Physiological responses of seedlings of different Quercus castaneifolia C.A. Mey. provenances to heterogeneous light environments

In this study, five biochemical traits obtained for seedlings of five different provenances of Quercus castaneifolia C.A. Meyer were used to evaluate the available light environment using instantaneous electronic readings as a standard. Experimental design was executed under controlled conditions at six different irradiance levels (10, 20, 30, 50, 60, and 70% of full light). Results show that among total chlorophyll (Chlmass), chlorophyll a to b ratio (Chla:Chlb), N, chlorophyll to N ratio (Chl:N), and peroxidase (POD) quantitative activity, the latter provides the highest realistic correlation with available irradiance. Ranking irradiance treatments on a Chlmass basis, Chl:N ratio, and Chla:Chlb ratio do not consistently distinguish different irradiance levels either within or between provenances, while the ranking produced by POD was an accurate reflection of the degree of irradiance within the shade houses, especially at 10-30%.