Effects of Decomposing Leaf Litter of Eucalyptus grandis on the Growth and Photosynthetic Characteristics of Lolium perenne

The essence of grass growth is a complex system that is driven by light energy. The accumulation of 90% of the dry matter comes from the production of photosynthesis. In this study, we investigated the effect of decomposing leaf litter of Eucalyptus grandis on the growth and photosynthetic characteristics of Lolium perenne by pot experiment. Four treatments with different amounts of leaf litter were designed, including A1 (30 g/pot), A2 (60 g/pot), A3 (90 g/pot) and control (0 g/pot; CK), and the blank experiment groups with distilled fallen leaves were set as the above. The growth indices (including shoot biomass, root biomass and leaf area) were measured, and the photosynthetic characteristics were tested during 9-00-11-00 am on a sunny day. The test results showed that increasing amounts of E grandis leaf litter significantly inhibited the accumulation of shoot and root biomass, growth of leaf area, synthesis of photosynthetic pigments (chlorophyll a, chlorophyll b and cartenoids), photosynthetic rate and gas exchange parameters (Gs, Ci and Tr) of L. perenne seedlings (P < 0.05). The parameters of photosynthetic rate in response to CO2 concentration and light intensity showed a remarkable downward trend except for the CO2 compensation point and were significantly difference from CK, namely, CK > A1 > A2 > A3 (P < 0.05). The blank experimental showed that soil chemical and physical properties have not been changed by leaf litter decomposition. This demonstrated that the allelochemicals from E. grandis leaf litter decomposition can negatively affect the photosynthetic capacity and decrease the accumulation of biomass, and eventually inhibit the growth of L. perenne.