Growth and nutrient content of hybrid bermudagrass grown for nursery purposes at different nitrogen, phosphorus, and potassium rates

The objective of this research was to study the effect of different nitrogen (N), phosphorus (P), and potassium (K) rates on growth and nutrient content of hybrid bermudagrass (Cynodon dactylon x C. transvaalensis) grown in pots for nursery purposes (producing stolons to obtain one-node sprigs to be used as propagation material). Starting from control N, P, and K rates (314, 52, and 198 mg L-1 substrate, respectively), each element was reduced to zero, halved, doubled, or tripled while the other two were kept unchanged (13 treatments in all). As expected, N, P, and K proved to be necessary for plant growth and development. In fact, when one element was not supplied, plants showed reduced growth and pale-green color. The dry weight of aerial part (shoots plus stolons) was mainly affected by N and increased along with this element with a nonlinear less than proportional trend. Phosphorus had a larger effect than N or K on the number of primary stolons, which varied along with P rate fitting a nonlinear regression model. Potassium rate influenced the characteristics of primary stolons (length, number of nodes, and ramifications) more than N or P. A significant linear regression was observed for the number of ramifications (secondary stolons), while stolon length and the number of nodes fit a nonlinear regression model. Plant growth response to the imposed rates revealed the possibility to halve N or P in respect to control rates, while for K the control rate proved to be necessary. In fact, when K rate was halved, the number of nodes, which is a main parameter for nursery purposes, significantly decreased. Half N, half P, and control K rates also ensured a satisfactory plant mineral composition, consistent with values previously reported for bermudagrass. Potassium competition with both calcium and magnesium was observed. Nitrogen, P, or K rates higher than the respective controls are not advisable since they did not enhance plant growth or mineral content.