EFFECTS OF A NATURAL SOURCE OF VERY HIGH CO2 CONCENTRATION ON THE LEAF GAS-EXCHANGE, XYLEM WATER POTENTIAL AND STOMATAL CHARACTERISTICS OF PLANTS OF SPATIPHYLUM-CANNIFOLIUM AND BAUHINIA-MULTINERVIA

Citation
Md. Fernandez et al., EFFECTS OF A NATURAL SOURCE OF VERY HIGH CO2 CONCENTRATION ON THE LEAF GAS-EXCHANGE, XYLEM WATER POTENTIAL AND STOMATAL CHARACTERISTICS OF PLANTS OF SPATIPHYLUM-CANNIFOLIUM AND BAUHINIA-MULTINERVIA, New phytologist, 138(4), 1998, pp. 689-697
Citations number
38
Categorie Soggetti
Plant Sciences
Journal title
ISSN journal
0028646X
Volume
138
Issue
4
Year of publication
1998
Pages
689 - 697
Database
ISI
SICI code
0028-646X(1998)138:4<689:EOANSO>2.0.ZU;2-1
Abstract
The effect of a very high CO2 mole fraction (27 000-35 000 mu mol mol( -1)) on photosynthesis and water relations was studied during the dry and the rainy season in plants of Spatiphylum cannifolium (Dryand.) Sc hott and Bauhinia multinervia (H.B.K.) DC. growing near natural cold C O2 springs. Xylem water potential in plants of both species was lowere d by drought, high CO2 growth-concentration decreasing it further in S . cannifolium. In plants of both species growing under high CO2 concen tration photosynthetic rates measured at a CO2 mole fraction of 1000 m u mol mol(-1) were higher than in plants growing at ambient CO2 mole f raction and measured at 350 mu mol mol(-1). The response was the resul t of a direct effect of CO2 on the photosynthetic machinery. Changes i n carboxylation efficiency in response to high CO2 were found during t he rainy season, with an increase in S. cannifolium and a decrease in B. multinervia; a significant interaction between growth CO2 concentra tion and season in B. multinervia resulted from significant effects of both factors. An increase in intrinsic water-use efficiency due to hi gh CO2 was determined in both species by an increase in photosynthetic rate as well as a decrease in leaf conductance. In high-CO2 plants of S. cannifolium a 71 % decrease in stomatal density and 73 % in stomat al index suggested that CO2 affected stomatal initiation, whereas in B . multinervia an 85 % decrease in stomatal index and a 72 % decrease i n stomatal density indicated that CO2 influenced stomatal initiation a s well as epidermal cell expansion. Our results indicate that very hig h CO2 concentrations did not inhibit photosynthesis in these species, and that growth under high CO2 allowed plants to attain carbon balance s higher than those of plants growing under low CO2. This was particul arly so during the dry season, since the photosynthetic rates at the c orresponding ambient concentration were higher in plants nearer the sp rings, and carboxylation efficiency and some stomatal characteristics of both species apparently acclimated to high CO2, but patterns were n ot consistent and bore no obvious relationship to photosynthetic capac ity.