Minimising cold damage during reproductive development among temperate rice genotypes. II. Genotypic variation and flowering traits related to cold tolerance screening

Abstract

Low temperature during microspore development increases spikelet sterility and reduces grain yield in rice (Oryza sativa L.). The objectives of this study were to determine genotypic variation in spikelet sterility in the field in response to low temperature and then to examine the use of physio-morphological traits at flowering to screen for cold tolerance. Multiple-sown field experiments were conducted over 4 consecutive years in the rice-growing region of Australia to increase the likelihood of encountering low temperature during microspore development. More than 50 cultivars of various origins were evaluated, with 7 cultivars common to all 4 years. The average minimum temperature for 9 days during microspore development was used as a covariate in the analysis to compare cultivars at a similar temperature. The low-temperature conditions in Year 4 identified cold-tolerant cultivars such as Hayayuki and HSC55 and susceptible cultivars such as Sasanishiki and Doongara. After low temperature conditions, spikelet sterility was negatively correlated with the number of engorged pollen grains, anther length, anther area, anther width, and stigma area. The number of engorged pollen grains and anther length were found to be facultative traits as their relationships with spikelet sterility were identified only after cold water exposure and did not exist under non-stressed conditions.

A QTL controlling low temperature induced spikelet sterility at booting stage in rice

“…It can cause serious yield losses, most significantly when the low temperature occurs during reproductive stages. Although the sowing time is usually adjusted to minimize the potential for low temperature damage at reproductive stages, low temperature still causes serious yield losses in these countries (Farrell et al 2006). Low temperature may affect the growth and development of rice from germination to grain filling (Ye et al 2009).…”

Mechanism of low‐temperature‐induced pollen failure in rice

“…Owing to its tropical origin, low temperature or chilling stress has been recognized as a unique environmental limitation that considerably reduces rice yield (Wen et al, 2002). Although the average yield of rice has increased substantially in Australia, cool night temperatures prior to flowering drastically reduce yields in some years (Oliver et al, 2005;Farrell et al, 2006;Mamun et al, 2006). Clearly, a solution to these losses is required, but attempts to select low-temperaturetolerant varieties using conventional breeding techniques have been relatively unsuccessful due to poor understanding of the physiological, cellular and molecular basis of the problem.…”

Near-Isogenic Lines of Japonica Rice Revealed New QTLs for Cold Tolerance at Booting Stage

“…Cold tolerance at this stage can be evaluated by seed setting rate, based on the cold deep-water irrigation (CDWI) system or cold greenhouse cultivation (CGC) [5,23]. Therefore, for assessment and evaluation of cold stress tolerance at booting stage of rice, this study was designed to consider both important aspects, CDWI for stress application and rate of seed setting (RSS) to evaluate cold tolerance attributes because it is most practical as well as accurate method and important attribute, respectively [19][20][21]52]. However, RSS can be collected after rice harvesting hence in anterior stage of rice life cycle, selection of appropriate material for cold tolerance analysis is difficult [5,53].…”

“…At booting stage, young microspores from the tetrad stage to the first contraction phase are more prone to chilling stress and are more critical for rice grain development [8,[18][19][20][21]. The chilling stress at the booting stage maximized spikelet sterility and caused minimum grain yields [22,23].…”