Margaret J. McMahon

Anatomy and pigments of chrysanthemum leaves developed under spectrally selective filters

Abstract The effects of selectively filtered sunlight on leaf pigments and morphology of Dendranthema X grandiflorum (Ramat.) Kitamura ‘Spears’ were studied. Light was filtered by water (control) which did not absorb solar radiation between 400 and 800 nm, a blue dye solution which absorbed primarily red light, and a solution of CuSO 4 which absorbed primarily far-red light. Comparisons were made with reported effects of chemical growth regulators on leaf anatomy. Leaves grown in CuSO 4 -filtered light had increased chl a, chl b, and carotenoids per unit area and on a dry weight basis compared with other treatments. Palisade cell number was increased per unit area under CuSO 4 filters. Light through CuSO 4 filters reduced leaf area, palisade cell length, and intercellular space but not leaf thickness. Increased pigment content appeared to be the result of more densely arranged palisade cells and reduced intercellular space. Leaf anatomy of plants grown under CuSO 4 filters often resembled that of leaves from plants treated with the chemical growth regulators daminozide or chlormequat. Chl a : chl b, xanthopyll : β-carotene, and total chlorophyll : total carotenoid ratios were not affected by filter. Number of stomata was not affected on a per unit area basis but number per leaf was reduced as a result of decreased leaf size by CuSO 4 -filtered light. Blue-dye-filtered light did not influence leaf pigments or morphology compared with controls.