Three different photoperiod treatments (8 h/16 h, 12 h/12 h, and 16 h/8 h of light/dark) were implemented to investigate the impact of growth, biomass, and phytochemical accumulation in two celery cultivars, namely ‘Zhangqiubaoqin’ (BQ) and ‘Hongchenghongqin’ (HQ), within a plant factory setting. The findings demonstrated that the 12 h/12 h photoperiod stimulated the growth of both celery varieties, while the 16 h/8 h photoperiod hindered their growth. Notably, the root length, shoot fresh and dry weight, plant height, chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid content of both celery cultivars exhibited the highest values under the 12 h/12 h light and dark photoperiod. Furthermore, the effective quantum yields of the electron transfer ratio (ETR) and the photochemical quenching coefficient (qP) displayed superior value under the 12 h/12 h light and dark photoperiod. With the exception of cellulose, the levels of soluble sugar, soluble protein, total phenol, and vitamin C were also highest under the 12 h/12 h photoperiod for both cultivars. BQ demonstrated the highest total apigenin content under the 12 h/12 h (light and dark) photoperiod, whereas HQ exhibited the highest content under the 16 h/8 h (light and dark) photoperiod. In summary, celery plants exhibited optimal performance and biomass production when subjected to the 12 h/12 h (light and dark) photoperiod treatment.

The MADS-box gene plays an important role in plant growth and development. As an important vegetable of Cucurbitaceae, chayote has great edible and medicinal value. So far, there is little molecular research on chayote, and there are no reports on the MADS-box transcription factor of chayote. In this study, the MADS-box gene family of chayote was analyzed for the first time, and a total of 70 MADS-box genes were identified, including 14 type I and 56 type II MICK MADS genes. They were randomly distributed on 13 chromosomes except for chromosome 11. The light response element, hormone response element and abiotic stress response element were found in the promoter region of 70 MADS genes, indicating that the MADS gene can regulate the growth and development of chayote, resist abiotic stress, and participate in hormone response; GO and KEGG enrichment analysis also found that SeMADS genes were mainly enriched in biological regulation and signal regulation, which further proved the important role of MADS-box gene in plant growth and development. The results of collinearity showed that segmental duplication was the main driving force of MADS gene expansion in chayote. RNA-seq showed that the expression levels of SeMADS06, SeMADS13, SeMADS26, SeMADS28, SeMADS36 and SeMADS37 gradually increased with the growth of chayote, indicating that these genes may be related to the development of root tubers of ‘Tuershao’. The gene expression patterns showed that 12 SeMADS genes were specifically expressed in the male flower in ‘Tuershao’ and chayote. In addition, SeMADS03 and SeMADS52 may be involved in regulating the maturation of male flowers of ‘Tuershao’ and chayote. SeMADS21 may be the crucial gene in the development stage of the female flower of ‘Tuershao’. This study laid a theoretical foundation for the further study of the function of the MADS gene in chayote in the future.

Farming is an important development direction of agriculture in the future, which is affected by various environmental factors, among which light plays an important role, and it is essential for the growth of organisms in nature. LED technology can regulate the growth and development of vegetables by adjusting the spectral composition of light. In order to explore light quality formulation with the aim of improving the quality and yield of celery, we set up six experimental treatments: W (white light), R (red light), B (blue light), 3R1B (red light/blue light = 3:1), 4R1B (red light/blue light = 4:1), and 5R1B (red light/blue light = 5:1). The results indicated that the 3R1B and 4R1B illumination treatments were conducive to promoting the growth of celery, enhancing plant height and root length. Specifically, the 3R1B treatment optimized the nutritional quality of celery by increasing the levels of soluble protein, soluble sugar, and total flavonoids while reducing nitrate and cellulose contents and elevating the anthocyanin content in petioles. Additionally, both treatments enhanced the contents of Ca and Mg in celery leaves and petioles. Furthermore, the 3R1B treatment promoted the accumulation of photosynthetic pigments, upregulated the activities of ANS and FNS enzymes, and induced the upregulation of gene expression levels of FNS and ANS, thereby enhancing the nutritional value of celery.

Light is essential for vegetable growth, with varying combinations of light quality affect differently on plant growth and development. In order to clarify the optimal light quality combination of celery LEDs, under hydroponic and full LED light conditions, this study investigated distinct combinations of light quality have various impacts on the growth and quality of celery using “Hongcheng Red Celery” as test material. Red-blue (R:B = 3:1, control), red-blue-purple (R:B:P = 3:1:1, purple (P)), red-blue-green (R:B:G = 3:1:1, green (G)), red-blue-yellow (R:B:Y = 3:1:1, yellow (Y)), and red-blue-far-red (R:B:FR = 3:1:1, far-red (FR)) light conditions were set up in the experiment, and plants were treated for 45 days. The findings indicated that the best growth in celery was achieved under the RBP, while RBG inhibited the growth of celery. The chlorophyll a and total chlorophyll contents of celery leaves were increased significantly by the RBP treatments compared to RB. In addition, net photosynthetic rate, stomatal conductance, and transpiration rate were highest in RBP. In RBP treatment, soluble protein, vitamin C, total phenols, total flavonoids, Ca, Fe, Zn in leaves and petioles of celery were higher than in other treatments. And the anthocyanins content in celery petioles was higher than other treatments. The RBP and RBG treatments reduced nitrate content. The RBP treatment increased the activities of apigenin synthesis-related enzymes CHS, FNS, ANS, and up-regulated expression of related genes CHS, FNS, and ANS, and increased apigenin content. In summary, the RBP is more favorable for celery growth and nutrient synthesis.