Midrib Nitrate Concentration as a Means for Determining Nitrogen Needs of Broccoli

Plant analysis has been used to evaluate the nutritional status of many crops for diagnostic and corrective purposes. This study was initiated to establish critical N plant tissue levels using midrib NO3-N concentration for broccoli (Brassica oleracea L., Botrytis group) during the growing season. Tissue samples for nitrate analysis were taken from broccoli plants over a period of three growing seasons beginning at the 4 to 6 leaf stage of growth and biweekly through pre-harvest. The midrib from the most recently matured leaf was sampled for NO3-N concentration determination.