Rice Yield In China Research Articles

Review and prospect on utilization of heterosis between <italic>indica</italic>-<italic>japonica</italic> rice subspecies

The utilization of heterosis between indica-japonica rice subspecies is important for the improvement of rice yield in China. This paper reviewed the historical development of the utilization of heterosis between indica-japonica rice subspecies. Since the discovery of wide compatibility gene in 1982, it has laid a theoretical foundation for the breeding of inter subspecies hybrid rice. In 1980s scientific research institutions bred the part of utilization of heterosis between indica-japonica hybrid rice combinations, Liangyoupeijiu and Xieyou 9308, which the heterosis was high. In 21st century, many scientific research institutions in Zhejiang Province bred the tipical indica-japonica hybrid rice combinations, Yongyou 6, Yongyou 12, Chunyou 58 and Chunyou 84, by breeding the japonica CMS lines and the indica-japonica wide compatibility restorer lines, which the heterosis was more obvious. They opened a new way for the using of heterosis between indica-japonica . This paper summarized the present situation of utilization of heterosis between indica-japonica from two aspects of basic theory research and research progress of utilization of heterosis between indica-japonica , and looked forward for the future utilization of heterosis between indica-japonica rice subspecies on the main problems existing in the utilization, and presented the solutions such as expandding the genetic relationship to enhance the heterosis, optimizing parental characteristics to enhance the yield of hybrid seed production, using the modern technology to improve the breeding efficiency, in order to provide a useful reference for the research on the utilization of heterosis between indica-japonica rice subspecies. According to the components of parents or the genetic distance between indica-japonica , we divided the hybrid between indica-japonica heterosis utilization into three stages: the part of utilization of heterosis between indica-japonica , the typical utilization of heterosis between indica-japonica and the complete utilization of heterosis between indica-japonica . We can believe that in the near future, the free combination of indica-japonica rice subspecies will be realized and the heterosis between indica-japonica rice subspecies can be completely used through the continuous efforts of breeders.

Assessing the impacts of temperature variations on rice yield in China

Using a unique county-level panel on single-season paddy rice yield and daily weather outcomes from 1996 to 2009, we examined the impacts of weather variations on paddy rice yield in China. We have five key findings: (i) in contrast to nearly all previous studies focusing on rice production in tropical and subtropical regions, we discovered that higher daily minimum temperature during the vegetative stage increased paddy rice yield; (ii) consistent with previous assessments, we found that higher daily maximum temperature during the vegetative and ripening stages reduced paddy rice yield; (iii) the impacts of sunshine duration and rainfall on paddy rice yield differed across the plant’s growth stages; (iv) estimated weather effects on yield differed by rice variety; and (v) weather variations caused a net economic loss of $17.4–53.0 million to China’s single-season paddy rice sector during the sample period, depending on econometric estimation strategies.

Characteristics of the acidity and sulphate fractions in acid sulphate soils and their relationship with rice yield

SUMMARYMost acid sulphate soils (ASSs) in the Pearl River Delta of South China have been traditionally reclaimed for rice cultivation, but the rice yield in most of these paddy fields is lower than the average rice yield in China due to extremely high soil acidity. In the present study, a range of sulphate and acidity parameters were investigated in ASS profiles in three types of paddy fields in Taishan City (Guangdong Province, China) divided based on the local rice productivity (4500, 3000 and 1500 kg/ha) using an abandoned ASS (uncultivated) as the control treatment to ascertain key yield constraining parameters. Soluble acidity (SA), exchangeable acidity (ExA), soluble sulphate (SS) and net acid-soluble sulphate (NAS) increased with increasing soil depths from 0 to 100 cm and then decreased abruptly with further increases in the depth. However, the depth distribution of exchangeable sulphate (ES) was uniform. The soil acidity and sulphate contents differed significantly in three sampled paddy fields. The values of SA and SS in the soils at depths of 0–100 cm in the studied ASS were lower compared with those in the uncultivated ASS and the ExA in soils at depths of 0–40 cm in ASS were lower compared with those observed in the uncultivated ASS. A correlation analysis revealed that SA was strongly correlated with SS and ExA with NAS. Soluble acidity, ExA, SS and NAS in the ASS were significantly associated with rice yield. Exchangeable acidity in the plough layer (0–20 cm) of soils was the most sensitive indicator of soil quality affecting rice yield among those in soils from 0 to 140 cm depth. It is interesting to note that SA, SS and NAS were more sensitive indicators of soil quality affecting rice yield at 60–100 cm than at 0–40 cm depth. Principal component analysis showed that pH value, ExA and ES in soils at depths of 0–40 cm and SA, SS and NAS in soils at depths of 60–100 cm constituted the critical soil acidity and sulphate characteristics that were strongly correlated with rice yields. This finding implies that controlling the ExA in the plough layer and the SA and NAS in the Jarosite layer should be the major focus of studies aimed at the amelioration of ASSs.

