Photosynthesis and water-use efficiency of seedlings from northern Australian monsoon forest, savanna and swamp habitats grown in a common garden

2010 ◽  
Vol 37 (11) ◽  
pp. 1050 ◽  
Author(s):  
Kim A. Orchard ◽  
Lucas A. Cernusak ◽  
Lindsay B. Hutley

Islands of monsoon rainforest and Melaleuca swamp punctuate vast tracts of savanna in monsoonal northern Australia. Seedlings of species from each of these habitat associations were grown in a common garden. Monsoon forest species had higher specific leaf area, lower photosynthetic capacity and lower photosynthetic light compensation points, and required lower irradiance to achieve 50% of light-saturated photosynthesis compared with savanna or swamp species. These traits probably contribute towards greater shade tolerance beneath dense monsoon-forest canopies, whereas savanna and swamp canopies are relatively open. Swamp species, especially two Melaleuca species, had high stomatal conductance and small CO2 drawdown during photosynthesis, and more negative leaf δ13C, compared with monsoon forest and savanna species. Higher stomatal conductance increases carbon uptake during photosynthesis and a high transpiration rate would increase transport of nutrients to absorbing surfaces in the root by mass flow. Thus, a strategy of high transpiration and low water-use efficiency appears to be favoured in swamp species compared with monsoon-forest and savanna species. Instantaneous measurements of the ratio of intercellular to ambient CO2 concentrations (ci/ca) explained 81% of variation in leaf δ13C across 44 species sampled in this and other studies, suggesting that leaf δ13C generally provides a robust proxy for comparisons of ci/ca, even when applied across species.


Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 186
Author(s):  
Matthew E. Akalusi ◽  
Charles P.-A. Bourque

There is a need to understand the physio-morphological responses of northern tree species to climate change. The hypothesis of the current study was that provenance and light intensity were both influential in the control of intrinsic water-use efficiency (iWUE). Diameter at breast height (DBH)-increment was hypothesized as being more affected by provenance. Intrinsic water-use efficiency (iWUE), the ratio of photosynthesis (A) to stomatal conductance (gs), was assessed in foliage under two levels of photosynthetically active radiation (PAR; i.e., 300 and 1200 μmol m−2 s−1) in 63-year-old balsam fir [Abies balsamea (L.) Mill.] provenances derived from seed sources from across the species’ natural range (namely, within 44–51° N latitudes and 53–102° W longitudes) and cultivated in a common garden in eastern Canada. Diameter at breast height (DBH) of provenances from the common garden were measured when they were 42 and 58 years old (DBH1998, DBH2014). The results confirmed the hypotheses regarding the roles of provenance on iWUE and DBH (p < 0.05), but showed a diminished role of PAR on iWUE. The lowest and highest mean iWUE and DBH among the provenances ranged between 0.028 and 0.031 and 0.079–0.083 μmol mmol−1 and 11.82–12.78 and 16.38–18.44 cm, respectively. Stomatal conductance of balsam fir had a strong relationship with iWUE at both light settings, whereas A had a weaker relationship with iWUE. There were no significant relationships between iWUE at the two light settings and climatic variables at the provenance source (p > 0.05). Diameter at breast height in 2014 was significantly greater than DBH1998 (p < 0.05). The relationships between DBH2014 and climatic variables at the provenance source were statistically significant (p < 0.05). There was a significant positive relationship between iWUE and DBH measured in 2014. Survivorship of provenances was shown to vary with DBH-increment. The results show that for present-day and future forest management, (i) selection in balsam fir, in relation to iWUE should ideally be based on a criterion of intraspecific stomatal conductance; (ii) shade tolerance of balsam fir, population differentiation, and consistent pace of DBH-growth under variable climatic conditions are important factors in the species’ sustained growth under changes in forest dynamics projected to accompany changes in regional climate; (iii) temperature variables are strong indicators of DBH-increment in balsam fir; (iv) the effect of tree size on its survival is maintained under variable climatic conditions; and (v) there is a clear association between iWUE and the species’ radial growth.



2016 ◽  
Vol 44 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Bianca do Carmo SILVA ◽  
Pêola Reis de SOUZA ◽  
Daihany Moraes CALLEGARI ◽  
Vanessa Ferreira ALVES ◽  
Allan Klynger da Silva LOBATO ◽  
...  

