| China is one of the most important apple-producing counties and the cultivation area and production of apple in China rank first in the world. In recent years, the harmness of ring rot disease is becoming more and more serious and caused great losses to apple production. The effects of different apple stocks on resistence to stem ring rot disease and on defense enzyme activity of Red Fuji apple were studied by means of field investigation and artificial inoculation, which provides theoretical basis for screening apple germplasm resources with resistance to ring rot disease and for researching mechanism of resistance to ring rot disease in scion affected by stocks. The main results were as follows:1.The differences of disease resistance among the combinations Malus micromalus×Malus zumi, M. micromalus×S19 and M. micromalus×P22 showed that male parent had great influence on disease resistance of hybrid progeny. The results of field investigation indicated that the incidence of progenies of M. micromalus×P22 was 27.03% and the disease index was 19.93; the incidence of progenies of Malus micromalus×Malus zumi was 21.05% and the disease index was 13.95; and the incidence of progenies of M. micromalus×S19 was 16.9% and the disease index was 11.27. The results of artificial inoculation indicated that the incidence of progenies of Malus micromalus×Malus zumi was 91.80% and the disease index was 33.20; the incidence of progenies of M. micromalus×S19 was 78.35% and the disease index was 28.87; and the incidence of progenies of M. micromalus×P22 was 80.85% and the disease index was 27.66.2. The segregation of resistance to ring rot disease in the hybrid progeny F1 population of Malus micromalus×Malus zumi, M. micromalus×S19 and M. micromalus×P22 showed that the resistance was controlled by polygenes. The results of field investigation indicated that the proportion of hybrid progeny of Malus micromalus×Malus zumi at 0-4 disease level was 78.95%, 3.16%, 9.47%, 0.00% and 8.42%, respectively; the proportion of hybrid progeny of M. micromalus×S19 at 0-4 level was 83.10%, 0.70%, 9.86%, 0.70% and 5.63%, respectively; and the proportion of hybrid progeny of M. micromalus×P22 at 0-4 level was 72.97%, 4.05%, 8.11%, 0.00% and 14.86%, respectively. The results of artificial inoculation indicated that the proportion of hybrid progeny of Malus micromalus×Malus zumi at 0-4 disease level was 8.20%,60.66%,21.31%,9.84% and 0.00%, respectively; the proportion of hybrid progeny of M. micromalus×S19 at 0-4 level was 21.65%,47.42%,24.74%,0.00% and 5.63%, respectively; and the proportion of hybrid progeny of M. micromalus×P22 at 0-4 level was 19.15%,55.32%,21.28%,4.26% and 0.00%, respectively.3. The incidence and disease index were both different among red Fuji apples grafted on stocks with different resistance. The incidence of red Fuji apples grafted on progenies at 0 level of Malus micromalus×Malus zumi, M. micromalus×S19, M. micromalus×P22 were 29.33%, 47.46% and 55.56%, respectively, and the disease index were 22.33,32.84 and 37.04, respectively. The incidence of red Fuji apples grafted on progenies at 2 level of Malus micromalus×Malus zumi, M. micromalus×S19, M. micromalus×P22 were 88.89%,78.57% and 100%, respectively, and the disease index were 69.44,60.71 and 62.5, respectively. The incidence of red Fuji apples grafted on progenies at 4 level of Malus micromalus×Malus zumi, M. micromalus×S19, M. micromalus×P22 were 100%,87.5% and 100%, respectively, and the disease index were 78.13,84.38 and 72.73, respectively.4. The defense enzyme activity was different in materials with different resistance and the activity of defense enzyme in materials with high resistance was higher than that in susceptible materials. The activity of SOD, POD, CAT, PPO and PAL in 1-13, progenies of Malus micromalus×Malus zumi with high resistance, were higher than those in 8-42, susceptible progenies, respectively. And the acticity of SOD and PPO had significant difference between these two materials, but there was no significant difference in POD and PAL acticity. The acticity of CAT had significant difference between leaves of 1-13 and 8-42, and had no significant difference between branches.The activity of SOD, POD, CAT, PPO and PAL in 2-9, progenies of Malus micromalus×S19 with high resistance, were higher than those in 9-26, susceptible progenies, respectively. And the acticity of POD,PPO and PAL had significant difference between these two materials, but there was no significant difference in SOD acticity. The acticity of CAT had significant difference between branches of 2-9 and 9-26, and had no significant difference between leaves. The activity of SOD, POD, CAT, PPO and PAL in 10-37, progenies of Malus micromalus×P22 with high resistance, were higher than those in 10-32, susceptible progenies, respectively. And the acticity of POD,PPO and PAL had significant difference between these two materials, but there was no significant difference in CAT acticity. The acticity of POD had significant difference between branches of 10-37 and 10-32, and had no significant difference between leaves.5.The defense enzyme activity was different in red Fuji apples grafted on stocks with different resistance. The activity of SOD, POD, PPO and PAL in red Fuji apples grafted on stocks with high resistance were higher than those on high susceptible stocks, but the activity of CAT did not show certain regularity. The activity of SOD, POD, CAT, PPO and PAL in red Fuji apples grafted on annual stock with high resistance 1-13 were higher than those on high susceptible stock 8-42. The acticity of CAT, PPO had significant difference between these two materials, but there was no significant difference in POD acticity. The acticity of SOD and PAL had significant difference between leaves of 1-13 and 8-42, and had no significant difference between branches. The activity of SOD, POD, PPO and PAL in leaves of red Fuji apples grafted on three years’ stock with high resistance 11 were higher significantly than those on high susceptible stock 210,but The activity of CAT in leaves of red Fuji apples grafted on three years’ stock with high resistance 11 were lower significantly than that on high susceptible stock 210. The activity of SOD, POD, CAT, PPO and PAL in red Fuji apples grafted on five years’ stock with high resistance 11 were higher than those on high susceptible stock 210. The acticity of SOD,PPO and PAL had significant difference between these two materials, but there was no significant difference in CAT acticity. The acticity of POD had significant difference between leaves of 1-13 and 8-42, and had no significant difference between branches.6. The acticity of SOD, POD, CAT, PPO and PAL were determined before and after inoculation in high resistant material 11-1 and high susceptible material 2-1. The results showed that defense enzyme activity in 11-1 and 2-1 increased in various degree after inoculation, and was higher than that in control. The maximum and average value of defense enzyme activity in 11-1 were both higher than those in 2-1 after inoculation by B.berengriana f.sp piricola.7. The acticity of SOD, POD, CAT, PPO and PAL were determined before and after inoculation in red Fuji apples grafted on high resistant material 2-9 and high susceptible material 2-1. The results showed that defense enzyme activity in these two materials both increased after inoculation by B.berengriana f.sp piricola, and was higher than that in control. The maximum and average value of defense enzyme activity in 2-9 were both higher than those in 2-1 after inoculation by B.berengriana f.sp piricola. |
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