Screening of Suitable Cutting Height for Pennisetum giganteum in the Subtropical Region of the Central Yunnan Plateau

Purpose The aim of this study was to screen the most suitable cutting height of Pennisetum giganteum in the subtropical region of the Central Yunnan Plateau, providing reference for the cultivation and planting of this forage.

Methods Four cutting heights, including 100, 150, 200, and 250 cm (control), were set to compare and analyze the yield and nutritional quality of P. giganteum at different cutting heights. The fuzzy mathematical membership function method was employed to comprehensively evaluate the production performance and nutritional quality of P. giganteum at different cutting heights.

Results With the increase of cutting height, the total yield of P. giganteum over three years showed an upward trend, reaching the highest (405.6 t/hm²) at a cutting height of 250 cm, but there was no significant difference compared with the cutting height of 200 cm (383.2 t/hm²) (P>0.05). The reviving rate, reviving height, and tiller number were negatively correlated with the cutting height. Compared with the cutting height of 250 cm, the reviving rate, reviving height, and tiller number of P. giganteum under the cutting heights of 100, 150, and 200 cm significantly increased (P<0.05). In terms of nutritional quality, as the cutting height increased from 100 cm to 250 cm, the dry matter, water-soluble carbohydrate, neutral detergent fiber, acid detergent fiber, and lignin contents exhibited an significant increasing trend (P<0.05), while the crude protein content significantly decreased (P<0.05).

Conclusion Comprehensive evaluation indicates that the suitable cutting height for P. giganteum in the subtropical region of the Central Yunnan Plateau is 150 to 200 cm.