Faster and more wheat production governed by LED light in controlled environment agriculture

(1) Wheat could complete its life cycle and produce seeds in a controlled environment with LED lighting. (2) The long-day condition combined with a spectrum rich in red light contributed to faster and more wheat production. (3) Red light improved grain number per spike and yield by enhancing carbohydrate supply and accelerating pollen development within the shortened growth time. Wheat ( Triticum aestivum L.) is a major food crop grown worldwide; yet, field-grown wheat is generally restricted to only one generation per year and has a fluctuating yield, limiting wheat improvement and failing to meet future food demand. To minimize generation time and increase total annually wheat production, five light regimens with varied day length and spectral distribution, including 12 h light/12 h dark+white light (P12W), 17 h light/7 h dark+white light (P17W), 22 h light/2 h dark+white light (P22W), 22 h light/2 h dark+red:green:blue light=6:3:2 (P22RGB), and 22 h light/2 h dark+red:blue light=6:1 (P22RB), were developed by adjusting the light emitting diodes (LEDs) in the controlled environment. The results showed that controlled wheat agriculture illuminated by LED sources equipped with various day lengths and spectral distributions had the potential for “faster” and “more” grain production. Prolonged day length (from 12 h to 17 h and then to 22 h) accelerated wheat development, particularly shortening the duration before flowering, and that the longer the prolonged time, the earlier the flowering. However, 22 h day length (e.g., P22W treatment) would affect plant morphological traits, reduce dry matter accumulation, and result in a loss of yield-related components due to increased stress and disrupted pollen development. Surprisingly, regulating the spectral distribution towards the red-light region under long-day conditions (e.g., P22RB treatment) could partially restore the grain yield of wheat. The light regime with a rich red-light region contributed to dry matter accumulation, carbohydrate flow to reproductive tissues, and sporopollenin biosynthesis, resulting in improved plant morphology and grain yield in wheat. Collectively, the optimized light regimes, represented by P17W and P22RB treatments in controlled environment agriculture, can produce 5-6 generations of wheat per year, yielding 3.16-5.87 kg m -2 yr -1 , which is 3.59-6.68 times higher than field cultivation. Thus, conducting appropriate LED light regimens is a favorable way to achieve the dual goals of “faster and more” in controlled wheat cultivation.