Seed-source variation in water relations, gas exchange, and needle morphology of mature ponderosa pine trees
1993
Cregg, B.M.
Xylem pressure potential, net photosynthesis, needle conductance, and transpiration were measured periodically throughout the 1991 growing season on 16 ponderosa pine (Pinus ponderosa Dougl. ex Laws.) trees growing in a 23-year-old provenance planting in eastern Nebraska. The trees studied were from four diverse sources: western Montana, northwest South Dakota, southern New Mexico, and central Arizona. In addition to water relations and gas exchange, specific leaf area, stomatal density, and surface to volume ratios were determined on 1-year-old foliage of each tree. Compared with the other seed sources, gas exchange of the South Dakota source was lowest early in the summer, when xylem pressure potential was generally high, and highest in the late summer, when xylem pressure potential declined. However, the relation needle conductance to xylem pressure potential did not appear to differ among the seed sources. The South Dakota source had lower stomatal density and needle length than the other sources tested. No differences in specific leaf area or surface to volume ratio were observed. Overall, variation in physiology and needle morphology wrong seed sources of mature ponderosa pine appears to be more subtle than intraspecific variation of seedlings of other species reported in the literature.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library