| Solution-cultured experiments with 3 treatments were conducted to investigate grain quality of rice (Oryza sativa L.) varieties from the different eras and its response to nitrogen supplying levels. Eight conventional indica rice (Oryza sativa L.) cultivars with similar whole growth duration from different eras were used as tested rice cultivar. Nitrogen application rates were low N (LN, 5mg/kg in 2004 and 1mg/kg in 2005), medium N (MN, 10mg/kg in 2004 and 8mg/kg in 2005), high N (HN, 15mg/kg in 2004 and 15 mg/kg in 2005), respectively. Results showed as follows:(1) The milling quality of rice varieties from the different eras showed almost no changes. The milling quality of rice varieties from 1960s, 1970s was slight better than those from other eras because of the better brown rice rate, milled rice rate and lead rice rate of rice varieties from 1960s, 1970s. The milling quality of rice varieties from the different eras was improved variously with N supply from LN to MN. And the rice varieties from 1970s were improved least, and the others were improved the biggist. Only the rice varieties from 1980s were improved with N supply from MN to HN, and the others went to bad.(2) The appearance quality of rice varieties from the different eras vary within a wide range. The appearance quality of rice varieties from 1990s was superior to those from other eras because of the lower percentage of chalky grain, chalkiness area and chalkiness degree. The appearance quality of rice varieties from different eras was improved variously with increasing N supply, and the rice varieties from 1980s were improved the biggist. But the rice varieties from 1970s went to bad with N supply from LN to MN. (3) The cooking quality of rice varieties from different eras also showed almost no changes. The cooking quality of rice varieties from 1990s was slight better than those from the other eras because of the lower amylase content and almost no changed gelatinization temperature, gel consistency. With increasing N supply, the cooking quality of rice varieties from the different eras was not improved but went to bad possibly. Only the rice varieties from 1990s were improved with N supply from MN to HN.(4) The nutrient quality of rice varieties from 1980s was a little weaker than those from the other eras. The nutrient quality of rice varieties from the different eras was not improved significantly with increasing N supply.(5) The grain starch viscosity of rice varieties from the different eras vary within a wide range. The texture of cooked rice and the eating quality of rice varieties from 1990s was better than those from the other eras because of higher breakdown viscosity and lower setback viscosity. The texture of cooked rice and the eating quality of rice varieties from the different eras were not improved with N supply from LN to MN. But the texture of cooked rice and the eating quality of rice varieties from 1990s were improved with N supply from MN to HN. |
