Rice Cropping System In China Research Articles

Energy budgeting and carbon footprint of different wheat–rice cropping systems in China

Wheat–rice cropping system in China, characterized by smallholder with conventional practice, is energy- and carbon-intensive. Cooperative with scientific practice is a promising practice to increase resource use while reducing environmental impact. However, comprehensive studies of the energy and carbon (C) budgeting of management practices on the actual field-scale production under different production types are lacking. The present research examined the energy and C budgeting of smallholder and cooperative using conventional practice (CP) or scientific practice (SP) at the field scale level in the Yangtze River Plain, China. The SPs and cooperatives exhibited 9.14 % and 6.85 % and 4.68 % and 2.49 % higher grain yields over the corresponding CPs and smallholders, respectively, while maintaining 48.44 % and 28.50 % and 38.81 % and 20.16 % higher net income. Compared to the CPs, the corresponding SPs reduced the total energy input by 10.35 % and 7.88 %, and the energy savings were primarily attributable to reductions in fertilizer, water, and seeds through the use of improved techniques. The total energy input in the cooperatives was 11.53 % and 9.09 % lower than that for the corresponding smallholders due to the mechanistic enhancements and improved operational efficiency. As a result of the increased yields and reduced energy inputs, the SPs and cooperatives ultimately increased energy use efficiency. The high productivity attributed to increased C output in the SPs, which increased C use efficiency and the C sustainability index (CSI) but decreased the C footprint (CF) over the corresponding CPs. The higher productivity and more efficient machinery of cooperatives increased the CSI and reduced the CF compared to the corresponding smallholders. Overall, the SPs coupled with cooperatives were the most energy efficient, C efficient, profitable and productive for wheat–rice cropping systems. In the future, improved fertilization management practices and integration of smallholder farms were effective means for developing sustainable agriculture and promoting environmental safety.

Simultaneously improving yield and nitrogen use efficiency in a double rice cropping system in China

The Nutrient Expert system (NE) has been proposed to improve yield and nitrogen (N) use efficiency (NUE) in the double rice cropping systems in China. However, the advantage of the NE system has yet to be quantified experimentally. A four-year field experiment was conducted in a double rice cropping system in China, to evaluate the ability of NE in improving yield and NUE. The experimental treatments consisted of NE based fertilization, current farmers’ practices (FP) and soil test based fertilizer recommendation (ST), and a series of nitrogen (N) rate treatments. The NUE decreased with increasing N application, while the yield did not increase significantly beyond N application rates of about 140 kg ha−1 (corresponding to the amount proposed by NE) in both early and late rice. NE increased grain yield (by 10.3% and 6.3%) and N uptake (by 5.7% and 4.0%) compared with FP and ST, respectively. NE significantly increased NUE compared with FP, and decreased the N surplus in comparison to FP and ST. The N dilution curve was Nc = 34.50 W−0.55 for early rice and Nc = 37.71 W−0.59 for late rice (where Nc is the N concentration in g kg−1, and W is the dry matter accumulation in t ha−1). The relationship between relative yield and the nitrogen nutrition index derived from the dilution curves confirmed that NE offered an optimum N application rate (approximately 140 kg ha−1) for both early and late rice. Carbon (C) and N translocation from vegetative organs to grains was enhanced with increasing N rate, while NE significantly increased C and N translocation compared with FP. Overall, the NE system ensured a high rice yield, increased N uptake and NUE. Therefore, the NE, as a user-friendly tool, is a sustainable fertilizer recommendation approach suitable for double rice cropping system, especially when soil testing is not available or timely for smallholders.

Simultaneously Improving Yield and Nitrogen Use Efficiency in a Double Rice Cropping System in China

Simultaneously Improving Yield and Nitrogen Use Efficiency in a Double Rice Cropping System in China

Brassinosteroid signaling may regulate the germination of axillary buds in ratoon rice

