Effects of simulated nitrogen deposition on N and P stoichiometric characteristics of soybean under drought stress
Investigating the impact of increased nitrogen(N)deposition under drought stress on the ecological stoi-chiometry of soybean(Glycine max)organs is pivotal for predicting ecological processes and guiding sustainable agricultural development.We explored the effects of simulated nitrogen deposition on N and phosphorus(P)stoi-chiometry of different organs of soybean cultivar"Tiefeng 29"following drought stress in a pot experiment.There were eight treatments with two water levels:normal moisture(W,75％±5％),drought(D,35％±5％),and four N addition levels:CK,LN,MN,HN(nitrogen application was divided into three times,with nitrogen addition amount totaling 0,50,100,150 kg·hm-2·a-1).The results showed that the interaction between drought stress and N deposition significantly affected N and P concentration and the N/P ratio in roots,stems,and leaves.Com-pared with the CK-D treatment,with the increase of N addition level,root N concentration gradually decreased after one time of N addition,and significantly decreased by 19.3％in the HN-D treatment.The stem P concentration first increased and then decreased,and significantly increased by 38.2％in the LN-D treatment.The leaf P concentra-tion gradually increased,and significantly increased by 31.2％in the HN-D treatment.After two times of N addi-tions,root N concentration was significantly lower than that of CK-D treatment,and there was no significant differ-ence among various N treatments(LN,MN,HN).The stem P concentration gradually decreased,and significantly decreased by 18.9％in the HN-D treatment.The leaf N concentration increased first and then decreased,and sig-nificantly increased by 18.5％in the MN-D treatment.After three times of N additions,root N concentration de-creased gradually,and significantly decreased by 19.7％in the HN-D treatment.Stem N concentration increased first and then decreased,and significantly decreased by 22.6％in the HN-D treatment.Leaf P concentration was significantly lower than CK-D treatment,and there was no significant difference among treatments(LN,MN,HN).Furthermore,after N application,in the power function relation of leaf N-P(N=βPα,both α andβare con-stants),α of W treatment was＜1,α of D treatment was＞1,with leaf N/P ratios exceeding 16.There was a signi-ficant relationship between root and stem N concentration,a highly significant relationship between stem and leaf N concentration,a highly significant positive correlation between root and leaf N concentration,and no significant re-lationship between stem N and P concentration.In conclusion,early N application can mitigate the negative effects of drought stress on soybean.However,as N deposition increases and the times of nitrogen application rises,soy-bean growth is limited by P availability.
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维普
