| Traditional grafting seedling cultivation does not remove the original root system of the rootstock or cut the double broken root grafting seedlings into the substrate for healing.The grafted seedlings are transported to the seedling farm with the substrate for cultivation.Tomato two-stage grafting seedling raising refers to the cultivation of tomato double broken root grafted seedlings in segments,using a place with good facilities,skilled grafting workers or mechanized grafting equipment,and combining the advantages of double broken root grafting to remove the original root system of the rootstock for regeneration,completing the first half of seedling raising,grafting,and centralized healing,and then transporting the grafted seedlings without substrate to the seedling farm for cutting cultivation,Compared to traditional grafting seedling raising,it ensures the quality of grafted seedlings and reduces the cost of grafting seedlings and transportation.Aiming at two stage grafting seedling raising of tomato:how to promote high-quality and rapid healing of grafted seedlings under high density in the first stage;How to promote rooting and seedling growth of cutting and grafting seedlings.In this experiment,with different light environments and cutting time as treatment,tomato variety ’Yuyifandu 153’ as scion and ’Jinzuan’ as rootstock,tomato seedlings were grafted by double root cutting,and the grafted seedlings were placed in high-density containers made of acrylic and high-density foam board.During the healing period,the combination of red(R),blue(B),and green(G)LED light was used.The best light quality treatment was selected by adding 0%,10%,20%,and 30%green light(R7B3,R7B3G1,R7B3G2,and R7B3G3)to R7B3,and using white light W as a control(CK).Under R7B3G3 conditions,the light intensity during the healing period is managed using gradient management:divided into three stages:1-2 d,3-4 d,and 5 d.PPF 50-100-150 μmol·m-2·s-1 is CK,PPF 30-60-90,40-80-120,60-120-180,and 70-140-210 μmol·m-2·s-1 was treated with T1,T2,T3,and T4,respectively,to select the optimal light intensity gradient.Under different light quality and intensity gradient conditions,tomato double root grafting seedlings were cut and cultivated at 24,72,and 120 hours to select the optimal cutting time range.The effects of different light environments and cutting times on the healing and root regeneration of tomato double root grafted seedlings in two-stage cultivation were studied.The main results are as follows:1.The effect of R7B3G3 treatment was the best in terms of light quality ratio.Adding green light to red and blue light promoted the healing,plant growth,and root development of two-stage cultivation of tomato double cut root grafting seedlings,and improved the survival rate of the grafting seedlings by 5.27%.Compared with the control treatment,the isolation layer and callus formation at the grafting junction of R7B3G3 treatment were formed 1 day earlier,and the proliferation and differentiation speed of callus tissue was accelerated.The differentiated vascular bundle bridge was the earliest to break through the isolation layer and connect with the original vascular bundle tissue.Compared with CK treatment,R7B3G3 treatment reduced leaf MDA by 39.2%and O2.-content by 60.9%,and significantly increased SOD,POD,CAT,and APX activities by149.8%,273.1%,42.1%,and 132%,respectively.Compared with CK treatment,R7B3G3 treatment increased the fresh weight of grafted seedlings by 17.1%,dry weight by 40.6%,leaf area by 36.5%,and root to shoot ratio by 40.8%.R7B3G3 treatment promoted grafting healing,slowed down the decay of photoelectron transport efficiency under high-density healing conditions,ensured the progress of photosynthesis,and promoted root regeneration of grafted seedlings.2.Under R7B3G3 conditions,use T2(40-80-120 μmol·m-2·s-1)light intensity gradient,it was found that the survival rates of tomato double root grafting seedlings cultivated in two stages were increased by 4%and 2.3%compared to T4 treatment,and the quality of the grafted seedlings was the highest.The adhesion between scions and rootstocks occurred at the earliest stage in T2 treatment,which was 1 day earlier than the control treatment.The isolation layer formed earlier and disappeared faster,callus proliferation and differentiation were enhanced,and grafting healing was accelerated.Compared with CK and T4 treatments,T2 treatment reduced leaf MDA by 6.5%and O2·-content by 22%,while SOD,POD,CAT,and APX activities increased by 12%,9%,16.3%,and 13.3%,respectively.Compared with T4 treatment,T2 treatment increased the fresh weight,dry weight,and leaf area of grafted seedlings by 32,4%,39.9%,and 13.9%,significantly increasing the root to shoot ratio by 44.7%.T2 treatment resulted in a smaller degree of stomatal opening and weaker transpiration rate in leaves,reducing the consumption of nutrients in scions and transporting more photo synthetic products to rootstocks,promoting grafting healing and root regeneration.3.Different light qualities and intensities were treated for 24 hours,72 hours,and 120 hours,and two stage cultivation of tomato double root grafting seedlings were cut.It was found that the survival rate of the grafted seedlings that were cut within 72 hours was increased by 2%compared to the grafted seedlings that were cut within 120 hours,with fast recovery and growth,and robust plants.The grafting seedlings that were cut within 72 hours showed a 19.6%decrease in height,a 15.2%increase in stem diameter,an excellent root phenotype,and a 16.6%increase in leaf area compared to the grafting seedlings that were cut within 120 hours,demonstrating excellent cutting cultivation effects.4.Two stage cultivation method for tomato grafted seedlings:when the rootstock and scion grow to three leaves and one heart,double broken roots are grafted,fixed with a sleeve,and the grafted seedlings are concentrated in a self-made container for hydroponic cultivation with Hoagland nutrition.Before use,the container should be disinfected with alcohol in advance,and the nutrient solution should be replaced every 2 days.Control the day and night temperature of 22℃/18℃(day/night);Relative humidity:1-2 d,above 99%;3-4 d,over 95%;5 d,over 90%;The light environment is set to 12/12 h,the light quality is R7B3G3,and the light gradient is T2(40-80-120 μmol·m-2·s-1)。The above results indicate that adding green light and setting a weaker light intensity gradient in red and blue light promoted the healing of tomato rootstocks and root regeneration in two-stage grafting seedling cultivation,with R7B3G3 and T2(40-80-120 μmol·m-2·s-1)treatment is the best,and the concentrated healing and cutting time should not exceed 72 hours under this light environment condition. |
