Light in Early Plant Development: Influence on Leaf and Floral Initiation in Tobacco1

Abstract

Quantitative effects of accumulated PAR (photosynthetically active radiation) on apical meristem and leaf development were investigated using a cultivar of flue‐cured tobacco (Nicotiana tabacum L.) grown in controlled‐environment rooms at day/night temperatures of 22/18 and 26/22 C. Times of floral initiation and days between emergence of successive leaves were determined over a PAR range of 10.5 to 40.5 E m‐2day‐1. The total numbers of leaves and leaf primordia at the time of floral initiation and the days between initiation of successive leaf primordia were determined over a PAR range of 10.5 to 25.5 E m‐2day‐1. There was an interaction between temperature and all measured responses. In general, the times of floral initiation, final number of leaves and leaf primordia, and time between initiation of leaf primordia were only slightly affected by PAR at 22/18 C. At 26/22 C, however, floral initiation was delayed, final number of leaves and leaf promordia were increased, and the time between initiation of leaf premordia decreased as PAR decreased. The days between emergence of successive leaves increased as PAR decreased at 22/18 C but decreased at 26/22 C. These results will be used in developing an onogenetic simulator for a dynamic model of tobacco growth and development.