中文摘要：

【目的】明确多效唑喷施时期和剂量对纤用亚麻（LinumusitatissimumL．）农艺性状、产量性状及抗倒伏能力的影响，为亚麻在南方冬闲田的抗倒伏稳产栽培提供参考。【方法】以中亚麻1号为试验材料，在沅江和长沙2个试验点进行试验。在亚麻的3个生长时期（苗期、快速生长期和开花期）分别喷施3种浓度（50、100和200mg/L）的多效唑，成熟期测定亚麻农艺性状、产量性状，并调查其表观倒伏率。【结果】苗期和快速生长期喷施不同浓度的多效唑可明显降低亚麻株高和工艺长度，但不同浓度和不同时期喷施多效唑对亚麻茎粗、分枝数和蒴果数的影响较小。苗期喷施多效唑可显著降低亚麻原茎产量（P〈0．05，下同），快速生长期和开花期喷施则对原茎产量无显著影响（P〉0．05）。在沅江试验点，不同时期喷施不同浓度多效唑均可降低亚麻表观倒伏率，其中快速生长期喷施100mg/L多效唑亚麻表观倒伏率较低（14．17％）且对产量性状影响不明显。相关性分析结果表明，亚麻表观倒伏率与株高、工艺长度和单株茎重呈显著正相关，与种子产量呈显著负相关。【结论】亚麻快速生长期喷施100mg／L多效唑可在不影响其产量的前提下减轻倒伏，是较好的抗倒伏稳产栽培措施。

英文摘要：

[Objective ]The present experiment was conducted to investigate effects of paclobutrazol spraying time and concentration on agronomic characters, lodging resistance and yield of flax, in order to provide references for cultivating lodging-resistant and stable-yieid flax in winter fallow field of Southern China. [Method]With flax variety Zhongyama 1 as materials, the experiments were conducted in Yuanjiang city and Changsha city, respectively. Three concentrations of pa- clobutrazol（50, 100 and 200mg/L） were sprayed on flax plant at three growth stages viz., seedling stage, fast growth stage and flowering stage. Then the agronomic traits, yield traits and apparent lodging rate were determined. [Result ]The results showed that, different concentrations of paclobutrazol spayed at seedling stage and fast growth stage could obviously reduced plant height and technical length. Compared with control, the different spaying time and concentration of paclobu- trazol had less impact on stem diameter, branch number and capsule number of flax. The paclobutrazol sprayed at seedling stage could reduce significantly stem yield （P〈0.05, the same below）, but the paclobutrazol sprayed at fast growth stage and flowering stage had nonsignificant impact on stem yield （P〉0.05）. In Yuanjiang experimental site, the different concentrations of paclobutrazol spayed at different stages could reduced apparent lodging rate. Above all, when 100 mg/L paclobutrazol was sprayed at fast growth stage, the apparent lodging rate of flax was the lowest （14.17%）, and there was nonsignificant impact on yield trait. The correlation analysis showed that the apparent lodging rate had significantly positive con＇elation With plant height, technical length and stem weight per plant, and significantly negative correlation with seed yield. [ Conclusion ] Spraying 100 mg/L paclobutrazol at fast growth stage is a optimal lodging-resistant and stable-yield cultivation method, because it can reduce apparent lodging rate without nonsignificant