Abstract:

Eighteen leading cultivars released from 1934 to 2006 and widely planted ever in south China were used, and classified into four rice genotypes, i.e. high-stalk cultivar (HC), dwarf cultivar (DC), dwarf and resistant cultivar (DRC), high-quality and super cultivar (QSC) in the present study conducted at 2006 and 2007 under conventional cultivation conditions. Plant height and growth duration as typical agronomical traits and grains per panicle, effective panicles and 1000-grain weight as main yield parameters were investigated in the study. Results showed that grain yield was increased with the increase of harvest index, grains per panicle and grain density in the evolution of the cultivars. The results further indicated that higher grains per panicle were closely related to the higher grain density. The regression analysis results showed that plant height and biomass tended to increase after 1980, while growth duration decreased. The correlation analysis showed that there were four key factors, biomass, plant height, harvest index, and grains per panicle, affecting grain yield.

Key words: Early season indica rice, Cultivar replacement, Agronomic trait, Evolution characteristic