The Effect Of Different Lights On Growth Of Cotton, Rapeseed And Non-Heading Chinese Cabbage Plantlets And Seedlings

Light is one of the most important environmental factors, which plays an important role in plant growth, development, morphogenesis and metabolism. Plants controlled the diverse growth and developmental responses to light parameters, such as spectrum, intensity, direction and duration by an array of photoreceptors. LEDs (light-emitting diodes) has many advantages, such as small size, long life, low energy consumption, securing wave length and low production of heat, but also can emit the exact spectrum based on the need of plants, so that it can be widely used in seedling breeding, vegetables cultivation and plant tissue culture. There are some previous studies of LEDs affecting flower, fruit and medicinal plantlets in vitro, however little is known about the effects of crop seedlings and plantlets in vitro. Spectral light changes evoke different morphogenetic and photosynthetic responses that can vary among different plant species. Thus, it is necessary to study the effects of LEDs on crop growth and development, so that promoting the application of LEDs lights widely used in seedling breeding, vegetables cultivation, upland cotton and plant tissue culture.In this study, upland cotton(Gossypium hirsutum L.) and rapeseed (Brassica napus L.) plantlets in vitro, upland cotton and non-heading Chinese cabbage(Brassica rapa L.) seedlings were tested to investigate the effects of light sources on growth and development of plants, and select the feasibility of application of LEDs light used in cotton seedling breeding, non-heading Chinese cabbage vegetable cultivation, cotton and rapeseed plant tissue culture.Main research results were as follows:1. Effects of different light-emitting diodes (LEDs) lights on growth and morphogenesis of upland cotton(Gossypium hirsutum L.) plantlets in vitro were investigated. The results showed that fresh weight, dry weight, stem length and second internode length were greatest in plantlets cultured under the blue plus red LEDs (B:R=1:1) light, followed by blue LEDs light, and they were lowest in plantlets cultured under a fluorescent lamps. Chlorophyll content, leaf thickness, palisade tissue length, leaf and stomata area were highest in plantlets cultured under blue LEDs light. Root activity, sucrose, starch and soluble sugar contents were highest in plantlets cultured under red LEDs light. Blue and red LEDs (B:R=1:1) was the most suitable light for the growth of upland cotton plantlets in vitro.2. The effects of different light sources on growth of upland cotton (Gossypium hirsutum L.) seedlings were investigated. The results showed that fresh weight, dry weight, root length, and stem width were greatest in seedlings grown under blue plus red (B:R=1:8) LEDs, and lowest were greatest in seedlings grown under fluorescent lamps. Palisade-tissue length, leaf thickness, stomatal area, photosynthetic rate, and chlorophyll content were greatest in seedlings grown under blue LEDs. When seedlings were grown under red LEDs, the palisade tissue and spongy tissue were loose, starch grains accumulated significantly in the chloroplasts and sucrose, soluble-sugar and starch concentrations were highest. A mixture of blue and red LEDs in the ratio B:R=1:8facilitated the growth of upland cotton seedlings.3. The effects of the six light sources on growth and morphogenesis of rapeseed (Brassica napus L.) plantlets in vitro were investigated. The results showed that the differentiation rate, fresh and dry masses, concentrations of pigments, sucrose, soluble sugar, stem diameter, leaf stomata length of abaxial surface, stomata frequency of adaxial surface and transplantion rate were greatest in plantlets cultured under B:R=3:1LEDs light. Stem length, content of starch and leaf thickness were highest in plantlets cultured under red LEDs light. The proliferation rate was greatest under blue LEDs light. Blue plus red LEDs (B:R=3:1) was the most suitable light for the growth of rapeseed plantlets in vitro.4. The effects of different light sources on non-heading Chinese cabbage(Brassica rapa L.) seedlings were surveyed. The results showed thatshoot dry weight, root fresh and dry weight was greatest when seedlings grown under red LEDs at low light. The shoot fresh weight was greatest under blue LEDs. When seedlings grown under the altered PPF level, shoot and root fresh weight was greatest under red LEDs. Shoot and root dry weight was greatest under blue plus red LEDs. In the case of the altered PPF level during growth, the starch content was greatest under red LEDs. The contents of chlorophyll a, chlorophyll b and total chlorophyll were greatest under blue LEDs. When altered the PPF level, the ascorbic acid and souble protein were greatest under blue LEDs. The number of flower was highest under red LEDs and blue plus red LEDs, and the number of flower bud was higher under LEDs than that under fluorescent lamps, and especially blue LEDs. The period of flower was highest under red LEDs and blue plus red LEDs. LEDs light sources were more effective than fluorescent lamps for the vegetable and procreation growth of non-heading Chinese cabbage, and blue LEDs can be used for vegetable growth, red LEDs and blue plus red LEDs can be used for the procreation growth.In conclude, blue puls red (B:R=1:1) and blue LEDs were the best lights for the growth of upland cotton plantlets, blue puls red (B:R=1:8) LEDs was the best light for the growth of upland cotton seedlings. Blue plus red (B:R=3:1) LEDs was the best light for growth of rapeseed plantlets. Blue LEDs was the best light for vegetable growth of non-heading Chinese cabbage seedlings, red LEDs and blue plus red (B:R=1:8) LEDs were the best lights for the procreation growth of non-heading Chinese cabbage seedlings. This study demonstrated the feasibility of application of LEDs lights being widely used in upland cotton seedling breeding, non-heading Chinese cabbage vegetables cultivation, upland cotton and rapeseed plant tissue culture.