Changes of Some Leaf Characteristics in Rice (Oryza sativa L.) Cultivars Released from 1958 to 2005 in Jilin Province

In order to understand the changes of leaf characteristics associated with yield during the genetic improvement of rice,33 japonica rice cultivars released from 1958 to 2005 were planted under same field conditions.Some indexes related to leaf characterristics,such as leaf number,leaf area per plant,leaf area duration (LAD),length,width and area of top three leaves,chlorophyll content index (CCI) and specific leaf weight (SLW) of flag-leaf were measured at 10 days after heading.The results showed that the grain yield was increased from 7 756.6 kg ha-1 in 1958 to 12 807.3 kg ha-1 in 2005,with the increase of 65.11% in 47 years and an annual increase rate of 1.39% according to the calculation of regression equation.The increasing of grain yield was mainly attributed to the increase of leaf number,leaf area per plant and LAD with years of release.By studying on the top three leaves of plant,our results showed that the significant decrease of flag-leaf length resulted in the decline of flag-leaf area;the changes of top second leaf area was not obvious;as the increase in the length and width of top 3rd leaf,significantly increased was found in its area with years of release.Leaf number,leaf area per plant and LAD were all positive correlated with years of release significantly.CCI and SLW of flag-leaf were positively correlated with year of release and with yield significantly.Our results showed that the increase of plant leaf area and LAD were resulted from the increase of leaf number and the area of the top 3rd leaf.CCI and SLW of flag leaf were increased with years of release.We suggested that leaf number,leaf area per plant,LAD,and CCI as well as SLW of flag leaf at 10 d after heading could be as potential indices in the future high yield rice breeding.