Effects Of GA₃and CPPU Applications On Fiber Quality And Yield Of Ramie

Ramie (Boehmeria nivea L.),belonging to Urticaceae Boehmeria, is a perennial herb bast fiber crops. It is one of the most important fiber plants in our country, with a long history of cultivation and processing. Textiles of ramie fiber are popular among customers at home and abroad for such advantages as good air permeability, cool wearing experience. So the need of ramie fiber in high quality is increasingly urgent to meet the market demand. Becaose of the shortage of labor force and planting area, the supply of raw ramie is insufficient.In this study, we sprayed plant growth regulators (GA3and CPPU) in five different concentrations on Huazhu No.4to investigate their influences on fiber yield and quality and the mechanism. The results may provide a theoretical basis for the application of plant growth regulators on ramie to improve the yield and quality of ramie fiber.The main results are as follows,Influences on photosynthesis of ramie:in the first and third harvest season, the treatment of spraying GA3promoted photosynthesis at first while prohibited it afterwards. By contrast, treatment in the second harvest season showed the opposite effect. The treatment of CPPU had different influence from that of GA3, it had different effects on photosynthesis at different season and in different concentration. Generally speaking, the influences of low concentration is better than high concentration.Influences on activity of POD in ramie leaf:in the second harvest season, the treatments of10mg/L and40mg/L GA3promoted POD activity all the time, while the treatments of other concentrations showed stimulative effect at first and prohibitive effect afterwards; the treatments of CPPU showed stimulative effect at first and prohibitive effect afterwards. In the third harvest season, all treatments of GA3showed stimulative effect at first and prohibitive effect afterwards; the treatments of40mg/L and80mg/L CPPU showed promotional effect all the time. The treatments of other concentrations of CPPU showed stimulative effect at first and prohibitive effect afterwards.Influences on yield:the application of both GA3and CPPU could increase the yield of ramie fiber. And with the concentration increased, the yield first increased and then decreased. The highest yield was reached when the concentration of both GA3and CPPU is10mg/L, with an increase of24.93%and12.46%compared with control respectively. When the concentration of CPPU increased, the yield of ramie first increased and then decreased, which may be due to the inhibition of photosynthesis under high CPPU concentration. The application of GA3and CPPU in low concentration increased its fiber ratio from fresh stem and fresh bark. The best effects came when the concentrations of GA3are10mg/L and20mg/L, and the concentrations of CPPU are5mg/L and10mg/L.Influences on fiber quality:the application of GA3on ramie in the first and third harvest season had no significant influence on gel content.40mg/L GA3could significantly decrease the gel content of ramie the second harvest season; the application of CPPU had no significant effect on ramie in all three harvest season, but CPPU in low concentration decreased the gel content of ramie. The application of20mg/L CPPU showed the best effect of decreasing gel content.The application of GA3and CPPU had no significant influence on fiber breaking strength, breaking elongation rate, fiber fineness and crystallinity of ramie on the whole.Ultimately,10mg/L is recommended to be the optimal concentration for both GA3and CPPU when they are applied in ramie production.