Effects Of Decomposing Leaf Litter Of Eucalyptus Grandis On The Physiological And Ecological Characteristics Of Cichorium Intybus

A pot experiment was carried out to investigate the effect of Eucalyptus grandis leaf litter on growth, photosynthesis and resistance physiology of Cichorium intybusduring the early stage of litter decomposition. There were four treatments in the present study:Ai (30g·pot-1), A2(60g·por-1), A3(90g·por-1) and CK (0g·por-1). Each pot contained12kg soil mixed with leaf litter and then C. intybus was sowed in those pots. The growth indicators and several indices of resistance physiology were tested at30,45,60and75d after sowing, and the photosynthesis characteristics of C. intybus were measured after the third leaf of seedling fully expanding in A3. In addition, the decomposition test of leaf litter was set to explore its allelochemicals release process, and it set the removal of allelopathic blank test substance (water-soluble and non-water-soluble secondary metabolites) to know that Whether the leaf litter was applied to soil aeration, water permeability shadow thereby affecting the growth of the recipient plant. The results were as follows.1. Using the E. grandis litter after extraction and stewing to proces the C. intybus (the blank test), the results showed that, within the range of application amount of90g·por-1, the leaf area, biomass, and net photosynthetic rate of C. intybus did not show a significant difference (P>0.05) between all treatments. The soil properties had not siginificantly changed during the early stage of litter decomposition and the C. intybus were due to impact by E. grandis leaf litter decomposition in the release of secondary metabolites. The physical barrier of litter to the C. intybus root which could not affect the growth of C. intybus which indicates that the test method was feasible.2. The amount of33volatile compounds decreased as the leaf litter decomposed, especially for terpenes which were the main allelochemicals.90d after sowing,10terpenes were released completely, indicating that these allelochemicals were released into soil to affect other plant growth during the decomposition of leaf litter, with the3. With the increasing amount of E. grandis leaf litter, the biomass accumulation and leaf area growth of C. intybus seedling were significantly inhibited.75d after sowing, the figure of biomass accumulation and leaf area wereCK<A1, and Other periods showed:CK> A1> A2> A3, especially in45d, the biomass of CK than A1, A2and A3increased by44.8%,70.8%and94.8%, leaf area increased by38.7%,66.2%and82.0%.At the same time, the biomass and leaf area growth rate of A3were the lowest. These results showed that, the allelochemicals released from the decomposing E. grandis litter leaf which had strongly inhibited the growth of C. intybus, and this inhibition began to weaken after45～60d.4. With the increasing amount of E. grandis leaf litter, the contents of photosynthetic pigments of C. intybus seedling leaf significantlydeclined. Compared with CK, the Chl (a+b), Chl a, Chl b and Car of A3process leaves were reduced by57.3%,57.3%,52.3%and52.0%(RJ<0). And the inhibition of Chl a was greater than Chl b.5. With the increasing amount of E. grandis leaf litter, Pn, Tr and Gs of C. intybus seedling leaf had a decreasing trend, and compared with CK, they reduced by51.3%,32.2%and56.0%, while C, showed an increasing trend:A3> A1> A2> CK, and Significant differences between different treatments; the parameters of light response and CO2response of C. intybus showed a significant downward trend and the differences between all litter addition treatments and control were significant. However, CO2compensation point showed an increasing trend with the increasing amount of leaf litter; Diurnal change of Pn had bimodal curves in all treatments, and the same trend with Gs and WUE, while the total diurnal as follows:CK> A1> A2> A3.6. The CAT activity in60d of each treatment showed an upward trend and the CK had highest activity, and then showed a downward trend. The CAT activity of A3was significantly lower than the activity of CK; Throughout the decomposition process, the POD activity showed CK> A1> A2> A3, and the activity of each treatment with the decomposing leaf litter increasing; Before45d, SOD activity was not significant difference among differ treatments. After45d, the CAT activity of A2was the highest and CK was the lowest, throughout the decomposition process, the SOD activity of each treatment first increased and then decreased; The MDA content in the first60d of each treatment showed an upward trend, and then showed a downward trend. At the same time, the MDA content of A2and A3were lower than CK.7. Throughout the decomposition process, the Soluble carbohydrate content of CK showed an increasing trend, while A1、A2and A3firstly showed an upward trend, and then showed a downward trend; The Soluble protein content showed a downward trend, and then showed an upward trend; The Proline content showed an increasing trend, The Proline content of A1, A2, A3were lower than CK, especially at the60d, increasing49.2%,21.2%and41.0%, the result showed that the leaf litter didn’t cause the water stress of the C. intybus growth.