The Physiological Characteristics In Relation To Nitrogen Fixation Of Different Sugarcane Varieties

Two native sugarcane varieties GT11 and ROC16 and four Brazilian nitrogen fixing sugarcane varieties B1, B3, B5and B8, were grown under different nitrogen-fertilizing conditions in the field. There were three nitrogen levels In the nitrogen ferti I izing experiment. At the same time, the six sugarcane varieties were grown in the barrels without nitrogen fertilization. The indexes of physiological characteristics in relation to nitrogen fixation were investigated. The indexes of agronomic characters of the plants in the nitrogen fertilizing experiment also were investigated. The main results were as follows:1. The nitrogen fixing activities were much higher in the four Brazilian nitrogen-fixing varieties than in the two native ones.2. The four Brazilian nitrogen fixing varieties were more efficient in photosynthesis with higher net photosynthetic rate, higher activity of ATPase and higher chlorophyll content.3. The activity of nitrate reductase and nitrogen content had no direct correlation with the nitrogen fixation in sugarcaneplants.4. Appropriate nitrogen fertilization improved the agronomic characters and the cane quality of the tested six sugarcane var iet ies.5. The variety B8 showed the highest nitrogen fixing activity and grew better than the others without nitrogen ferti I izer. The variety GT11 has the lowest nitrogen fixing activity and was more susceptible to lacking nitrogen.