Marandu Palisadegrass Mineral Nutrition and Production Related to Nitrogen and Potassium Supply

Nitrogen (N) and potassium (K) fertilization play a key role in forage crops and can significantly increase yields of ‘Marandu’ palisadegrass Brachiaria brizantha (Hochst. exA. Rich.) Stapf.], one of the most important forage crops in Brazil. This study aimed to identify the concentrations of total N and K, nitrate (NO₃^?), and ammonium (NH₄⁺), chlorophyll meter readings (SPAD), and nitrate reductase activity (At-RNA) required to maximize yield. Plants were grown in quartz substrate and treated with nutrient solutions that ranged from 2 to 33 mmol L^?1 for N and 0.5 to 11 mmol L^?1 for K. Dry matter production and At-RNA increased with increasing N and K supplies. SPAD readings correlated strongly with N leaf concentration and dry matter production and can be used to assess the N status of this species. The supply of N and K in the fertilization promoted high yield and adequate N and K concentration for plant metabolism.