The line intersection method to estimate total foliage length in Potamogeton pectinatus L

• Published in: Aquatic botany 2000-09, Vol.68 (1), p.79-85
• Main Authors: Sidorkewicj, N.S, Fernández, O.A
• Format: Article
• Language: English
• Subjects: Freshwater; Intersection method; Potamogeton pectinatus; Total plant length
• ISSN: 0304-3770; 1879-1522
• DOI: 10.1016/S0304-3770(00)00107-8

A non-destructive line intersection method, earlier used to measure total length of roots of terrestrial plants, is described to estimate the total foliage length of individual plants of Potamogeton pectinatus L. Plant foliage was spread over an acrylic plate, and copied using a photocopier. Photocopied stems and leaves that intersected horizontal and vertical lines of three sizes of transparent grids (1 cm×1 cm, 2 cm×2 cm, 3 cm×3 cm) were counted, added and multiplied by a conversion factor ( F: 0.0078, 0.0158 and 0.0233 m per intersection for the three grid sizes, respectively) to obtain total foliage length (in meters). Estimates obtained using the line intersection method and measurements of actual length made using an opisometer were significantly correlated ( p0.25). Estimated values (±S.E.) were 0.19 m (±0.22) for the Y-intercept, and 0.99 (±0.01) for the slope. From the results obtained, it can be concluded that the line intersection method using a 3 cm×3 cm grid is a workable alternative to estimate total foliage length in fine-leaved and branched plants, owing to its high precision and accuracy, and the short time required for preparing and measuring the plant material.