COMPARISON OF SPAD 502 CHLOROPHYLL METER AND CARDY NO3 METER WITHTRADITIONAL METHODS OF DETERMINING PLANT NITROGEN STATUS

摘要

A nitrogen rate evaluation was conducted at sites in Missouri and Mississippi in 2002. Four methods of midseason N monitoringwere compared for two different growth stages, first flower plus 3 weeks and cut out. No method for either growthstage was well correlated to cotton lint yields. All monitoring methods were more predictive of yields at first flower + 3weeks than at cut out. Dry petiole N% at first flower + 3 weeks had the greatest correlation (R2 = 0.46) followed by theCardy NO_3 meter (R~2 = 0.34).