LED-infused photoperiod and light intensity regulation on morpho-physiological attributes, productivity, quality and resource use efficiency in french bean (Phaseolus vulgaris L.)

Abstract Photoperiod and light intensity are critical environmental factors influencing the growth, development of higher plants. To evaluate their effects on french bean, an experiment was conducted at the University of Agricultural Sciences, Bengaluru, Karnataka. The study comprised five infused photoperiod regimes, namely 4 h (8:00 AM–12:00 Noon), 6 h (8:00 AM–2:00 PM), 8 h (8:00 AM–4:00 PM), 10 h (8:00 AM–6:00 PM), and 12 h (8:00 AM–8:00 PM), along with ambient light as the control. In each photoperiod treatment, ambient sunlight was supplemented with LED illumination at a constant light intensity. The results revealed that french bean plants grown under infused photoperiod exhibited significantly greater leafiness than those grown under ambient light alone (33–41% at 20 DAS and 19–70% at 40 DAS). Enhanced leaf development resulted in substantial improvements in photosynthetic rate (65–87% and 47–97%) and instantaneous water use efficiency (77–102% and 43–116%). Consequently, dry matter accumulation increased by 5–30% under the infused photoperiod regimes compared with the control. The improved physiological performance translated into remarkable enhancements in yield-attributing traits and seed yield (29–100%) over ambient light-grown plants. Furthermore, exposure to elevated photoperiods at a constant light intensity improved seed quality by increasing protein and fat contents, while also enhancing nitrogen, phosphorus, and potassium uptake by plant. These findings demonstrate the potential of photoperiod manipulation through supplemental lighting to improve productivity, quality, and resource use efficiency in french bean cultivation.