Interactions among individuals of Setaria Italica at different levels of genetic relatedness under different nutrient and planting density conditions

Plants frequently interrelate with their neighbors at different levels of genetic relatedness in close contiguity due to sessile in nature and limited seed dispersal. Niche differentiation may diminish competition among the neighboring plants, and the interactions among neighbors may also be influenced according to their identity or genetic relatedness. However, it is still unclear how interactions among individuals at different levels of genetic relatedness can be affected by different nutrient and planting density conditions. To answer this question, we conducted a greenhouse experiment. The materials were three genotypes of Setaria italica, i.e., Special early no.1 (focal plant), GT 35-1 (neighbor) and Golden valley 808 (neighbor), and Triticum aestivum (neighbor). According to the affinity level, plants were grown with different combinations, such as close kin (A1A1), far kin (A1A2), non-kin (A1A3), and stranger group (A1B). Planting density in the pots set either short distance or long distance with low and high of two levels of nutrient supply. Results showed spike diameter, spike length and aboveground biomass significantly higher in the close-kin treatment, but simultaneously root competition was more intense at short planting distance, under the condition of low and high nutrient levels in close kin treatment as compared to other interactions. We concluded that interactions among individuals of Setaria italica at different nutrient conditions influenced by both neighbor's identity and planting density.