Effects of Cultivar and Planting Density on Growth Traits, Yield, and Feeding Quality of Silage Maize Under Arid Irrigated Conditions in Xinjiang, China

Arid regions of Xinjiang are characterized by abundant solar and thermal resources but limited precipitation, making appropriate matching of silage maize (Zea mays L.) cultivars with planting density an important strategy for improving the productivity and feeding quality of silage maize. To characterize cultivar-specific responses to planting density and identify cultivar–density combinations with superior overall performance, a two-year field experiment was conducted in Bole, Xinjiang, China, during 2025–2026. A two-factor randomized block design comprising four maize cultivars and five planting densities was used. Growth traits, yield, and feeding quality were evaluated at the milk stage, and Pearson correlation analysis, structural equation modeling (SEM), and a hierarchical combined-weight TOPSIS method were used for comprehensive assessment. Cultivar and planting density significantly affected multiple growth, yield, and feeding-quality traits, whereas cultivar × planting density interactions were trait-dependent. C3 (Xinsiyu 12) generally exhibited higher fresh forage yield, dry matter yield, and crude protein content, whereas D3 (105,000 plants ha−1) performed favorably in terms of fresh forage yield, dry matter yield, and dry-to-fresh ratio. Among the cultivar–density combinations, C3D3 (Xinsiyu 12 × 105,000 plants ha−1) produced the highest fresh forage and dry matter yields in both years, exceeding those of the locally conventional C1D3 treatment (Xianyu 1321 × 105,000 plants ha−1) by 22.38% and 15.60% and by 19.10% and 13.04% in 2025 and 2026, respectively. Its crude protein and starch contents were also higher than those of C1D3 by 29.86% and 33.90% and by 18.72% and 17.77%, respectively. SEM indicated positive associations of LAI and plant height with fresh forage yield. The hierarchical combined-weight TOPSIS analysis ranked C3D3 first, with the highest comprehensive score of 0.7937. Overall, Xinsiyu 12 grown at 105,000 plants ha−1 provided a favorable balance between yield and feeding quality and represents a promising cultivar–density combination for Bortala, Xinjiang, and other arid irrigated regions with similar agroecological conditions.