Rice Yield Response Research Articles

High night temperature effects on wheat and rice: Current status and way forward.

Rapid increases in minimum night temperature than in maximum day temperature is predicted to continue, posing significant challenges to crop productivity. Rice and wheat are two major staples that are sensitive to high night-temperature (HNT) stress. This review aims to (i) systematically compare the grain yield responses of rice and wheat exposed to HNT stress across scales, and (ii) understand the physiological and biochemical responses that affect grain yield and quality. To achieve this, we combined a synthesis of current literature on HNT effects on rice and wheat with information from a series of independent experiments we conducted across scales, using a common set of genetic materials to avoid confounding our findings with differences in genetic background. In addition, we explored HNT-induced alterations in physiological mechanisms including carbon balance, source-sink metabolite changes and reactive oxygen species. Impacts of HNT on grain developmental dynamics focused on grain-filling duration, post-flowering senescence, changes in grain starch and protein composition, starch metabolism enzymes and chalk formation in rice grains are summarized. Finally, we highlight the need for high-throughput field-based phenotyping facilities for improved assessment of large-diversity panels and mapping populations to aid breeding for increased resilience to HNT in crops.

Response of rice yield and quality to nano-fertilizers in comparison with conventional fertilizers

Nano-fertilizers propose new techniques to be used for crop management. Present study investigated the influence of conventional and nano-fertilizers on grain yield and quality of two rice cultivars (Tarom and Shiroudi) in 2016 and 2017. The treatments included 10 nano and/or conventional fertilizers, i.e., control (without fertilizer), conventional nitrogen (N), phosphorus (P), potassium (K), and NPK and nano-N (nN), nano-P (nP), nano-K (nK), and nano-NPK (nNPK) and its combination (NPK + nNPK). Results showed that application of conventional and nano-fertilizers, particular in NPK, nNPK and its combination (NPK + nNPK) increased the grain yield (11.24–149.78% in Tarom and 16.86–95.85% in Shiroudi cultivars) and milled rice yield (25.33–157.35% in Tarom and 16.05–112.39% in Shiroudi cultivars). Fertilization treatments, especially N, nN, nNPK and NPK + nNPK, improved the grain quality by increasing milling quality (brown, milled and head rice rate), elongation ratio and gelatinization temperature and reduction of gel consistency and amylose content. Between fertilizer forms, application of nN and nNPK significantly increased the grain yield and milled rice yield as compared to their conventional forms (N and NPK). Moreover, quality (milling quality, elongation ratio, gel consistency and amylose content) of rice grains fertilized with nK was higher than that K. However, the highest grain quality was observed in N, nN, nNPK and NPK + nNPK fertilizer, while application of nNPK and NPK + nNPK were more effective on grain and milled rice production. According to the obtained results, application of nNPK can be an effective approach to obtain a balance between rice yield and quality, along with maintaining fertilizers efficiency.

The response of agronomic characters and rice yield to organic fertilization in subtropical China: A three-level meta-analysis

Organic fertilizer plays a critical role in developing sustainable cropping systems due to its positive impacts on soil fertility, crop productivity, and environmental sustainability. Yet, a systematic and quantitative analysis on how organic fertilization affects soil physicochemical properties, nutrient uptake and physiological use efficiency, agronomic characteristics, yield, and yield components of rice (Orzya sativa L.) is lacking. In this study, a synthesized three-level meta-analysis from 74 peer-reviewed papers which concentrated on rice production with organic fertilizer application at 85 sites in subtropical China was conducted to investigate how organic manure affects soil fertility and rice productivity. The results showed that organic fertilization significantly increased soil organic carbon (SOC) by 15.6 %, and available nutrients varied from 2.3%–20.2%. Moreover, organic fertilization significantly increased leaf area index, content of chlorophyll, and total biomass accumulation at grain-filling and ripening stages, which was favorable to the promotion of grain filling. Overall, organic fertilization significantly increased rice yield by 8.3 %, which was attributed to the higher nutrient uptake and physiological use efficiency. In addition, the response of rice yield was various under different subcategories. The magnitude of the increase in rice yield was the greatest under the treatment with animal manure (10.5 %), followed by biochar (8.3 %) and crop straw (7.2 %) due to the higher SOC sequestration and nitrogen use efficiency with animal manure incorporation compared with biochar and crop straw amendment. In addition, organic fertilization was most effective at improving the rice yield when the content of SOC was <10 g kg−1, indicating that it was an effective way to improve the crop production of infertile soil. The response of rice yield to organic fertilization increased as the experimental duration increased, which was of great significance as the rice yield could be improved through long-term application of organic fertilizer. The results of the present study indicated that organic fertilization is an effective practice for rice production in subtropical China.

