Species differences in seedling growth and leaf water response to light quality

Tue, 01/25/2011 - 21:03

For the majority of forest species slight canopy opening reduces light limitations suggesting that light quality often measured as red:far red ratio (R:FR) plays a significant role in the development of seedlings. The effect of different levels of R:FR was studied on seedlings of four Ghanaian timber species of different ecological guilds to assess their growth and leaf water response to changes in R:FR. The experiment was conducted in shade houses of varying light qualities (0.30, 0.46 and 0.76 R:FR) achieved with the use of bamboo slats, green filter and white cotton cloth. Relative height growth of all species declined in high R:FR with Guarea cedrata and Celtis mildbraedii, shade bearers, having a slower decline of height growth with increasing R:FR than Terminalia ivorensis, pioneer, and Albizia zygia non-pioneer light demander. Relative diameter growth on the other hand increased in higher R:FR treatments except for G. cedreta. Relative biomass growth was not significantly affected by R:FR. Leaf area ratio did not vary in different R:FRs for G. odorata but for the other species it was lower in higher R:FRs. Specific leaf area was also not affected by R:FR except in G. cedreta where it dropped with increase in R:FR. The diurnal pattern of change in stomatal conductance and leaf water potential of T. ivorensis and G. cedrata were similar in lower R:FR ratio but opposite in higher R:FR. This results show that the response of seedlings to changes in R:FR is different for different species and is more of morphological change rather than growth (biomass accumulation). Pioneers are more sensitive to these changes than non-pioneers.

Responsible party
Forestry Research Institute of Ghana (FORIG)
Attachment Size
seedling_growth.pdf 1.48 MB