Ectomycorrhizal effect on net photosynthesis of Pinus brutia var. Eldarica seedlings
Ectomycorrhizal effect on net photosynthesis of Pinus brutia var. Eldarica seedlings
Shad K. Khalil and John G. Mexal
ABSTRACT
Pinus brutia var. eldarica seedlings were inoculated with two ectmycorrhizal fungi i.e. Rhizopogon vinicolor and Hebeloma crustuliniforme, to determine how different mycorrhizal and non mycorrhizal (NM) fungi control affect the response of photosynthesis, dry matter, shoot-root partitioning and photosynthetic water use efficiency (PWUE). Containerized seedlings were grown in greenhouse for about 9 months under well-watered and nitrogen fertilized conditions, and then transferred to a growth chamber where measurements were made three days latter. All seedlings were watered to field capacity the evening before measurements were made. Net photosynthetic rate and PWUE over one day period were measured, followed by harvesting and determination of dry matter of foliage. Both mycorrhizal fungi caused substantial increase in net photosynthesis and PWUE over non mycorrhizal (NM) control, but none of the mycorrhizas resulted in significant change in total dry matter or shoot-root allocation of dry matter. Net photosynthesis measured over time increased from morning then it declined to the minimum at mid-day, thereafter, net photosynthesis slightly increased towards the end of the day. Seedlings inoculated with Hebeloma crustuliniforme mycorrhizal fungi resulted in maximum net photosynthesis compared with seedlings either inoculated with Rhizopogon vinicolor or non mycorrhizal (control). It is proposed that net photosynthetic rate is correlated with the rate of export of photosynthates to the sink generated by mycorrhizal growth. Strong mycorrhizal demand for photosynthates stimulates photosynthesis to the mycorrhizal fungi.
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March 1997
Vol. 47, Iss. 1