패널모형을 활용한 논벼 수량성과 온도조건 간의 상관성 분석: 3개 농업기후지대의 지역성 비교를 중심으로

The impact of climate change on paddy rice yield is thought to be spatially heterogeneous and local. We analyzed the relationship between climate factors and paddy rice yield over the past 18 years using fine-scale gridded weather data, temperature bin-based degree days, and unobserved effect panel model. A 1-km-resolution PRISM dataset was added to the national map of paddy rice distribution. Extreme weather events and technological changes were also considered afterwards. A model with temporal and spatial autocorrelation correction showed large disparities in rice yield response to temperature conditions over different agroclimatic zones and growth stages. Integration of crop growth models and the expansion of included weather variables could lead to further advancements in this approach to modeling paddy rice yield response.

Impacts of Climate and Phenology on the Yields of Early Mature Rice in China

Phenological variables are closely correlated with rice (Oryza sativa L.) yields as they play important roles in influencing and controlling the carbon allocations between plant organs, but their impacts on rice yields and their relative importance compared with climatic variables are not yet well investigated. In this study, the impacts and the relative importance of climatic and phenological variables on the yields of early mature rice were assessed using the trial data from 75 agricultural stations across China, spanning from 1981–2010. We found that both daily maximum (Tmax) and daily minimum (Tmin) temperatures during the growing season (from transplanting to maturity) increased significantly, while sunshine duration (SD) and precipitation (Prep) did not change significantly. The average transplanting date was advanced by 3.18 days/decade, and the heading (maturity) dates were delayed by 2.47 (4.55) days/decade, with yields significantly increased by 9.65 g/m3 per decade across all sites. Partial correlation coefficients between most phenological variables and rice yields were negative, whereas most of the climatic variables were positively correlated with rice yields. The average of partial correlation coefficients between transplanting, heading, and maturity dates and rice yields were −0.10, −0.15, and −0.01, respectively, and the average of coefficients between Tmax, Tmin, SD, and Prep and rice yields were 0.08, 0.02, 0.12, and −0.05, respectively. Interestingly enough, phenological variables were the dominating influencing factors on rice yields at 63% of the sites, suggesting that the relative importance of phenology to rice yields may be even higher than that of climate. The climatic variables were closely correlated with rice yields as they are fundamental growth materials for crops, and phenological variables strongly influenced the growth and development of rice. Our results highlight that phenology should be precisely evaluated in crop models to improve the accuracy of simulating their response to climate change. Furthermore, due to limited understanding of phenological processes, manipulative experiments are urgently needed to comprehensively improve our understanding of rice phenology and rice yield response to ongoing climate change.

