Influence of field bed position, ground surface color, mycorrhizal fungi, and high root-zone temperature in woody plant container production

High root-zone temperatures can stress plants and reduce nursery productivity of container produced crops. Field studies were conducted to study position of containers in field beds, ground surface color, mycorrhizal fungi and high root-zone temperatures in the production of selected woody plants. Root-zone temperature profiles in containers were established to determine nursery production conditions for white and black ground bed surfaces. White surfaces increased container medium temperatures in beds of plants with open canopies by 2-4°C compared to full canopied plants. Under field conditions with container medium temperatures as high as 40-50°C, the open canopied Berberís thunbergii DC. 'Atropurpurea', Pinus eldarica Medw. and Buxus microphylla Seibold and Zuce, were more susceptible to temperature stress compared to the more close canopied Pittosporum tobira (Thunb.) Ait. 'Wheeler's dwarf. When compared to controls, P. tobira colonized with mycorrhizal fungi [Glomus etunicatus Baker and Gerd, and Glomus fasciculatum (Thax. sensu Gerd.) Gerd, and Trappe] had increased shoot growth in all bed areas except the western exposure, and increased root growth in western and eastern bed regions. Greatest root damage generally occurred in containers of colonized and noncolonized B. thunbergii in southern and western bed exposures. Mycorrhizal colonization did not improve plant growth of the more high temperature susceptible B. thunbergii.