The Optimal Light Environment For Spinach Growth

Plant factory has become one of the most promising directions in modern agriculture as it has the precision control ability to internal environment,can provide the most suitable environmental conditions for plant growth,has the capacity of realizing the anniversary continuous production,and helps agriculture cast off the yoke of the natural environment.As a new type of light source,LED has been widely used in the plant factory due to its significant advantages.The main content of this paper includes the following four aspects:1.The LED plant cultivation chamber was designed and built up.After studied the characteristics of plant growth,influence factors(light uniformity especially)of light environment and controlling methods of light supplement in depth,we chose the light quality,light quantity and photoperiod as the control target,along with the necessary light control technologies to build up LED plant cultivation,chamber.2.The feasibility of the orthogonal experimental design method was verified and it was applied to the searching of the optimal light environment by using lettuce as the model plant.The results showed that:the optimal light environment derived from morphology indices is the same as the actual test results,while that derived from biochemical indices is different.The reasons may be caused by the factor that the ratios of the red and the blue light in the two levels are too close and by the growth principle of the plant leaves.3.Two batches of spinach were cultivated by using the hydroponic method.There were several abnormal situations happened in the first batch of spinach,due to the unsuitable experimental conditions and the defects of light quantity evaluation method.The second batch of spinach grew well.The optimal light environment for the morphology indices is:R:B=80:20?mol·m-2·s-1 13/11h;the optimal light environment for the biochemical indices is:R:B=120:30?mol·m-2·s-1 9/15h.A suitable evaluation for these two light conditions was also given.4.The results of the orthogonal experiments were analyzed by using the comprehensive evaluation method and the matrix analysis method.Based on the experimental results,the advantages and disadvantages of orthogonal experimental design method were discussed.