| Double root-cutting（DRC）grafting is a new grafting method,and the light environment affects the survival rate,healing process and later performance of grafted seedlings.In this experiment,tomato ’ Beaded Curtain ’ was used as scion and tomato ’Rootstock No.1’ as rootstock for DRC grafting.During the healing period,the light quality of LED with different proportions of red（R）,blue（B）and green（G）was combined light（R7B3,R7B3G10,R7B3G20,R7B3G30）,and white light W was used as control（CK）.The light intensity was managed by gradient: it was divided into four healing stages: 1-2 d,3-4 d,5-6 d and 7-8 d.PPF 0-50-100-150 as CK,PPF 25-75-125-175,50-100-150-200,75-125-175-225,100-150-200-250 μmol·m-2· s-1were treated as T1,T2,T3 and T4,respectively.The effects of light environment on grafting healing and root regeneration of tomato DRC grafting were studied.The main results are as follows:1.The addition of G light to RB light promoted the healing of DRC grafted tomato seedlings,root growth and grafted seedling quality,among which R7B3G30 treatment had the best effect.Compared with CK,the callus formation rate of R7B3G30 treatment was faster,the disappearing time of isolation layer was shorter,the grafted seedlings healed after 8 days of healing,and the survival rate of grafting was significantly increased by 4.5%.The activities of SOD,POD,CAT and APX at the joint of grafted seedlings were significantly increased by R7B3G10,R7B3G20 and R7B3G30 compared with CK and R7B3.The grafted seedlings treated with R7B3G30 promoted the accumulation of chlorophyll content,leaf area and plant biomass,and the strong seedling index increased significantly by 23.9%.R7B3G30 treatment improved the xylem transport capacity of grafted seedlings,which was beneficial to the material transport of grafted seedlings,thus promoted the root regeneration of grafted seedlings,developed the regenerated roots,and significantly increased the root activity by 12%.2.The DRC grafted tomato seedlings were treated with different light intensity gradients at the healing stage.It was found that the grafted seedlings treated with T3 had the best healing effect,the highest survival rate and the best quality of grafted seedlings.The survival rate of grafting with different light intensity gradient treatments was more than 90%,and T3 treatment was the highest,which was significantly higher than that of CK by 5.1%.The activity of antioxidant enzymes of the grafted seedlings treated with T3 increased significantly,promoted the formation of callus at the junction,the isolation layer disappeared for a short time,and the grafted seedlings healed after 6 days of healing.After 6 days of healing,when the light intensity gradient was T3,the root activity,chlorophyll an and chlorophyll b content of grafted seedlings increased significantly,which was beneficial to the root regeneration of grafted seedlings.When the light intensity was 225 μmol·m-2· s-1,the root system of grafted tomato seedlings was well developed,the total root length,root volume and root surface area were significantly higher than those of other treatments,and the root-shoot ratio and strong seedling index were the highest.After 10 days of healing,the light intensity was increased to 250 μmol·m-2· s-1,which significantly increased the leaf area and biomass accumulation of DRC grafted tomato seedlings.To sum up,the addition of G light to RB light and medium light intensity gradient improved the healing effect of tomato DRC grafting.When light quality R7B3G30 and light intensity gradient T3(PPF 75-125-175-225 μmol·m-2· s-1),the graft healing was the best,the grafting survival rate and grafted seedling growth were improved,and the root regeneration of rootstock was promoted. |
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