Browsing by Subject "stomata"

Plant growth and morphology can be manipulated with light. Previously light manipulation experiments were mostly conducted by modifying the solar spectrum with light absorbing filters. Today, research can be conducted with modern LED lighting techniques, which enables specific spectrum tailoring. Light can be tailored specifically for a species or a family, and the needs of the farmer can also be taken into consideration. In this study, tomato (Solanum lycopersicum L. cv ’Efialto’) seedlings were grown under six different spectra. Plant morphology, stomatal function and drought tolerance were measured. Growth measurements included stem height, plant fresh and dry weight, leaf -area and leaf number. In addition, the effect of light quality on leaf morphology was studied by measuring leaf blade and petiole length. All measurements were conducted on well-watered and water-stressed plants, in order to study the effect of drought on vegetative growth and drought tolerance. Stomata conductance was studied by measuring leaf temperature prior to and during water stress. Leaf surface temperature indicates transpiration rate; thus the higher the conductance the lower leaf temperature. In addition to leaf temperature measurements, photosynthesis and stomatal conductance were measured by leaf level infra-red gas analysis. R:FR ratio was the dominant factor for affecting plant morphology. However, the B:G ratio also played a key role; when the B:G ratio was low, it further enhanced the elongation growth, a response caused by low R:FR ratio. Irradiance in green and yellow wavebands regulated stomatal closure. During water stress, the light treatment with the highest green irradiance, induced more rapid stomatal closure which was evident as increased leaf temperature and decreased gas exchange. Light-depenedent stomatal closure and decreased transpiration could explain the improved performance of these seedlings during the drought period. Light spectral quality thus affected the drought tolerance of tomato plants through its effects on plant morphology and stomata function.