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2. Photosynthetic acclimation to elevated CO2 in relation to leaf saccharide constituents in wheat and sunflower
- Creator:
- Ghildiyal, M. C., Rafique, S., and Sharma-Natu, P.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- dry matter production, feedback inhibition, ribulose-1,5-bisphosphate carboxylase activity, RuBPC content, starch, stomatal conductance, and sugars
- Language:
- Multiple languages
- Description:
- Wheat (T. durum cvs. HD 4502 and B 449, T. aestivum cvs. Kalyansona and Kundan) and sunflower (Helianthus annuus L. cv. Morden) were grown under atmospheric (360±10 cm3 m-3, AC) and elevated CO2 (650±50 cm3 m-3, EC) concentration in open top chambers for entire period of growth and development till maturity. Leaf net photosynthetic rate (PN) of EC-grown plants of wheat measured at EC was significantly decreased in comparison with AC-plants of wheat measured at EC. Sunflower, however, showed no significant depression in PN in EC-plants. There was a decrease in ribulose-1,5-bisphosphate carboxylase (RuBPC) activity, its activation state and amount in EC-plants of wheat, whereas no significant decrease was observed in sunflower. The above different acclimation to EC in wheat and sunflower was related with saccharide constituents accumulated in the leaves. Under EC, sunflower accumulated in the leaves more starch, whereas wheat accumulated more sugars. and M. C. Ghildiyal, S. Rafique, P. Sharma-Natu.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Photosynthetic response of wheat and sunflower cultivars to long-term exposure of elevated carbon dioxide concentration
- Creator:
- Pandurangam, V., Sharma-Natu, P., Shreekanth, B., and Ghildiyal, M. C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- cultivar differences, feedback inhibition, Helianthus, photosynthetic acclimation, species differences, starch, sugars, and Triticum
- Language:
- Multiple languages
- Description:
- Wheat (Triticum aestivum L. cv. HD 2329 and DL 1266-5) and sunflower (Helianthus annuus L. cv. MSFH 17 and MRSF 1754) plants were grown in field under atmospheric (360±10 cm3 m-3, AC) and elevated (650±50 cm3 m-3, EC) CO2 concentrations in open top chambers for entire period of growth and development till maturity. Net photosynthetic rate (P N) of wheat cvs. when compared at the same internal CO2 concentration (Ci), by generating PN/Ci curves, showed lower PN in EC plants than in AC ones. EC-grown wheat cultivars also showed a lesser response to irradiance than AC plants. In sunflower cultivars, PN/Ci curves and irradiance response curves were not significantly different in AC and EC plants. CO2 and irradiance responses of photosynthesis, therefore, further revealed a down-regulation of P N in wheat but not so in sunflower under long-term CO2 enrichment. Wheat cvs. accumulated in leaves mostly sugars, whereas sunflower accumulated mainly starch. This further strengthened the view that accumulation of excess assimilates in the leaves under EC as starch is not inhibitory to PN. and V. Pandurangam ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Photosynthetic response of wheat cultivar to long-term exposure to elevated temperature
- Creator:
- Pushpalatha, P., Sharma-Natu, P., and Ghildiyal, M. C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- CO2 and irradiance response curves, internal CO2 concentration, ribulose-1,5-bisphosphate carboxylase, oxygenase (RuBPCO) content and activation state, and RuBPCO activase
- Language:
- Multiple languages
- Description:
- Wheat (Triticum aestivum L. cv. HD 2285) was grown in control (C) and heated (H) open top chambers (OTCs) for entire period of growth and development till maturity. The mean maximum temperature of the entire period was 3 °C higher in H-compared to C-OTCs. Net photosynthetic rate (P N) measured at different temperature (20-40 °C) of C-and H-grown plants showed greater sensitivity to high temperature in H-plants. PN measured at respective growth temperature was lower in H-compared to C-plants. The CO2 and irradiance response curves of photosynthesis also showed lesser response in H-compared to C-plants. The initial slope of PN versus internal CO2 concentration (PN/Ci) curve was lower in H-than C-plants indicating ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) limitation. In irradiance response curve, the plateau was lower in H-compared to C-plants which is interpreted as RuBPCO limitation. RuBPCO content in the leaves of C-and H-plants, however, was not significantly different. Ribulose-1,5-bisphosphate carboxylase (RuBPC) initial activity was lower in H-plants, whereas activity of fully activated enzyme was not affected, indicating a decrease in activation state of the enzyme. This was further substantiated by the observed decrease in RuBPCO activase activity in H-compared to C-plants. RuBPCO activase was thus sensitive even to moderate heat stress. The decrease in PN under moderate heat stress was mainly due to a decrease in activation state of RuBPCO catalysed by RuBPCO activase. and P. Pushpalatha, P. Sharma-Natu, M. C. Ghildiyal.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public