（1. College of Agriculture, Hunan Agricultural University, Changsha 410128, China; 2. Institute of Cotton Sciences of Hunan Province, Changde 415101, China）   

Abstract: Xiang FZ001 was used as a test variety in this experiment, which was conducted in a plant factory with a cycle of 16 hours of light and 8 hours of darkness to study the effects of varying light intensities on the growth and development of cotton (Gossypium hirsutum L.), three light intensity treatments with parameters of L1: 450 µmol·m-2·s-1, L2: 600 µmol·m-2·s-1, and L3: 750 µmol·m-2·s-1, were established to determine the dry weight of each cotton organ. The height of the cotton plant was measured using a straightedge, the chlorophyll content of cotton leaves was measured using a SPAD-502 chlorophyll meter. Additionally, six chlorophyll fluorescence parameters were measured, including initial fluorescence (F0) and maximum fluorescence (Fm), using a Flour Pen 110. The relative chlorophyll content and plant height of cotton were greatest under the L1 light intensity treatment, the root dry weight of cotton was greatest under the L2 light intensity treatment, and the total weight of cotton stems, leaves, and individual plants under the three light intensity treatments were L3>L2>L1 in descending order, and the F0 and Fm were L1>L2>L3 in descending order. The maximum photochemical quantum yield (Fv/Fm) was L2>L3>L1 in descending order. The photochemical bursting coefficient (qp) and effective quantum yield (φPSII) of cotton under the same light intensity treatment showed the same curves of change. During the pre-growth era, there was no significant difference in the qp, φPSII, and non-photochemical burst (NPQ) of cotton under the three light intensity treatments. However, in the late period, there was a greater difference. For the late growth stage, cotton’s qp and φPSII under the three light intensity treatments were high to low in the order of L3>L2>L1, and high to low in the order of L2>L3>L1. High light intensities increase the dry weight, stem dry weight, and leaf dry weight of cotton plants; low light intensities enhance the height of the cotton plant, but too high or too low a light intensity prevents the growth of cotton roots. Compared with cotton under L1 and L3 light intensity treatments, L2 light intensity was suitable for cotton growth, avoiding both inter-plant competition for light and the phenomenon of photoinhibition, with moderate chlorophyll content, resulting in the highest photochemical efficiency of cotton. This study can provide a guidance for cotton factory production and cotton breeding accelerator development and application.

Key words: plant factory; light flux density; Gossypium hirsutum L.; growth and development; photosynthetic characteristics

（Acta Laser Biology Sinica, 2024, 33(2): 115-122）