Evaluation of growth and female flowering in early transplanting of grafted cucumber transplants under different light intensities and photoperiods

초록

With climate change causing more extreme weather, plant factories with artificial lighting (PFAL) are becoming a practical solution for consistent and cost-effective transplant production. The objectives of this study to identify the optimal light intensity (200, 300, and 400 mu mol center dot m(-2) s(-1)) and photoperiod (12, 16, and 20 h d(-1)) combination for growth and morphological traits. In addition, the research was to evaluate the effects of light stress, with low light (LL) at photosynthetic photon flux density (PPFD) 50 mu mol center dot m(-2) s(-1) and high light (HL) at PPFD 600 mu mol center dot m(-2) s(-1), on cucumber transplant production after graft union formation in PFAL with white LEDs. The assessment of female flowering was performed over 21 days in a semi-closed greenhouse using three grafted cucumber cultivars (rootstock: Cucurbita ficifolia 'Heukjong'): 'Goodmorningbaekdadagi,' 'Nakwonseongcheongjang,' and 'Shinsedae.' Longer photoperiods at the same light intensity increased the compactness of all three cucumber cultivars. Optimal cultivation conditions with aspects of growth and morphological traits were 16H-300L for 'Goodmorningbaekdadagi' and 'Shinsedae,' and 16H-300L and 20H-300L for 'Nakwonseongcheongjang.' All grafted cucumber transplants were more affected by LL and HL exposure in later stages just before production of transplanting time. Therefore, special care is needed to avoid LL and HL damage, particularly prior to shipping. The 'Goodmorningbaekdadagi' produced fewer female flowers per node under treatment conditions compared to the reference groups (grown all in a semi-closed greenhouse). Interestingly, the female flowers of 'Goodmorningbaekdadagi' appeared more sensitive to the differences between sunlight and white LEDs compared to other cultivars. Results indicate the potential application of the plant factories as a nursery production to determine lighting manipulation and reduce light stress risks in cucumber transplant production under climate change.

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