Rice yield response to potassium: An economic analysis

AbstractPotassium fertilizer represents a non‐trivial input cost in rice (Oryza sativa L.) production and its rate recommendation is often based on yield and K deficiency observations alone. However, profit‐maximizing fertilizer‐K rate not only hinges on the yield response to both initial available soil K and applied fertilizer K, but also the crop value and fertilizer cost. To that end, K application rate studies for rice, performed across 91 site‐years from 2001 to 2018, allowed estimation of a generic yield response curve to calculate profit‐maximizing K rates for producers in the mid‐southern United States. To determine whether those calculation efforts are justified, we compared profit‐maximizing fertilizer‐K rates to those currently recommended. Using rice prices and yields, fertilizer‐K cost, and a range of initial soil‐test K values, as observed over the last 10 yr, we find that current fertilizer‐K rate recommendations are too high. Profit‐maximizing rates added from US$0.88 ha−1 at initial Mehlich‐3 K availability values of 75 mg K kg−1 to $28.19 ha−1 at 105 mg K kg−1 on average. The corresponding fertilizer‐K reductions were 0.35 and 56 kg K ha−1, respectively, resulting in attendant yield penalties of only 4 kg ha−1 and 105 kg ha−1. Hence, performing soil tests and using decision support software to obtain profit‐maximizing fertilizer‐K rates is expected to enhance producer profit at rice yield penalties that are smaller than fertilizer cost savings. While profit‐maximizing rate recommendations do vary in a field with varying available soil K, using the mid‐range estimate rather than variable‐rate technology was deemed most feasible.

Hybrid rice yield response to potted-seedling machine transplanting and slow-release nitrogen fertilizer application combined with urea topdressing

Machine transplanting and the application of slow-release nitrogen (N) fertilizer (SRNF) have played vital roles in the modernization of rice production. We aimed to determine the effects of potted-seedling transplanting—a new machine-transplanting method—and SRNF on hybrid rice yields. A 2-year split-plot experiment (2016–2017) was conducted in Meishan, Sichuan province, China, using two machine-transplanting methods (potted-seedling and blanket-seedling) and three N treatments. Total green leaf area, high-effective leaf area and its rate at heading, net photosynthetic rate of flag leaves 7 days after heading, glutamate synthase (GOGAT) and glutamine synthase (GS) activity after heading, dry matter production, and N accumulation at heading and maturity increased under the potted-seedling method or 70% SRNF as a base + 30% urea application at the panicle initiation stage (SBUP). Stem diameter and number of small and of all vascular bundles at the neck–panicle node in potted-seedling plants increased as a result of increasing numbers of effective panicles, secondary branches, and spikelets. In potted-seedling plants, treatment with SBUP increased the number of large and total vascular bundles at the panicle–neck internode and the number of differentiated and surviving secondary branches and spikelets and decreased the number of ineffective tillers and degenerated secondary branches and spikelets. We conclude that the potted-seedling machine transplanting method and SRNF combined with urea topdressing can strengthen the source–sink relationship in rice, resulting in higher yields.

Effective Tiller Numbers, Photosynthetic and Yield Response of Rice (Oryza sativa) to Shallow Wet–Dry Irrigation Water Controlled at Tillering Stage in Black Soil Area

In order to study the effects of shallow wet–dry irrigation at tillering stage on effective tiller numbers, photosynthetic activity, yield and water use efficiency (WUE) of rice in black soil region, a pot experiment was conducted at Qingan National Irrigation Test Station of Heilongjiang Province from May to September in 2019. Four irrigation treatments were set up at tillering stage, namely light shallow wet–dry irrigation (T1), moderate shallow wet–dry irrigation (T2), severe shallow wet–dry irrigation (T3) and shallow water irrigation (CK). The results showed that under water controlled conditions at tillering stage, the ineffective tiller numbers were reduced and earing rate was increased as compared to CK. The photosynthetic (Pn), stomatal conductance (gs) and transpiration rate (Tr) were decreased with the decrease in soil water potential while SPAD and intercellular CO2 concentration (Ci) were opposite. The Pn, gs, Tr and Ci in T1 and T2 treatments reached the normal level after re-watering at heading and milk-ripening stages. The yield (Y) and WUE in T1 treatment were higher than that of the other treatments, significantly (P < 0.05). Therefore, the study can provide the theoretical basis and reference for water-saving and high yield of rice in black soil region.

