Effect Of Intra-specific Competition And Rooting Volume And Soil Depth On Growth And Reproduction Of Pisum Sativum

A classical theory called as "Tragedy of the commons" considers that the competition leads to increase in the root biomass and decrease in the seed yield. But recently the theory is also refuted by different results of some experiments. Considering two factors rooting volume and soil depth, we conducted the experiment with Pisum sativum to test this theory. The results showed:(1) In shallow soils, the competition led to the increase in root biomass, but did not influence the aboveground biomass and reproductive output;(2) In deep soil, the competition had not affect the root biomass, but decreased the aboveground biomass and reproductive output;(3) Regardless of competition, the soil depth significantly increased root, shoot biomass and reproductive output;(4) The changes of rooting volume increased aboveground, underground biomass and reproductive output. Soil depth interacted with rooting volume and completion, respectively. Therefore, our results did not support the "tragedy of the commons". We drew the conclusion that the soil depth can change the direction of the effect of intraspecific competition on aboveground biomass, and the degree of the effect of rooting volume on aboveground and underground biomass in Pisum sativum.