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1.
Under constant salinity we analysed the leaf characteristics of Laguncularia racemosa (L.) Gaertn. in combination with gas exchange and carbon isotopic composition to estimate leaf water-use efficiency (WUE) and potential nitrogen-use efficiency (NUE). NaCl was not added to the control plants and the others were maintained at salinities of 15 and 30 ‰ (S0, S15, and S30, respectively). Leaf succulence, sodium (Na), nitrogen (N), and chlorophyll (Chl) contents increased under salinity. Salinity had a negative impact on net photosynthetic rate (P
N) and stomatal conductance (g
s) at high and moderated irradiances. Potential NUE declined significantly (p<0.05) with salinity by 37 and 58 % at S15 and S30, respectively, compared to S0 plants. Conversely, compared to S0 plants, P
N/g
s increased under saline conditions by 12 % (S15) and 50 % (S30). Thus, WUE inferred from P
N/g
s was consistent with salinity improved short-term WUE. Long-term leaf WUE was also enhanced by salinity as suggested by significantly increased leaf δ13C with salinity. Improved WUE under salinity explains the eco-physiological success of mangrove species under increasing salinity. Conversely, decline in NUE may pose a problem for L. racemosa under hyper-saline environments regardless of N availability. 相似文献
2.
Photosynthesis and growth characteristics of Parthenocissus quinquefolia were measured under differing soil water availability within a pot. Decreased soil moisture significantly reduced the leaf relative water content (RWC) and the above- and below-ground biomass. However, more biomass was allocated to the root than to the leaf. Net photosynthetic rate (P
N), stomatal conductance (g
s), and transpiration rate (E) were also significantly decreased but water use efficiency (WUE) was increased. Midday depressions in P
N and g
s were not evident for the well-irrigated plants. With the lower water availability, midday reductions in P
N and g
s were much more marked and the duration of the depression was longer. Additionally, the P
N-irradiance response curves also indicated that water supply affected photosynthesis capacity. The growth and photosynthetic response of P. quinquefolia to water supply indicated that this species could resilient to water availabilities and adapt to Hunshandak conditions very well. 相似文献
3.
R. Z. Wang 《Photosynthetica》2007,45(3):463-468
The inter-and intra-specific physiological differences, e.g. rates of net photosynthesis (P
N) and transpiration (E), stomatal conductance (g
s), and water use efficiency (WUE), were compared between two grasses, Calamagrostis epigeios (L.) Roth. and Psammochloa villosa (Trin.) Bor., and between their leaf types in a desertification steppe in North China. The two species had a similar habitat,
but differed in leaf area and rhizome depth. Leaf P
N, E, and g
s for P. villosa were significantly greater than those for C. epigeios in the growing season, but WUE for the former species was only 50 and 80 % of that for the latter one in dry and rainy seasons,
respectively. In general, leaf P
N, E, g
s, and WUE for both vegetative and reproductive shoots of the two species exhibited little variations between leaf types or
with leaf age, even though there were some remarkable differences between dry and rainy seasons. The mean leaf P
N and E in reproductive shoots of P. villosa were significantly lower than those in its vegetative shoots in rainy season, while these differences were much smaller for
those of C. epigeios. P. villosa with deeper rhizome roots has relative higher leaf P
N, E, and g
s, but a smaller WUE in the arid desertification steppe region. 相似文献
4.
High variability in leaf gas exchange and related traits were found in 30 genotypes of field grown finger millet. The variability in carbon exchange rate per unit leaf area (P
N) can be partly attributed to the differences in the stomatal conductance (gs) and area leaf mass (ALM). The P
N was positively correlated with total dry matter (TDM). However, no relationship between P
N and seed yield was found. The leaf area showed a positive and significant correlation with total biomass. None of the other gas-exchange traits had significant relationship either with TDM or with seed yield. The ALM showed a strong positive association with P
N. However, it was not correlated with either total biomass or seed yield. As a result, the use of ALM as surrogate for P
N for identifying high biomass producing genotypes only had a limited value. Hence selection for high P
N would result in higher biomass producing types. 相似文献
5.
