本试验旨在研究棉秆剪切力与营养成分含量之间的相关关系。将棉秆按照近地面1/3（下1/3）、中部1/3（中1/3）和上部1/3（上1/3）切为3段，测定各段的质量和长度，计算线性密度；测定茎秆和侧茎的剪切力及主要营养成分的含量。结果表明：棉秆线性密度及直径由上至下逐渐升高，3段之间差异显著（P<0.05）；全株棉秆粗蛋白质含量为8.78%；中性洗涤纤维在茎秆下1/3含量（62.54%）最高，棉叶中含量（35.51%）最低；棉秆茎秆中粗蛋白质及粗灰分含量与剪切力间呈负相关关系（P<0.001）；干物质、中性洗涤纤维、酸性洗涤纤维及半纤维素含量与剪切力呈正相关关系（P<0.001）。棉秆不同部位中，剪切力大小主要受其直径和营养成分含量的影响，棉秆的剪切力与营养成分含量之间具有较强的线性关系。

This experiment was conducted to study the correlations between shearing force and nutrient contents of cotton stem. Cotton stems were cut into three parts at 1/3 from bottom (bottom 1/3), 1/3 in the middle (middle 1/3) and 1/3 from top (top 1/3), respectively. The mass and length of different parts were tested, and the linear density was calculated; the shearing force and main nutrient contents of stem and lateral branch were determined. The results showed as follows:the linear density and diameter increased from top to bottom, and the differences among three parts were significant (P<0.05); crude protein content of whole cotton stem was 8.78%; neutral detergent fibre content in stem bottom 1/3 was the highest (62.54%), while that in cotton leaves was the lowest (35.51%); crude protein and ash contents had negative correlations with shearing force (P<0.001); dry matter, neutral detergent fibre, acid detergent fibre and hemicellulose had positively correlations with shearing force (P<0.001). In conclusion, in different parts of cotton stem, shearing force is mainly affected by diameter and nutrient contents, and strong linear relationships exist between shearing force and nutrient contents.