氮胁迫下不同黑木相思基因型综合评价

[Objective]To explore the growth,physiological and biochemical responses of different Acacia melanoxylon genotypes to nitrogen deficiency stress,and to provide a theoretical basis for early breeding of Acacia melanoxylon with excellent stress resistance.[Method]In this study,4 genotypes(F1,SR3,SR14 and SR17)seedlings of Acacia melanoxylon as objects,based on the improved Hoagland nutrient solution,using the sand culture pot test method,set CK(16mmol·L-1 N)and-N(0 mmol·L-1 N)two nitrogen levels to explore the effects of nitrogen deficiency on the growth and physiological and biochemical characteristics of four Acacia melanoxylon genotype seedlings,and use principal component analysis combined with membership function to comprehensively evaluate the low nitrogen tolerance ability.[Result]Under nitrogen deficiency,the plant height,ground diameter,above-ground dry weight and whole plant dry weight of four Acacia melanoxylon genotype seedlings were all inhibited,and the genotype with the smallest decrease in above-ground dry weight and whole plant dry weight was F1,the biggest one is SR17;the root dry weight of other genotypes showed a downward trend except for the increase of F1;the nitrogen accumulation of the whole plant was significantly reduced,among which the F1 genotype had the smallest decrease of 39%,and the SR17 had the largest decrease.A reduction of 58.2%.Under nitrogen deficiency,the root-to-shoot ratios of the four genotypes were significantly increased,and the nitrogen accumulation in the root system was higher than that of CK;while the chlorophyll a(Chla)content,chlorophyll b(Chlb)content,(Car)content and chlorophyll a+b(Chla+b)content were significantly decreased;the net photosynthetic rate(Pn)of the four genotypes was significantly decreased,the stomatal conductance(Gs)showed a downward trend,and the intercellular CO2 concentration(Ci)increased significantly,and the stomatal limit value(LS)decreased,which was mainly due to non-stomatal factors.Among them,the Pn of SR17 decreased the most,reducing by 76.8%;the Fv/Fm of SR17 decreased significantly under nitrogen deficiency,and was lower than 0.8,while other Genotype had no effect,and Fv'/Fm'was significantly reduced in F1,SR3 and SR17,while SR14 had no significant difference.Under nitrogen deficiency,the activities of POD,CAT and SOD of the four genotypes were significantly increased,and the content of MDA was also significantly increased;the comprehensive evaluation value was obtained by conducting principal component analysis on 20 indicators of growth,physiological and biochemical combined with membership function for comprehensive evaluation D shows that the order of adaptability of the four genotypes to nitrogen deficiency stress is F1>SR3>SR14>SR17.[Conclusion]Under nitrogen deficiency stress,the growth and development of the four genotype seedlings of Acacia melanoxylon were inhibited,the nitrogen accumulation in the whole plant was significantly reduced,the content of photosynthetic pigments was reduced,and photosynthesis was inhibited;nitrogen deficiency would increase antioxidant-related enzymes,However,excessive reactive oxygen species still caused damage to membrane lipids;F1 had the strongest ability to tolerate low nitrogen,and the stress had little effect on it,while SR17 had the weakest ability to tolerate low nitrogen,showing the largest decrease in photosynthetic rate and nitrogen accumulation in the whole plant,the PSII center of the seedlings was more damaged.