No-tillage effect on rice yield in China: A meta-analysis

Rice production in China has been constrained by changes in socioeconomic and physical environments such as decreased labor availability and degraded soil. No-tillage (NT) may be an alternative system for rice production in China because it has potential benefits including labor saving and soil conservation. Here, we conducted a meta-analysis to evaluate the effect of NT on rice yield in China and to investigate how the effect varies with the environmental and management factors. Results showed that decrease in panicle number per unit land area was observed in NT rice across a wide range of environmental and management conditions in China, but grain yield was not reduced because it was compensated for by more spikelet number per panicle and higher spikelet-filling percentage. Grain yield responses to NT were affected by region (climate), soil, cropping system and proportion of N applied during the vegetative period (PNVP). Typically, grain yield showed a positive response to NT in south-west region (where the climate during rice-growing season is characterized by frequent fog and clouds, high humidity and insufficient sunlight). NT resulted in a decreased grain yield in soils with pH lower than 6.0 and low fertility. Grain yield was decreased in rice–rice cropping systems but increased in rice–upland cropping systems by NT. NT had negative effect on grain yield under PNVP of 70% and 80% but had no significant effect under PNVP of 90%. However, responses of grain yield to NT did not vary with establishment method (transplanting vs. seedling throwing vs. direct seeding), cultivar type (hybrid vs. inbred), duration of NT adoption (<3 years vs. 3–6 years vs. >6 years) and residue management practice (removal vs. retention). We conclude that adoption of NT for rice production in China should be site-specific and depend on agronomic practices including cropping system and N management.

Farmers' Adaptation to Extreme Weather Events through Farm Management and Its Impacts on the Mean and Risk of Rice Yield in China

AbstractWe explore how rice farmers adjust their farm management practices in response to extreme weather events and determine whether their adjustments affect the mean, risk, and downside risk of rice yield. Based on a survey of 1,653 rice farmers in China, our econometric analyses show that the severity of drought and flood in the study areas significantly increases the risk and downside risk of rice yield. The applied farm management measures respond to severe drought and flood and can be considered as adaptation to climate change, an issue often ignored in previous studies. We model adaptation and its impact on rice yield for adapters and non‐adapters. Utilizing a moment‐based approach, we show that adaptation through farm management measures significantly increases rice yield and reduces the risk and downside risk of rice yield. Several policies, including scaling up the cost‐effective farm management adaptation and providing public services related to natural disasters, are recommended to improve adaptive capacity of farmers, particular the poor, in response to extreme events.

Impacts of temperature on rice yields of different rice cultivation systems in southern China over the past 40 years

The impact of climate change on rice yield in China remains highly uncertain. We examined the impact of the change of maximum temperature (Tmax) and minimum temperature (Tmin) on rice yields in southern China from 1967 to 2007. The rice yields were simulated by using the DSSAT3.5 (Decision Support System for Agro-technology Transfer)-Rice model. The change of Tmax and Tmin in rice growing seasons and simulated rice yields as well as their correlations were analyzed. The simulated yields of middle rice and early rice had a decreasing trend, but late rice yields showed a weak rise trend. There was significant negative correlation between Tmax and the early rice yields, as well as the late rice yields in most stations, but non-significant negative correlation for the middle rice yields. An obviously negative relationship was found between Tmin and the early and middle rice yields, and a significant positive relationship was found between Tmin and the late rice yields. It indicated that under the recent climate warming, the increased Tmax brought strong negative impacts on early rice yields and late rice yields, but a weak negative impact on the middle rice yields; the increased Tmin had a strong negative impact on the middle rice yields and the early rice yields, but a significant positive impact on the late rice yields. It suggested that it is necessary to adjust rice planting date and adapt to higher Tmin.

Impacts of Climate Change on Rice Yield in China From 1961 to 2010 Based on Provincial Data

The impacts of climate change on rice yield in China from 1961 to 2010 were studied in this paper, based on the provincial data, in order to develop scientific countermeasures. The results indicated that increase of average temperature improved single cropping rice production on national level by up to 11% relative to the average over the study period, however, it resulted in an overall loss of double cropping rice by up to 1.9%. The decrease of diurnal temperature range (DTR) in the major producing regions caused the decrease by up to 3.0% for single cropping rice production and 2.0% for double cropping rice production. Moreover, the contribution of precipitation change reached about 6.2% for single cropping rice production, but no significant effect for double cropping rice production in recent 50 years.

