施氮时期对高产夏玉米氮代谢关键酶活性及抗氧化特性的影响

选用玉米品种登海661和郑单958为材料，研究了高产条件下施氮时期对夏玉米产量、氮素利用率、氮代谢相关酶及抗氧化酶活性的影响.结果表明： 拔节期一次性施氮不利于夏玉米产量提高和氮素积累，分次施氮且增施花粒肥显著提高了植株和籽粒的吸氮量，并提高了籽粒产量.拔节期、10叶期、花后10 d按2∶4∶4施氮，登海661产量最高可达14123.0 kg·hm^-2；基肥、拔节期、10叶期、花后10 d按1∶2∶5∶2施氮，郑单958产量最高可达14517.1 kg·hm^-2，这2种施氮方式较拔节期一次性施氮分别增产14.5%和17.5%.花前分次施氮可以显著提高开花期硝酸还原酶活性；登海661和郑单958在花后0~42 d中，施氮处理的谷氨酰胺合成酶、谷氨酸合成酶、谷氨酸脱氢酶活性分别平均提高了32.6%、47.1%、50.4%和145%、61.8%、25.6%，减缓了其下降趋势；超氧化物歧化酶、过氧化氢酶活性提高了22.0%、36.6%和13.4%、62.0%，丙二醛含量显著降低.在高产条件下，分次施氮且适当增加花粒肥施入比例可以提高氮代谢相关酶活性，延缓植株衰老，促进氮素吸收利用，进而提高籽粒产量.

Research advances in biodiversity remote sensing monitoring

Quickly and regularly monitoring and assessing regional biodiversity is of great significance for biodiversity research and conservation.In recent years,remote sensing technology is extensively applied in biodiversity research,and can provide regional,continental,and global biodiversity information.This approach is low cost and high data consistency,and updated regularly.This paper introduced the principles and advantages of remote sensing in biodiversity research,and summarized the main application aspects of biodiversity remote sensing in practice,including landscape indices,NDVI,spectral variation hypothesis(SVH),and hyperspectral remote sensing,with the focus on the analysis of the advantages and disadvantages of these application aspects and the recent research advances in SVH research and optimal band selection.The deficiencies in the remote sensing biodiversity research were pointed out,and the development trend in this research field,such as models,remote sensors,and scale effect,were prospected.