Light Wavelength’s Effect on Early Stage Garden Bean Development

Overview

The energy efficiency of light-emitting diodes (LEDs) makes them attractive for indoor plant lighting. However, LEDs do not create broad-spectrum lighting efficiently. LEDs’ effect on the growth of garden beans (Phaseolus vulgaris) is not well known. This study sought to find light colors to grow bean plants effectively under indoor conditions. The hypothesis was that each light color of purple, red, and green would promote early bean growth better than natural sunlight as expressed qualitatively and quantitatively. Twenty bean plants each grew under red, green, purple LED lights (Phillips, 8 watt) and natural sunlight for 16 days after planting the seeds in soil. Average plant height after 16 days under purple, red, green, and natural light were 332 mm, 285 mm, 280 mm, and 326 mm, respectively. The average leaf width for plants under purple, red, green, and natural lights were 43 mm, 80 mm, 76 mm, and 36 mm, respectively. Bonferroni adjusted T-tests found four pairwise comparisons on plant height and four pairwise comparisons on leaf width were statistically significant. Significantly different plant height comparisons: those under green light vs. those under purple light and those under natural light, those under red light vs. those under purple light and those under natural light, with p-values all at 0.000, 0.001, 0.000, 0.000, respectively. Significantly different leaf width comparisons: those under green light vs. those under purple light, those under green light vs. those under natural light, and those under red light vs. those under purple light, and those under red light vs. natural light, all with p-values 0.000. Qualitative observations, based upon visual inspections of leaf health, maturity, and root development revealed the plants under red light were the healthiest, nearest to fruition and had the healthiest roots, followed by those under green light. The findings of this study suggest particular narrow-spectrum light can perform better than broad-spectrum light on early garden bean growth.

Competition history

• AJAS 2020 Category not listed

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