氮沉降对半附生和地生榕属植物种子萌发和幼苗生长的影响OA

To understand the effect of atmospheric nitrogen deposition on seed germination and seedling growth of Ficus,the early regeneration process and growth conditions of four epiphytic and four terrestrial Ficus species treated with different nitrogen concentration(0,5,30,60,90,and 120 mmol/L)were analyzed.The results showed that at a low nitrogen concentration(5 mmol/L),compared with the control,there were no significant differences in the germination rate,emergence rate,survival rate,and germination and emergence speed of eight Ficus species seeds.However,the root complexity,main root length,bud length,and biomass all significantly increased(P<0.05).When the nitrogen concentration exceeded 5 mmol/L,the emergence and survival rates of seeds,the growth of roots and buds,and the biomass of all species significantly decreased.Under different nitrogen treatments,the survival rate and growth ability of epiphytic Ficus species were significantly higher than those of terrestrial Ficus species(P<0.05).When the nitrogen concentration was 30 mmol/L,the survival rate,root length,root complexity,seedling vigor index,and biomass of terrestrial Ficus species decreased by 43.8%,85.6%,82.3%,57.4%,and 57.1%,respectively.Under the highest nitrogen treatment(120 mmol/L),all these indicators decreased by more than 87%,and the corresponding indicators of epiphytic Ficus species decreased by 44.9%,90.4%,58.1%,60.2%,and 56.3%,respectively.Therefore,these indicate that in the context of increasing atmospheric nitrogen deposition,epiphytic Ficus species have stronger tolerance and competitiveness.