In a field rain-fed trial with 15 cassava cultivars, leaf gas exchanges and carbon isotope discrimination (Δ) of the same
leaves were determined to evaluate genotypic and within-canopy variations in these parameters. From 3 to 7 months after planting
leaf gas exchange was measured on attached leaves from upper, middle, and lower canopy layers. All gas exchange parameters
varied significantly among cultivars as well as canopy layers. Net photosynthetic rate (P
N) decreased from top canopy to bottom indicating both shade and leaf age effects. The same trend, but in reverse, was found
with respect to Δ, with the highest values in low canopy level and the lowest in upper canopy. There were very significant
correlations, with moderate and low values, among almost all these parameters, with P
N negatively associated with intercellular CO2 concentration (C
i), ratio of C
i to ambient CO2 concentration C
i/C
a, and Δ. Across all measured leaves, Δ correlated negatively with leaf water use efficiency (WUE = photosynthesis/stomatal
conductance, g
s) and with g
s, but positively with C
i and C
i/C
a. The later parameters negatively correlated with leaf WUE. Across cultivars, both P
N and correlated positively with storage root yield. These results are in agreement with trends predicted by the carbon isotope
discrimination model. 相似文献
6.
Thirty-days-old plants of two cultivars of okra (Hibiscus esculentus L.), Sabzpari and Chinese-red, were subjected for 30 d to two water regimes (100 and 60 % field capacity). Leaf water potential and osmotic potential of both lines decreased significantly with the imposition of drought. Both the leaf pressure potential and osmotic adjustment were much lower in Chinese-red than those in Sabzpari. Chlorophyll (Chl) b content increased, whereas Chl a content remained unchanged and thus Chl a/b ratios were reduced in both lines. Drought stress also caused a significant reduction in net photosynthetic rate (P
N), transpiration rate (E), stomatal conductance (g
s), and water use efficiency (WUE) especially in cv. Sabzpari. The lines did not differ in intrinsic WUE (P
Ngs) or intercellular/ambient CO2 ratio. Overall, the growth of two okra cultivars was positively correlated with P
N, but not with g
s or P
N/E, and negatively correlated with osmotic adjustment. 相似文献
7.
Stomatal dynamics are limited by leaf hydraulics in ferns and conifers: results from simultaneous measurements of liquid and vapour fluxes in leaves
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Samuel C. V. Martins Scott A. M. McAdam Ross M. Deans Fábio M. DaMatta Tim J. Brodribb 《Plant, cell & environment》2016,39(3):694-705
Stomatal responsiveness to vapour pressure deficit (VPD) results in continuous regulation of daytime gas‐exchange directly influencing leaf water status and carbon gain. Current models can reasonably predict steady‐state stomatal conductance (gs) to changes in VPD but the gs dynamics between steady‐states are poorly known. Here, we used a diverse sample of conifers and ferns to show that leaf hydraulic architecture, in particular leaf capacitance, has a major role in determining the gs response time to perturbations in VPD. By using simultaneous measurements of liquid and vapour fluxes into and out of leaves, the in situ fluctuations in leaf water balance were calculated and appeared to be closely tracked by changes in gs thus supporting a passive model of stomatal control. Indeed, good agreement was found between observed and predicted gs when using a hydropassive model based on hydraulic traits. We contend that a simple passive hydraulic control of stomata in response to changes in leaf water status provides for efficient stomatal responses to VPD in ferns and conifers, leading to closure rates as fast or faster than those seen in most angiosperms. 相似文献
8.
H. X. Cui G. M. Jiang S. L. Niu Y. G. Li C. D. Jiang M. Z. Liu L. M. Gao 《Photosynthetica》2004,42(4):529-534
Net photosynthetic rate (P
N), transpiration rate (E), water use efficiency (WUE), stomatal conductance (g
s), and stomatal limitation (Ls) were investigated in two Syringa species. The saturation irradiance (SI) was 400 µmol m-2s-1 for S. pinnatifolia and 1 700 µmol m-2s-1 for S. oblata. Compared with S. oblata, S. pinnatifolia had extremely low gs. Unlike S. oblata, the maximal photosynthetic rate (P
max) in S. pinnatifoliaoccurred around 08:00 and then fell down, indicating this species was sensitive to higher temperature and high photosynthetic photon flux density. However, such phenomenon was interrupted by the leaf development rhythms before summer. A relatively lower P
N together with a lower leaf area and shoot growth showed the capacity for carbon assimilation was poorer in S. pinnatifolia.This revised version was published online in March 2005 with corrections to the page numbers. 相似文献
9.
