Screening Of Eggplant Genotypes For High Nitrogen Use Efficiency And Studying Of Mechanism Of Different Nitrogen Use Efficiency

In order to understand the character of nitrogen uptake and utilization and screen the genotypes of high nitrogen use efficiency in eggplant, Field experiment and testing analysis are conducted to study the genotypic variation in nitrogen use efficiency in ten eggplant genotypes by analyzing fruit yield, nitrogen utilization efficiency, nitrogen response and total nitrogen. To screen eegplant genotypes with high nitrogen use efficiency and compare their differences, these genotypes were cultured under different nitrogen levels by solution culture. The mechanism of different nitrogen use effiency is uncovered by analyzing the changes of root character, nitrogen accumulation and distribution in eggplant seedlings, which is important to breed high nitrogen use efficiency cultivars. The main results obtained from the research are shown as follows.1. There were significant variations in fruit yield, nitrogen utilization efficiency, nitrogen responsiveness and total nitrogen among different eggplant genotypes under normal nitrogen and low nitrogen stress in the field experiment.2. The tested eggplant genotypes could be classified into five different types based on their nitrogen use efficiency under normal nitrogen and low nitrogen stress. 06-991 belonged to HH-LH type (high N use efficiency at high nitrogen level, high N use efficiency at low nitrogen level);06-917 belonged to HH-LM type (high N use efficiency at high nitrogen level, mid N use efficiency at low nitrogen level); 06-961 and 06-867 belonged to HH-LL type (high N use efficiency at high nitrogen level, low N use efficiency at low nitrogen level); 06-972, 06-947, 06-854, 06-830 and 06-909 belonged to HM-LL type (mid N use efficiency at high nitrogen level, low N use efficiency at low nitrogen level); 06-910 belonged to HL-LL type (low N use efficiency at high nitrogen level, low N use efficiency at low nitrogen level).3. Nitrogen use efficiency is comprised of nitrogen uptake efficiency and nitrogen utilization efficiency. Through path analysis, it was found that the effect of nitrogen uptake efficiency on nitrogen use efficiency was more important than nitrogen utilization efficiency unde normal nitrogen and low nitrogen stress in the field experiment.4. The eggplant genotype 06-991 and 06-867 with significantly different in nitrogen use efficiency were grown in solutions supplied with different nitrogen levels to study the differences in nitrogen uptake and utilization. The results showed that plant height, leaf number, total N, leaf area, content of chlorophyll and dry root weight decreased for both 06-991 and 06-867 as the N supplying decreased, but the ratio of dry weight root/shoot and the ratio of total nitrogen uptake in root increased. The 06-991 was higher than 06-867 in nitrogen use efficiency under low nitrogen stress. The volume of root, dry root weight, lengh of root, dry plant weight and dry weight root/shoot ratio for 06-991 were higher than that for 06-867 when they were in low N stress. The variation of nitrogen uptake efficiency for the two eggplant genotypes was due to the difference in root characters. The variation of nitrogen uptake efficiency was the main reason to variation of nitrogen use efficiency in different genotypes under normal nitrogen and low nitrogen stress.5. The dry plant weight, root/shoot ratio and volume of root were significantly correlative with nitrogen use efficiency under solution culture, which could be regarded as the indexs to screen high nitrogen efficiency genotypes. Because of the effect of different cultivars in the biological characters, it is reasonable to estimate nitrogen use efficiency using their relative indexs under several nitrogen levels.