Effects Of Rhizobium Inoculation On Nitrogen Nutrition And Abrine Metabolism In Abrus Mollis

In this study, the content of nitrigen, ammonia nitrogen, nitrate nitrogen and abrine were measured in different parts and different periods through the naphthyl’s colorimetry, ninhydrin method, salicylic acid method and high performance liquid chromatography (HPLC). Combined with statistics software, the dynamic change and accumulated distribution of nitrogen nutrition and abrine metabolism in Abrus mollis were summarized and investigated preliminarily. The results were as follows:(1) The effects of the growth traits and nodulation ability of Abrus mollis which were inoculated with different sources of rhizobium were different. The height, stem diameter, above-ground biomass and below-ground biomass of Abrus mollis which were inoculated from Nanning NN strains were increased significantly and showing good growthy trend. Abrus mollis showed good nodulated ability after inoculated BS strains which from Baise.(2) The above-ground biomass, below-ground biomass and total biomass of potted Abrus mollis which were inoculated rhizobium showed increasing trend. By analysis of variance, differences between inoculated and blank on above-ground biomass, below-ground biomass and total biomass in July, August, September and October were significant level except June. The blank didn’t nodulate, while the number of nodules and nodule weight of Abrus mollis which were inoculated increased with the propulsion of the growth period, particularily September to October.(3) The nitrogen contents of roots, steams and leaveas of potted inoculated Abrus mollis showed bimodal curve and the peak was in July and September. What’s more, the nitrogen contents in July greater than September, while the trend of blank was not obvious. The nitrogen levels of two treatments were the lowest in August, In the early stage, the nitrogen accumulation of roots were more than leaves’and stems were the least. The nitrogen distribution gradually transferred from the roots to the leaves in the mid-stage that vegetative and reproductive growth were coexisted, In the late, the nitrogen contents of roots and legumes increased gradually and the nitrogen contents of leaves declined with the nitrogen was obtained through roots from nodules.(4) The ammonia nitrogen contents of two treatments in leaves and stems showed same variation of a single peak curve and the maximum in July, In the early growth stage, the accumulation of stems were much more than roots, and leaves’were the least, In the mid-stage, as much ammonia nitrogen contents were accumulated in leaves, the more contents were assimilated. Abrus mollis growed into reproductive stage with legumes growing in the late. The ammonia nitrogen contents of legumes increased and the contents of leaves declined with assimilations were transported to legumes.(5)The effects of nitrate accumulation and distribution in different parts and periods of potted inoculated Abrus mollis were significantly different, In the early growth stage, the nitrate contents of leaves of inoculated treatment were lower than blank’s, and the trend was overall upward with the maximum in September. The nitrate contents of stems and roots presented first rose and then fell and then rose law. In the early stage, nitrate accumulation amount of roots were more than leaves, and stems’were the least. Nitrate distribution changed with the reproductive process moved forward, especially in the late growth. Nitrate accumulation of roots and legumes decreased, while the leaves accumulation continued to increase. Nitrate might be main nitrogen components which were transported to the leaves at the time that vegetative and reproductive growth were coexisted.(6) The glutamine synthetase activity of potted Abrus mollis were greatly effected by inoculated rhizobium. In the early growth stage, the activity of GS in inoculated Abrus mollis was lower than blank’s, and higher in the mid-stage, In addition, the activity of GS of inoculated Abrus mollis presented a clear upward trend which was particularly obvious from August to September, while the blank control showed slow upward trend.(7) The effects of abrine integration and accumulation in different parts and periods of potted inoculated Abrus mollis were significantly great. The trends of roots and stems were same and the maximum was in August with abrine contents increasing. The trend of leaves was opposited to roots and stems and showed increase and then decrease, while the abrine contents of legumes increased with the vegetative growth changed to reproductive growth. In the early growth stage, the abrine accumulation of leaves was the most and followed by the roots and stems. In August, with the formation of the legumes, the abrine distribution changed until the late growth stage. The distribution was always same which the abrine accumulation of legumes was the highest, and followed by leaves, roots and stems.(8) Tryptophan synthase and tryptophan decarboxylase as key enzymes in the metabolic pathway of alkaloids showed significantly different enzyme activity in different periods. The enzyme activity in the two treatments were rendered high-low-high trends, which was consistent with the change trend of abrine content. Especially in October of the late growth, TSB and TDC activity compared to September had substantial rise. The activity of both enzymes of inoculated Abrus mollis was higher than the blank treatment. Thus, TDC and TSB may be the regulatory sites of abrine metabolism.