Effects Of Different Nitrogen Application Rates On Photosynthetic,Quality And Yield Of Lycium Ruthenicum Murr.

Lycium ruthenicum is perennial shrub,which is mainly distributed in Gansu,Xinjiang,Qinghai and Ningxia.The fruit is rich in polysaccharide,anthocyanin,flavonoid and other active components.It has the effects of anti-oxidation,anti-fatigue,lowering blood pressure,lowering blood lipids,enhancing immunity,preventing and treating diabetes,etc.Because of its high nutritional composition and medicinal value,it enjoys the reputation of"soft gold".With the gradually decrease of the number of wild L.ruthenicum,the artificial cultivation area of L.ruthenicum is expanding year by year.However,the problems of low quality and yield have not been solved.In order to solve these problems from the source,this experiment takes the amount of nitrogen application as a factor and adopts a single-factor random block design.Through setting five nitrogen application gradients(0,50 g·plant^-1/8 kg·hm^-2,100 g·plant^-1/16 kg·hm^-2,150 g·plant^-1/24 kg·hm^-2,200 g·plant^-1/32kg·hm^-2)in three periods?initial fruit stage,summer fruit stage and autumn fruit stage?in two years?2018 and 2019?,to research the effects of different nitrogen application rates on leaf photosynthetic characteristics,fruit quality and yield of L.ruthenicum,and clarify the value of reasonable nitrogen application rate to L.ruthenicum,so as to provide scientific basis and guidance for artificial cultivation of L.ruthenicum in arid areas.The main conclusions are as follows:1.With the increase of nitrogen application rate,plant height,stem diameter,crown width and leaf area increased to a certain extent,and it would lead to negative effects when the amount of nitrogen application exceeded the optimum amount of nitrogen application.Therefore,proper nitrogen application can promote the field growth indexes such as plant height,stem diameter,crown width and leaf area.In 2018,under different nitrogen application rates,plant height increase was the largest in N3,stem maximum increase in N2,crown increase in N1,and leaf area increase in N1;In2019,under different nitrogen application rates,plant height increase was the largest in N1,stem maximum increase in N2,crown increase in CK and leaf area increase in N1.2.Nitrogen application may have an inhibitory effect on C_i,but no obvious effect on LCP,LSP and R_d.In addition,it can promote other indexes,and excessive nitrogen application will have an inhibitory effect.In the three stages of 2018,the content of Chl a,Chl b,Chl a+b and the maximum value of P_n are all in N3,the maximum value of T_r is respectively in N4,N3 and N4,the maximum value of C_i is in CK,and the maximum value of G_s is in N2,N2,N1;In the three stages of 2019,the maximum content of Chl a,Chl b and Chl a+b are respectively N4,N3 and N4,the maximum value of P_n is respectively N3,N2 and N3,and the maximum value of T_r is N2,N3 and N3.The maximum value of G_s is in N3,N1,and N3,respectively.In 2018 and 2019,the maximum values of AQY and P_nmaxmax are in N3,the maximum value of R_d is in N2,the maximum value of LCP in 2018 is in N2,the maximum value of LSP is in CK,the maximum value of LCP in 2019 is CK,the maximum value of LSP N3.3.Nitrogen application could promote the synthesis of SOD,POD and CAT in L.ruthenicum,but excessive nitrogen application could inhibit it.Nitrogen application could inhibit MDA synthesis in L.ruthenicum.In the three stages of 2018,the maximum SOD activity was N4,N4,and N3,the maximum POD activity was N3,N4,and N4,the maximum CAT activity was N4,N4,and N3,and the maximum MDA content was N4,N4,and N4.N3 processing;In the three stages of 2019,the maximum SOD activity is N4,the maximum POD activity is N3,N4,and N3,the maximum CAT activity is N4,N4,and N3,and the maximum MDA content is N4,CK,and N4.4.Nitrogen application could promote the contents of polysaccharides,total flavonoids,anthocyanins,anthocyanins,100-grain weight and yield per plant in L.ruthenicum,but the excess could inhibit it.In 2018,the yield per plant reached the maximum at N3,N4 and N3,respectively,and the maximum yield was 113.62 g,116.61 g and 85.26 g.The yield per plant reached the maximum at N3,N4 and N3 in 2019,and the maximum yield was 111.25 g,123.99 g and 79.21 g,respectively.5.A certain amount of nitrogen increase the yield,net photosynthetic rate,transpiration rate,stomatal conductance,and instantaneous water use efficiency at different times of the day,but it inhibits the intercellular CO₂ concentration of two species of each period in one day.It also reduces the stomatal limitation,which is beneficial to the photosynthesis.Nitrogen application had significant effects on the photosynthetic parameters of L.barbarum compared with L.barbarum.150g·plant^-11 is the best nitrogen application amount for the daily average net photosynthetic rate and yield of L.ruthenicum,the daily average net photosynthetic rate(P_Na)is 9.842?mol·m^-2·s^-1,and the yield per plant is 173.621 g.187.730 g·plant^-1 is the best nitrogen application amount for the daily average net photosynthetic rate of L.barbarum,the daily average net photosynthetic rate is 11.616?mol·m^-2·s^-1,and 150 g·plant^-1 is the best nitrogen application amount for the yield of L.barbarum,the yield per plant is 205.264 g.