The Relationship Between Rice Yield And Carbon Isotope Discrimination And The QTL Analysis

The experiments were conducted to investigate the correlation of CID(Carbon isotope discrimination) with yield and yield components of rice,during 2006 and 2007.The recombinant inbred lines derived from a cross between Zhenshan97 and Minghui63 were employed in this study.In 2006 and 2007,four rice varieties (Zhenshan97,Minghui63,Shanyou63 and Liangyoupeijiu) along with N1(130kg N ha^-1) and N2(0kg N ha^-1) as nitrogen treatments were used.While in 2007,six rice varieties(Chuanxiagyou727,â…¡you838,Liangyoupeijiu,99you029,Huanghuazhan and Liangyou125) were evaluated under six different nitrogen treatments[0 kg N ha^-1(N1),90 kg N ha^-1(N2),135 kg N ha^-1(N3),180 kg N ha^-1(N4),225 kg N ha^-1(N5) and 270 kg N ha^-1(N6)].The effect of nitrogen application rates on the CID of these varieties was our main focus.We also studied the relationship between ash content and carbon isotope discrimination.The results showed that:1.A significant transgressive segregation for CID was found in the population and the frequency of CID was almost normally distributed.The CID at heading stage was negatively correlated with heading date.The population was divided into 10 groups according to heading date.Negative correlation of CID at 30 days after transplanting was observed with biomass and spikelets per panicle.While a positive correlation of CID at 30 days after transplanting was found with harvest index and number of panicles.Grain yield,grain filling percentage and 1000-grain weight did not show any significant correlation with CID at 30 days after transplanting.Similarly at heading stage CID correlated negatively to grain yield,biomass,spikelets and grain filling percentage,and positively to harvest index and number of panicles.2.A total of 4 and 5 QTLs for CID at heading stage were identified in 2006 and 2007,respectively.They were on chromosomes 3,6,7,10 and 12.The QTL located at R1440-C 1023 on chromosome 7 and the QTL located at C909b-R496 were repeatedly detected in two years.A total of 4 QTLs located on chromosomes 1,2,3 and 8 were detected for CID at 30 days after transplanting,which jointly explained 44.16%of the total phenotypic variation.3.CID varied significantly at heading stage for different rice varieties,and non-significantly for the two nitrogen treatments.In case of interaction of varieties and N application rate,CID of Zhenshan97 was higher at heading stage under both N levels.In experiment 2,CID at 30 days after transplanting was significantly different among various rice genotypes.Differences of CID were also significant among nitrogen treatments.The CID of all the genotypes was maximum at 0 kg N ha^-1 except for variety 99you029.While at 180 kg N ha^-1 minimum CID was recorded for all the varieties except for Liangyoupeijiu.4.No significant correlation was found between ash content and carbon isotope discrimination.It was accordingly concluded that ash content couldn't be used as substitution index.