Objectives Fenlong is a new tillage method that is operated by machine to a depth of 40 cm to break soil hard plant effectively. We studied its beneficial effects on soil and sugarcane plant for the adoption of the new tillage technology.
Methods Sugarcane cultivar of Guitang42 was used as the test crop in a two-year field experiment in Guangxi Province. The traditional plough (25 cm deep) was used as the control (CK) and Fenlong tillage (40 cm deep) as the treatment. Sugarcane was planted with plant bud (new cane) and ratoon (ratoon cane). The bulk density and available NPK contents of soils were measured in the main growing stages of sugar cane. The agronomic traits of sugarcane, the vascular bundle morphology and root activity, and the nitrogen metabolism related enzyme activity in leaves were measured.
Results Fenglong tillage significantly reduced soil bulk density by 8.6% to 16.9%, increased soil available N and P by 8.7%–77.6% and 8.2%–25.6%. Compared with CK, the Fenlong tillage raised leaf N and P concentrations by 11.4%–19.4% and 5.3%–34.8%, respectively, increased the seedling rate, tillering rate, plant height, stem diameter, effective stems and yield significantly. Using Fenglong tillage, the vascular bundles of sugarcane plants were larger and more densely distributed, and the number of vascular bundles, vascular bundle area, vessel diameter of metaxylem and phloem area of new sugarcane were increased by 15.2%, 28.0%, 7.8% and 29.7%, respectively, and those of ratoon cane were increased by 16.7%, 17.8%, 7.9% and 30.8%, respectively; the root activity was significantly increased throughout the growth period by 1.25–1.39 times. At the seedling stage, the activities of glutamine synthase (GS) and amino acid synthase (GOGAT) in new cane were enhanced by 149.6% and 40.3%, and the indexes of ratoon cane were 65.9% and 37.9% higher, respectively, as compared to control. Fenlong tillage significantly enhanced nitrite reductase (NR) activity of ratoon cane at the elongation stage by 9.5%, and the GS and GOGAT activities by 36.5% and 69.1%. The indexes of ratoon cane were 36.0% and 42.4% higher with Fenglong than those of control, respectively at the mature stage, and the activities of glutamine synthase (GS) in newly planted sugarcane were 65.6% and the indexes of ratoon cane were 93.3% higher than those of control.
Conclusion Fenlong tillage can significantly increase soil nutrient availability and their uptake by sugarcane plants, improve the vascular bundle structure and the activities of enzymes related to N metabolism and root activity. As a result, it promotes the uptake and translocation of water and nutrients, especially N metabolism and amino acid synthesis, providing a material basis for protein synthesis, facilitating plant growth and development on the ground, and increasing sugarcane yield and sugar content.
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