Induction Of Virus-Free Seedlings And Their Photosynthetic Charcteristics In Sugarcane

With Sugarcane varieties Badila, GT11, T16, T22 and T25 as the plant materials, two methods of tissue culture i.e apical culture and callus culture were studied in this experiment. The variety Badila was infected by sugarcane mosaic virus (SCMV), and GT11 was infected by sugarcane ratoon stunting disease (RSD). The explants were separately treated with heat and chemical. The culture process including induction, differentiation, propagation, developing roots and planting were investigated. The available media, phytohormone and phenol pollution were studied. The chlorophyll content, photosynthetic parameters (Pn, Gs, Tr) and chlorophyll fluorescence parameters (Fv/Fm, Fv/Fo, Yield) of virus-free seedlings, which were obtained through tissue culture, were observed. The effects of these methods on eliminating disease were compared. The main results were as follows:(1) In the apical meristem culture, the induction rate of milling cane varieties were lower than chewing cane variety (Badila); and the phenol pollution was more serious in the milling varieties. The growth rate of the chewing cane plants was higher than milling cane varieties. In all of experimental media, the phenol pollution was the lowest in the MS medium with BA2.0mg/L+NAA0.1mg/L, and the induction rate was the highest. The best result was obtained when the apical meristem in summer was used.(2) In the apical meristem culture, the explants were pretreated with sterile water for 30 min, and active carbon (AC) and PVP were directly added into the media, and the explants were transferred onto fresh media. This could minimize the phenol pollution and increased the induction rate.(3) In the callus culture, the induction rate of T16 was the highest of all; the quality ofchewing cane (Badila) callus tissue was the best, and that of T16 was the worst of all in callus differentiation culture and the milling cane varieties differentiated more seedlings with chlorosis and variant seedlings than chewing cane (Badila).(4) In the propagation culture, the seedlings of chewing cane (Badila) propagated most rapidly in the apical meristem culture. The quality of sugarcane plantlets was improved when PP333 was added into the medium.(5) The 1/2 improved MS medium with NAA1.0-5.0mg/L+IBA0.5-2.0mg/L and 0.05% AC was of benefit to developing roots.(6) After planting, all sugarcane seedlings from tissue culture survived easily. The survival rates of the seedlings from apical meristem culture reached 100% for Badila, GT11 and T22. The survival rates of the seedlings from callus culture also reached 100% for Badila and GT11.(7) Chlorophyll content and some parameters of Pn, Gs, Tr, Fv/Fm, Fv/Fo and Yield of virus-free seedlings of chewing cane (Badila) were higher than those of infected ones. The chlorophyll content of the seedlings from callus culture was higher than those of the seedlings from apical culture, while there was no difference between heat treatment and chemical treatment. The Pn, Gs, Tr, Fv/Fm, Fv/Fo and Yield of the seedlings from heat treatment and callus culture were the highest of all.(8) The Chlorophyll content of virus-free seedlings of GT11 from apical meristem culture was higher than that of the seedlings from callus culture. There were differences in Pn, Gs, Tr for all treatments. Pn of the seedlings with chemical treatment was higher than heat treatment, while Gs and Tr in the seedlings with heat treatment were higher than those with chemical treatment. Fv/Fm, Fv/Fo and Yield in the seedlings from apical meristem culture were higher than those of the seedlings from callus culture.