Continuous and dynamic illumination induce divergent water transport dynamics, growth and development in sweet pepper ( Capsicum annuum L.)

The study of light emitting diodes (LEDs) as supplemental light and as steering light for sweet pepper (Capsicum annuum L.) is covered in existing literature with focus on three main aspects: light quality, light quantity and photoperiod. This study focuses on the effect of dynamic light intensity toward water transport dynamics, growth and development in sweet pepper. Sweet pepper plants received a bell-shaped illumination scheme with intensities ranging from 32.7 to 382.4 mu mol s(-1) m(-2) while control plants received a continuous light intensity of 291.5 mu mol s(-1) m(-2). Both treatments had a photoperiod of 18 h and had an equal daily light integral of 18.7 mol day(-1) m(-2). During the experiment, sap flow rate, stem diameter variation and leaf thickness variation were continuously monitored. Plants that were exposed to continuous illumination invested more resources in generative growth, while plants exposed to bell-shaped illumination showed vegetative growth. The generative or vegetative state of the plant was most likely induced by a difference in flower and fruit abortion rate. Between both treatments, clear differences in water transport dynamics were observed, which were argued to respond to the generative or vegetative state of the plants. Illumination schemes may therefore play an important role in modifying crop growth and development.