| ViolaXwittrockiana is a self-pollinated plant with very small flower organs, and the cultivation of sterile lines is still in the exploratory stage, and the application of heterosis mainly depended on artificial emasculation. It usually caused a large workload to cultivate advantage hybrids of Viola×wittrockiana by artificial emas-culation and pollination, the hybrid seed-production was inefficient, and F1 seeds usually tended to be not pure because of human error in hybrid process. Therefor, it is imperative to speed up the breeding of new varieties and improve the overall quality of seeds. Chemical hybriding agents(CHA) is a kind of effective method in the heterosis utilization, which not only has been widely used in seed production of crops vegetables and fruit trees in open field, but also in ornamental flowers. We made a preliminary exploration on effect of 4 Sulfanilylurea (Tribenuron-methyl, Pyrazo-sulfuron-methyl, Bensulfuron-methyl, and Nicosulfuron-methyl), the results indicat-ed that:Tribenuron-methyl had best efficiency in inducing male sterility but low impact on the growth of Viola’X-wittrockiana. After repeated experiments in two years, some conclusions were got as follow:1.Tribenuron-methyl was an excellent CHA that could induce male sterility of Viola X wittrockiana efficiently. The optimal concentration of Tribenuron-methyl praying on leaf ranged from 0.30μg/mL to 0.50μg/mL. The key period of spraying was 1 or 2 weeks before flowering, plant height was about 15-20cm. The effect was better with the higher temperature and stronger light.15-20 mL of Tribenuron-methyl was used for each spraying and 86.95%～86.95% of the male sterile flowers were obtained with twice treatments, and male sterility rate was 93.33%～100%. The time of sterility could last for 23 days to 27 days. The sterile flowers had following characteristics:the flower diameter was 1.65±0.28 cm, the color of top petals became shallow, the shape of middle petals changed from round to rectangular the size of below petals became smaller, and the color also changed from yellow to white, purple spots disappeared, just left a little yellow in the flower centra. Or in some case, all of the petals became lilac.2. The flower number directly affected the seed setting rate, and the concentration of Tribenuron-methyl had the greatest impact on the seed number. Mixed emasculation agent, which composed of 0.30μg/mL Tribenuron-methyl,0.30μg/mL carbamide,0.20μg/mL GA3,0.20μg/mL detergent, had better effect than spraying Tribenuron-methyl alone. After processing, the plant height of Viola Xwittrockiana F1 plants was significantly lower than normal, but there was no difference in other ornamental traits, such as flower color, flower diameter, flower number, and crown diameter.3. The physiological metabolism in leaves and flower buds of Viola X wittrockiana had changed significantly after dealed with Tribenuron-methyl. Generally speaking, the content of soluble sugar in leaves and flower buds had significantly increased compared with fertile plants. The content of soluble protein in leaves and flower buds had dramatically decreased than fertile plants. The activity of SOD, CAT, POD in leaves were significantly higher than fertile plants. And change of SOD and POD were the same but was the opposite of CAT in flower buds. The differences of change may result in an imbalance of reactive oxygen metabolism in flower buds, and also caused nutritional losses during microspore development. It indicated that the imbalance of active oxygen was one of the mechanism of Tribenuron-methyl induced male infertility in Viola X wittrockiana. |
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