Field experiments and model simulation based evaluation of rice yield response to projected climate change in Southeastern China

Evaluating the impact of climate change factors, especially temperature and carbon dioxide (CO2), on rice yield is essential to ensure future food security. Because of the wide biogeographical distribution of rice, such evaluations are conducted exclusively through modeling efforts. However, geographical forecasts could, potentially, be improved by the inclusion of field-based data on projected increases in temperature and CO2 concentration from a given rice-growing region. In this study, the latest version of the ORYZA (v3) crop model was evaluated with additional yield data obtained from a temperature-controlled free-air CO2 enrichment system (T-FACE) in Southeastern China. ORYZA (v3) results were then evaluated in the context of phase five of the Coupled Model Intercomparison Project (CMIP5) for representative concentration pathways (RCP) 4.5 and RCP 8.5 using five global change models (GCMs). Our findings indicate that climate change, i.e., inclusion of CO2 and temperature effects, decreased mean rice yield by 3.5%, and 9.4% for RCP 4.5; and by 10.5 and 47.9% for RCP 8.5 for the scenarios in the 2050s and 2080s, respectively. The CO2 fertilizer effect partially compensated but did not offset the negative impacts of rising temperature on rice yields. Warmer temperatures were the primary factor that influenced yield by adversely affecting the spikelet fertility factor and spikelet number. Overall, climate change would have positive effects on rice yields until the middle-century in Southeastern China but negative effects were noted by the end of the century. These results may be of interest for informing policy makers and developing appropriate strategies to improve future rice productivity for this region of China.

Yield Response of Upland Rice as Influenced by Enhanced-Efficiency Nitrogen Fertilizers in the Brazilian Cerrado

Nitrogen (N) fertilizers have their use efficiency adversely affected by the rate and source of N. A two-year field experiment was conducted to examine the yield response of upland rice by using NBPT (urease inhibitor), PCU (polymer-coated urea) and uncoated urea under different N application rates. It was hypothesized that either NPBT or PCU may result in increased yield components of upland rice when compared to conventional urea. The experiment was set up in a randomized block design in a 3 &amp;times; 4 + 1 factorial scheme, with four replicates. Treatments comprised three sources (conventional uncoated urea, NBPT-treated urea, and polymer-coated urea) and four rates (30, 60, 90 and 120 kg ha-1) of N, in addition to a control treatment (no fertilizer application). Nitrogen fertilizers were applied in two split doses: 50% at the seedling stage, and 50% at the tillering stage (~80 days after planting). The results revealed that the use of enhanced-efficiency N sources increased the productivity and plant height of upland rice crop when compared to conventional urea. As compared to when it is untreated or polymner-coated, treating urea with NBPT resulted in increased 100-grain weight.

Non‐flooding rice yield response to straw biochar and controlled‐release fertilizer

AbstractThe non‐flooding plastic film‐mulching cultivation (NFMC) is an important water‐saving rice (Oryza sativa L.) production technique for mountainous areas. Several studies indicated that this promising production system had positive effects on rice growth compared with the traditional flooding method. However, two obvious disadvantages need to be modified for its wider application: technical difficulties for mid‐season application of fertilizer and the observed loss of soil C. The solution for these problems may lead to enhanced and more sustainable rice production under NFMC conditions. A 2‐yr field experiment was conducted to evaluate the effects of combining straw biochar and controlled‐release urea with the NFMC system. The experimental design included two treatments of traditional flooded cultivation: (a) no N fertilizer; (b) urea alone; and four treatments under NFMC conditions: (a) no N fertilizer; (b) urea alone; (c) controlled‐release urea + urea; (d) a combination of straw biochar and controlled‐release urea + urea. Compared to a basal application of urea, controlled‐release urea plus urea together with straw biochar significantly increased rice grain yield and effective panicles. It also increased total biomass accumulation, the greenness of the leaves (SPAD value) and improved recovery efficiency of applied N. Our results show that the combination of controlled‐release urea and straw biochar can increase yield and N use efficiency of rice under NFMC conditions.

