2019 ASHS Annual Conference

This study was conducted to determine the effects of nitrogen and boron on celtuce (Lactuca sativa L. var. augustana) yield and quality in hydroponics system. Two commercial celtuce cultivars ‘Celtuce’ and ‘Summer 38’ were selected for morphological and physiological differences that could potential affect the yield and quality. The study was conducted in 2018 and 2019 in a hydroponics system with 32 troughs and 8 independent nutrient solution resivioir systems on the North Carolina State University campus, Raleigh, NC. Plants received 8 different nutrient levels as the combination of 4 nitrogen levels (50, 100, 150, 200 mg·L^-1) and 2 boron levels (0.5, 1 mg·L^-1) through a constant feed system. Photosynthetic rates were measured 5 days after transplanting to the hydroponic system and then measured every 10 days. When harvested, stem fresh weight, dry weight, length, diameter, firmness, soluble solids content, nitrate content and leaves fresh weight, dry weight, number, soluble solids content, nitrate content were measured. The cultivar ‘Celtuce’ had overall significantly better yield and quality than ‘Summer 38’ under same conditions. Higher nitrogen treatments resulted in higher photosynthetic rates throughout the cultivation period. The 100 and 150 mg·L^-1 nitrogen levels significantly increased the yield and quality of celtuce by increasing the stem fresh weight, stem length and diameter, and soluble solids content. Plants under 50 mg·L^-1 nitrogen had significantly lower yield. The 200 mg·L^-1 nitrogen treatment improved the yield and quality, but also increased the nitrate content of celtuce. The 1 mg·L^-1 boron level resulted in increased diameter and firmness of the stem. These results indicate that hydroponic production of celtuce with varying nitrogen and boron levels can increase the yield and quality of finished product.