Investigation of photosynthetic effects, carbohydrate and starch content in cress ( Lepidium sativum) under the influence of blue and red spectrum

Ladan Ajdanian; Mehdi Babaei; Hossein Aroiee

doi:10.1016/j.heliyon.2020.e05628

Investigation of photosynthetic effects, carbohydrate and starch content in cress ( Lepidium sativum) under the influence of blue and red spectrum

Heliyon. 2020 Dec 5;6(12):e05628. doi: 10.1016/j.heliyon.2020.e05628. eCollection 2020 Dec.

Authors

Ladan Ajdanian¹, Mehdi Babaei¹, Hossein Aroiee¹

Affiliation

¹ Department of Horticultural Sciences, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.

Abstract

In order to study the effect of the quality of different LED light spectra (90%R+10%B, 60%R+40%B and control) on photosynthetic parameters (photosynthetic rate (PG), Fv/Fm and ΦPSII) of stomatal conductance, transpiration rate, carbohydrate, starch and chlorophyll index on cress (Lepidium Sativum), a pot experiment was conducted under the greenhouse cultivation-without-soil (hydroponics) condition in the form of split plot based on a completely randomized design with 6 replications. The results showed that the combined application of blue and red light spectra with different percentages had a positive and significant effect on all traits. The highest amounts of each of the photosynthetic parameters in the 60R:40B treatment were 12.4, 0.87, and 0.92 (μmol CO₂ m^-2 s^-1), respectively, and the lowest amounts (19.6, 0.39, and 0.44 (μmol CO₂ m^-2 s^-1)) were observed in the control treatment. The highest amounts of stomatal conductance, carbohydrate and starch of leaves which were 0.3 (cm.s^-2), 5.59 and 6.44 (mg.g-1 FW), respectively, were observed in the 90R: 10B treatment as a result of red light increase. Furthermore, in the control treatment, the light source of which was the natural sunlight, the lowest amounts of 0.11 (cm.s^-2), 1.98 and 1.09 (mg.g^-1 FW) were observed. The highest transpiration rate (25/83 (mol.m^-2.s^-1)) was observed in the 60R: 40B treatment which had experienced a significant increase compared to the control light (sunlight) treatment and the lowest transpiration rate (5.5 (mol.m^-2.s^-1)) was in the control (sunlight) treatment. The chlorophyll index in the 60R: 40B treatment was 41.18, which showed a significant difference from the other treatments (p ≤ 0.01) and the lowest amount of 25.5 was detected in the control treatment. As a result, it can be stated that the use of blue and red light spectra in combination with different percentages can have various positive effects on the growth and development of plants; therefore, the existence of both types of spectra is suggested. This technology means that a particular combination of LED light spectra can be useful for a variety of commercial greenhouse products, especially the valuable ones.

Keywords: Agricultural science; Agricultural technology; Agronomy; Blue light; Chlorophyll; Horticulture; Leaf vegetable; Organic farming; Photosynthetic rate.