Response of rice yield traits to elevated atmospheric CO2 concentration and its interaction with cultivar, nitrogen application rate and temperature: A meta-analysis of 20 years FACE studies

The Free Air CO2 Enrichment (FACE) facility simulates future high CO2 environment in an open field, and is considered the best approach to assess the actual response of crop production to climate change. This meta-analysis synthesizes all studies conducted under FACE conditions on rice yield response to elevated atmospheric CO2 concentration ([CO2]) and its interaction with cultivar, nitrogen application rate and temperature. On average, elevated [CO2] enhanced rice yield by 16.2%, which resulted from positive response of each yield component. The yield enhancement by elevated [CO2] of hybrid rice (24.7%) was significantly greater than conventional rice (14.2%), and among conventional rice cultivars, indica rice had a larger yield response (20.4%) than japonica rice (12.7%). The superior performance of hybrid and indica rice under FACE conditions was mainly attributed to the larger increase in spikelet density. The response of rice yield to elevated [CO2] varied with nitrogen supply. The maximum increase of 21.1% occurred at the nitrogen application rate of 21–30 g m−2. Both insufficient and excess nitrogen supply negate yield increase by FACE but through different approaches. Elevated [CO2] increased rice yield by 16.7% at ambient temperature but only 10.1% at elevated temperature (1–2 °C); The smaller yield increase at elevated temperature was due to the negative response of filled grain percentage and grain mass. In conclusion, atmospheric CO2 concentration projected in the middle of this century will enhance rice yield mainly through the increase of spikelet density, whereas the magnitude of CO2 fertilizer effect will be affected by the cultivar, nitrogen application rate and temperature.

Performance assessment of the AquaCrop model to estimate rice yields under alternate wetting and drying irrigation in the coast of Peru

Peru is the second-largest rice producer in Latin America, with 406166 ha grown annually, predominately on the Peruvian north coast. However, rice is primarily irrigated by flooding (93%), which demands high water use (15000-18000 m3 ha−1) owing to low water-use efficiency. Additionally, the intensification of climate change is of great concern as it causes high variability as well as a decreasing trend in water resource availability. Alternate wetting and drying (AWD) irrigation technique reportedly reduce the irrigation volumes while maintaining conventional yield rates. The AquaCrop model was calibrated and assessed to simulate rice yield response to the AWD technique under water shortage conditions on the Peruvian central coast. The AquaCrop model exhibited a “very good” to “good” performance in predicting canopy cover development, soil water content, aerial biomass, and grain yield using performance indicators, such as the Nash-Sutcliffe efficiency coefficient, the RMSE observations standard deviation ratio (RSR), Willmott index, and determination coefficient. The calibrated model showed a good performance of rice under AWD irrigation, indicating that this technique can be used to assess rice production under Peruvian arid conditions.

Genotypic yield responses of lowland rice in high‐altitude cropping systems

AbstractRising global mean temperatures open opportunities in high‐altitude production systems for temperature‐sensitive crops such as lowland rice. Currently, the cropping window for rice in higher altitudes is still narrow, and thus, genotypes that tolerate a certain degree of chilling are needed to achieve their potential yield. Final yield depends on the interaction between genotype and environmental conditions. Exposing the genotype to a wide range of environments is a way to evaluate its adaptability into an expanding cropping calendar. Over a 2‐year period, an experiment was conducted in lowland rice systems in Madagascar at two locations differing in altitude. Twenty genotypes with contrasting levels of tolerance to low temperature were sown monthly in a non‐replicated rice garden trial. Plant development was monitored and yield and yield components were determined. Yield stability across the different growing environments was investigated. While crop duration was affected by sowing dates and altitude, yield was mainly determined by sowing date. Panicle number per m2 and number of spikelets per panicle were the most limiting factors for yield potential in mid‐altitude, while in high altitude, yield was mainly limited by spikelet fertility. Resulting cropping calendar and genotype recommendations are discussed.

