Interactions Between Setaria Italica And Its Neighbors With Different Kinship Levels Under Different Nutrient And Density Conditions

In recent years,some studies have revealed that the interactions between the neighboring plants may be affected by the kinship effect.Different varieties of millet(Setaria italica)were used as focus plants,and different varieties of mille,wheat as neighbors,interactions between millet and its neighbors with different kinship levels under different nutrient and density conditions were carried out,aiming to reveal the performances of the patterns of the relationships among these neighboring plants with different kinship levels at different nutrients and density conditions.Crops were often grown in the form of pattern using single variety,which may easily lead to a result that neighboring plants are often the individuals with close kinship levels,which is very different from the plant community in natural conditions.However,there have been few results relating to the interactions between crop neighbors.In this paper,the variety of Setaria italica,"Tezao 1" was used as the main material,and different planting treatments in the greenhouse were set,from the aspects of morphological indices,fitness and biomass allocation,the ecological consequences of the interactions between Setaria italica and its neighbors with different kinship levels and the effect of environmental factors on it under different planting densities and nutrient levels,were explored.The main conclusions were as follows:1)Stem diameters of Setaria italica were not affected significantly by interactions between kin neighbors under treatments of different soil nutrient levels and plant densities.Plant heights were affected only under the conditions of high plant densities;plant heights in the kin groups were significantly lower than near-kin,far-kin and non-kin groups.2)Ear diameter and length of Setaria italica were both significantly affected by interactions between kin neighbors,but not for TSW(thousand seed weight).Under the conditions of high planting density,ear diameter significantly increased in the kin groups than that in other groups despite the changes of soil nutrient levels.With the planting density increase,ear diameter significantly decreased in the kin group,but under the conditions of high nutrient levels,no significant differences between the kin groups and far-kin groups and non-kin groups were found,but significantly lower than that in the near-kin groups.Ear length decreased with the decrease of the kin levels of neighbors,and under low nutrient levels,no significant difference between non-kin group and kin group were found.Ear length was significantly affected by the changes of planting density only in the kin groups and near-kin groups,but not in far-kin groups and non-kin group2.3)The aboveground and underground biomasses of Setaria italica were both significantly affected by neighbor interactions.The aboveground biomass declined with the decrease of kinship levels of neighbors.Planting density did no significantly affect the aboveground biomass of the plant in the kin-groups,far-kin groups and non-kin groups,but did significantly affect that in the near-kin groups.As the planting densities between neighboring plants increased,aboveground biomass of the plants in the near-kin groups increased under low nutrient levels,while decreased under high nutrient levels.Under high planting density conditions,root biomasses of plants in the kin group were significantly higher than that in other groups,but not in the conditions of low planting densities.4)Setaria italica "Tezao 1" tended to be able to recognize the identities of the kin neighbors,and the ability was higher with the increase of kinship levels of the neighbors.Under the conditions of low planting densities and low soil nutrient levels,no significant differences between the different groups in terms of root biomass were found,but the ear diameter and length and aboveground biomass in the kin group were significantly higher than those in other groups.Reproductive fitness of Setaria italica was significantly higher in the kin groups than those in other groups,while the competition was almost same in all groups.However,the reproduction abilities were stronger when the kinship levels between neighbor plants were closer.5)The positive interaction between the kin neighbors may be the result of combined actions of the kin recognition,competition between neighbors and other environmental factors.The ability of competition and kin recognition of Setaria italica may varies with the changes of the habitat environment.The positive interaction between the kin neighbors tended be stronger in the conditions of higher planting density and higher soil nutrient levels,and also,the competition was increased correspondingly.On the one hand,Setaria italica increased root biomass allocation in the case of root competition with the kin neighbors,on the other hand,Setaria italica tended to recognize their kin neighbors to weaken the effect of competition,and increase the reproductive fitness allocation,and also change the growth strategies in the different habitat conditions.