Field Crop 2025, Vol.8, No.6, 284-292 http://cropscipublisher.com/index.php/fc 289 6.3 Optimal planting scheme selection and adaptability analysis Which combination is the most suitable? At present, a combination of medium and high broadcast volume and moderate nitrogen reduction is a relatively reliable solution. This can not only increase the output but also reduce the lodging (Figure 2) (Wu et al., 2024). Going deeper, meticulous management techniques like Rapid Fertilization (FRF) also have the potential to further enhance yield stability. In terms of species, early-maturing indica rice is particularly suitable for direct seeding in double-cropping rice systems, which can be seen from the experimental performance. Both its yield and lodging resistance are not bad. But don't forget that the soil fertility and climate vary from place to place. To achieve success, it still depends on the management of specific plots as a guarantee. Especially in areas with abundant rainfall, if not properly managed, problems such as nutrient loss and even soil erosion are likely to occur. Overall, as long as it is equipped with appropriate agronomic measures, mechanical direct seeding rice can still gain a firm foothold in South China and become a good option for stable production, high efficiency and adaptation to climate change. Figure 2 Lodging index (LI) under different seeding rates and nitrogen application rates in direct-seeded and double-season rice. (A-D) represented early season 2020, late season 2020, early season 2021, and late season 2021, respectively. LSR, low seeding rate (30 cm × 18 cm); HSR, high seeding rate (30 cm × 12 cm); N1, nitrogen fertilization at 100 kg/ha; N2, nitrogen fertilization at 150 kg/ha; N3, nitrogen fertilization at 200 kg/ha; HHZ, Huanghuazhan; XYXZ, Xiangyaxiangzhan. Different lowercase letters indicate statistical significance between treatments (p< 0.05) (Adopted from Wu et al., 2024) 7 Recommendations for Optimized Cultivation and Promotion 7.1 Recommended ranges for optimal sowing date and planting density When is the best time to sow seeds? This issue cannot be addressed in a one-size-fits-all manner, but experience tells us that the 10 to 15 days before the start of the rainy season is a relatively safe time window, mainly to ensure sufficient soil moisture so that seeds can germinate smoothly and seedlings can grow solidly. In subtropical regions, it is usually from late May to early June. However, it is not accurate every year. The climate fluctuates greatly and specific arrangements should be made based on the local annual rainfall rhythm (Santiago - Arenas et al., 2022). In terms of density, the currently recommended mechanical row seeding rate is 30 to 70 kilograms per hectare. This range can balance uniform seedlings, reasonable density and maximum yield, and also control the cost of seed input. However, one should not merely focus on the broadcast volume; the depth of broadcast is equally crucial. Under dry sowing conditions, the seedlings are generally kept at a depth of 2 to 3 centimeters. For wet sowing, they should be slightly deeper, controlled between 3 and 5 centimeters, so that the seedlings can emerge more evenly and uniformly.
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