Effect Of Artificial Light And Nutrient Solution On Cucumber Growth And Fruit Quality

Plant production factories use series of plant growth facilities to achieve year-round production of plants through artificial regulation of indoor environment, such as lightning, temperature, nutrient solution etc. Light-emitting diode(LED), as a new-type, energy-saving light source, can accurately setting spectra for what plants need to improve the efficiency of solar energy utilization. Nutrient solution is the key point for soilless cultivation, which can provide elements for plants to absorb. Cucumber(Cucumis sativus L.), as most widely planted vegetable around the world in the open field and facilities, researches about fruiting stage of cucumber under LED light and nutrient solution are very limited.The variety ‘Zhongnong No.29’ was used as test material to study the effect of formula and concentration of nutrient solution on growth, photosynthesis, fruit quality and yield of cucumber under LED light. At the same time, this research is also focusing on the effect of light intensity and light quality on plant growth, fruit formation and yield of cucumber in order to provide more technical data on application of hydroponic culture system and light environment of cucumber cultivation in plant production factory.1. The formula ‘Hoagland’ played obvious improvement on the growth, photosynthesis, fruit quality and yield of cucumber under 100 μmol m-2s-1 2:1(red: blue) LED light among four commonly used formula- Hoagland, garden-style, Yamasaki and SCAU. Formula ‘SCAU’ cannot provide enough elements for plants, therefore lead to weak performance of plant quality and yield.2. The concentration of Hoagland nutrient solution at the fruiting stage influenced the growth, partitioning of nutrients, fruit quality and yield of cucumber under 100 μmol m-2s-1 2:1(red: blue) LED light. Because of less nutrient supply, the growth of cucumber irrigated with one time concentration of Hoagland nutrient solution was suppressed and the fruit cannot properly inflate. The ion concentration is too high in 2.5 time nutrient solution which can lead to stress effects and inhibition of plant growth. Compared to other three concentration of Hoagland nutrient solution, 1.5 time nutrient solution played better performance on plant growth, photosynthesis and fruit formation. Therefore, 1.5 time Hoagland nutrient solution is proper for cucumber at fruiting stage under 2:1(red: blue) LED light.3. Compared to 100 μmol m-2s-1 2:1(red: blue) LED light, the natural light promotes plant growth, photosynthesis and fruit development. However, transferring plants from natural light to artificial light make this promotion weaken, which lead to the drop on growth index. On the contrary, plants that transferred to natural light showed fast growth rate and increase on yield. In a word, it is good for plants growth and fruit formation under natural light that is at high light intensity and full spectrum. But high light intensity will broke the structure of plant optical system.4. Cucumber growth improved under LED light after adding white light and increasing the light intensity. Plants grown under 200 μmol m-2s-1 light showed better performance on growth, photosynthesis, fluorescence parameters, fruit quality and yield compared to other three treatments – 80, 100, 150 μmol m-2s-1. Therefore, considering cucumber grown under LED light, light intensity plays a major role than light quality and nutrient solution.