- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
Productivity of intensive rice cropping systems plays a pivotal role in national food security in China. By 2030, a 20% increase in rice yield will be required to meet the growing demand for food that will result from population growth. The success of China’s super hybrid rice was expected to provide an opportunity to cope with the increased demand for rice. However, in China the planting area of super hybrid rice is less than 8% of the national total rice planting area and the planting area of hybrid rice has continued to decline since 1996. The decreased planting area of hybrid rice is related to the shift in rice establishment methods from manual transplanting to direct seeding and mechanical transplanting. These shifts can result in increased seeding rates and reduced morphological advantages of heterosis (e.g. reduced panicle size), both of which can influence cultivar choice by rice farmers, who will tend to favor cheaper inbred cultivars. The shifts in rice establishment methods can also eliminate or reduce the seedling nursey period and subsequently shorten the growth duration and negatively affect the yield. We anticipate that the above problems will be resolved by integrating mechanization (e.g. designing high-precision seed sowing machines) with agronomy (e.g. improving management practices for increasing seed vigor) and breeding (e.g. developing high-yielding cultivars with short growth durations). This strategy also has implications for production of other crops in intensive farming systems in China and for other developing countries with rice-based intensive cropping systems.
3. Strategies for improving rice production in China
To overcome the above constraints on rice production in China, it is necessary to develop new technologies. One strategy to reduce seed costs in direct-seeded and machine-transplanted hybrid rice production is to reduce seed prices, which can be achieved by reducing the cost of seed production through developing mechanized seed production technologies (Peng, 2016). Another strategy is to reduce seeding rates. Improving seed sowing accuracy is the first step to reducing seeding rates for both direct-seeded and machine-transplanted rice, and designing high-precision seed sowing machines is the most effective way to achieve this step. In recent years, remarkable advances have been made in improving rice seed-sowing machines in China. For example, the South China Agricultural University has invented a precision hilldrop drilling machine for direct-seeded rice production (Luo et al., 2008), and the Hunan Agricultural University has developed a mechanical single-seed sowing system for single-seedling machine-transplanted rice (Fig. 5). It is reported that 30–75% of rice seeds can be saved by adopting these machines, and seedling age can be prolonged by 7–10 days for machine-transplanted rice due to increased room for seedling growth.