The research of growth curve for monoculture and mixture planting crops grown under different density conditions

According to metabolic scaling theory (MST), plant metabolic rate is nearly isometric to body size (biomass) for seedlings and samplings, and the scaling power is convergent to a constant 3/4 with the increasing plant size. Recently, we developed the dynamic growth model of individual sampling and seedling based on MST. However, plant individual which grown under intraspecies or interspecies competition pressure, will be strongly affected by the neighbors competition during development, it's unclear whether the growth model is suitable to the plant individuals with different pressure from intra and interspeciesneighbor competition. Therefore, three crops including spring wheat, flax, corn were selected and planted by monoculture and pair combination mixture cultivation ways, with three originally sowing densities(i.e. high, middle and low densities). We tracked the dynamic growth of individual plants in each plot for six times from germination to mature period including plant height, caudex, canopy and biomass. After fitting the growth curves based on the dynamic growth model proposed by Deng et al.(2012),we found that the growth curvesof plant individuals conform to the modelregardless of density gradient and planting way. However, the plant grows better and has bigger mature size for the species with similar nichesand in mixture cultivation plots than that in monoculture cultivation plots. Furthermore, and the growth rates and mature sizes decrease with the increasing densities or competition intensities for all species and planting ways. In a word, although the growth rate and mature size of plant vary with the competitive pressureof neighbors, growth curves of plant individual is still conformed to our growth model under different intra and interspeciescompetitive pressure. In current paper, we not only examined the growth model of small plant and the metabolic scaling theory, but also further pushing the development of metabolic theory.