Regulation Of Night Light On Cucumber Seedling Morphology

Cucumber is an important protected cultivation vegetable crop which acts an important position in the market supply. Cucumber planting usually use the way of seedling transplanting. Seedling breeding is an important link in vegetable production. The healthy of seedling directly related to the crop growth, development, yield and production quality, nurturing seedling is one key technology in vegetable production processes. Growth regulating and spindling controlling of crop seedling are important to cultivate strong seedling, to improve the young plant quality and vegetable products quality and quantity. Llight regulation method is energy saving, cost effective, simple to operator and could avoid the damage of crop seedling. To promote the development of breeding technology under controlled environment, it is important to research on the technology of light environmental regulation and develop a light environmental control strategy for plant seedling morphology regulation and design lighting-regulating equipment for nursery greenhouse.For using light environmental regulation technology to control the growth and development of young plants and designing lighting-regulating equipment, it’s a key point to clearly the influence of light on plant growth and development and seedling morphology regulation for using light environmental regulation technology to control the growth and development of young plants and designing lighting-regulating equipment. At present, research on the effects of light on plant growth and development mainly in terms of the effects of light on photosynthesis, light duration on plants flowering and bud differentiation and light quality on plant morphogenesis and so on. To promote the development of breeding techniques under controlled environment and use the technology to regulating the growth and development of plant seedling, further researches of light effect on plant morphology should be done, and lighting-regulating system which could regulate light intensity, light quality and light duration according to the growth status of plants also should be developed.To study the regulation of light on morphology of seedlings, cucumber seedlings were taken as test materials, artificial lights were used as night light for cucumber seedling, and suitable light quality and duration were selection. Also, the reaction of cucumber seedling at different stage to night light were analyzed, light control strategy suit to morphology regulation of cucumber seedling were made, and light regulation system for seedling morphology was designed. The primary contents and conclusions are as follows.(1) To determine the best light duration and light quality for night light to regulate cucumber seedling morphology, cucumber seedlings were lighted for 2h (19:00-21:00), 4h (19:00-23:00) and 6h (19:00-1:00) 3 different duration in the night with LI (70%R, 30%B), L2 (80%R,20%B), L3 (90%R,10%B) and L4 (100%R) 4 types light-emitting diodes (LED) and no light were taken as contrast to study the regulation of night light on cucumber morphology, and comprehensive evaluation analyze method were used to analyze the influence of night light on cucumber seedling morphology. The results show that:light quality effects hypocotyls length and stem diameter significantly at 0.05 level, and effects seedling height, leaf area, chlorophyll, dry weight and seedling index significantly at 0.01 level. Light duration have significant effect at 0.05 level on seedling index and significant effect at 0.01 level on hypocotyls length, seedling height and dry weight. Light quality and light duration have significantly interaction effects at 0.01 levels on hypocotyls length, seedling height and stem diameter and significantly interaction effects at 0.05 levels on seedling index.the cucumber seedling which were lighted for 4 hours had best quality, and that were lighted by L2 light quality had best quality, and that were lighted by L4 light quality had the biggest leaf area(2) The reactions of cucumber seedling at different stage to night light were analyzed. L2 (80%R,20%B), L4 (100%R) and L5 (100%B) were used to light cucumber seedling for 4h (19:00-23:00) in the night, and no light was taken as contrast to study the reaction of cucumber seedling at cotyledon stage, one-leaf stage, two leaf stage and adults seedling stage to night light. The results show that, at cotyledons stage, night light of L2 or L4 light quality could improve the growth of cotyledons, night light of L5 light quality could inhibit over growth of cucumber seedlings. At one-leaf stage, night light of L4 and L5 light quality control the elongation of hypocotyls and promote the growth of stem diameter at 3d leaf age, and night light of L4 light quality could improve the growth of cotyledons area and leaf area and curb the elongation of hypocotyls. At two-leafage, the qualities of cucumber seedlings at nigh light of L4 light quality were the best. At adult seedling stage, qualities of cucumber seedlings at night light of L2 light quality were the best.At cotyledon stage and one-leaf stage seedlings that lighted by L4 light had best comprehensive quality at these stages, at 23d leaf age stage seedlings that lighted by L4 had best seedling quality at this stage, and at 35d leafage stage seedlings lighted by L2 light had best quality.(3) Night light strategy for regulation on cucumber seedling morphology was established. Hypocotyls length, cotyledon area, stem diameter, leaf area, internodes length, dry weight, chlorophyll content and seedling index were measured to the influence of L2 and L4 LED night light on cucumber seedling morphology at different stage. Logistic curve was used to fitting the growth rate of leaf area, and night light strategy for regulation on cucumber seedling was established according to the reaction of cucumber seedling to night light. Based on the night light strategy seedling night light experiment was designed to modify the light process of cucumber seedling. The strategy was established as follow, at cotyledon and one-leaf stage L4 light quality was used as night light to promote the growth of cucumber seedlings, and at two-leaf stage L2 light quality was used as night light to improve the dry weight and biomass of cucumber seedlings and to health the seedlings. The results of test based on the night light strategy for cucumber seedlings show the same performance with the prediction of the strategy. The strategy for cucumber seedlings morphology regulation is the basic for the designing of light regulation system.(4) A light regulation system for seedling morphology and growth was designed. According to the effect of light quality, light intensity and light duration on the growth and development of young plant, a night light process which could automatically adjust light quality and light duration to fit the light requirement of seedling at different stage was established, and light regulation algorithm that lighting based on the growth stage, status and cultivation purpose was designed. Light system contains two subsystems was designed based on the night light process and light regulation algorithm. One subsystem is plant morphology detection system based on the technology, and the other subsystem is LED light regulation system which takes microcontroller as controller and could automatically regulate light quality, intensity and light duration. This system could judge the stage of plant stage and plant growth status based on the morphology detection, light quality and intensity and light duration were regulated according to the night light strategy, and the output LED light quality and intensity were adjusted by PWM. The result of test for light system shows that, the light system could provide night light that fit the light requirement of plant seedling at different stage, and could light for seedlings to regulate the morphology according to the night light strategy based on the cultivation purpose.