Sugarcane is an important crop for sugar and biofuel production worldwide. It is mostly grown on hilly area by smallholders in China, which makes harvesting by a combine harvester impractical. Harvesting sugarcane by a small-scale harvester could be more practical. However, information about the impact of small-scale mechanical harvesting on soil compaction (SC), early growth and cane yield, and its yield components is still limited. The scarcity of quantitative information is equally true for the genotype and harvesting method interaction for traits describing early growth and final yield in sugarcane. Field experiments were conducted in a plant and two consequent ratoon crops (RCs) during 2016–2018 in Kaiyuan, Yunnan Province, China, to determine the impact of small-scale mechanical harvesting followed by tractor passages (SMH) on SC, sugarcane early growth and yield, and yield components, and to determine the genotype x treatment (harvesting methods, GT) interactions. The results indicated that, when compared to manual harvesting (MH), SMH significantly (p < 0.05) increased SC at 5, 10, and 20 cm depths by 0.6, 0.71, and 0.69 MPa for the first ratoon crop (RC), respectively; and increased by 1.4, 2.02, and 1.72 MPa at 10, 20, and 30 cm depths for the second RC, respectively. The amounts of underground bud bank (UBB) in RCs were nearly nine times the buds for establishing the plant crop (PC); positive correlations between the UBB and seedling counts were observed, with the highest correlations (r = 0.8453) occurring in May for the second RC. As compared with MH, stool damage and gaps were significantly higher in SMH; meanwhile, the UBB was lower in two RCs; the amount of seedlings, plant height, and height uniformity were significantly lower in SMH. Cane yield declined more in SMH, particularly declining by 20.59% from the first RC to the second RC. With respect to sugarcane production by SMH, the existence of significant GT interactions for stool damage, gaps, early seedling, millable stalks, and height uniformity at the maturing stage suggested that genotype selection trials should be conducted under the SMH rather than in MH.

Sugarcane is a complex polyploid aneuploid cash crop, and transgenic varieties are important for molecular genetic and traditional breeding approaches. Herein, the sugarcane variety ROC22 served as the receptor, the Bar gene served as a screening marker, and positive and negative fragments of the ScD27.2 gene, upstream of strigolactones (SLs) biosynthesis genes driven by the 35S promoter, were introduced by Agrobacterium tumefaciens-mediated transformation. Regenerated plants were obtained by co-culture, screening culture, and differentiation induction, and 27 sense and antisense ScD27.2 transgenic seedlings were obtained by herbicide screening. PCR detection and 1% Basta (Glufosinate) application on leaves revealed Bar in all lines, with all testing positive for herbicide application and 23 containing the target gene (positive resistance screening rate = 87.5%). q-PCR and phenotypic analyses showed that ScD27.2 expression, plant height, tiller number, root length, stem diameter, and fresh weight were decreased in transgenic (ScD27.2R-9) compared with non-transgenic (NT and ScD27.2F-2) lines. ScD27.2 expression was downregulated, and growth potential was inhibited. Under 20% PEG treatment, malondialdehyde (MDA) content in ScD27.2R-9 was higher than in NT, while proline content was lower. Under drought stress, ScD27.2 expression, MDA levels, and proline content in ScD27.2F-2 and NT were higher than in non-treated controls, ScD27.2 expression increased with time, and MDA and proline levels also increased. ScD27.2 expression in ScD27.2R-9 decreased under 20% PEG treatment, MDA and proline increased (but not to NT levels), and growth was lower than NT. The 20% PEG treatment also increased the levels of (±)-2′-epi-5-deoxystrigol and (+)-abscisic acid in the rooting culture media of ScD27.2F-2, ScD27.2R-9, and NT lines, but the levels of (+)-abscisic acid content in ScD27.2R-9 was lower than in NT. Thus, interfering with ScD27.2 expression decreased resistance to 20% PEG treatment. ScD27.2 encodes a β-carotene isomerase involved in SLs biosynthesis that might function in sugarcane resistance to drought stress. It explains the role of SLs in sugarcane growth and development and responses to drought stress.

Monoculture of single varieties tends to exacerbate risks associated with pest outbreaks, disease epidemics, and lodging. Plant diversification strategies, including intraspecific cultivar mixtures, offer an ecological solution to these challenges. Across major crops, cultivar mixtures have been shown to reduce disease severity, enhance yield stability, and improve lodging resistance through both mechanical support and enhanced stem strength. In sugarcane, varieties differ substantially in their resistance to smut, stem borers, and lodging, suggesting that strategic mixing of resistant and susceptible genotypes could help limit pathogen spread, mitigate insect damage, and reduce the incidence of lodging. Nevertheless, the practical implementation of such mixtures in sugarcane faces several bottlenecks: low propagation coefficient, high seed-cane demand, need for compatible combinations, and long-term stability over ratoon cycles. To address these constraints, future research should focus on developing predictive tools for assessing variety compatibility, conducting multisite field trials, and establishing agronomic guidelines for mechanized operations. Ultimately, translating diversity mixtures into sugarcane fields promises to overcome continuous cropping obstacles and promote sustainable production.