BackgroundRice ratooning has traditionally been an important component of the rice cropping system in China. However, compared with the rice of the first harvest, few studies on factors effecting ratoon rice yield have been conducted. Because ratoon rice is a one-season rice cultivated using axillary buds that germinate on rice stakes and generate panicles after the first crop’s harvest, its production is mainly affected by the growth of axillary buds. The objectives of this study were to evaluate the sprouting mechanism of axillary buds to improve the ratoon rice yield.ResultsFirst, we observed the differentiation and growth dynamics of axillary buds at different nodes of Shanyou 63, and found that they differentiated from bottom to top before the heading of the mother stem, and that they developed very slowly. After heading they differentiated from top to bottom, and the ones on the top, especially the top 2nd node, developed much faster than those at the other nodes. The average length and dry weight of the axillary buds were significantly greater than those at other nodes by the yellow ripe stage, and they differentiated into pistils and stamens by 6 d after the yellow ripe stage. The morphology of vegetative organs from regenerated tillers of Shanyou 63 also suggested the superior growth of the upper buds, which was regulated by hormones, in ratoon rice. Furthermore, a comprehensive proteome map of the rice axillary buds at the top 2nd node before and after the yellow ripe stage was established, and some proteins involved in steroid biosynthesis were significantly increased. Of these, four took part in brassinosteroid (BR) biosynthesis. Thus, BR signaling may play a role in the germination of axillary buds of ratoon rice.ConclusionsThe data provide insights into the molecular mechanisms underlying BR signaling, and may allow researchers to explore further the biological functions of endogenous BRs in the germination of axillary buds of ratoon rice.

Limited yield advantage of early-season rice hybrids over inbreds in middle-lower reaches of the Yangtze River

Early-season rice plays a significant role in double rice-cropping system in China to improve the grain yield per unit of area. But recently, the stagnation of grain yield increase has been witnessed for early-season rice varieties in middle-lower reaches of the Yangtze River, particular in the national rice regional adaption trials of southern China. Further, in the early cropping season, hybrid rice did not always perform better than inbred rice in grain production. It is relevant to question whether yield ceilings have been reached in early-season indica rice before a new breakthrough on the germplasm exploitation. Field experiments were conducted to evaluate the yield performance of five inbreds and their 12 derived hybrid rice varieties in 2017 and 2018 in Hangzhou, China. Limited yield advantage of early-season hybrids over inbreds was observed, commonly less than 5.00% and averaged as 0.62% in 2017 and 3.20% in 2018. The hybrids always produced more panicles per plant but less grains per panicle with similar growing periods compared with the inbreds. Then, the genetic distance of the hybrid parents was surveyed using 48 selected molecular markers, showing low polymorphisms. Further, they were genotyped for four critical quantitative trait loci for both yield traits and heading date and three ones only for yield traits. So did 60 major early-season indica rice varieties at the four pleiotropic loci. Evidence was shown for the high uniform of their haplotype combinations across the tested materials, which could lead to early heading and low yield potential. Our work revealed the low genetic diversity, or called genetic bottleneck, for early-season hybrids to further improve grain yield potential. Moreover, along with the popularization of low-input requirements, the inbred rice varieties of cheap seed price might be a more suitable alternative for this cropping season in middle-lower reaches of the Yangtze River.

No‐tillage increases nitrogen scavenging by fallow weeds in a double‐season rice cropping system in China

Naturally occurring fallow weeds are an alternative strategy for reducing nitrogen (N) loss from annual cropping systems by scavenging inorganic N from the soil. Soil tillage is a major factor affecting the growth of weed populations. This study was carried out to determine the effect of a no‐tillage (NT) system on the N scavenging capacity of fallow weeds in a double‐season rice cropping system. A fixed field experiment was carried out at the Experimental Farm of Hunan Agricultural University, Hunan Province, China, from 2008 to 2011. The results indicated that NT had 80% greater aboveground biomass of fallow weeds than conventional tillage (CT). There was no significant difference in N concentration in fallow weeds between NT and CT. N uptake by fallow weeds was 82% higher under NT than under CT. The stem density of fallow weeds was 50% higher under NT than under CT. The difference in the single‐stem biomass of fallow weeds was not significant between NT and CT. These results suggest that the N scavenging capacity of fallow weeds in the double‐rice cropping system can be increased by increasing the stem density and aboveground biomass through the adoption of NT farming. Our study identifies a potential new ecosystem service provided by NT farming.

