Landscape architects occupy a strategic position in the landscape industry; yet, they have not been generally considered an important customer group by nurserymen. They influence selection of plant material for commercial, government, and residential landscapes and are generally the first to know what will be in demand. A recent survey of Georgia landscape architects found they specify $85 M of plants. This compares to the $200 M estimate for the 1989 wholesale value of nursery stock produced in Georgia. In addition, 60% of the landscape architectural firms influence which production nursery supplies plants by determining or recommending the production nursery where the landscape contractor obtains plants. More importantly, 92% of the large firms, which account for 67% of the dollar value, are involved in selection of the production nursery. The results provide the first quantitative estimate of the influence of landscape architects on nurserymen and suggest that nurserymen should view landscape architects as important customers.
Photoperiodism is best studied through the use of live plant material in the laboratory so that students can observe a progression of developmental stages. This paper describes photoperiod compartments which are simple and easy to construct, inexpensive, and require only a modest amount of greenhouse bench space. The compartments can be used to demonstrate various photoperiod responses including flower initiation and development, pigment production, leaf fall, onset of dormancy, runnering, and the formation of underground food storage organs.
The effect of age on CO2 exchange rates of cucumber (Cucumis sativus L.) cotyledons was measured. A biphasic process was noted, with a period of relatively high exchange rates up to 17-18 days from planting, when the first true leaf was nearly fully expanded, followed by a decline in exchange rates thereafter. The relative contribution of cotyledons versus leaves to photosynthesis as a function of age was measured. At 16 days from planting, the cotyledons accounted for 80% of the total net CO2 exchange and slightly more than 50% of the total foliage area. Twenty-four days after planting, the cotyledons still accounted for about one-fourth of the total net CO2 exchange and 20% of the total foliage area. The use of cotyledons in chilling injury studies of cucumber is justified by both the large photosynthetic contribution of cotyledons to growth and development, and the presence of cotyledons during early growth when chilling is most likely to occur.