Under the environment with LED light source in plant factory，taking cucumber‘ Zhongnong
No.26’ as test material, this paper studied the effects of different substrate water content on cucumber seedling growth characteristics and water requirement regulation．The results showed that the plant height，stem
diameter，biomass，root system morphology index and strong seedling index, etc. of cucumber seedlings were the
best when the substrate water content was 85%-90%．The total water consumption of seedling treated with 85%-
90% substrate water content was the highest，reaching 129.72 mL；and the seedling water use efficiency was
significantly improved．The relationship between the number of days after sowing and water consumption quantity
was the best based on the linear equation．The expression was y=0.355 3 x-1.887 5．Considering comprehensively
the growth and water consumption characteristics of cucumber seedlings，under the environment with LED light
source，85%-90% substrate water content could cultivate high-quality and strong seedling while achieving high
efficient water usage．