Nutritional Composition and Productivity of cv. "Mombasa" Under Different Levels of Nitrogen Fertilization and Water Deficit.

This study investigates the production and nutritional quality of cv. Mombasa grass under varying levels of water stress and nitrogen (N) fertilization, aiming to enhance forage production in harsh environments. Four irrigation levels (5760, 6912, 4608, and 3456 m ha year) and three N fertilizer doses (115, 57.5, and 0 kg ha year) were tested. The results indicate that Mombasa grass produced higher fresh and dry weights under higher irrigation levels (I1 and I2) compared to water deficit conditions across all cuts. Interestingly, under moderate water stress (I3), the dry weight was not significantly different from that under higher irrigation for the sixth harvest in the first season. Water deficit conditions led to a significant reduction in protein content across all treatments. However, under lower irrigation levels (I3 and I4), there was a significant increase in phosphorus (P), potassium (K), iron (Fe), and zinc (Zn) concentrations. A heatmap analysis of shape descriptors grouped the productivity and nutritional traits into two clusters based on their response to combined fertilization and drought stress. This analysis revealed that the dry weight, number of leaves, and Fe and Zn contents were positively affected under moderate water stress (80% of control; 4608 m ha year) with recommended N fertilization. The study concludes that cv. Mombasa is tolerant to moderate water stress and is suitable for forage production in the Qassim region, Saudi Arabia.