The Cadmium Poison To Strawberry & Its Mechanism And Control Research

Cadmium poison to strawberry had been systematically researched through the three ways of individual development, cell structure and physiological and biochemical characteristics.And the mechanism of cadmium poison to strawberry had been discussed in accordance with cadmium distribution and chemical forms in strawberry. The controlled measures, reducing the poison from cadmium, had been set forth.The main results are as follows:1.Effect of cadmium on strawberry抯 growth and fruit settingIt had been proved that the low-concentration cadmium may be able to promote strawberry growth, on the contrary, the high-concentration cadmium would inhibit its growth. And it occurred that the inhibition strengthen when the concentration rose. When the cadmium was ~ 10 mg/kg, the index such as strawberry抯 root length, root weight and biomass increased, when its concentration was over 25mg/kg, the index shown as above, began to decline; the roots of strawberry suffered more severely effect than shoot, the root activity and the foliar water content of strawberry steadily decreased with the concentration increase. It was made clear in the experiment that various cultivars of strawberry existed some disparities in response to cadmium. Cadmium produced effect to the fruit setting and the quality of strawberry. Cadmium would reduce the yield, fruit weight, vitamine C and some mineral element content.However, It was more serious that cadmium remained in the fruit when it was absorbed by strawberry. The content in fruit appeared quite relevant to the concentration of the cadmium in soil. When the cadmium in soil was over 0.267mg/kg, the cadmium content would excel the healthy food criterion and result in it is impossible to be touched.2.Effect of cadmium on strawberry抯 cell ultrastructureBy transmit electron microscope, it had been proved that the chloroplast structure in the cell of strawberry抯 leaves were destroyed after treated with cadmium. Chloroplast grana lamella was few and scattered, stood in a litter, and itappeared vacuole or disintegration. Reduction of mitcondria numbers, cristae and electron density and even disintegration were observed in mitcondria of root cell. In a word, the cadmium treatment caused the cell membrane separating from its wall, cell break,and finally led to the dismiss of cell structure. Meanwhile, the changes in distribution of organelle of chloroplasts etc, were also observed. A condensed substances appeared inner the cell.AtIer cadmium treatment, the cell membrane permeability of strawberry抯 leaves enhanced, k-leakage rate increased, and the structure of cell membrane was destroyed.3.Effect of cadmium on physiological and biochemical characteristics3.1Effect of cadmium on photosynthesis of strawberryCadmium reduced total amount of chlorophyll in strawberry抯 leaves and changed the ratio of chlorophyll a and chlorophyll b. Cadmium also reduced the photosynthetic rate in strawberry. But at the primary period of cadmium stress, low concentration cadmium would increased the photosynthetic rate of strawberry抯 leaves. Cadmium also reduced the leaf抯 stomatal conductance and the leaf抯 transpiration rate,but the concentration of intercellular CO2 unevidently declined. These results showed that photosynthetic system of strawberry was destroyed by cadmium.3.2Effect of cadmium on the nitrogen metabolism of strawberryIt was proved that cadmium significantly affected the nitrogen metabolism of strawberry. It not only reduced the nitrogen content in leaves and root and total amino acid content, but also inhibited the activity of nitrate reductase. However, it would increased the activity of ribonuclease in strawberry. Under the cadmium stress, the content of strawberry抯 free proline and the content of soluble protein rose. The fact that some of amino acid content in the cultivars with stronger tolerance increased may show the adapting response of strawberry to the poison from cadmium.3.3Effect of cadmium on mineral element accum...