Improving both grain yield and resource use efficiencies simultaneously is a major challenge in rice production. However, few studies have focused on integrating dense planting with delayed and reduced nitrogen application to enhance grain yield, nitrogen use efficiency (NUE) and radiation use efficiency (RUE) in rice (Oryza sativa L.) in the double rice cropping system in South China. A high-yielding indica hybrid rice cultivar (Yliangyou 143) was grown in field experiments in Guangxi, South China, with three cultivation managements: farmers’ practice (FP), dense planting with equal N input and delayed N application (DPEN) and dense planting with reduced N input and delayed N application (DPRN). The grain yields of DPRN reached 10.6 and 9.78 t ha^–1 in the early and late cropping seasons, respectively, which were significantly higher than the corresponding yields of FP by 23.9–29.9%. The grain yields in DPEN and DPRN were comparable. NUE in DPRN reached 65.2–72.9 kg kg^–1, which was 61.2–74.1% higher than that in FP and 24.6–30.2% higher than that in DPEN. RUE in DPRN achieved 1.60–1.80 g MJ^–1, which was 28.6–37.9% higher than that in FP. The productive tiller percentage in DPRN was 7.9–36.2% higher than that in DPEN. Increases in crop growth rate, leaf area duration, N uptake from panicle initiation to heading and enhancement of the apparent transformation ratio of dry weight from stems and leaf sheaths to panicles all contributed to higher grain yield and higher resource use efficiencies in DPRN. Correlation analysis revealed that the agronomic and physiological traits mentioned above were significantly and positively correlated with grain yield. Comparison trials carried out in Guangdong in 2018 and 2019 also showed that DPRN performed better than DPEN. We conclude that DPRN is a feasible approach for simultaneously increasing grain yield, NUE and RUE in the double rice cropping system in South China.

The introduction and use of foreign germplasms have played an important role in the improvement of crop varieties in China.  Based on published materials and scientist interviews, we collected data on the sown area, morphological characteristics, and pedigree of the popular rice varieties grown in the 15 major rice production provinces and 1 autonomous region in China, from 1982 to 2011.  Results showed that China’s scientists developed the largest number of rice varieties worldwide, and that rice yield potential and grain quality have substantiality improved during the studied period.  In contrast, resistance of newly-released varieties to diseases and insect pests has decreased since the 1990s.  Germplasms from the International Rice Research Institute (IRRI) and from Japan have contributed 16.4 and 11.2% of genetic materials to China’s rice varieties developed between 1982 and 2011, respectively.  While IRRI’s materials contributed to the improvement of yield potential, growth duration, and blast and bacterial blight resistance, Japanese materials contributed to the improvement of grain quality.  Materials from other countries contributed to the improvement of resistance to diseases and insect pests, particularly to rice blast disease, brown planthoppers, white-backed planthoppers, and striped stem borers.

Chinese farmers are often accused of overusing pesticides that play a crucial role in enhancing crop yield by reducing losses to crop pests. Pesticide overuse has caused a series of negative health and environmental externalities. This paper quantifies the productivity effect and the optimal amount of pesticides in rice, cotton and maize production in China from the economic perspective. Using survey data collected in 2012 and 2013, both Cobb-Douglas and Weibull damage control specifications are used to estimate the production function. Results show that pesticides have statistically significant productivity effect on crop yield. On the condition of Weibull damage control specifications, the marginal products of 1 kg of the active ingredients of pesticides for rice, cotton and maize are 71.06, 22.73 and 98.45 kg, respectively. However, 57, 64 and 17% of the actual amount of pesticides are overused for rice, cotton and maize, respectively. Moreover, the productivity effect of pesticides would be overestimated using Cobb-Douglas specification without incorporating a damage control agent.

Genetically modified (GM) technology can significantly reduce pesticide use and increase yield in crop production. However, the benefit from reducing pesticide use varies substantially among farmers. The overall goal of this paper is to understand the relationship between farmers’ knowledge of GM technology and pesticide use in genetically modified papaya (GMP) production. Based on a survey of 223 farms in three main papaya production provinces in 2010, the data show that almost all papaya planted in 2009 was genetically modified. However, only 28% of papaya farmers knew that they planted GMP, and 55% of them did not know GMP is resistant to papaya ringspot virus (PRSV). Further analyses using the general least squares (GLS) method show that farmers’ knowledge of GMP significantly affects their pesticide use, and potential gain from GM technology is far below its full potential. The paper concludes with policy implications.