Akihiro Isoda1, Hongxia Mao2, Zhiyuan Li3 and Peiwu Wang3

(1Graduate School of Horticulture, Chiba University, Matsudo 271-8510, Japan; 2Tianye Agricultural Institute, Shihezi, Xinjiang, China; 3Shihezi Agricultural and Environmental Institute for Arid Areas in Central Asia, Shihezi, Xinjiang, China)


Abstract: The growth and seed yields of 2 Japanese and 3 Chinese cultivars of soybeans cultivated in 2002-2005 using a drip irrigation system in the arid area of Xinjiang, China, were analyzed with respect to growth parameters and air temperature. Seed yield was very high in 2002, 2003 and 2004, but relatively low in 2005. The variation among years in seed yield clearly depended on pod number. The mean leaf area index (LAI) and crop growth rate (CGR) in 2005 was lower than those in the other 3 years. CGR showed significant positive correlations with mean LAI at the early growing stages, and with net assimilation rate (NAR) at the later growing stages. The increasing rate of pod number (IRP) was positively correlated with the mean LAI and CGR at the pod setting period, suggesting that an adequate supply of photosynthates would be required for pod setting. It was concluded that excellent growth in the years with high yields was supported by the large LAI before the pod setting periods and by high NAR and vigorous pod growth at the latter half of the growing season.
Key words: Air temperature, Arid areas, Drip irrigation, Growth parameters, Pod number, Soybean.