| The interaction between plant individuals and their material and energy metabolism are important scientific issues in ecology,and always are the hotspots in ecological research.Although plants in nature grow steadily,individual plants can influence each other in a direct or indirect way.Positive and negative interactions among plant individuals have important effects on population dynamics,community structure,composition,community construction,and ecosystem function.In addition,organisms need different material energy to obtain from the environment.There are differences in the redistribution of material energy by various life activities in the body,resulting in differences in the metabolic rate of the organism.Therefore,the metabolic rate of the organism has also become an important physiological index.Although a large number of studies have shown that the intensity of competition has a particularly important effect on the interaction patterns between plant neighbors and their growth and metabolism,it is still unknown whether this effect has kinship selection or niche differentiation effects.Therefore,based on the positive and negative interactions of plants,metabolic ecology theory and kinship selection theory,this study takes crops with different phylogenetic distances and different niche as the research object,and explores the interaction between plant neighbors and the dynamic changes of growth and metabolism under different plant species combination(that is,different kinship distances)and different planting density gradients.The main results show:(1)In the case of monoculture planting of wheat,corn and soybean,the positive and negative interactions between plant neighbors are greatly affected by the population density and the growth period.The specific performance is as follows: the individual morphological characteristics of the plant,such as plant height and base diameter,are affected by density changes and have strong plasticity,and with increasing population density,the plant height and base diameter of wheat,soybean,and corn show a downward trend;At the different growth stages,the aboveground biomass of plants and the biomass of each organ decrease with the increase of population density,and the allometric exponent is not a constant value;the distribution of biomass among different organs follows the allometric growth law and has different allometric exponents;In the early stages of plant growth or low-density populations,the interaction between plant neighbors is mainly positive,but with the growth of crops and increasing planting density,the interactions among plant individuals gradually change from reciprocity to competition.(2)The studies on allometric growth of wheat,corn,and soybean in monoculture plots at different density gradients and different growth stages,show that: 1)There is no general rule for the influence of population density and growth period on plant biomass,and the allometric exponent is not a certain constant value;2)The relationship between individual growth rate and individual size of each species exhibits density dependence,and the allometric exponents decrease from 0.951 in low density to 0.744 in high density;3)The allometric exponents between the individual growth rate and the individual size of these three species exhibit obvious time dynamics at different growth stages.The allometric exponents between corn leaf biomass(that is growth rate)and individual size fluctuate between 0.934 and 1.07,showing an isometric growth trend;the allometric exponents between soybean leaf biomass and individual size are approximately equal to 1 at the seedling stage,the branching stage and the flowering period,and after the pod setting period the allometric exponents begin to decrease and fall to 0.647 at the mature stage.While,the allometric exponents of wheat leaf biomass and individual size approach to 1 at the seedling stage,and then decrease to 0.678 at the flowering stage,but increase to 0.796 at the mature stage,close to 3/4;4)At different growth stages,the allometric exponents between stem biomass and individual size of the three species are basically greater than 3/4.The allometric exponents between corn stem biomass and individual size fluctuate between 0.744 and 0.97,basically greater than 3/4;the allometric exponents between soybean stem biomass and individual size fluctuate between 0.8-1.03,close to 1;the allometric exponents between wheat stem biomass and individual size fluctuate between 0.786 and 1.07;5)At the different growth stages,the allometric exponents between reproductive organ biomass and individual size are much greater than 1,which is 1.83 for corn;for soybean,which fluctuate between 1.54-1.63,while for wheat which fluctuate between 1.15-1.29.(3)In experiments that focus plant planting with different phylogenetic levels species,we find that the plant height,basal diameter,crown breadth,specific leaf area,and above-ground biomass of the target plant soybean(Glycine max)strain Fendou 56 are significantly affected by neighboring plants,but there is no uniform change law.Moreover,with the growth of crop or population density increasing,competition intensity increases,and the strategies of response of the height,base diameter,crown width,specific leaf area and above-ground biomass of Fendou 56 to the phylogenetic level of neighboring plants changed.The specific performance are as follows: 1)At the seedling stage of Fendou 56,the basal diameter of individuals in close relative group is significantly higher than that in non-relative groups under low-density and high-density conditions,while there is no difference under medium density,and at the branching stage there is no significant difference in the basal diameter of individual in different kinship groups;2)At the seedling stage and branching stage of Fendou 56,the crown breadth of individuals in close relative groups is significantly higher than that in nonelative groups,while it is the opposite at the flowering stage and pod formation stage;3)During the flowering period of Fendou 56,the height of individuals in close relative group is significantly higher than that in non-relative group under the medium density and very high density,while it is the opposite under the low density and high density conditions;4)The specific leaf area of Fendou 56 is not affected by the level of kinship at the seedling stage and the branching stage,but the specific leaf area of individuals in close relative groups is significantly higher than that in non-relative groups at the flowering stage;5)In the flowering stage of Fendou 56,the aboveground biomass of individuals in close relative groups is significantly higher than that in non-relative groups,and while it is the opposite at the seedling stage and branching stage under the low density conditions.In addition,the allometric growth exponents of Fendou 56 in different periods have a large fluctuation range,but the difference among the different relative groups is not significant.(4)There is no significant difference among different kinship level of neighbors on morphological characteristics such as plant height,basal diameter and crown breadth of adzuki beans.It also has no effect on the photosynthesis and respiration enzyme activity of plant leaves,but it weakly affects the instantaneous photosynthetic rate of leaves and the interactions pattern between plant neighbors.Overall,our study elucidates the influence of competition intensity,species growth period,and kinship between neighbors on plant interaction and growth metabolism.This research is of great significance to the research of population dynamics,community structure,composition and community construction. |
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