plants grown in Arkansas and Texas. A second round of divergent selection was made among F3 progeny followed by F3:4 progeny testing. Fissure susceptible F2:3 progeny fissured twice as much as FR progeny, with an average response to selection of 13.5%. Response to F3 selection was smaller (averaging 2.6%), suggesting some fixation of alleles due to the F2 selections. Narrow‐sense heritabilities (h2) were 0.54 and 0.73 for the FR and FS F2 selections, respectively. This study documented successful early‐generation selection for FR, opening new opportunity for breeders to develop rice cultivars improved for this important trait.