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Quantitative Caloric Energy Distribution and Variations in Two Rice Varieties Related to Different Nitrogen Application Levels in Paddy Field

Yang, Jingping, Weske, Boniface, Jie, C., Nin, J.
Journal of plant nutrition 2003 v.26 no.4 pp. 709-729
Oryza sativa, climate, cultivars, energy, farming systems, fertilizer rates, field experimentation, hulls, inflorescences, leaves, nitrogen, nitrogen fertilizers, paddies, plant organs, rice, China
A field experiment was conducted in Hangzhou, Zhejiang Province, P.R. of China in 1999 to investigate the quantitative caloric energy characteristics of two rice cultivars (Oryza sativa L.), early crop rice Jia yu 948 and late crop rice Jia yu 93390 were grown in different nitrogen levels and climate conditions. The two cultivars were grown with 0, 80, 120, 160, and 200 kg ha-1 of nitrogen fertilizer and in ample water and farming management activities. Analysis of caloric energy showed that significant differences occurred among treatments and plant organs in both rice cultivars. However, no significant differences occurred among same organs under different nitrogen treatments in both cultivars except for the panicles. The mean caloric energy of both cultivars increased with nitrogen fertilizer application. However, no optimal level of nitrogen fertilizer treatment with caloric energy was established, as there was still an increase in caloric energy even at 200 kg N ha-1 fertilizer treatment. Cultivar Jia yu 948 had a higher mean caloric energy of 4172 cal g-1 compared to 4117 cal g-1 of cultivar Jia yu 93390. There were significant differences in caloric energy among the plant organs. The ascending order of energy distribution was as follows; root, stem, husk, leaf, grains, and panicles. Of great interest is the relatively high amount of energy invested in the husks. This amount was similar to that of the leaf. There was a linear relationship between caloric energy and nitrogen application levels. The basic rice caloric values are 4058 cal g-1, an increase in 1 kg N ha-1 of nitrogen (pure) resulted in an increase of 0.41 cal -1 and 0.29 cal g-1 of dry weight in the cultivar Jia yu 948 and cultivar Jia yu 93390 respectively. Thus Jia yu 948 had a better utilization efficiency of nitrogen nutrient than Jia yu 93390 considering the caloric value increase.