Limits...
Are plant growth and photosynthesis limited by pre-drought following rewatering in grass?

Xu Z, Zhou G, Shimizu H - J. Exp. Bot. (2009)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Science, Beijing, PR China.

ABSTRACT
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.

Show MeSH

Related in: MedlinePlus

Responses of photosynthetic potential and photochemical activities to stomatal conductance (gs). (A) Open squares, Asat light-saturated CO2 accumulation rate; filled squares, Asat after rewatering; crosses, Vc,max maximum carboxylation velocity. The dotted line denotes the initial Asat response to gs; the dashed line denotes Asat=constant value of Asat,maX estimated; and the intersection of the two lines represents a point at which Asat initially levelled off. (B) Open circles, α maximum photosynthetic quantum yield of CO2 uptake; filled circles, α after rewatering; open triangles, ΦPSII the actual PSII efficiency; filled traingles, ΦPSII after rewatering. (C) Open squares, the maximal efficiency of PSII photochemistry (Fv/Fm); open diamonds, non-photochemical quenching (NPQ).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2736889&req=5

fig5: Responses of photosynthetic potential and photochemical activities to stomatal conductance (gs). (A) Open squares, Asat light-saturated CO2 accumulation rate; filled squares, Asat after rewatering; crosses, Vc,max maximum carboxylation velocity. The dotted line denotes the initial Asat response to gs; the dashed line denotes Asat=constant value of Asat,maX estimated; and the intersection of the two lines represents a point at which Asat initially levelled off. (B) Open circles, α maximum photosynthetic quantum yield of CO2 uptake; filled circles, α after rewatering; open triangles, ΦPSII the actual PSII efficiency; filled traingles, ΦPSII after rewatering. (C) Open squares, the maximal efficiency of PSII photochemistry (Fv/Fm); open diamonds, non-photochemical quenching (NPQ).

Mentions: As shown in Fig. 5, the response of Asat to gs was better fitted with a three-component exponential function of the form estimated by non-linear regression [Asat=54.58×(1–e– 11.21×gs)–35.15; R2=0.74, P <0.01; Fig. 5A], rather than a linear function. Initially, Asat rapidly increased with increasing gs, then levelled off at a maximum of 19.4 μmol m−2 s−1 at a gs of 0.25 mol m−2 s−1. However, the correlation of Vc,max with gs was obviously scattered (R2=0.17), indicating that no close association existed.


Are plant growth and photosynthesis limited by pre-drought following rewatering in grass?

Xu Z, Zhou G, Shimizu H - J. Exp. Bot. (2009)

Responses of photosynthetic potential and photochemical activities to stomatal conductance (gs). (A) Open squares, Asat light-saturated CO2 accumulation rate; filled squares, Asat after rewatering; crosses, Vc,max maximum carboxylation velocity. The dotted line denotes the initial Asat response to gs; the dashed line denotes Asat=constant value of Asat,maX estimated; and the intersection of the two lines represents a point at which Asat initially levelled off. (B) Open circles, α maximum photosynthetic quantum yield of CO2 uptake; filled circles, α after rewatering; open triangles, ΦPSII the actual PSII efficiency; filled traingles, ΦPSII after rewatering. (C) Open squares, the maximal efficiency of PSII photochemistry (Fv/Fm); open diamonds, non-photochemical quenching (NPQ).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2736889&req=5

fig5: Responses of photosynthetic potential and photochemical activities to stomatal conductance (gs). (A) Open squares, Asat light-saturated CO2 accumulation rate; filled squares, Asat after rewatering; crosses, Vc,max maximum carboxylation velocity. The dotted line denotes the initial Asat response to gs; the dashed line denotes Asat=constant value of Asat,maX estimated; and the intersection of the two lines represents a point at which Asat initially levelled off. (B) Open circles, α maximum photosynthetic quantum yield of CO2 uptake; filled circles, α after rewatering; open triangles, ΦPSII the actual PSII efficiency; filled traingles, ΦPSII after rewatering. (C) Open squares, the maximal efficiency of PSII photochemistry (Fv/Fm); open diamonds, non-photochemical quenching (NPQ).
Mentions: As shown in Fig. 5, the response of Asat to gs was better fitted with a three-component exponential function of the form estimated by non-linear regression [Asat=54.58×(1–e– 11.21×gs)–35.15; R2=0.74, P <0.01; Fig. 5A], rather than a linear function. Initially, Asat rapidly increased with increasing gs, then levelled off at a maximum of 19.4 μmol m−2 s−1 at a gs of 0.25 mol m−2 s−1. However, the correlation of Vc,max with gs was obviously scattered (R2=0.17), indicating that no close association existed.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Science, Beijing, PR China.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus