ALTERATIONS IN LEAF MORPHOLOGY OF 2 LANDSCAPE SHRUBS IN RESPONSE TO DISPARATE CLIMATE AND PACLOBUTRAZOL

Paclobutrazol at 0 and 750 mu l.liter(-1) was sprayed on shoots of Fei joa sellowiana O. Berg. and Ligustrum japonicum Thunb. grown under sim ilar production regimes in central Arizona (subtropical desert) and so uthern Georgia (humid temperate). Five months after application, Feijo a and Ligustrum leaves were generally smaller and thicker in Arizona t han in Georgia. Arizona leaves were thicker than those in Georgia beca use of more layers of palisade and spongy mesophyll cells. Compared wi th leaves from control plants, paclobutrazol 1) increased Feijoa leaf area in Georgia, 2) decreased Ligustrum leaf area at both locations by approximate to 50%, and 3) decreased leaf thickness of both species i n Arizona. Arizona Feijoa leaves had trichomes on adaxial and abaxial surfaces, whereas Georgia Feijoa leaves had trichomes on abaxial surfa ces only. Paclobutrazol increased trichome frequency on adaxial surfac es of Arizona Feijoa leaves. Stomatal frequency of Georgia Feijoa leav es was about doubled by paclobutrazol. Reflectance of near-infrared ra diation by paclobutrazol-treated Feijoa leaves was 1.4 times higher th an that of nontreated leaves in Georgia and 1.9 times in Arizona. Near -infrared reflectance by Georgia Ligustrum leaves was 1.3 times higher than by Arizona Ligustrum leaves and was not affected by paclobutrazo l. Leaf reflectance of photosynthetically active radiation (PAR) by Ar izona Feijoa was higher than by Georgia Feijoa. Paclobutrazol increase d PAR reflectance by Arizona Feijoa leaves. In contrast, Georgia Feijo a PAR reflectance was decreased by paclobutrazol. Paclobutrazol or loc ation did not affect Ligustrum PAR reflectance. Chemical name used: yl )-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol (paclobutrazol).