Study On The Relationship Among The Inter Supplemental LED And The Light Utilization Characteristics,the Plant Growth-and-development Of Tomato Produced In Greenhouse

Tomato ?Lycopersicon esculentum Mill.? is one of the most important vegetable crops in the production of vegetable plants in China, and has relatively high demanding for light. In order to solve the light insufficiency problem among the lower canopies, which occurs during the intensive greenhouse cultivation and influces the plant development and reproductivity, we assembled the light-emitting diodes ?LEDs? of polychromatic light qualities, red + blue ?R/B?, white + red + blue?W/R/B?, white + red + far red ?W/R/FR?, and white + blue ?W/B? from the underneath canopy ?with light orientation to the abaxial epidermis of lowest leaves? or from the inner canopy ?with light orientation to the adaxial epidermis of leaves around fruit? of greenhouse produced tomato as supplemental lighting resources. The relationship among the polychromatic light quality, the light orientation, the light utilization of leaf, and the growth and development of plant were systematically studied. For the higher economic return, we studied the effects of four kinds of light intensity treatments,i.e. 100, 200, 300 and 400 ?mol·m^-2·s^-1, on the tomato production. Meanwhile, with the ¹³C tracer we identified the distribution patterns of C-assimilates in relation to leaf position, and investigated the efficient supplemental lighting location and pruning methord. With above methods, we finally put forward an efficient supplemental lighting scheme which was suitable for the greenhouse intensive tomato cultivation. The main findings are as follows:1. The use of inter supplemental lighting significantly improved the inter-plant light environment,increased the photosynthetic efficiency, and reduced stomatal closure while promoting plant growth and fruit development. Beyong that the use of LED as the supplemental lighting source will not significantly cause changes in the inter-plant thermal environment.2. The effects of W/R/B and W/B treatments on promoting plants growth were significantly better than those of R/B and W/R/FR. Plants treated with W/R/B and W/B presented low stem diameter, high biomass accumulation, high health index and more flower number. Meanwile, W/R/B-treatedplants had the highest soluble sugar content, while W/B-treated plants had the highest starch content.3. There was no significant difference in the leaf chlorophyll content among supplemental lighting treatments. The different carbon dioxide ?C02? utilization abilities caused variations in photosynthetic performance of leaves among treatments. The enhanced blue light fraction in the W/R/B and W/B could better stimulate stomatal opening and promote photosynthetic electron transport activity, thus better improving photosynthetic rate.4. The use of supplemental lighting from the underneath canopy maintained relatively stable light irradiation conditions in the lower canopy, and could better enhance the carbon dioxide assimilation efficiency and excessive energy dissipation, leading to an improved photosynthetic performance,fruit yield and better economic return. Combined with the previous results, the W/R/B and W/B from the underneath canopy had best performance, among all supplemental lighting treatments.5. The use of supplemental lighting from the inner canopy shortened the distance between the light source and fuit, which introducing higher soluble solid content of the fruit as a result of higher exposure to direct supplemental light to fruit. This indicated that the supplemental lighting from the inner canopy is more suitable for meeting the demond from sweet-fruit-prefer markting.6. The light intensity had a significant effect on the leaf photosynthetic characteristics, plant growth and fruit development of tomato. When the light intensity was in the range of 100-200 ?mol·m^-2·s^-1,with the increase of light intensity, the stomatal open introduced while the stomatal resistance weakened, the primary light energy conversion efficiency enhanced, the energy for the electron transfer increased, thereby the accumulation of photosynthetic products and fruit development was promoted. When the light intensity continuing increased to 300 ?mol·m^-2·s^-1, leaf photosynthetic ability, plant matter accumulation, fruit weight, and other indexes did not change significantly with the increase of light intensity. When the light intensity continuly increased to 400 ?mol·m^-2·s^-1,the values of different indexex decreased.7. The fruit development pattern varied with fruit orders. The high irradiation tolerance capacity decreased as fruit order increased. In order to ensure the fruit development, the supplemental lighting intensity should be reduced to prevent excessive irradiation. Combined with the results of economic analysis, the light intensity of supplemental lighting from underneath canopy set as 200?mol·m^-2·s^-1 washighly economical beneficial to tomato cultivation.8. After plants treated with ¹³CO₂ for 3 h, the ¹³C-assimilates distributed in different organs showed that the six leaves around the fruit had higher carbon fixation ability. After the six leaves around the fruit teated with ¹³CO₂ for 3 h respectively and another 48 h of translocation, the distribution patterns of fixed ¹³C by each source leaf showed that the supplemental lighting area should be located on the 3 leaves below the first-truss, and the other leves could be pruned.