| Oriental melon(Cucumismelo var.makuwa Makino)is a kind of typical photophilic and thermophilic crop.However,under autumn and winter cultivation conditions in solar greenhouse,the influence of rainy,snowy and smog weather,which often causes insufficient light,seriously affects plant growth and development,and causes harmful effects on yield production and fruit quality.Therefore,this study used the orange flesh oriental melon 'Hong dao bian' as the experimental material,and used light-emitting diode(LED)to supplement the light of oriental melon plants and earlier harvested melon fruits during autumn and winter in solar greenhouse.On the one hand,the effects of different light qualities and different supplemental lighting forms on sugar and ?-carotene accumulation in oriental melon fruits were studied.On the other hand,the effects of different light qualities on sugar and ?-carotene accumulation among earlier harvested melon fruits during storage and ripening were studied to provide theoretical reference and technical support for the application of LED supplemental lighting in the production of oriental melon fruits during autumn and winter in solar greenhouses.The main results are as follows:1.Supplemental lighting experiments of different light qualities was conducted at 10 days after flowering of the melon female flower under the natural light conditions in the field: red light(R),blue light(B),red and blue 4:1(RB 4:1)and red and blue 6:1(RB 6:1),with the natural light as control.The plants was treated with artificial lights for 10 h daily,samples were taken at different time after treatments.The results showed that the melon fruit weight was significantly increased in all supplemental lighting treatments;The content of chlorophyll a and chlorophyll b in leaves of plants treated with blue light was the highest;the fruit weight,the contents of soluble solids and soluble sugar were the highest in RB 4:1 and RB 6:1 treatments,followed by blue light and red light was the lowest.The content of ?-carotene in red light treatment was the highest,followed by RB 4:1 and RB 6:1,and blue light treatment was the lowest.The relative expression levels of genes related to sucrose synthesis(Cm SPS01,Cm SS01)and ?-carotene synthesis and metabolism(Cm PSY1,Cm PSY2,Cm PDS,Cm ZDS,Cm LCY-b and Cm CCD1)were promoted by different light qualities treatments.Among which the red light treatment was the best,followed by the two kinds of compounded light qualities treatments.In summary,different light qualities of LED supplemental lighting significantly promoted the accumulation sugar and ?-carotene of melon fruit during autumn and winter in solar greenhouse,and the effects of RB 4:1 and RB 6:1 were the best.2.Field experiments of different supplemental lighting forms were carried out with red and blue 6:1(RB 6:1).Three treatments were set up: canopy supplemental lighting(T),inter-plant supplemental lighting(M)(the first functional leaf above the first fruit)and vertical inter-lighting(S),with natural light as control(CK).The results showed that the melon weight in all treatments was higher than that of the control;The sucrose content of the fruit was the highest in the two kinds of inter-lighting treatments,and there was no significant difference between the two treatments.The content of ?-carotene was the highest in the vertical inter-lighting treatment,and the difference between the inter-plant lighting and vertical inter-lighting was not significant.The expression of Cm SPS01 and Cm SS01 in fruit ripening process was the highest in inter-lighting supplementation treatment except on the 7th day after treatment.Different ways of supplemental lighting have different effects on genes related to ?-carotene synthesis,and no consistent rule has been found.In conclution,although the ?-carotene content in vertical inter-lighting treatment was higher than in inter-lighting treatment,there was no significant difference in single melon weight,fruit firmness and sucrose content between the two treatments.In terms of economy and electricity consumption,the effect of inter-plant supplemental lighting treatment was the best.3.The melon fruits with uniform growth and size were harvested at 30 days after flowering to the laboratory to investigate the effects on the post-harvest fruits of different supplemental lighting treatments.Two kinds of light qualities treatments,red(R)and blue light(B)were set up,darkness was taken as control(CK),and stored in dark for 12 hours after harvest.and the fruits with continuous light for 12 hours were stored in dark.Samples were taken at different days at the beginning of the experiment to determine the relevant indicators of fruit appearance and quality.The results showed that the fruits treated with the red light had the highest soluble sugar content and ?-carotene content,and the relative expression of Cm SPS01 under red light treatment was the highest by q RT-PCR.The gene expression of ?-carotene synthesis and metabolism was up-regulated at different stages under the red treatment,while it was down-regulated under the blue light treatment.In summary,red light treatment could increase the soluble sugar and ?-carotene content of post-harvest melon fruits by promoting the expression of Cm SPS01 and genes related to ?-carotene synthesis. |
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