Discussion On The Allometric Growth And Nutrient Relationships In Nitraria Tangutorum

Plant growth includes the plant size,biomass allocation,allometric,growth stages,biological stoichiometry,and the like.To explore the allometric partitioning of biomass in different growth stages,the biomass/quantity investment trade-off of different organs,and the problem of biological stoichiometry is meaningful for understanding plant growth under the background of the global climate change and nitrogen deposition acceleration.In this study,Nitraria tangutorum Bobr.was used as the research object.The biomass of different organs in the flowering,fruiting and vegetative growth stages in two years were determinated to discussing the problem of allometric partitioning of biomass in different growth stages or ages.And the quantity,the biomass and the content of C,N and P elements of different organs under nitrogen and phosphorus addition were determinated to discussing the problems of trade-offs between quantity investment and biomass investment in different organs,and their stoichiometry problems.The main findings show that:1.The effect of reproductive allocation of Nitraria tangutorum on biomass allocation pattern is mainly reflected in the biomass allocation(36.00%)rather than the scaling of plant size dependence(16.00%).And the difference in size dependence of its biomass allocation between years(47.06%)was greater than between growth stages.2.The allocation rate of biomass in the underground part of Nitraria tangutorum will increase with the accumulation of its biomass or age,but the reproductive allocation can slightly decrease this rate.And Nitraria tangutorum have a higher rate of biomass distribution to supporting organs as the biomass of the plant increases,but over time,it is more likely to distribute biomass to assimilating organs.3.Leaves,branches,and roots of Nitraria tangutorum have different trade-offs between average biomass and quantity: This trade-off is common in branches and is generally not significantly affected by the addition of nitrogen and phosphorus;leaves may not have such trade-offs,or only occurred to some certain circumstances;while the roots show that thistrade-off is gradually eliminated or even offset as the concentration of nitrogen or phosphorus increases,but this trade-off will be aggravated when the phosphorus is excessive.4.The trade-off between the average biomass and quantity of the organs of Nitraia tangutorum shows a regularity in different nutrient(nitrogen,phosphorus)habitats,indicated that there is a stability between the average biomass and the quantity of the organs,and this stability can be well represented by a fitting formula between the quantity of organs and the maximum value of the average biomass for a certain quantity.5.The response of different organs of Nitraia tangutorum to nutrient addition were different: the elemental content of roots and leaves responded more strongly to the addition of nitrogen and phosphorus,while the response of the branches in 2016 and 2017 were weaker.And the response of different elements to nutrient addition were also different: for the carbon content,there are 4 significant differences in the 6 organs under different treatments,for the nitrogen content,all the 6 organs are significant different,and for the phosphorus content,only leaves and roots have significant differences.6.The total mass of C,N,and P in each organ of Nitraria tangutorum is dependent on the size of the organ,and they can be well expressed by derivation models.7.Through the ratio of the fitting function between the total elements mass and total biomass of each organ of Nitraria tangutorum,the theoretical models of ecological stoichiometry depending on plant size of each organ and whole plant were deduced(P < 0.002).And this provides a new way to analyze the ecological stoichiometry in plant growth further.