%A ZHANG Hao,TAN Gui-Lu,XUE Ya-Guang,LIU Li-Jun,YANG Jian-Chang %T Changes in Grain Yield and Morphological and Physiological Characteristics during 60-year Evolution of Japonica rice Cultivars in Jiangsu Province,China %0 Journal Article %D 2010 %J Acta Agronomica Sinica %R 10.3724/SP.J.1006.2010.00133 %P 133-140 %V 36 %N 1 %U {https://zwxb.chinacrops.org/CN/abstract/article_4420.shtml} %8 2010-01-12 %X

Great progress has been made in japonica rice breeding. However, little is known about physiological and agronomical features responsible for the improvement. In this study, 12 typical japonica rice cultivars (including super rice) applied in the production in Jiangsu province during the last 60 years were used, and classified into six types of 1950s, 1960s, 1970s, 1980s, and 1990s in the 20th century and since 2000 according to their application times. All the tested cultivars were grown in the field and the evolution characteristics of grain yield and its components, source-sink relationships, morphology and physiology were investigated. Results showed that the grain yield was progressively increased with the evolution of the cultivars. Increase in grain yield was attributed mainly to the increase in total number of spikelets, which resulted mainly from large panicles. The percentage of filled grains was increased for cultivars from 1950s to 1980s in 20th century, whereas it was decreased for those at 1990s in 20th century and since 2000. There was no significant difference in 1000-grain weight among the six types of cultivars. With the improvement of rice cultivars, biomass, especially after heading, and harvest index were simultaneously increased. At main growth stages, with the improvement of rice cultivars, root dry weight, root-shoot ratio, root oxidation activity and leaf photosynthetic rate were increased significantly, but root oxidation activity and leaf photosynthetic rate during grain filing for super rice were declined rapidly. Improvement of rice cultivars significantly increased total, effective, high-effective leaf areas and grain-leaf ratio (the ratio of total spikelet number to leaf area) at heading, and increased panicle length, number of primary and secondary panicle branches greatly. From 1950s to 1990s in the 20th century, plant height was reduced, while it was increased significantly for super rice since 2000, with a plant height of about 120 cm. The leaf angle of the top three leaves on stems were significantly decreased with the improvement of rice cultivars. The results indicate that agronomical and physiological characteristics of japonica cultivars are improved during the evolution, and low percentage of filled grains limits grain yield potential in super rice cultivars.