Effects Of Nitrogen And Phosphorus Addition On The Reproduction Of Pedicularis Szetschuania And Its Relationship With Pollinators

Over the past decade,with a large number of fossil fuel combustion,N and P fertilizer is widely used in planting and artificial grassland,emissions of nitrogen compounds and greenhouse gases in the atmosphere are significantly increasing,resulting in a corresponding increase in nitrogen deposition and temperature generally increased.The alpine meadow ecosystem of Tibetan Plateau is very fragile and extremely sensitive to human activity and global change.At present,nitrogen deposition and phosphorus deposition are mainly simulated by applying chemical fertilizers.In this paper,under the background of climate change,we used Pedicularis szetschuania as the research material to discuss the effects of applying nitrogen and phosphorus on plant characteristics of Pedicularis szetschuania,the correlations between characteristics.At the same time,the linear relationships between plant characteristics and visiting frequency of the pollinators were studied,we want to discuss affecting plant characteristics whether pollen limitation or nutrient addition.The characteristics of plant in the evolution of adaptive significance by phenotype selection analysis of male and female fitness component was explored.The results showed that the addition of nitrogen resulted in a shorter leaf length and an increase in the number of seeds in 2015.The pollinators preferred the higher plants,the longer leaves,the greater number of flowering of Pedicularis szetschuania,with the increase in the visiting frequency,the number of seeds increased.However,the addition of nitrogen fertilizer reduced the selection of plant characteristics,and there was no correlation between visiting frequency and the number of seeds.The addition of phosphate fertilizers leads to pollinators prefer the number of plants with more flowering,and the number of seeds increases accordingly.whereas,there was also no correlation between visiting frequency and the number of seeds.Persistent nitrogen application and phosphorus fertilizer significantly affected the correlation between plant characteristics and the linear relationships between pollinators and plant characteristics.In the natural population,the pollinator preferred to visit high plants,long leaves and more flowering,and the higher the number of seeds,the higher the number of seeds.However,the addition of nitrogen fertilizer reduced the selection of flower characteristics,There was no correlation between the flow rate and the number of seeds.The addition of phosphate fertilizer resulted in the increase of the number of seeds,and the number of seeds was not related to the number of seeds.Phenotype selection analysis was performed using the relative seed number as the female component.It was concluded that the results of the phenotype selection analysis of the plantcharacteristics were the same as the natural population.The higher plant height,the longer leaf,the more the number of flowering,the more the number of seeds produced by the individual,indicating that: the addition of nitrogen fertilizer did not significantly affect the the selection of the characteristics of the plant and the individual female fit.In 2016,the addition of the nitrogen and phosphorus fertilizer resulted in the disappearance of the linear selection of plant height and leaf length,indicating that the addition of nitrogen and phosphorus fertilizer reduced the selection of plant characteristics,reducing the individual female fit.Different treatment on the number of flowers have a positive linear selection difference and linear selection gradient in different years.In general,the number of flowers is more conducive to improving the individual fitness,which in different treatment conditions are consistent.When the relative visit frequency was used as the male fitness component for phenotype selection analysis,it was concluded that in the natural population,the pollinators preferred plants with higher,longer leaves and more flowering of Pedicularis szetschuannia,but the addition of nitrogen fertilizers caused pollinators to the choice of these plant characteristics disappeared;the addition of phosphate fertilizer led pollinators to prefer plants with more flowering,that is,the greater the number of flowering,the number of pollinators to visit flowers increased,thereby improving the male fitness.