Interactive effect of gibberellic acid and NPK fertilizer combinations on ramie yield and bast fibre quality

Understanding the effects of different combinations of nitrogen (N), phosphorus (P) and potassium (K) fertilizers and the effects of GA(3) (gibberellic acid) foliar spray on the fiber quality and yield of ramie are important for maximizing the economic value of these plants. Three pot experiments were conducted using low NPK (140: 70: 140 kg/ha), normal NPK (280: 140: 280 kg/ha), and low NPK + GA(3) (10 mg/L) treatments. In each experiment, following fertilizers were applied: no fertilizer (control), N, P, K, NP, NK, PK, and NPK. Ramie was harvested three times from each plant; ramie grown without fertilizers had significantly lower biomass and yield than plants grown with fertilizers. At both normal and low fertilization rates, application of NPK resulted in greater growth and yield than application of N, P, K, NP, NK, or PK. Unfertilized plants produced the thinnest fibres (22-24 mu m), with lowest elongation rate (3.0-3.1%) and breaking strength (22.7-23.3 cN). Fibre yield and fibre quality were improved by application of GA(3) + fertilizers. Maximum fibre yield was obtained at low NPK + GA(3) treatment, resulting in 65-81% more yield than low NPK alone. GA(3) with low NPK treatment significantly improved fibre diameter, fibre elongation, and breaking strength compared to both NPK alone and control treatment.