Abstract: Kin selection theory predicts that kin individuals could cooperate to increase their fitness through kin recognition. Previous studies confirmed that kin selection occurred in some plant species, and kin responses differed among species. However, the tested species were still seldom, and the influences of environmental factors were not considered. In order to verify kin selection in different ecotypes of Arabidopsis thaliana, our study selected three Arabidopsis ecotypes of Columbia (Col), Landsbergerecta (Ler) and Wassileskijia (Ws) as the research objects, to explore the influence of density on kin selection through measuring differences in plant phenotypic traits (plant height, rosette area, leaf area and seed number, etc.) and biomass (root, stem, leaf and seed biomass) between kin groups and nokin groups under three simulated densities. Our study showed significant differences in aboveground traits, but no differences in root distribution between kin and stranger groups of each ecotype. Kin response differed among the three ecotypes: Col and Ws ecotypes mainly responded to kin recognition in reproduction tissue (seeds), while Ler mainly in vegetable tissues (leaf and stem). Which phenotypic and biomass traits and how the traits of same ecotypes responded to kin recognition mainly relied on planting density, suggesting that density was an important factor in plant kin selection.

Key words: influencing factor., evapotranspiration, Huaihe Basin, Boreal Ecosystem Productivity Simulator (BEPS)