| Chrysanthemum is a kind of traditional flower of China, and the majority are potted chrysanthemums, while cut flower number of chrysanthemum accounts for30%of the world cut flower number.’Jinba’ is currently the largest planting variety in China. Until2012, the total planting area of cut flower chrysanthemum has reached6166.6hm2, annual output is about126million, annual export around13million to Japan. But the shortage of technology is too serious to meet the requirements of the chrysanthemum. The price of export is lower than Japanese domestic chrysanthemum30-40Yen, less than50%of Japanese domestic price of cut flower chrysanthemum.Therefore, Chinese enterprise requires management measures of cut chrysanthemum cultivation consisted with China’s climate characteristics.In order to speed up the development of cut chrysanthemum production and achieve connecting with the international flower market, important technologies fulfilled annual production system of cut chrysanthemum has got attention.Different Red:Far-red LED short day treatments were designed based on chrysanthemum response to light quality. The effects of different R:FR ratios on stomatal characters, stomatal conductance, leaf water potential and stem flow rate were studied. The model of stomatal conductance and transpiration rate were established. The results could provide theoretical basis for cut chrysanthemum in greenhouse cultivation. The main results were as follows:(1)To study the dynamic effects of different red (660±10) nm:far-red (730±10) nm ratios on stomatal characters of greenhouse Chrysanthemum leaves, an experiment was carried out in the experimental greenhouse of Nanjing University of Information Science and Technology from August2011to December2011.The experimental material was chrysanthemum morifolium Ramat.cv.’Jinba’.The results showed that:after35days of the short-day treatment, the maximum stomatal length of the upper epidermis and lower epidermis occurred at R:FR=4.5and6.5respectively, while the minimum length both occurred at R:FR=2.5; the stomatal density and aperture reached maxima at R:FR=2.5,while the minima occurred at R:FR=6.5. Stomatal density and aperture on the lower epidermis were significantly higher than those on the upper epidermis. No significant differences in stomatal opening ratio and stomatal index were observed among different R:FR treatments. From R:FR=2.5to6.5, leaf stomatal index, stomatal density and stomatal aperture decreased significantly with an increase in the red light component.(2)In budding period, stomatal conductance were correlated to R:FR ratio in the following descending order:2.5,4.5,6.5,0.5, and the maximum stomatal conductance were0.115mol·m-2·s-1, 0.076mol·m-2·s-1,0.065mol·m-2·s-1å'Œ0.048·m-2·s-1respectively. In flowering period, stomatal conductance at R:FR=4.5were the highest, and the maximum was0.240mol·m-2·s-1, R:FR=2.5were the second, R:FR=0.5were the lowest, and the maximum was0.071mol·m-2·s-1. Determination coefficient (R2) between stomatal conductance simulated by Bp neural network model and measured based on the1:1line was0.720, which root mean squared error (RMSE) was0.042mol·m-2·s-1. The precision was higher than Ball-berry model.(3) Leaf water potential of chrysanthemum under different R:FR ratios were all higher in the morning and evening, lower at noon. The minima of leaf water potential were correlated to R:FR ratio in the following descending order:2.5,4.5,0.5,6.5, the order of the daily change extent was in contrast. The effects of different R:FR ratios on stem flow rate of chrysanthemum had significant differences. Under different weather conditions, the order of stem flow rate and its change extent were both2.5>4.5>6.5>0.5. In budding and flowering period, R:FR=2.5always had the highest daily transpiration, and were4.73mm·d-1and9.03mm·d-1espectively. The study showed that transpiration rate had significant positive correlation with temperature, relative humidity, and R:FR values, and negatively correlated with CO2concentration, saturation water vapor pressure.(4) According to specific microclimate environment of experimental greenhouse, leaf area index and PAR of chrysanthemum canopy interception under different R:FR ratios were estimated based on Penman-Monteith equation, and the transpiration model contained meteorological data, leaf area index and canopy net radiation under different R:FR ratios were established. Simulating the transpiration rate of budding and flowering period, then comparing with measured transpiration. The determination coefficients of transpiration rate between simulated and measured values based on the1:1line were0.870,0.812,0.803,0.502respectively, root mean squared error (RMSE) were0.710mm·d-1,1.140mm·d-1,0.985mm·d-1,1.217mm·d-1respectively, which showed that the model could simulate transpiration well.The simulated model of transpiration rate could provide a scientific basis for further studying water requirement rule of chrysanthemum under different R:FR. |
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