关键词: 生物量, 密植, 光照强度, 刈割, 光合作用, 甜高粱, 分蘖

Abstract: INTRODUCTION: Light intensity is an important environmental factor affecting plant photosynthesis. High-density planting, an important crop cultivation practice for high yields, can reduce canopy light intensity. Under field conditions, canopy light intensity can affect yield formation by influencing the rate of photosynthesis and the number of plant tillers. Given the large size of sweet sorghum plants and the tendency of the canopy to be depressed, we hypothesized that mowing could help to improve photosynthetic rate and tillering, and thus population biomass formation, by improving the light environment within the canopy in high-density planted sweet sorghum. RATIONALE: There is currently a serious shortage of high-quality forage in China. Sweet sorghum, a high quality forage crop ideal for silage, has attracted considerable attention due to its high biomass production and excellent palatability. This study aims to elucidate the patterns and physiological-ecological mechanisms by which mowing increases the population biomass of sweet sorghum, thus providing a theoretical basis for high-yield sweet sorghum cultivation. RESULTS: With increasing planting density, the main stem height of sweet sorghum increases, while stem diameter and leaf area decrease, accompanied by a reduction in the number of tillers. At the same time, higher planting density reduces canopy light intensity, leaf photosynthetic performance and fresh weight per plant, although fresh forage yield increases significantly. Mowing significantly increases the number of tillers in all density treatments and reduces tiller mortality. In addition, mowing significantly improves canopy light conditions, leaf photosynthetic efficiency and plant fresh weight in densely planted sweet sorghum, further increasing fresh grass yield. Analysis shows that average canopy light intensity and net photosynthetic rate of functional leaves on the main stem are the main factors influencing actual tiller number and main stem fresh weight, respectively. CONCLUSION: High density planting is an important cultivation measure for high yields of sweet sorghum. Mowing can improve the light environment within the canopy of densely planted sweet sorghum, thereby increasing the photosynthetic rate and the number of tillers per plant, and further increasing the population biomass.

Key words: biomass, high density planting, light intensity, mowing, photosynthesis, sweet sorghum, tillering