Field Chlorophyll Measurements for Evaluation of Timothy Nitrogen Status for Optimized Seed Yield

Abstract

Leaf chlorophyll content, determined with a portable chlorophyll meter (Minolta SPAD-502) in the field, was used to predict N availability of timothy (Phleum pratense) for high seed production. Critical chlorophyll meter readings (SPAD values) were calculated from data derived from experiments with various N fertilizer levels using the Cate-Nelson procedure. According to the results of this study it can be stated that the critical SPAD values at the beginning of stem elongation (GS 30) were 35 SPAD units for timothy seed yield. The optimum seed yield occurred at 42 SPAD units. Determination of leaf chlorophyll content using the chlorophyll meter could be an effective diagnostic tool for optimizing seed production of timothy by N fertilization.

Key Words:

• chlorophyll content
• seed yield
• timothy