The net photosynthetic rate (PN), stomatal conductance (gs) and transpiration (E) ofHardwickia binata Roxb. leaves were reduced due to decrease in the leaf water potential (ψw) from -2.0 to - 5.7 MPa. PN partially recovered in the treated plants upon rewatering. Decrease in gs due to water stress may be the main factor for reduction of PN.
This work was supported by a financial grant from the MNES, India to KP. 相似文献
10.
The aim of this study was to extent the range of knowledge about water relations and stomatal responses to water stress to
ten Mediterranean plants with different growth forms and leaf habits. Plants were subjected to different levels of water stress
and a treatment of recovery. Stomatal attributes (stomatal density, StoD), stomatal conductance (g
s), stomatal responsiveness to water stress (SR), leaf water relations (pre-dawn and midday leaf water potential and relative
water content), soil to leaf apparent hydraulic conductance (K
L) and bulk modulus of elasticity (ε) were determined. The observed wide range of water relations and stomatal characteristics
was found to be partially depended on the growth form. Maximum g
s was related to StoD and the stomatal area index (SAI), while g
s evolution after water stress and recovery was highly correlated with K
L. Relationships between SR to water deficit and other morphological leaf traits, such as StoD, LMA or ε, provided no general
correlations when including all species. It is concluded that a high variability is present among Mediterranean plants reflecting
a continuum of leaf water relations and stomatal behaviour in response to water stress. 相似文献
11.
Critical responses of photosynthetic efficiency of goldspur apple tree to soil water variation in semiarid loess hilly area 总被引:4,自引:0,他引:4
Goldspur apple (Malus pumila cv. Goldspur) is one of the main fruit trees planted in semiarid loess hilly areas. The photosynthetic efficiency in leaves
of eight-year-old trees were studied under different soil water conditions with a Li-6400 portable photosynthesis system and a Li-Cor1600 portable steady state porometer in order to explore the effects of soil water stress on photosynthesis and the suitable soil
water content (SWC) for water-saving irrigation of apple orchards. The results showed that the leaf net photosynthetic rate
(P
N), transpiration rate (E), water-use efficiency (WUE), stomatal conductance (g
s), intercellular CO2 concentration (C
i), and stomatal limiting value (L
s) displayed different threshold responses to soil water variation. When SWC was within a range of about 60%–86% of field capacity
(FC), P
N and E were maintained in a relative steady state. At an elevated level but below 60% of FC, both P
N and E decreased evidently with decreasing soil moisture. The SWC needed to support WUE in a relatively steady state and at a high
level was in the range of about 50%–71% of FC. When SWC was less than 48% of FC, g
s and L
s declined with decreasing soil moisture, while C
i increased rapidly. Based on the analysis of the stomatal limitation of photosynthesis using two criteria (C
i and L
s) suggested by Farquhar and Sharkey, it was implied that the predominant cause of restricting P
N had changed from stomatal limitation to nonstomatal one under severe water stress. In terms of water-saving irrigation for
enhancing water-use efficiency, it was concluded that in semiarid loess hilly areas, the suitable range of SWC for water-saving
irrigation in goldspur apple orchards is in the range of about 50%–71% of FC, and the most severe degree of soil water stress
tolerated for photosynthesis is about 48% of FC. 相似文献
12.
13.