Boron (B) is a very important nutrient required by forest plants; when supplied in adequate amounts, plants can ameliorate the negative effects of abiotic stresses. The objective of this study was to (i) investigate gas exchange, (ii) measure oxidant and antioxidant compounds, and (iii) respond how B supply acts on tolerance mechanism to water deficit in young Schizolobium parahyba plants. The experiment employed a factorial that was entirely randomised, with two boron levels (25 and 250 µmol L-1, simulating conditions of sufficient B and high B, respectively) and two water conditions (control and water deficit). Water deficit induced negative modifications on net photosynthetic rate, stomatal conductance and water use efficiency, while B high promoted intensification of the effects on stomatal conductance and water use efficiency. Hydrogen peroxide and electrolyte leakage of both tissues suffered non-significant increases after B high and when applied water deficit. Ascorbate levels presented increases after water deficit and B high to leaf and root. Our results suggested that the tolerance mechanism to water deficit in young Schizolobium parahyba plants is coupled to increases in total glutathione and ascorbate aiming to control the overproduction of hydrogen peroxide and alleviates the negative consequences on electrolyte leakage and gas exchange. In relation to B supply, this study proved that sufficient level promoted better responses under control and water deficit conditions.



2018 ◽  
Vol 36 (1) ◽  
pp. 7-13
Author(s):  
Melissa C. Smith ◽  
Richard N. Mack

Abstract Suitable plant water dynamics and the ability to withstand periods of low moisture input facilitate plant establishment in seasonally arid regions. Temperate bamboos are a major constituent of mixed evergreen and deciduous forests throughout temperate East Asia but play only an incidental role in North American forests and are altogether absent in the Pacific Northwest forest. Many bamboo species are classified as mesic or riparian, but none are considered drought tolerant. To assess their ability to withstand low water, we subjected five Asian temperate and one North American temperate bamboo species to three irrigation treatments: 100%, 50%, and 10% replacement of water lost through evapotranspiration. Plants were irrigated every four days over a 31-day period. Plant response to treatments was measured with stomatal conductance, leaf xylem water potentials, and intrinsic water use efficiency (iWUE). Pleioblastus distichus and Pseudosasa japonica showed significant reductions in conductance between high and low irrigation treatments. Sasa palmata had significantly lower stomatal conductance in all treatments. Pleioblastus chino displayed significantly higher iWUE in the mid irrigation treatment and Arunindaria gigantea displayed significantly lower iWUE than P. chino and S. palmata in the low irrigation treatment. The Asian bamboo species examined here tolerate low water availability and readily acclimate to different soil moisture conditions. Index words: Temperate bamboos, irrigation response, stomatal conductance, intrinsic water use efficiency. Species used in this study: Giant Cane [Arundinaria gigantea (Walt.) Muhl.]; Pleioblastus chino (Franchet & Savatier) Makino; Pleioblastus distichus (Mitford) Nakai; Pseudosasa japonica (Makino); Sasa palmata (Bean) Nakai.



2021 ◽  
Author(s):  
Fasih Ullah Haider ◽  
Muhammad Farooq ◽  
Muhammad Naveed ◽  
Sardar Alam Cheema ◽  
Noor ul Ain ◽  
...  

Abstract The synergistic effects of biochar and microorganisms on the adsorption of Cd and on cereal plant physiology remained unclear. Therefore, this experiment was performed to evaluate the combined effects of biochar pyrolyzed from (maize-straw (BC1), cow-manure (BC2), and poultry-manure (BC3), and microorganisms including (T. harzianum L. and B. subtilis L.), to evaluate, how incorporation of biochar positively influences microorganisms growth and nutrients uptake in plant, and how it mitigates under various Cd-stress levels (0, 10, and 30ppm). Cd2 (30 ppm) had the highest reduction in the intercellular CO2, SPAD value, transpiration rate, water use efficiency, stomatal conductance, and photosynthesis rate, which were 22.36, 34.50, 40.45, 20.66, 29.07, and 22.41% respectively lower than control Cd0 (0 ppm). Sole application BC, resulted in enhanced intercellular CO2, SPAD value, transpiration rate, water use efficiency, stomatal conductance, and photosynthesis rate were recorded in BC2, which were 7.27, 20.54, 23.80, 5.96, 13.37, and 13.50% respectively greater as compared to control and decreased the Cd-concentration in root and shoot of maize by 34.07 and 32.53%, respectively as compared to control. Similarly, among sole microorganism’s inoculation, minimized the Cd-concentration in shoot, root, and soil by 23.77, 20.15, and 10.35% respectively than control. These results suggested that integrated application of cow manure biochar BC2 and inoculation of microorganisms MI3 as soil amendments had synergistic effects in improving the adsorption of nutrients and decreasing the Cd-uptake in maize, and enhancing the physiology of plant grown in Cd-polluted soils as opposed to using either biochar or inoculating microorganisms alone.



