ABSTRACT

Phenoclimatology is ultimately strongly dependent upon field research but controlled environment studies have been extremely useful analyzing specific climatic parameters. Data on appearance of defined developmental stages — this is phenology — usually as a function of days after sowing or emergence or simple calendar dates are essential. Phenological tables most often use the intervals from: sowing to flower initiation, flower initiation to anthesis, and nthesis to crop maturity. Climate assessment includes some measure of accumulated thermal and irradiance and/or daylength factors during the calendar year or growing season. This chapter discusses acquisition of daylength and low temperature sensitivity with age in considerations of juvenility, but of equally great practical significance in some flower crops is the loss of daylength requirements for flower initiation and development. Daylength is an easily managed parameter in greenhouses and for this reason control of photoperiod is commonly found in production of chrysanthemums, carnations, poinsettia, azalea, and other photoperiodically sensitive flower crops.