The responses of gas exchange and chlorophyll fluorescence of field-growing Ulmus pumila seedlings to changes in simulated precipitation were studied in Hunshandak Sandland, China. Leaf water potential (Ψwp), net photosynthetic rate (P
N), stomatal conductance (g
s), and transpiration rate (E) were significantly increased with enhancement of precipitation from 0 to 20 mm (p<0.01), indicating stomatal limitation of U. pumila seedlings that could be avoided when soil water was abundant. However, P
N changed slightly when precipitation exceeded 20 mm (p>0.05), indicating more precipitation than 20 mm had no significant effects on photosynthesis. Maximum photochemical efficiency
of photosystem 2, PS 2 (Fv/Fm) increased from 0.53 to 0.78 when rainfall increased from 0 to 10 mm, and Fv/Fm maintained a steady state level when rainfall was more than 10 mm. Water use efficiency (WUE) decreased significantly (from
78–95 to 23–27 μmol mol−1) with enhancement of rainfalls. P
N showed significant linear correlations with both g
s and Ψwp (p<0.0001), which implied that leaf water status influenced gas exchange of U. pumila seedlings. The 20-mm precipitation (soil water content at about 15 %, v/v) might be enough for the growth of elm seedlings.
When soil water content (SWC) reached 10 %, down regulation of PS2 photochemical efficiency could be avoided, but stomatal
limitation to photosynthesis remained. When SWC exceeded 15 %, stomatal limitation to photosynthesis could be avoided, indicating
elm seedlings might tolerate moderate drought. 相似文献
14.
Leaf stomatal density (SD), net photosynthetic rates (P
N), and stomatal conductance (g
s) of Hordeum vulgare and Pisum sativum cultivars in Himalaya increased with altitude. Higher P
N and leaf temperature under low CO2 partial pressure at high altitudes could evoke a higher g
s and SD to allow sufficient influx of CO2 as well as more efficient leaf cooling through transpiration. 相似文献
15.
Environmental factors that induce spatial heterogeneity of stomatal conductance, g
s, called stomatal patchiness, also reduce the photochemical capacity of CO2 fixation, yet current methods cannot distinguish between the relative effect of stomatal patchiness and biochemical limitations
on photosynthetic capacity. We evaluate effects of stomatal patchiness and the biochemical capacity of CO2 fixation on the sensitivity of net photosynthetic rate (P
N) to stomatal conductance (g
s), θ (θ = δP
N/g
s). A qualitative model shows that stomatal patchiness increases the sensitivity θ while reduced biochemical capacity of CO2 fixation lowers θ. We used this feature to distinguish between stomatal patchiness and mesophyll impairments in the photochemistry
of CO2 fixation. We compared gas exchange of sunflower (Helianthus annuus L.) plants grown in a growth chamber and fed abscisic acid, ABA (10−5 M), for 10 d with control plants (-ABA). P
N and g
s oscillated more frequently in ABA-treated than in control plants when the leaves were placed into the leaf chamber and exposed
to a dry atmosphere. When compared with the initial CO2 response measured at the beginning of the treatment (day zero), both ABA and control leaves showed reduced P
N at particular sub-stomatal CO2 concentration (c
i) during the oscillations. A lower reduction of P
N at particular g
s indicated overestimation of c
i due to stomatal patchiness and/or omitted cuticular conductance, g
c. The initial period of damp oscillation was characterised by inhibition of chloroplast processes while stomatal patchiness
prevailed at the steady state of gas exchange. The sensitivity θ remained at the original pre-treatment values at high g
s in both ABA and control plants. At low g
s, θ decreased in ABA-treated plants indicating an ABA-induced impairment of chloroplast processes. In control plants, g
c neglected in the calculation of g
s was the likely reason for apparent depression of photosynthesis at low g
s.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
In summer seasons of 1991 and 1992 the gas exchange and leaf water relations were analysed in two peanut cultivars: drought tolerant cv. GG 2 (DT) and drought sensitive cv. JL 24 (DS). Soil moisture stress was imposed by withholding irrigation at pod development phase. The decrease in photosynthesis (PN) under stress was associated with a decrease in stomatal conductance (gs) and relative water content (RWC). The PN and RWC were significantly higher under stress in DT than DS. On relief of stress the gs and RWC recovered more quickly in DT than DS. The maintenance of higher RWC (>80 %), gs and PN under stress appears to be imparting drought tolerance in peanut. 相似文献
17.
