| Taxus chinensis has high medicinal value,and it belongs to the rare species under national first- class protection.Since its value was discovered,its habitat has been destroyed,resulting in a large number of deforestation threats,but its growth rate is very slow,leading to a sharp reduction in its number,so how to effectively protect and use it,Has become a production practice problem to be solved urgently.Compound fertilizer provides essential nutrients for plants,promotes the growth and development of plants and increases the yield,so as to have a positive effect on the growth of plants.Therefore,it is of great significance for the artificial domestication of taxus cuspidate and the restoration of germplasm resources to find out the fertilization conditions suitable for the growth of taxus cuspidate.In this experiment,7-year old potted Taxus Taihang was selected as the research object from March to November of 2021 to 2022.The lower limit of soil matrix potential 20cm directly below the drip irrigation head in potted plants was controlled at-20 k Pa for different fertilization treatments.Five treatments and seven replicates were set with five different compound fertilizer contents,which were 0 kg/m3（C0）,1.8 kg/m3（C1）,3 kg/m3（C2）,4.2 kg/m3（C3）,5.4kg/m3（C4）,respectively.The effects of different fertilizer application rates on physiological characteristics and plant growth quality of Taxus chinensis under unified drip irrigation（-20 k Pa）were studied,and the suitable fertilizer application range for growth of taxus chinensis was explored,providing theoretical basis for artificial domestication and cultivation technology of taxus chinensis.The main research results are as follows:（1）Appropriate fertilization treatment can promote the synthesis of photosynthetic substances such as chlorophyll in leaves,so as to improve the net photosynthetic efficiency of crops.In the study of2021-2022,it was found that with the increase of fertilizer application,the total content of chlorophyll a,b and total content in July and September showed a trend of slow rise first and then decline,and the content of chlorophyll in all treatments in July was higher than that in September,while the content of chlorophyll in unfertilized treatment was lower than that in fertilized treatment.The content of chlorophyll in C3 treatment was the highest,followed by C4,C2,C1 and C0.In addition,the net photosynthetic rate,stomatal conductance and transpiration rate of Taxus cuspidate leaves all showed a trend of first increasing and then slowly decreasing with the increase of fertilizer application rate,but the intercellular CO2 concentration showed a trend of first decreasing and then increasing.In addition,the photosynthetic characteristics in 2022were higher than those in 2021,with the maximum value in July.No fertilization treatment was significantly lower than fertilization treatment,but the degree of fertilization treatment was different,showing a trend of C3>C4>C2>C1>C0.The results showed that C3 treatment significantly improved the photosynthesis of Taxus cuspidate,and maintained a higher net photosynthetic rate.By increasing stomatal conductance,transpiration rate and carbon source required for photosynthesis,the nutrient supply of plant leaves can be increased.Therefore,C3（4.2kg/m3）is favorable for the increase of photosynthetic rate of Taxus chinensis.（2）Appropriate compound fertilizer can improve the fluorescence intensity and fluorescence performance of plants.The chlorophyll fluorescence characteristics of plants are closely related to their environment.Low temperature in spring can reduce the photosynthetic electron transfer rate and the photosynthetic quantum yield of plants.When the temperature is high in summer,appropriate fertilization can not only provide nutrients needed by plants,but also improve the fluorescence activity of plants.With the gradual decrease of temperature,the duration of light and the increase of precipitation in autumn,the soil water content is easy to be too high,which affects the absorption of nutrient elements by crops,and thus weakens the effectiveness of fertilizer application.In this experiment,with the increase of fertilizer application rate,fluorescence parameters of Fv/Fm,ETR,Y（Ⅱ）and q P under different treatments showed a trend of gradual increase and then decrease,and C0 treatment was significantly lower than C2,C3 and C4treatment,with the maximum fluorescence value in July,but NPQ was on the contrary,showing a trend of first decreasing and then slowly increasing.And C0 treatment was significantly higher than fertilization treatment.There was no significant difference among all treatments in September and there was a downward trend in fluorescence parameters compared with July,but the non-fertilized treatment was still lower than the fertilized treatment,except that the unexpected fluorescence parameters of NPQ were C3>C4>C2>C1>C0,and the trend of NPQ was opposite.In addition,due to the influence of light intensity,as well as the reduction of light intensity and sunshine duration in autumn and winter,the fluorescence characteristics of plants are not as obvious as in summer.It was found that photosynthetic efficiency of C3 treatment was higher than that of other treatments during 2021-2022,and the photosynthetic product production rate was better adapted to light conditions.（3）Malondialdehyde content and relative electrical conductivity of plant leaves were affected by different fertilization treatments.In the period of 2021-2022,it was found that the content of malondialdehyde increased slowly from April to September with the accumulation of substances.The content and relative conductivity of malondialdehyde in September were significantly higher than those in April and July,and with the increase of fertilizer application,there was a trend of first decreasing and then slowly increasing among different treatments.The malondialdehyde content and relative conductivity of C2,C3 and C4 were significantly lower than C0,showing that C3<C4<C2<C1<C0,and C3 treatment was the lowest.The results showed that C3 treatment could reduce cell membrane damage,reduce cell membrane permeability and electrolyte exusion rate,reduce the degree of leaf membrane lipid peroxidation,and increase the osmotic pressure of root and leaf surface cells.Increase water and nutrient absorption,reduce the relative electrical conductivity of plant cells,delay leaf senescence.Therefore,C3 treatment（4.2 kg/m3）can improve chlorophyll synthesis and physiological activity.（4）Fertilizer application is very important for crop growth.Appropriate fertilizer application can promote crop growth,improve yield and quality,increase crop biomass,promote crop growth and improve nutrient utilization rate.In 2021-2022,with the increase of fertilizer application amount,plant height and crown width of taxus cuspus showed a significant increase trend,and the increase in 2022 was more than that in 2021.The significant difference in LAI was small,basically keeping with the trend of crown width,but there was no significant difference in ground diameter.C2,C3 and C4 increased significantly,but C3 was the most significant.The contents of total flavonoids and polysaccharides in leaves were the highest in November,and there was no significant difference in May.However,among different treatments,C3treatment was the highest,which was significantly higher than C0 and C1 treatments,and there was no significant difference in numerical value compared with C2 and C4 treatments.The results showed that the growth of plant height and crown width in C3 treatment was the largest and the difference was the most significant.Therefore,C3 treatment（4.2kg/m3）was beneficial to the growth and development of taxus cuspidate,and promoted the accumulation of flavonoids and polysaccharides. |
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