Photosynthetic Light Response of Bottomland Oak Seedlings Raised Under Partial Sunlight

Abstract

Seedlings of cherrybark oak (Quercus pagoda Rafinesque), Nuttall oak (Quercus nuttallii Palmer) and overcup oak (Quercus lyrata Walter) were grown under two light levels, partial (20 percent) or full sunlight, to study physiological acclimation of leaves to low light availability. Shifts in leaf morphology were noted for seedlings raised beneath partial sunlight, and photosynthetic light response curves indicated that bottomland oaks varied in their degree of physiological acclimation to low light availability. Greatest shifts in leaf function under partial sunlight were observed for cherrybark oak which exhibited a 48 percent decrease in net photosynthesis at light saturation (P_n-sat), and a 55 percent n-sat decrease in dark respiration rate (R_d) (based on leaf area). These adjustments to the d photosynthetic mechanism were accompanied by a 46 percent decrease in the light compensation point (LCP). In contrast, Nuttall oak leaves showed similar rates of P_n-sat, R_d and apparent quantum yield (j) regardless of the light environment in which they developed. Overcup oak leaves were intermediate in response exhibiting a 53 percent decreased in R_d and a 57 percent increase in j, but P_n-sat was not decreased for leaves grown under partial sunlight. Silvicultural implications of these results for bottomland oak regeneration are presented.

Parent Publication

• Proceedings of the eleventh biennial southern silvicultural research conference

Citation

Gardiner, Emile S. 2002. Photosynthetic Light Response of Bottomland Oak Seedlings Raised Under Partial Sunlight. Gen. Tech. Rep. SRS–48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. pp. 86-91