Luo Xiwen’s research while affiliated with South China Agricultural University and other places

Mechanical hill wet-seeded rice machine is beneficial for establishing and growing uniform rows of seedlings. However, there is limited knowledge regarding the effects of the establishment of furrows on growth, lodging and yield, and their relationships with root traits. In this study, field experiments were conducted during 2012 and 2013 using two super rice varieties (hybrid rice Peizataifeng and inbred rice Yuxiangyouzhan) under three furrow establishment treatments (T1, both water and seed furrows were established by the machine; T2, only seed furrows were established by the machine; and T3, neither water nor seed furrows were established by the machine). Lodging index, lodging-related traits, grain yield, above-ground dry weight and root traits were measured. The results showed that the lodging index was significantly affected by the treatments with furrows (T1 and T2). The strongest lodging resistance was detected in the mechanical hill wet-seeded rice with furrow treatment (T1) in both 2012 and 2013. Lodging resistance was strongly related to the breaking resistance. No significant difference was found in grain yield or dry weight of the mechanical hill wet-seeded rice. Therefore, the mechanical hill wet-seeded rice with furrow treatment increased rice lodging resistance, which was related to root traits.

In order to meet the requirement of field direct seeding for super hybrid rice: 1-3 seeds per hill, a pneumatic rice direct-seeder with six seeding metering devices was designed. Transmission system of pneumatic rice direct-seeder and seed metering device were analyzed in this study. And the pipeline structure and vortex pump were designed and selected. The pressure distribution of the pipeline was tested. The pressure value of each sub-pipeline under the conditions of different main pipeline pressure value was obtained and the reasons for pressure loss were analyzed. The results showed that the variation coefficient between sub-pipelines was less than 5%. The pipeline pressure could be evenly distributed. Further, the field experiments were carried out on super hybrid rice Peizataifeng using two-factor testing, by which the effects of different negative pressure and different forward speed (namely, rotational speed of suction plate) for seeding precision were studied. It found that: (1) the optimal negative pressure was 2 kPa; (2) under the optimal negative pressure, the probabilities of 1-3 seeds per hill for the direct-seeder were 93.41%, 95.47% and 97.50%, respectively, when the forward speed of the direct-seeded was high, medium and low speed; (3) the probability of empty hole was less than 2%, which satisfied the field direct seeding requirements of super hybrid rice. Additionally, hill spacing was measured, and the factors affecting the hill spacing were analyzed. The results showed that the fluctuation of hill spacing in the small range will not affect the seeding effect. In this study, a new type of pneumatic rice direct-seeder was designed. The main working components were tested and analyzed. The best parameters of field work were obtained. It provides the basis for the field application of the pneumatic rice precision seeder. © 2017, Chinese Society of Agricultural Engineering. All rights reserved.

Deep application of fertilizer with precision hill-drilling machine in super rice is a new mechanized mode with high efficiency and labor saving advantages. Field experiment was carried out with different rates of fertilizers using precision hill-drilling machine with the objective of determining super rice grain yield and NPK fertilizer use efficiency in South China area. There were five fertilizer treatments including no fertilizer, 100 kg N ha-1, 100 kg N ha-1 + 60 kg SiO2 ha-1, 125 kg N ha-1, and 125 kg N ha-1 + 60 kg SiO2 ha-1. Super rice special fertilizer comprised 12.5% N, 6.0% P2O5, 10.0% K2O, and 15% organic matter. The super rice varieties were Yuejingsimiao 2 (inbred) and Peizataifeng (hybrid) which are widely grown in South China. Treatments were arranged in a split-plot design with three replications. Grain yield and accumulation of NPK and Si were affected by variety and fertilizer. The highest grain yield was obtained from 125 kg N ha-1 treatment. Grain yield, affected by silicon, increased at lower N rate and decreased at higher N rate. Peizataifeng was higher in grain yield than Yuejinsimiao 2. Nitrogen, P, K and Si accumulation at maturity were higher with Yuejinsimiao 2 when 125 kg N ha-1 and 100 kg N ha-1 were applied, while concentration of N, P, K and Si was least in Yuejinsimiao 2 with no fertilizer added. Physiological phosphorus use efficiency (PPUE) and potassium use efficiency (PKUE) were highest with Peizataifeng when 125 kg N ha-1 + 60 kg SiO2 ha-1 was applied, while Physiological nitrogen use efficiency (PNUE) was highest with Yuejinsimiao 2 when no fertilizer was added.