The Effect of Different Doses of Blue Light on the Biometric Traits and Photosynthesis of Dill Plants

Abstract

The supplementation of blue light to red light enhanced plant growth compared with the use of red alone. The aim of the
study was to determine the effect of different doses of blue light on the biometric traits and photosynthesis of dill plants. The
plants were grown in pots in a growth chamber. They were grown in red light (100 μmol m-2 s-1) and blue light (from 10 to 50
μmol m-2 s-1) in five combinations. Light emitting diode modules were the source of light. The plants were evaluated every 7
days during vegetation, for the first time - seven days after germination and later on the 14th, 21st and 28th day after
germination. The share of blue light in the spectrum significantly influenced the biometric traits of the dill plants. It
significantly inhibited the elongation growth of the plants and negatively affected the increase in fresh weight. A small dose of
blue light (20%) had positive effect on the plants’ area. The research did not reveal a simple relationship between the amount
of blue light and dry weight yield. The value of physiological indexes depended both on the combination and measurement
time. The plants from the combination with 30% blue light were characterised by the greatest photosynthesis intensity. An
effective share of blue light in the spectrum may range from 10 to 30% in relation to red light and depends on the plant’s
development phase and on the result we want to achieve in the cultivation of plants.