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Effects of a natural source of very high CO 2 concentration on the leaf gas exchange, xylem water potential and stomatal characteristics of plants of Spatiphylum cannifolium and Bauhinia multinervia
Author(s) -
FERNÁNDEZ MARÍA DOLORES,
PIETERS ALEJANDRO,
DONOSO CAROLINA,
TEZARA WILMER,
AZKUE MERCEDES,
HERRERA CECILIA,
RENGIFO ELIZABETH,
HERRERA ANA
Publication year - 1998
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.1998.00161.x
Subject(s) - photosynthesis , stomatal conductance , xylem , stomatal density , transpiration , botany , chemistry , growing season , horticulture , biology
The effect of a very high CO 2 mole fraction (27000–35000 μmol mol −1 ) on photosynthesis and water relations was studied during the dry and the rainy season in plants of Spatiphylum cannifolium (Dryand.) Schott and Bauhinia multinervia (H.B.K.) DC. growing near natural cold CO 2 springs. Xylem water potential in plants of both species was lowered by drought, high CO 2 growth‐concentration decreasing it further in S. cannifolium . In plants of both species growing under high CO 2 concentration photosynthetic rates measured at a CO 2 mole fraction of 1000 μmol mol −1 were higher than in plants growing at ambient CO 2 mole fraction and measured at 350 μmol mol −1 . The response was the result of a direct effect of CO 2 on the photosynthetic machinery. Changes in carboxylation efficiency in response to high CO 2 were found during the rainy season, with an increase in S. cannifolium and a decrease in B. multinervia ; a significant interaction between growth CO 2 concentration and season in B. multinervia resulted from significant effects of both factors. An increase in intrinsic water‐use efficiency due to high CO 2 was determined in both species by an increase in photosynthetic rate as well as a decrease in leaf conductance. In high‐CO 2 plants of S. cannifolium a 71% decrease in stomatal density and 73% in stomatal index suggested that CO 2 affected stomatal initiation, whereas in B. multinervia an 85% decrease in stomatal index and a 72% decrease in stomatal density indicated that CO 2 influenced stomatal initiation as well as epidermal cell expansion. Our results indicate that very high CO 2 concentrations did not inhibit photosynthesis in these species, and that growth under high CO 2 allowed plants to attain carbon balances higher than those of plants growing under low CO 2 . This was particularly so during the dry season, since the photosynthetic rates at the corresponding ambient concentration were higher in plants nearer the springs, and carboxylation efficiency and some stomatal characteristics of both species apparently acclimated to high CO 2 , but patterns were not consistent and bore no obvious relationship to photosynthetic capacity.