Abstract:

The measurement of 117 rice germplasm resources at different growing stages proved that the net photosynthetic rate (P_n) from initial heading to full heading stage was stable (Fig.1), which could be need to compare the varietal difference in photosynthetic rate. The result showed that different rice varieties had great difference in their photosynthetic rates (Table 1,2). The photosynthetic rate showed a normal distribution skewed (Fig.2). According to the result from clustering analysis, 117 rice varieties were classified into five groups, i.e. very high, high, middle high, middle low, and low of P_n. The photosynthetic rates were close to or higher than 25 µmol·m^-2·s^-1 in 14 germplasm resources, which accounted for 11.97% of the total materials tested, including Indica rice Ainanzao, Teqing, Fulidao, Ai50, Ketan Bajong, etc; japonica rice Longdao, Longken 46 and Daoshaguang; and Oryza glaberrima Steud Rico-1. The results of the relationship between agronomic characters and photosynthetic rate showed that the resources with high photosynthetic rate have such characteristics as green or dark green leaves, middle erective or nearly erective flag leaves and moderate loose plant type (Table 3).

Key words: Photosynthetic rate, Germplasm resource, Rice