Research Of The Influence Of Nitrogen-chromium Combined Application Upon The Growth And Chromium Accumulation Of Alismatis(Alisma Orientale(Sam.) Juzep)

Heavy metal chromium in Alisma orientate(Sam.)3uzep is in excess of the standards. However, nitrogen can alleviate the stress of heavy metals on plants. Through Soil culture and hydroponic experiments, chromium dynamic accumulation in A. orientale seedlings and plants and the effect of chromuim on the growth of A. orientale under nitrogen-chromium coupling at different concentration are studied. In this way. we could provide theoretical guidance to A. orientale standard planting and its safe quality.The main results are as follows:1.The effects of nitrogen-chromium combined application on the growth of A. orientaleWith increasing amount of nitrogen,the plant height, leaf number, length of the longest fibrous roots and the dry matter of various parts of A. orientale have been promoted. While with the increasing of the chromium supply, plant height, leaf number, longest fibrous root length and dry matter of various parts of A. Orientale seedlings were inhibited; During the early stage, A. Orientale plant height and leaf number rised and aboveground dry matter is greater than that of the underground part under higher chromium level. Nitrogen supply can ease the impact of chromium on A. Orientale growth.2. Nitrogen and chromium dynamic accumulation in soil and each part of A. OrientaleNitrogen and chromium content in soil and each part of A. Orientale are significantly affected under the different level of nitrogen-chromium combined application. The total nitrogen and available nitrogen in soil were significantly increased with higher nitrogen level, while the effective chromium content of soil declined. Moreover, more nitrogen application also rised A. Orientale seedlings nitrogen uptake amount and nitrogen amount of various parts of the plant. What’s more, more chromium content existed in the leaves and tubers of A. Orientate seedlings and the plant, with more nitrogen application, and on the other hand, less chromium content left in root of A. Orientale. Higher amount of chromium application significantly or extremely significantly inhibited the available nitrogen of soil while total chromium content and the effective chromium content in it were significantly increased. Nitrogen accumulation and chromium content in A. Orientale seedlings and various parts of the plant were reduced and increased respectively at the same time.Nitrogen-chromium combined application also had a dramatically impact on the chromium transfer coefficient and enrichment factor of A. Orientale seedlings and the plant. Adding nitrogen, chromium transfer coefficient of A. Orientale seedlings and the plant, chromium enrichment factor of the plant’s leaves and tubers increased, while chromium enrichment factor of the root declined. With the increasing amount of the chromium application, chromium transfer coefficient of A. Orientale seedlings and the plant went up at the early stages, and chromium enrichment factor of the leaves of A. Orientale were sharply rised in the whole time as well as that of the tubers and roots were dramatically or extremely significantly increased at the later stages.3.The correlation between nitrogen content in soil and chromium content of both soil and each part of A. Orientale, chromium content in soil and nitrogen content of each part of A.OrientaleThe available nitrogen content and available chromium content in soil was negatively related,and on Dec.14th, Dec.29th, the correlation coefficients were-0.796,-0.781, reaching the significant level. Total soil nitrogen content and pH value of the soil at the whole stages as well as the available nitrogen and pH value at the early stages were significant or highly significant positive related. Adding nitrogen supply by improving0.1to0.33pH units of the soil, reduced the effectiveness of chromium in the soil.Excluding minority periods, both total nitrogen and available nitrogen content in soil had a significant or extremely significant positive correlation with and the nitrogen content in various parts of A. Orientale. From Oct.30th to Nov.29th, the correlation coefficient between available chromium content of soil and tubers, roots nitrogen content were greater than-0.761, arriving at the significant level.Both soil total nitrogen, available nitrogen content had a very significant positive correlation with the chromium content in the leaves and tubers at the early stages, with the correlation coefficient up to0.936. On the other hand, soil total nitrogen, available nitrogen content had a dramatical or very significant negative correlation with the chromium content in the roots at the later stages. Besides, at the early stages, soil total chromium content and chromium amount in leaves was significant positive related, while at the later stages, soil available chromium content and tubers, roots chromium amount were significantly or very significantly positive related, with the correlation coefficient peaking at0.793.4.The correlation between nitrogen content in soil and dry matter of A. Orientale, chromium content in soil and dry matter of A. Orientale, nitrogen content and dry matter of A. Orientale, chromium content and dry matter of A. OrientaleDuring the whole investigation period, the correlation coefficient between A. Orientale seedlings nitrogen uptake amount and root chromium content was from-0.428to-0.796, showing a significant or very significant negative correlation. But, a significant or highly significant positive correlation existed between A. Orientale seedlings nitrogen uptake amount and the dry matter of leaves, tubers, A. Orientale seedlings nitrogen uptake amount and the dry matter of tubers, roots in the early and later investigation stages respectively. Moreover, the chromium amount in leaves and tubers was sharply positively related with the dry matter of that at the early study periods. While at the later investigation periods, it showed the opposite trend, that is to say, having a very significantly negative correlation, with the highest correlation coefficient peaking at-0.672. The correlation coefficient between the chromium content and the dry matter of roots were greater than-0.605in the whole study stages, peaking at-0.778, reaching the very significant negative correlation level.Both total nitrogen and available nitrogen in the soil were significantly or highly significantly positively related with leaves dry matter in the early stage, and the correlation coefficient was up to0.889. Meanwhile, at the later stage, available nitrogen in the soil were significantly positively related with the dry matter of tubers and roots. and the correlation coefficient was0.769to0.866. The correlation between soil lotal chromium content and the dry matter accumulation of each part of A Orientale was not significant. On the contrary, with the correlation coefficient being from-0.755to-0.882. the available chromium content had a significantly or very significantly negative correlation with dry matter of tubers of A. Orientale. 5.The correlation between the nitrogen, chromium application amount and the chromium content, yield of tubers respectivelyAt the harvest time, the correlation coefficient between nitrogen application amount and the chromium amount in tubers of A. Orientate, nitrogen application amount and its yield were0.583、0.769respectively, reaching the obviously or extremely significantly positive correlation level. In addition, chromium application amount showed a very significantly positive correlation with the chromium amount in tubers of A. Orientale and a sharply significantly negative correlation with its yield, and the correlation coefficient was0.690and-0.796respectively. Adding the chromium supply promoted the accumulation of chromium in the tubers of A. Orientale, influenced its quality and reduced its production while increasing nitrogen supply raised the yield of A. Orientate, but at the same time it promoted the accumulation of chromium in the tubers.