Effect of Growth Regulators on Photosynthesis, Transpiration and Related Parameters in Water Stressed Cotton 总被引:6,自引:0,他引:6
Gas exchange in Gossypium hirsutum L. cv. H-777 as affected by water deficit and growth regulators (IAA, GA3, BAP, ABA, ethrel) was examined. Sixty days after sowing, growth regulators in concentration 50 µM were applied as foliar spray and irrigation was withheld to get desired (moderate and severe) water deficit. All the parameters were measured on the third leaf from the top between 10:00 and 11:00. Net photosynthetic rate (PN), transpiration rate (E), stomatal conductance (gs), carboxylation efficiency (CE), and water potential (w) decreased significantly with the increasing water stress, however, water use efficiency (WUE) was unaffected. Foliar spray with IAA, GA3 and BAP partially counteracted the effect of water deficit on the above parameters except w, which became more negative. ABA and up to some extent ethrel increased WUE and maintained higher w, however, caused further decrease in PN, E, and gs. 相似文献
18.
Effect of water stress on leaf photosynthesis,chlorophyll content,and growth of oriental lily 总被引:4,自引:0,他引:4
Y. J. Zhang Z. K. Xie Y. J. Wang P. X. Su L. P. An H. Gao 《Russian Journal of Plant Physiology》2011,58(5):844-850
The photosynthetic characterization of the oriental lily (Lilium) cv. Sorbonne and its response to increasing water stress were analyzed based on the net photosynthetic rate (P
n), stomatal conductance (g
s), intercellular CO2 concentration (Ci), transpiration rate (E), water use efficiency (WUE), and stomatal limitation (Ls) in the Horqin Sandy Land of western China. A photosynthesis-PAR
response curve was constructed to obtain light-compensation and light-saturation points (LCP and LSP), the maximum photosynthetic
rates (P
max) and dark respiration rates (R
D). The growth of lilies in the pots was analyzed after anthesis. Various intensities of water stress (5, 10, and 20 days without
water, and an unstressed control) were applied. The results indicated that drought stress not only significantly decreased
P
n, E, g
s, photosynthetic pigment content (Chl a, Chl b, and Chl (a + b)) and increased intrinsic water use efficiency (WUE), but also altered the diurnal pattern of gas exchange. Drought stress
also affected the photosynthesis (P
n)-PAR response curve. Drought stress increased LCP and R
D and decreased LSP and P
max. There were both stomatal and nonstomatal limitations to photosynthesis. Stomatal limitation dominated in the morning, whereas
nonstomatal limitation dominated in the afternoon. Thus, drought stress decreased potential photosynthetic capacity and affected
the diurnal pattern of gas exchange and P
n-PAR response curves, thereby reducing plant quality (lower plant height, flower length, flower diameter, and leaf area).
Water stress is likely the main limitation to primary photosynthetic process in the lily. Appropriate watering is recommended
to improve photosynthetic efficiency and alleviate photodamage, which will increase the commercial value of the lily in the
Horqin Sandy Land. 相似文献
19.
Net photosynthetic rate (P
N), transpiration rate (E), and stomatal conductance (g
s) in an adult oil palm (Elaeis guineensis) canopy were highest in the 9th leaf and progressively declined with leaf age. Larger leaf area (LA) and leaf dry mass (LDM) were recorded in middle leaves.
P
N showed a significant positive correlation with g
s and a negative relationship with leaf mass per area (ALM). The oil palm leaf remains photosynthetically active for a longer
time in the canopy which contributes significantly to larger dry matter production in general and greater fresh fruit bunch
yields in particular. 相似文献
20.
Net photosynthetic rate (P
N), transpiration rate (E), and stomatal conductance (g
s) declined from upper leaves to the lower ones during dry and rainy seasons, indicating that long-term carbon budget should take into account P
N variations for different leaf types. Relatively greater P
N in the dry season suggested that this species is more able to maintain higher P
N under drought, but the relatively higher E in the dry season might reduce water use efficiency (P
N/E) for the species. Significant correlations between P
N and g
s indicated that g
s may be the critical factor for P
N variability in the desert region. 相似文献