Effect of NH_4^+-N/NO_3^--N Ratios on Growth and Some Physiological Parameters of Chinese Cabbage Cultivars

The responses of three cultivars of Chinese cabbage (Brassica chmensis L.), one of the main vegetable crops in China, to different ratios of NH4+-N/NO3--N was investigated to find the optimal ratio of ammonium to nitrate for maximal growth and to explore ways of decreasing the nitrate content, increasing nitrogen use efficiency of Chinese cabbage, and determining distributions of nitrogen and carbon. Three cultivars of Chinese cabbage were hydroponically grown with three different NH4+-N/NO3--N ratios (0:10…

Absorption of Glycine by Three Agricultural Species Under Sterile Sand Culture Conditions

Seedlings of wheat (Triticum aestivum L.), Chinese cabbage (Brassica campestris L.) and mung bean (Phaseolus radiatus L.) were grown for 30 days in sterile sand media with 6 N treatments, i.e. NH4+-N, glycine-N, 3 different ratios of glycine-N:NH4+-N (NH4+-N was labeled with 15N) and a control receiving no N, to assess the importance of amino acids in excessive N nutrition along with inorganic N interactions. The contribution of nitrogen derived from glycine-N to total plant N was investigated. The total plant N of the three species treated with N was significantly greater (P < 0.05) than the control treatment. Also, seedlings from all the three species had significantly more total N as NH4+-N (P < 0.05) than at least two of the four treatments with glycine-N. However, for all species, differences in total N among treatments with a mixture of glycine-N and NH4+-N were mostly not significant. The contribution of N derived from glycine-N to plant total N content for all species increased with increasing glycine-N:NH4+-N ratio in the treatment solution. These results indicated that agricultural plants could effectively use organic nitrogen from organic nitrogen sources (e.g., glycine) and from organic and inorganic N mixtures (e.g., a glycine-N and NH4+-N mix). There were also genotypic differences in glycine-N and NH4+-N uptake by agricultural species.

Change of 3 Kinds of Enzyme Activity and Soluble Sugar in 3 Chinese Cabbage Varieties with Different Resistance Level During the Process of Plasmodiophora brassicae Infecting Their Roots

There are different levels of resistance in Chinese cabbage varieties against clubroot.The content of catalase(CAT),peroxidase(POD),phenylalanin ammonia-lyase(PAL),Super Oxide Dismutase(SOD)and soluble sugar activities of 3cultivars with different clubroot-resistant levelswere detected after inoculation in this study.The results suggest that the changing rates of CAT,PAL and SOD contents of resistance cultivars after inoculation were higher than those of susceptible cultivars(Baigengbaiye>Zaobaicaitai>Huangjinxiaobaicai);the POD activities of resistance cultivars reached a peak on an earlier day than those of susceptible cultivars;the increasing rate of soluble sugar of susceptible cultivars was higher than that of the resistance cultivars,and ended with two peaks.Therefore,the four enzymes(CAT,POD,PAL and SOD)and soluble sugar may be used as physiological and biochemical reference indexes for the resistance identification to clubroot after inoculation with P.brassicae.