Geographic Variation of Rice Yield Response to Past Climate Change in China

Previous studies demonstrated climate change had reduced rice yield in China, but the magnitude of the reduction and the spatial variations of the impact have remained in controversy to date. Based on a gridded daily weather dataset, we found there were obvious changes in temperatures, diurnal temperature range, and radiation during the rice-growing season from 1961 to 2010 in China. These changes resulted in a significant decline of simulated national rice yield (simulated with CERES-Rice), with a magnitude of 11.5%. However, changes in growing-season radiation and diurnal temperature range, not growing-season temperatures, contributed most to the simulated yield reduction, which confirmed previous estimates by empirical studies. Yield responses to changes of the climatic variables varied across different rice production areas. In rice production areas with the mean growing-season temperature at 12–14°C and above 20°C, a 1°C growing-season warming decreased rice yield by roughly 4%. This decrease was partly attributed to increased heat stresses and shorter growth period under the warmer climate. In some rice areas of the southern China and the Yangtze River Basin where the rice growing-season temperature was greater than 20°C, decrease in the growing-season radiation partly interpreted the widespread yield decline of the simulation, suggesting the significant negative contribution of recent global dimming on rice production in China's main rice areas. Whereas in the northern rice production areas with relatively low growing-season temperature, decrease of the diurnal temperature range was identified as the main climatic contributor for the decline of simulated rice yield, with larger decreasing magnitude under cooler areas.

Effect of crop residue retention on rice yield in China: A meta-analysis

Crop residue management affects both crop productivity and soil fertility as well as human and environmental health, thus playing a critical role in the sustainability of cropping systems. We conducted a meta-analysis to examine the effect of in situ retention of crop residues on rice yield in China, and evaluated their fertilizer value for rice production. Results indicated that overall, crop residue retention significantly increased rice yield by 5.2% in China. Spikelet number per panicle and grain weight showed significant positive responses to crop residue retention, whereas the number of panicles and the percentage of filled grains were not significantly affected. Yield gains under crop residue retention were lowest, but significant, at mean annual temperature of 11–15°C. Yield responses to crop residue retention were not significantly affected by soil N content, residue types (legume vs. non-legume), and tillage regimes (no-tillage vs. conventional tillage). Rice yield gains under crop residue retention increased with increasing experimental duration. Yield responses to crop residue retention increased when the proportion of inorganic N fertilizer applied in the vegetative stage increased from 70% to 100%. Compared to full rates of inorganic fertilization alone, rice yield was not adversely affected by crop residue retention with reduced rates of inorganic N, P, and K fertilizers by averages of 29.4%, 8.3%, and 21.9%, respectively. Therefore, we conclude that crop residue retention can significantly increase rice yield and substitute a part of inorganic fertilizers, while the magnitude of yield gains and fertilizer reduction may be site-specific and depend on agronomic practices.

Potassium Internal Use Efficiency Relative to Growth Vigor, Potassium Distribution, and Carbohydrate Allocation in Rice Genotypes

Potassium (K) deficiency in soils is widespread and has become one of the most nutritional limiting factors for increasing rice yield in China and Asia. Improving K use efficiency by exploiting genetic potential largely depends on understanding physiological and genetic mechanisms underlying K efficiency in lowland rice. In this study, the K internal use efficiency (KIUE) at low K supply relative to K accumulation and distribution, tillering and grain filling rates, dry matter accumulation and allocation were examined under field conditions. The relative K concentrations in upper and lower leaves at booting and grain filling stages decreased with decreasing K internal use efficiency among the rice genotypes, indicating that K-efficient genotypes had greater K translocation ability than the K-inefficient genotypes at low K. The KIUE in biomass production at seedling and tillering stages was closely and positively correlated with the KIUE in grain production at the harvest stage. Significant positive correlations were noted between the KIUE at low K and the relative dry matter yield at the tillering stage and the harvest index among the rice genotypes. The K-efficient genotypes had a greater relative tillering rate during the tillering stage and a greater relative grain filling rate at the late grain filling stage, as compared with the inefficient genotypes. The relative net photosynthetic rate in the upper, and especially in the lower leaves was much lower in the K-inefficient genotypes than in the efficient ones at the grain filling stage, which may partly be due to the fact that the efficient genotype could maintain greater stomatal conductance and ribulose diphosphate carboxylase (RuBPcase) activity in functioning leaves under low K. The results indicate that (i) the K internal use efficiency could be an important index for measuring rice tolerance to low K stress, and (ii) K internal use efficiency is closely associated with efficient translocation and distribution of both K and carbohydrate within rice plants.