干旱持续时间对内蒙古草原中坚韧胶衣和分指地卷固氮活性的影响 [Effect of drought duration on nitrogen fixation of Collema tenax and Peltigera didactyla in a semiarid grassland of Inner Mongolia, China]

Author:
刘华杰 房世波 吴清凤 [Liu H.-J., Fang S.-B. & Wu X.-F.]
Year:
2009
Journal:
Mycosystema
Pages:
28(6): 783-789
Url:
thumb
[in Chinese with English abstract: ] Collema tenax and Peltigera didactyla are N-fixing lichens in arid and semiarid grasslands, where water and nitrogen availability are essential factors influencing ecosystem structure and functions. The response of N-fixing activity of lichens to drought in temperate grasslands of China has received little attention in the past ecological studies. The purpose of the present study was to investigate the effects of drought duration on N fixation of C. tenax and P. didactyla by measuring potential N-fixing activity of both lichens that have been subjected to drought for 0, 1, 2, 4, 8 and 16 days. All samples were collected from a semiarid grassland in Inner Mongolia and N-fixing activity was measured using acetylene reduction assay. Most drought duration treatments yielded insignificant differences in N-fixing activity between species. N-fixing activity of both C. tenax and P. didactyla sigmoidally decreased with drought duration (R2 = 0.9996 and R2 = 0.9954, respectively). These results show an inhibitory effect of drought on N fixation for both lichens. This effect can be intensified by prolonged drought duration. No significant changes in N fixation of both lichens were found in the drought duration less than 2 days. However, a 4-day drought resulted in a significant decline in N-fixing activity of C. tenax and P. didactyla (decreased by 34% and 54%, respectively). N-fixing activity of both lichens decreased by up to 90% when being dried for 8 days, and declined by more than 99% in 16-day drought duration. The negative effects of drought on N fixation of both lichens could be attributable to the low levels of photosynthate and energy, and to the lag time after rewetting before N-fixation was initiated and before maximal N-fixing activity was reached. Key words: lichen, water, acetylene reduction assay.
Id:
27347
Submitter:
zdenek
Post_time:
Wednesday, 24 August 2016 12:12