Effects Of Manganese Stress On Soybean Growth And Yield

The research on growth and yield of soybean were carried out under the influence ofmanganese deficiency and excess stress based on analyses of the index of morphology,photosynthesis, material content and stress related indicators under the condition of differentmanganese stress levels. Dong nong47and Dong nong48were selected as test materials, andexperiments on treatments of manganese stress to soybean at whole growth stage were carriedout under five manganese levels. The five levels are severe lack of manganese (S1), mild lack ofmanganese (S2), the optimal concentration of manganese (CK), mild excess of manganese (S3)and severe excess of manganese (S4). The results are as follows:1. Compared with the control, soybean plant height, stem diameter and root length wereinhibited with manganese stress treatment in early growth stage, while there was no significantdifference between different stress treatment and control in middle and late growth stage. Drymatter of leaf, stem, root and pods were significantly reduced under different manganese stresslevels, and the reduction increased with the increasing of manganese stress.2. Compared with the control, manganese stress significantly inhibited the chlorophyll contentof soybean leaves, photosynthetic rate, intercellular CO2concentration, stomatal conductance,and the inhibition increased with stress. However, soybean leaf transpiration rate wassignificantly higher than that of the control with different manganese stress levels.3. Compared with the control, N, P content of leaf, stem, root, pod and seed were significantlydecreased with manganese stress, and so N content of root, but there was no significant effectson root P content. K content of the pod and kernel were significantly reduced with manganesestress, while K content of leaf, stem, and root had no significant effect.4. Compared with the control, manganese stress significantly inhibited the soybean leaf, stemand root of POD, CAT activity and leaf SOD activity, but had no significant effects on shoot androot SOD activity. Manganese stress significantly increased the leaf, stem and root MDA content,and this effect is enhanced with the deepening of the degree of stress.5. Compared with the control, the manganese stress significantly reduced the fat content andthe protein content of soybean seed, and the reduction increased with increasing of stress level.6. Compared with the control, except for100grain weight had no significant difference, manganese stress significantly reduced soybean3pod number and grain number per plant, andsignificantly reduce the grain weight per plant, and the inhibition increased with stress.