Spatio-temporal changes in rice area at the northern limits of the rice cropping system in China from 1984 to 2013

Rice area has been expanding rapidly during the past 30 years under the influence of global change in northeastern China, which is the northernmost region of rice cultivation in China. However, the spatio-temporal dynamic changes in rice area are still unclear, although they may have important policy implications for environmental protection and adaptation to climate change. In this study, we aimed to identify the dynamic changes of the rice area in Heilongjiang Province of northeastern China by extracting data from multiple Landsat images. The study used ground quadrats selected from Google Earth and the extraction of a confusion matrix to verify the accuracy of extraction. The overall accuracy of the extracted rice area was higher than 95% as a result of using the artificial neural network (ANN) classification method. The results showed that the rice area increased by approximately 2.4×106 ha during the past 30 years at an annual rate of 8.0×104 ha, and most of the increase occurred after 2000. The central latitude of the rice area shifted northwards from 46 to 47°N during the study period, and moved eastwards from 130 to 133°E. The rice expansion area accounted for 98% of the total change in rice area, and rice loss was notably rare. The rice expansion was primarily from dryland. In addition, rice cultivation in marshland and grassland played a minor role in the rice expansion in this region.

Phosphorus efficiency in a long-term wheat–rice cropping system in China

SUMMARYLong-term (over 14 years) experiments on winter wheat (Triticum aestivum L.)–rice (Oryza sativa L.) crop rotations were conducted in Southwest China to investigate phosphorus (P) fertilizer utilization efficiency, including the partial factor productivity (PFP), agronomic efficiency (AE), internal efficiency (IE), partial P balance (PPB), recovery efficiency (RE) and the mass (input–output) balance. The seven treatments were Control, N, NP, NK, NPK, NPKM and NPKSt, representing various combinations of inorganic fertilizers (N, P and K), manure (M) and the application of rice straw (St). Without P application, the soil could supply c. 14·7–22·5 kg P/ha annually and produce, on average, c. 1·8 t/ha wheat and 6·0 t/ha rice. Phosphorus fertilization increased crop yields by 65·5 and 11·4% for wheat and rice, respectively, over the 14 years. The PFP values ranged from 80·2 to 177 kg grain/kg P fertilizer for wheat and from 222 to 255 kg/kg for rice in the NPK treatments. However, the mean AE over the 14-year period was 31·9 and 21·3 kg grain/kg inorganic P fertilizer for wheat and rice, respectively. The mean IE was 214 and 318 kg grain/kg P uptake for wheat and rice, respectively, during the cultivation period. The PPB for the whole rotation system over the 14 years ranged from 0·58 to 0·64. However, the mean RE of P fertilizer was 0·26 (varying from 0·22 to 0·29) in the wheat–rice cropping system over the 14-year period. For every 100 kg surplus P/ha per year, the concentration of soil P extracted by 0·5 m NaHCO3 at pH 8·5 (Olsen-P) would increase by, on average, 4·12 mg/kg in soil. For the wheat–rice cropping system, the current P application rate of 55–65 kg P/ha per year is able to sustain annual yields of about 3 t/ha for wheat and 7 t/ha for rice. This study suggests that, in order to achieve higher crop yields, the P fertilizer utilization efficiency should be considered when making P fertilizer recommendations in wheat–rice cropping systems.

Agronomic performance of late-season rice under different tillage, straw, and nitrogen management

In double rice-cropping system in China, zero tillage in late-season rice with straw return from early season rice is an emerging technology for saving inputs, shortening the lag time between rice crops, avoiding straw burning, and conserving natural resources. The objective of this 2-year field study was to determine the effects of tillage and straw return on N uptake, grain yield, and N use efficiency of late-season rice. Treatments were arranged in a split-plot design with four combinations of tillage and straw return as main plots and three N management practices as subplots. Tillage was either conventional soil puddling or zero tillage with newly harvested crop residue from early season rice either removed or placed on the soil surface without incorporation. The N treatments were zero-N control, site-specific N management (SSNM), and farmers’ N-fertilizer practice (FFP). Straw return regardless of tillage or N management did not reduce rice yield. In the second year, straw return significantly increased grain yield in the zero-N control. Chlorophyll meter readings at heading and total N uptake at maturity were higher with straw return in the zero-N control, suggesting that straw provides nutrients to rice in the late growing period. Zero tillage did not reduce N uptake, grain yield, and N use efficiency compared with conventional tillage. Despite large differences in timing and rate of N application between FFP and SSNM, these two N treatments resulted in comparable N uptake and grain yield of late-season rice regardless of tillage and straw return. These results suggest that zero tillage after early rice with straw return could replace conventional tillage for late rice in the double rice-cropping system in China.