Effects Of Strontium On Physiological And Biochemical Properties, Mineral Nutrients Uptake Of Ryegrass

After the Chernobyl accident of Russia in 1986, the research on radio ecology have been attracted much more attentions. Radiostrontium is a kind of critical nuclides for its biological significance. Radiostrontium contamination is the result of nuclear power testing, nuclear waste disposal, weapons production and accidents resulting from nuclear power generation. The radioactive dust subsiding in the soil or floating in the air can enter into the plants via three pathways: root uptake, foliar absorption and surface adhesion of resuspended contamination on leaves and stems, and finally do internal irradiation harm to human body via food chain.Furthermore, radiostrontium can reach quite high concentration in the bone tissue and finally result in damages to bone and bone marrow. However, the current information about the Sr uptake, its accumulation in plants and the tolerance to plants growth from soil to plants is very limited. The strontium, whose biochemical behavior are quite similar to radiostrontium in the environment, were used as the substitute of radiostrontium to study its geochemical processes widely. In this paper,the change of physiological and biochemical properties of ryegrass, and the effects of Sr on the nutrient uptake of ryegrass were investigated under the different Sr²⁺ concentrations in two tested soils, which are red paddy soil and Stragnogleyed paddy soil.The results obtained are as follows:1. The growth of ryegrass was influenced by Sr²⁺ greatly, the plant height, the fresh weight and the content of Chla, Chlb, Chl (a + b) were found to be increasd with the low concentration of strontium while compared to the CK treatment,and the plant height, the fresh weight and the content of Chla, Chlb, Chl (a + b) were found to be decreasd with the high concentration of strontium while compared to the CK treatment .There are obvious differences within the tested ryegrass in the different tested soils. The shoot fresh weight of ryegrass had the greatest variation in the two tested soil, where as the extent of change were different. It showed significant differences on the tolerance of ryegrass to different Sr²⁺ treatment levels in different tested soils.2. Along with the increase of strontium treatment levels, the SOD activity, CAT activity and POD activity in the leaves of ryegrass increased at the beginning of the growth stage and decreased thereafter. There are a little differences within the tested ryegrass in the different tested soils. MDA content of ryegrass in the red paddy soil was increased firstly and then declined, but which of ryegrass in the Stragnogleyed paddy soil was continued significantly increasing. These results indicated that low concentration of Sr²⁺ can stimulate leaves enzyme activity, catalyse reaction and decrease OH-, and thus can protect the membrane system. However, high concentrations of Sr²⁺ stress gave rise to injury and destroyed the leaf-defense system. Ryegrass subjected to oxidative stress as strontium levels increasing.3. The content of mineral elements of the ryegrass have a better correlation with the added-Sr²⁺. Sr²⁺ accumulation in shoot decreased K, Ca, Mg ,Fe uptake. The toxic effects of Sr + on ryegrass can be attributed to the interaction of essential mineral uptake, which disturbed the elements equilibrium in plants.