Seasonal pattern of photosynthetic rate and its relationship with chlorophyll content, ribulose-1,5-bisphosphate carboxylase activity and biomass production

1995 ◽  
Vol 37 (3) ◽  
Author(s):  
C. V. Naidu ◽  
P. M. Swamy
1974 ◽  
Vol 54 (2) ◽  
pp. 409-412 ◽  
Author(s):  
E. N. ASHWORTH ◽  
L. V. SVEC

Photosynthetic rate on an area basis did not differ when tobacco (Nicotinana tabacum L., ’White Burley’) leaf discs were sampled from margin and base tissue but was greater at the leaf base when expressed per unit chlorophyll or fresh weight. Chlorophyll concentration, ribulose-1,5-diphosphate carboxylase activity, and fresh and dry weights were significantly higher in discs from the margin. If location on the leaf and method of expressing data are not standardized when making comparisons of photosynthesis on a microbasis either within a single leaf, a single plant or among plants, invalid comparisons and conclusions could result.


2013 ◽  
Vol 37 (5) ◽  
pp. 1334-1342 ◽  
Author(s):  
Elcio Ferreira dos Santos ◽  
Bruno José Zanchim ◽  
Aline Grella de Campos ◽  
Raphael Florencio Garrone ◽  
José Lavres Junior

Few studies in Brazil have addressed the need for micronutrients of physic nut focusing on physiological responses, especially in terms of photosynthesis. The objective of this study was to evaluate the effects of omission of boron (B), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) on Jatropha curcas L.. The experimental design was a randomized block with four replications. The treatments were complete solution (control) and solution without B, Cu, Fe, Mn, and Zn. We evaluated the chlorophyll content (SPAD units), photosynthetic rate, dry matter production and accumulation of micronutrients in plants, resulting from different treatments. The first signs of deficiency were observed for Fe and B, followed by Mn and Zn, while no symptoms were observed for Cu deficiency. The micronutrient omission reduced the dry matter yield, chlorophyll content and photosynthetic rate of the plants differently for each omitted nutrient. It was, however, the omission of Fe that most affected the development of this species in all parameters evaluated. The treatments negatively affected the chlorophyll content, evaluated in SPAD units, and the photosynthetic rate, except for the omission of B. However this result was probably due to the concentration effect, since there was a significant reduction in the dry matter production of B-deficient plants.


2009 ◽  
Vol 57 (3) ◽  
pp. 321-333 ◽  
Author(s):  
H. Moussa ◽  
S. EL-Gamal

Treatment with CdCl 2 (0, 100, 400 and 1000 μM) resulted in the inhibition of root dry biomass and root elongation and to increased Cd accumulation in the roots. These treatments also decreased the relative water content, chlorophyll content, 14 CO fixation, phosphoenol pyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase activity and abscisic acid (ABA) content, while increasing the malondialdehyde, hydrogen peroxide and free proline contents and causing changes in the chloroplast and root ultrastructure. Pretreatment of seeds with SA (500 μM) for 20 h resulted in the amelioration of these effects.


1986 ◽  
Vol 235 (3) ◽  
pp. 839-846 ◽  
Author(s):  
B E Terzaghi ◽  
W A Laing ◽  
J T Christeller ◽  
G B Petersen ◽  
D F Hill

Oligonucleotide-directed mutagenesis of cloned Rhodospirillum rubrum ribulose bisphosphate carboxylase/oxygenase with a synthetic 13mer oligonucleotide primer was used to effect a change at Met-330 to Leu-330. The resultant enzyme was kinetically examined in some detail and the following changes were found. The Km(CO2) increased from 0.16 to 2.35 mM, the Km(ribulose bisphosphate) increased from 0.05 to 1.40 mM for the carboxylase reaction and by a similar amount for the oxygenase reaction. The Ki(O2) increased from 0.17 to 6.00 mM, but the ratio of carboxylase activity to oxygenase activity was scarcely affected by the change in amino acid. The binding of the transition state analogue 2-carboxyribitol 1,5-bisphosphate was reversible in the mutant and essentially irreversible in the wild type enzyme. Inhibition by fructose bisphosphate, competitive with ribulose bisphosphate, was slightly increased in the mutant enzyme. These data suggest that the change of the residue from methionine to leucine decreases the stability of the enediol reaction intermediate.


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