Influence of Prolonged Photoperiod Regimes on Growth Kinetics and Biomass Productivity of Spirulina Platensis

Saida Parvin 1, M. Zayed Rahman 2, Tanmim Akter Mim 1, Tamima Dastagir 1 and A.F.M. Jamal Uddin 1*

1 Department of Horticulture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh.

2 College of Agricultural Sciences, International University of Business Agriculture and Technology, Dhaka, Bangladesh.                                                                                         

✉ *Corresponding author: jamal4@yahoo.com.

Research article first published online: 12 August 2026.

DOI https://doi.org/10.18801/jbar.360226.340

Abstract

An experiment was conducted in the Department of Horticulture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, in 2026 to study the effects of prolonged photoperiod regimes on growth kinetics and biomass yield of Spirulina platensis. The experimental design used for this experiment was a Completely Randomised Design (CRD) with three replications and three treatments: T₁ (8h Light: 16h Dark), T₂ (12h Light: 12h Dark), and T₃ (16h Light: 8h Dark). The experiment showed that there were significant differences in optical density, wet biomass yield, dry biomass yield, dry biomass concentration and percent dry biomass production increase over T1. The highest values for optical density, wet biomass yield, dry biomass yield and dry biomass concentration were observed in treatment T₃ and were recorded to be optical density ~1.40 at 560 nm at 12 DAI, 59.5 g for wet biomass yield, 5.46 g for dry biomass yield, 0.91 g/L for dry biomass concentration, representing a 30% increase in dry biomass production over T1. The minimum values for optical density, wet biomass yield, dry biomass yield, and dry biomass concentration were observed in treatment T₁ and recorded to be 1.000 optical density at 12 DAI, the wet biomass is 52.0 g, the dry biomass is 4.20 g, and the concentration of the dry biomass is 0.70 g/L. This study demonstrated that the extended photoperiod of 16 hours has greatly improved the growth kinetics and biomass productivity of Spirulina platensis, thus proving the hypothesis that sufficient exposure of the biomass to light is essential for the production of biomass.

Keywords

Microalgae, light duration, biomass, spirulina

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