Modeling morphological adaptations of bell pepper (Capsicum annuum) to light spectra

Plant growth lighting research has typically focused on the effects of specific lamps with spectra resulting from the various materials used in building the lamps (eg HPS, Metal Halide, etc). In recent years a single waveband or the pairing of two wavebands as become common as part of LED lamp technology. In this work, we developed eight models to predict height, stem diameter, shoot dry weight, leaf area, dry weight partitioning between leaves and the rest of the shoot, specific leaf weight, and two compactness scores of pepper seedlings. Bell pepper plants were grown under eight light treatments with various combinations of blue, green, red, and far-red light. Physiological measurements were recorded, and the data were fit using general linear models based on spectral quality. Our models explained 82%-98% of the between-groups variation for predicted variables, demonstrating the ability of empirical models to accurately predict growth outcomes for bell pepper seedlings based on light quality. Phytochrome photostationary state, a measure of active to inactive phytochrome under steady illumination, was the most impactful variable in every model, supporting the importance of phytochrome in regulating a wide variety of physiological responses. Blue light played an important role in reducing plant height and increasing stem diameter, partitioning of dry weight into leaves, and both compactness scores, while green light increased leaf area.