Author(s):  
Juan D. Franco‐Navarro ◽  
Miguel A. Rosales ◽  
Paloma Cubero‐Font ◽  
Purificación Calvo ◽  
Rosario Álvarez ◽  
...  


2014 ◽  
Vol 94 (2) ◽  
pp. 303-310 ◽  
Author(s):  
Olanike Aladenola ◽  
Chandra Madramootoo

Aladenola, O. and Madramootoo, C. 2014. Response of greenhouse-grown bell pepper (Capsicum annuum L.) to variable irrigation. Can. J. Plant Sci. 94: 303–310. In order to optimize water use in bell pepper production information about the appropriate irrigation water applications and agronomic and physiological response to mild and severe water stress is necessary. Different water applications were tested on yield, quality and water stress threshold of greenhouse-grown bell pepper (Capsicum annuum L.) cultivar Red Knight in 2011 and 2012 on the Macdonald Campus of McGill University, Ste Anne De Bellevue, QC. The study was carried out on a soil substrate in the greenhouse. Irrigation was scheduled with four treatments:120% (T1), 100% (T2), 80% (T3), and 40% (T4) replenishment of crop evapotranspiration in a completely randomized design. The highest marketable yield, water use efficiency and irrigation water use efficiency were obtained with T1 in both years. T1 received 20% more water than T2 to produce 23% more marketable yield than T2. Fruit total soluble solids content was highest in T4, and smallest in T1. The mean crop water stress index (CWSI) of the irrigation treatments ranged between 0.08 and 1.18. Leaf stomatal conductance of bell pepper was 75 to 80% lower in T4 than in T1. Regression obtained between stomatal conductance and CWSI resulted in a polynomial curve with coefficients of determination of 0.88 and 0.97 in 2011 and 2012, respectively. The result from this study indicate that the yield derived justifies the use of an extra quantity of water. Information from this study will help water regulators to make appropriate decision about water to be allocated for greenhouse production of bell pepper.



2012 ◽  
Vol 2 (2) ◽  
pp. 71-79 ◽  
Author(s):  
Anatoly Kosobryukhov ◽  
Evgeniya Markovskaya ◽  
Liudmila Sergienko

CO2 gas exchange, transpiration, stomatal conductance, water use efficiency and chlorophyll content were investigated at the leaves of three species of the family Plantaginaceae: Plantago maritima L., Plantago subpolaris Andrejev and Plantago schrenkii C.Koch under natural conditions of the habitat on high and low tide areas of the White Sea’ coasts. The high rate of photosynthesis at saturating CO2 (PNmax) at P. maritima (85.0±4.8 μmol m-2 s-1), as compared to P. subpolaris and P. schrenkii (45.2± 7.5 and 36.9±3.2 μmol m-2 s-1) was caused by high activity of ribulose-1,5-bisphoshate carboxylase/oxygenase (RuBPCO), the rate of electron transport, the rate of triose phosphate utilization, TPU), as well as high efficiency of carboxylation. The rates of photosynthesis at ambient concentration of CO2 (PN) at P. maritima were 1.4 and 1.7 times higher compared to P. subpolaris and P. schrenkii. Plants of P. schrenkii are characterized by lower values of stomatal conductance and water use efficiency compared to P. maritima and P. subpolaris. In natural habitat, the limiting factor of CO2 assimilation P. subpolaris is the rate of photosynthetic electron transport, the activity of RuBPCO in P. schrenkii.



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