Cultivaral difference in growth sustainability of rice [Oryza sativa] species grown in low nitrogen-input condition
2005
Araki, T.(Kyushu Univ., Fukuoka (Japan). Faculty of Agriculture) | Yasuoka, M. | Kubota, F.
The experimental materials used here were 12 rice cultivars released and grown in the past one century in the southern area of Japan and two African cultivars. With plants water-cultured under standard and low nitrogen applications, their dry matter weight, leaf area and net assimilation rate (NAR), rubisco content and chlorophyll content in leaves were investigated. Results obtained were as follows: By reducing the nitrogen concentration of culture-solution to l0% of the standard, the average plant dry matter weight and leaf area of the 14 cultivars were decreased to 25% and 20%, respectively. To evaluate the growth sustainability of cultivars grown under the low nitrogen application, the sustainability index (SIL) was used here: SIL of dry matter weight (SIL-DM), leaf area (SIL-LA) and NAL (SIL-NAR) were significantly different among cultivars. For these three parameters, large values were found in Koshihikari, one of the high quality cultivars widely grown in Japan today, and the small ones were observed in old, traditional cultivars, such as Asahi and Shinriki, and in G174 (O. glaberrima) . A significant cultivaral difference in response to nitrogen application was also found in the rubisco and chlorophyll contents and their SILs.
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