TY - JOUR T1 - Growth and Iron Content of Three Legume Tree Species at High Root-Zone Temperature JF - Arboriculture & Urban Forestry (AUF) SP - 313 LP - 317 DO - 10.48044/jauf.1991.069 VL - 17 IS - 12 AU - William R. Graves Y1 - 1991/12/01 UR - http://auf.isa-arbor.com/content/17/12/313.abstract N2 - Root-zone temperatures in city landscapes are supraoptimal for the growth of many temperate tree species, and selection of heat-resistant genotypes will aid in the development of successful urban forests. The purpose of this study was to compare the growth of Gleditsia triacanthosvar. inermis (honeylocust), Maackia amurensis (Amur maackia), and Sophorajaponica (pagoda tree) athigh root-zone temperature. Nutrient solution in which seedlings were grown was held at 35°C, for 0, 6,12, and 24 hr/day for 42 days. For honeylocust and Amur maackia, dry mass was similar for plants at 35°C 0 and 6 hr/day but was reduced among plants at 35°C for 12 and 24 hr/day. In contrast, mass of pagoda tree was decreased 55% by 35°C root-zone temperature for 6 hr/day, but mass increased as exposure to 35°C increased beyond 6 hr/day. Young lamina of honeylocust and Amur maackia at 35°C for 12 and 24 hr/day were chlorotic, and a high-temperature-induced reduction in the concentration of iron in leaves of all species was confirmed. These results indicate that growth of pagoda tree seedlings is more sensitive to cyclic episodes of high rootzone temperatures than to constant heat. The influence of high root-zone temperature on growth of Amur maackia was similar to that of honeylocust, which in previous studies was more heat resistant than other trees used in temperate urban forests. ER -