Plant Gene and Trait 2025, Vol.16, No.3, 113-122 http://genbreedpublisher.com/index.php/pgt 114 while also maintaining soil nutrients (Tripathi et al., 2020; Manju et al., 2025). Generally speaking, based on the different densities of tree planting, high-density systems can be divided into common high-density (such as 800 to 3 000 trees per hectare) and ultra-high-density (more than 4 000 trees per hectare) (Ladaniya et al., 2020; Tripathi et al., 2020). The density level varies depending on the type and variety of fruit trees, the selection of rootstocks, management methods and planting purposes. In addition, there are many types of planting layouts, such as square planting, diagonal planting, single row, double row and cluster planting, etc. This can better adapt to different mechanization requirements and management methods (Tripathi et al., 2020; Das et al., 2023). 2.2 Historical evolution in viticulture practices Over the past few decades, the costs of land and labor have been rising continuously, and the demand for high-yield and high-quality fruits has also been increasing. So fruit trees like grapes also began to adopt high-density planting. This approach has become a very important technique in modern orchard management (Tripathi et al., 2020; Manju et al., 2025). Traditional vineyards usually have relatively large plant and row spacings, resulting in low land utilization and difficulty in increasing yields. High-density planting, by reducing the row and plant spacing, selecting dwarf varieties or rootstocks, and combining with the technology of regulating plant growth, enables orchards to produce more per unit area and obtain profits earlier (Tripathi et al., 2020; Manju et al., 2025). This approach is also more suitable for mechanized operations, saving manpower, improving the utilization rate of resources, and making grape cultivation more efficient and intelligent (Tripathi et al., 2020). 2.3 Key agronomic parameters (spacing, row orientation, trellis design) In high-density vineyards, key planting parameters such as plant spacing, planting direction, and twill structure will directly affect the growth of grapevines, light, ventilation effect, convenience of machine operation, and the quality of fruits (Tripathi et al., 2020; Keller and Mills, 2021; Manju et al., 2025). High density usually adopts a relatively compact planting method. For example, the plant spacing is between 0.91 and 2.5 meters, and the row spacing is between 2 and 3 meters. In this way, more grapevines can be planted in the same field (Ladaniya et al., 2020; Keller and Mills, 2021; Manju et al., 2025). However, too high a density also has problems. It can make the tree canopy too dense, which is not conducive to ventilation and light, thereby affecting fruit development and quality (Keller and Mills, 2021). Choosing the right row direction is also very important. For example, planting in the north-south direction can make the sunlight exposure more uniform, which is conducive to fruit ripening and sugar accumulation, and can also make the fruit color more attractive. In addition, the trellises commonly used in high-density orchards are also more suitable for machine harvesting, such as V-shaped, Y-shaped or horizontal trellises. These structures can better manage the tree canopy, control pests and diseases, and also facilitate mechanical operations (Tripathi et al., 2020; Manju et al., 2025). 3 Mechanical Harvesting in Viticulture 3.1 Types of mechanical harvesters and working principles There are mainly two types of mechanical grape harvesting equipment: one is semi-hanging type, which requires a tractor to tow; Another type is self-propelled, with its own power system, which can move by itself in the orchard (Da Costa Neto et al., 2019). This type of machine usually vibrates or shakes the grapevines to make the fruits fall off, and then collects the fruits with the device inside the machine. Modern harvesters like the PELLENC 8090 Selective Process not only have highly efficient vibration systems but also can automatically separate fruits, suitable for the harvesting requirements of different plots and varieties (Figure 1) (Da Costa Neto et al., 2019; Burg et al., 2021). 3.2 Benefits and limitations of mechanical harvesting The greatest advantage of mechanical harvesting is that it saves labor and time, and its efficiency is much higher than that of manual harvesting. It is particularly suitable for situations where there is a shortage of manpower or the orchard area is relatively large (Burg et al., 2021; Coşkun, 2023; Sanjay et al., 2024). In orchards with large-scale planting, such as those over 41.92 hectares, the cost of mechanical harvesting is significantly lower than that of manual harvesting (Aguila and Domingues, 2016; Strub et al., 2020). Moreover, many studies have
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