Journal
JOURNAL OF EXPERIMENTAL BOTANY
Volume 60, Issue 13, Pages 3737-3749Publisher
OXFORD UNIV PRESS
DOI: 10.1093/jxb/erp216
Keywords
Chlorophyll fluorescence; gas exchange; grassland ecosystem; relative plant growth rate (RGR); rewatering; water stress
Categories
Funding
- National Key Basic Research Specific Foundation [2006CB400502]
- National Natural Science Foundation of China [40625015, 90711001]
- Japan Society for the Promotion of Science [P07622]
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Although the relationship between grassland productivity and soil water status has been extensively researched, the responses of plant growth and photosynthetic physiological processes to long-term drought and rewatering are not fully understood. Here, the perennial grass (Leymus chinensis), predominantly distributed in the Euro-Asia steppe, was used as an experimental plant for an irrigation manipulation experiment involving five soil moisture levels [75-80, 60-75, 50-60, 35-50, and 25-35% of soil relative water content (SRWC), i.e. the ratio between present soil moisture and field capacity] to examine the effects of soil drought and rewatering on plant biomass, relative growth rate (RGR), and photosynthetic potential. The recovery of plant biomass following rewatering was lower for the plants that had experienced previous drought compared with the controls; the extent of recovery was proportional to the intensity of soil drought. However, the plant RGR, leaf photosynthesis, and light use potential were markedly stimulated by the previous drought, depending on drought intensity, whereas stomatal conductance (g(s)) achieved only partial recovery. The results indicated that g(s) may be responsible for regulating actual photosynthetic efficiency. It is assumed that the new plant growth and photosynthetic potential enhanced by pre-drought following rewatering may try to overcompensate the great loss of the plant's net primary production due to the pre-drought effect. The present results highlight the episodic effects of drought on grass growth and photosynthesis. This study will assist in understanding how degraded ecosystems can potentially cope with climate change.
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