The 13th International Conference on Plant Growth Substances was held from the 17th to the 26th July, 1988 in Calgary, Alberta Canada under the auspices of the IPGSA (International Plant Growth Substances Association) and the University of Calgary. Over 550 participants from allover the world attended, along with 70 Associates and 25 University of Calgary graduate students who assisted in audiovisual presentations when not attending the scientific sessions. Fine weather prevailed, as was usual for summer on the eastern slopes of the Canadian Rockies, and participants arriving early visited the famous Calgary Stampede. A hosted buffet opened the Conference on Sunday evening. On Wednesday evening, following an afternoon field trip into the mountains of the Kananaskis Valley, the IPGSA traditional banquet became a western barbecue on Richards' Ghost River Ranch in the foothills of the Rockies, with folk and country and western music provided by the Great Western Orchestra. The fine Alberta weather continued through the weekend, and the Conference ended with a field trip to Sun shine Meadows, a World Heritage Site in Banff National Park.

R. P. PHARIS and D. M. REID The idea of a separate Encydopedia volume dealing with the "interrelations of plant hormones with factors in the environment of the plant, and its organs and tissues" originated with N. P. KEFFORD, and we are most appreciative of the help and advice provided by Prof. KEFFORD in the formative stages of this volume. We have thus interpreted "environment" very broadly to indude not only factors external to the plant, e. g. , gravity, light, temperature, wind, mechanieal wounding, water, organism s (induding pollen), and magnetic and electric stimuli, but internaI factors as well (e. g. , nutrients, both inorganic and photoassimilate, direction, and time). In our definition of "hormonaI effect", or "hormonaI involvement", we have asked our authors to take a broad ap proach, and to examine not only phenomena that are mediated by the known plant hormones, but to discuss as well a wide variety of processes and events where hormonal involvement is implied through more indirect analyses and observations. The volume begins with environmental factors internaI to the plant; R. J. WEAVER and J. O. JOHNSON thus examine "hormones and nutrients", their inter relationship in movement, accumulation, and diversion. As one studies a plant during its rapid growth phase, and later as maturation and aging proceed, it becomes apparent that time is an environmental cue of great significance, one which may exert a major influence via hormonal messages.