夏季休闲是黄土高原旱地小麦常见的蓄纳雨水、恢复地力的措施。随着氮肥用量的增加,一季小麦收获后,旱地土壤剖面累积的硝态氮量不断增加,休闲期间降雨量高,残留硝态氮的去向是值得研究的问题。利用^(15)N标记法研究小麦收获后残留肥料...夏季休闲是黄土高原旱地小麦常见的蓄纳雨水、恢复地力的措施。随着氮肥用量的增加,一季小麦收获后,旱地土壤剖面累积的硝态氮量不断增加,休闲期间降雨量高,残留硝态氮的去向是值得研究的问题。利用^(15)N标记法研究小麦收获后残留肥料氮在黄土高原旱地(陕西长武)夏季休闲期间的去向,即小麦收获后在微区土壤表层(0~15 cm)施入^(15)N标记的硝态氮肥(30 kg hm^(-2)(以纯氮计),约相当于当地小麦一季作物收获后土壤残留肥料氮量),休闲结束后,采集0~200 cm土壤样品,测定了土壤全氮、硝态氮含量及其^(15)N丰度。结果表明,小麦收获(即休闲开始)时0~200 cm土壤剖面硝态氮累积量在205~268 kg hm-2之间(平均244 kg hm^(-2)),累积量较高。夏季休闲期间降水量为157 mm,属欠水年,但休闲结束后,^(15)N标记肥料氮向下迁移已达80 cm土层,下移深度在45~65cm之间,说明,旱地休闲期间硝态氮的淋溶作用不可忽视。夏季休闲结束后,加入的^(15)N标记肥料氮平均损失率为28%,损失机理值得进一步研究。展开更多
A bstract Gut microbiota impacts the health of crustaceans. V ibrio alginolyticus is a main causative pathogen that induces the vibriosis in farmed swimming crabs, Portunus trituberculatus. However, it remains unknown...A bstract Gut microbiota impacts the health of crustaceans. V ibrio alginolyticus is a main causative pathogen that induces the vibriosis in farmed swimming crabs, Portunus trituberculatus. However, it remains unknown whether gut bacteria perform functions during the progression of vibriosis. In this study, 16 SrRNA gene amplicon sequencing was used to investigate temporal alteration of gut bacterial community in swimming crabs in response to 72-h V. alginolyticus challenge. Our results show that V. alginolyticus infection resulted in dynamic changes of bacterial community composition in swimming crabs. Such changes were highlighted by the overwhelming overabundance of V ibrio and a significant fluctuation in the gut bacteria including the bacteria with high relative abundance and especially those with low relative abundance. These findings reveal that crab vibriosis gradually develops with the infection time of V. alginolyticus and tightly relates to the dysbiosis of gut bacterial community structure. This work contributes to our appreciation of the importance of the balance of gut bacterial community structure in maintaining the health of crustaceans.展开更多
文摘夏季休闲是黄土高原旱地小麦常见的蓄纳雨水、恢复地力的措施。随着氮肥用量的增加,一季小麦收获后,旱地土壤剖面累积的硝态氮量不断增加,休闲期间降雨量高,残留硝态氮的去向是值得研究的问题。利用^(15)N标记法研究小麦收获后残留肥料氮在黄土高原旱地(陕西长武)夏季休闲期间的去向,即小麦收获后在微区土壤表层(0~15 cm)施入^(15)N标记的硝态氮肥(30 kg hm^(-2)(以纯氮计),约相当于当地小麦一季作物收获后土壤残留肥料氮量),休闲结束后,采集0~200 cm土壤样品,测定了土壤全氮、硝态氮含量及其^(15)N丰度。结果表明,小麦收获(即休闲开始)时0~200 cm土壤剖面硝态氮累积量在205~268 kg hm-2之间(平均244 kg hm^(-2)),累积量较高。夏季休闲期间降水量为157 mm,属欠水年,但休闲结束后,^(15)N标记肥料氮向下迁移已达80 cm土层,下移深度在45~65cm之间,说明,旱地休闲期间硝态氮的淋溶作用不可忽视。夏季休闲结束后,加入的^(15)N标记肥料氮平均损失率为28%,损失机理值得进一步研究。
基金Supported by the National Natural Science Foundation of China(No.41673076)the Major Agriculture Program of Ningbo(No.2017C110007)the K.C.Wong Magna Fund in Ningbo University
文摘A bstract Gut microbiota impacts the health of crustaceans. V ibrio alginolyticus is a main causative pathogen that induces the vibriosis in farmed swimming crabs, Portunus trituberculatus. However, it remains unknown whether gut bacteria perform functions during the progression of vibriosis. In this study, 16 SrRNA gene amplicon sequencing was used to investigate temporal alteration of gut bacterial community in swimming crabs in response to 72-h V. alginolyticus challenge. Our results show that V. alginolyticus infection resulted in dynamic changes of bacterial community composition in swimming crabs. Such changes were highlighted by the overwhelming overabundance of V ibrio and a significant fluctuation in the gut bacteria including the bacteria with high relative abundance and especially those with low relative abundance. These findings reveal that crab vibriosis gradually develops with the infection time of V. alginolyticus and tightly relates to the dysbiosis of gut bacterial community structure. This work contributes to our appreciation of the importance of the balance of gut bacterial community structure in maintaining the health of crustaceans.
