Within‐Panicle Variability of Grain Filling in Rice Cultivars with Different Maturities

Abstract

Rice(Oryza sativa L.) milling quality is a complex trait and influenced by many factors including the uniformity of grain filling and other grain characteristics. Although much is known concerning genotypic differences in rate and duration of grain filling, quantitative information on uniformity or non‐uniformity of grain filling and kernel characteristics on the panicle is lacking. This study investigated and compared the degree of non‐uniformity of grain filling among 6 rice cultivars of different grain types, maturities, and the plant characteristics that may influence the uniformity of grain filling. Models of grain growth and rate of growth were developed for grains on the upper, middle and lower parts of the panicle. Non‐uniformity of grain filling parameters (duration and rate of grain filling, maximum grain weight) were estimated and compared among cultivars of different grain types and maturities. Results showed that, in general, grain size and rate of filling decrease from upper part to the lower part of the panicle. The ranges among grain growth curves from the upper, middle and lower parts of the panicle of the very early, and early maturing cultivars were greater than those of intermediate and late maturing cultivars. However, non‐uniformity of grain filling is not necessarily a function of maturity. Plant and grain characteristics such as even distribution of grain size, high grain filling rate between 10–15 days after heading, and optimum weight ratio of panicle to above‐ground leaf and stem matter may be selected for by breeders to improve the uniformity of grain filling, independent of maturity. Zusammenfassung Uniformität der Rispenentwicklung von Reiskultivaren mit unterschiedlichen Rei‐fezeiten Die Reis (Oryza sativa L.)‐mahlqualität ist eine komplexe Eigenschaft und wird von zahlreichen Faktoren, einschließilich der Einheitlichkeit der Kornfüllung und anderer Korneigenschaften beeinßlufk. Obwohl zahlreiche Informationen bezüch genotypischer Differenzen hinsichtlich der Rate und der Dauer der Kornfüng bekannt sind, besteht ein Mangel an Informationen hinsichtlich der Einheitlich‐keit oder Uneinheitlichkeit der Kornfüng und von Korneigenschaften der Rispe. Die vorliegende Untersuchung vergleicht den Grad der Uneinheitlichkeit der Kornfüllung von sechs Reiskultivaren unterschiedlichen Korntyps, unterschiedlicher Reife und unterschiedlicher Pflanzeneigenschaften, die Einflufß auf die Einheitlichkeit der Kornfüllung nehmen können. Modelle für Kornwachstum und Wachstumsrate wurden für Körner des oberen, mittleren und unteren Abschnitts der Rispe entwickelt. Uneinheitlichkeit der Kornfüllung (Dauer und Rate der Füllung sowie maxi‐males Korngewicht) wurden geschätzt und mitden Kultivaren unterschiedlichen Korntyps und unterschiedlicher Reife verglichen. Die Ergebnisse zeigen, daß die Korngröße und Kornfüllungsrate grundsätzlich vom oberen zum unteren Teils der Rispe sehr früher und früher Kultivare waren größer als diejenigen der Kultivare mittlerer und später Reife. Allerdings ist Uneinheit...

The effects of free-air CO2 enrichment (FACE) on carbon and nitrogen accumulation in grains of rice (Oryza sativa L.)

“…Therefore, the numbers of inferior and superior grains increased simultaneously. Compared with superior grains, the cooking quality and appearance of inferior grains are usually lower (Chaudhry and Nagato, 1970; Iwasaki et al , 1992; Jongkaewwattana et al , 1993). Moreover, although the GM in inferior grains was significantly increased by elevated [CO 2 ], some inferior grains were still too small and thus would be discarded when the grain was sieved to evaluate the thousand grain weight and grain quality (Lieffering et al , 2004), resulting in an overall protein loss.…”

“…It is apparently not affected (Baker and Allen, 1993; Ziska et al , 1997), increased (Yang et al , 2006), or has a minor effect on the overall yield increase (Kim et al , 2003). It should be noted that the reported individual grain weight is the average across all grains harvested at maturity, but that grain weight, quality, and development vary widely depending on the grain position within the panicle (Iwasaki et al , 1992; Jongkaewwattana et al , 1993; Wang et al , 2007). …”

Grain growth of different rice cultivars under elevated CO2 concentrations affects yield and quality

“…Because inferior grains are usually smaller and have poorer appearance quality than superior grains (Iwasaki et al, 1992;Jongkaewwattana et al, 1993;Wang et al, 2008;Mohapatra et al, 2011), opaque kernels are more likely to occur in IS. Since E-[CO 2 ] stimulated the growth of inferior grains, the percentage of opaque kernels may have been reduced.…”

Pre-treating paclobutrazol enhanced chilling tolerance of sweetpotato

“…There is a dramatic difference in weight and quality among grains within a panicle (Jongkaewwattana et al 1993;Umemoto et al 1994;Yang et al 2000;Cheng et al 2003a). The difference can be ascribed to different ability among florets within a panicle in mobilizing carbohydrates (Wang 1981;Mohapatra and Sahu 1991).…”