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Water Vapor Conductance and CO"2 Uptake for Leaves of a C"4 Desert Grass, Hilaria Rigida
Author(s) -
Nobel Park S.
Publication year - 1980
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1935182
Subject(s) - daytime , stomatal conductance , deserts and xeric shrublands , saturation (graph theory) , zoology , environmental science , ecology , atmospheric sciences , horticulture , botany , biology , photosynthesis , geology , mathematics , combinatorics , habitat
Availability of soil water was the major influence on seasonal stomatal activity of Hilaria rigida (Thurb.) Benth. ex Scribn. over a 2—yr study period in the Colorado desert section of the Sonoran desert. Major stomatal opening (water vapor conductance >2mm/s) occurred for 4.6 mo in the relatively cool winter—spring (maximum daytime temperatures averaging 17°C) and for 1.7 mo in the late summer—early fall (maximum daytime temperatures averaging 31°C). The temperature optimum for CO 2 uptake was generally above daytime temperatures, particularly in the winter. When the daytime growth temperature was raised from 16° to 49°C in laboratory experiments, the temperature optimum for CO 2 uptake shifted from 29° to 43°C. Besides the rather high temperature optimum for CO 2 uptake, H. rigoda displayed other typical C 4 characteristics including Kranz anatomy, a low CO 2 compensation point (12 μl/1), and a lack of light saturation of CO 2 uptake at full sunlight. Under optimal field conditions, the CO 2 uptake rate can be 67μmol°m — 2 °x — 1 (106mg CO 2 °dm — 2 h — 2 ), higher than has been reported for any other species. The accompanying high water use efficiency (mass CO 2 taken up by leaf blades/mass H 2 O lost) may help explain the success of this hardy grass in both the Mojave and Sonoran deserts.