Application of Chinese milk vetch affects rice yield and soil productivity in a subtropical double-rice cropping system

Green manure can be used as a substitute for chemical fertilizer without reducing rice yield. We studied the responses of soil fertility and rice yield to different combinations of Chinese milk vetch (CMV; Astragalus sinicus L.) and chemical fertilizer in a subtropical double-rice cropping system. Our goal is to reduce chemical fertilizer use and decrease environmental contamination. Compared with the recommended rate of chemical fertilizer (CF), both early- and late-rice yields in the two treatments supplied with 15 and 22.5 Mg CMV ha−1 plus 60% CF (represented as 60A and 60B, respectively) showed no significant differences while the two treatments supplied with 30 and 37.5 Mg CMV ha−1 plus 60% CF (represented as 60C and 60D, respectively) showed significantly higher values. The sustainable yield index (SYI) values in the 60C and 60D treatments with double-rice croppong system were significantly higher than those in other treatments (P<0.05). Early-rice yield showed a significant positive relationship with the Chinese milk vetch incorporation rate. The coefficients increased annually from 2009 to 2013 and then decreased in 2014. Soil organic matter increased over time by the end of the experiment in all of the treatment groups. Soil organic matter in 60A, 60B and 60C showed no significant difference compared with that in CF, while soil organic matter in 60D was significantly higher than that in CF. The slopes of soil organic matter and total nitrogen over six years were the highest in 60C and 60D. The soil total nitrogen content in 60A, 60B, 60C and 60D was higher than that in CF, but the differences were not significant (P>0.05). Therefore, a relatively high Chinese milk vetch incorporation rate (≥30 Mg ha−1) was more effective in improving the productivity and sustainability of paddy soil. The decreased coefficients of early-rice yield and the Chinese milk vetch incorporation rate in 2014 implied that the benefits of soil fertility and rice yield created by Chinese milk vetch input may decline after five years under a continuously high rate of Chinese milk vetch incorporation.

Rice yield response forecasting tool (YIELDCAST) for supporting climate change adaptation decision in Sahel

Rice yield responses forecast (YIELDCAST) is a very useful decision support tool in climate adaptation in Sahel, where crops are purely rainfed climate-stressors sensitive. This study aims to construct upland rice yield responses forecasting algebraic formulation code referred as YIELDCAST by using gene-expression programming (GEP) based on observed rainfall and temperatures data (1979–2011), and forcing with global climate model (GCM) downscaled outputs under CO2 emission scenarios SR-A1B, A2 and B1 (2012–2100) over Bobo-Dioulasso, a Sahelian region. Statistically, GEP is a capable tool to downscale climate variables in the region (R = 0.746−0.949), and construct reliable rice YIELDCAST tool (R = 0.930; MSE = 0.037 ton/ha; MAE = 0.155 ton/ha, RSE = 0.137 ton/ha). Yields forecasted (2012–2100) showed a noticeable statistically significant difference between scenarios; however, fluctuating with no substantial increase (average below 1.60 ton/ha); suggesting that the increase observed in temperatures and decrease in rains will either reduced or hindered yield to largely increase in Sahel. With no such YIELDCAST tool to support adaptation decision, Sahel will still be under the trap of the broad array of adaptation strategy, which is a trial and error, less specific and costly. The model can help anticipate adaptation decision support on-farm water management, shift to suitable planting periods, and use of improved drought resistant and short duration varieties adapted to a local weather pattern.

Developing a Proximal Active Canopy Sensor-based Precision Nitrogen Management Strategy for High-Yielding Rice

RapidSCAN is a portable active canopy sensor with red, red-edge, and near infrared spectral bands. The objective of this study is to develop and evaluate a RapidSCAN sensor-based precision nitrogen (N) management (PNM) strategy for high-yielding rice in Northeast China. Six rice N rate experiments were conducted from 2014 to 2016 at Jiansanjiang Experiment Station of China Agricultural University in Northeast China. The results indicated that the sensor performed well for estimating rice yield potential (YP0) and yield response to additional N application (RIHarvest) at the stem elongation stage using normalized difference vegetation index (NDVI) (R2 = 0.60–0.77 and relative error (REr) = 6.2–8.0%) and at the heading stage using normalized difference red edge (NDRE) (R2 = 0.70–0.82 and REr = 7.3–8.7%). A new RapidSCAN sensor-based PNM strategy was developed that would make N recommendations at both stem elongation and heading growth stages, in contrast to previously developed strategy making N recommendation only at the stem elongation stage. This new PNM strategy could save 24% N fertilizers, and increase N use efficiencies by 29–35% as compared to Farmer N Management, without significantly affecting the rice grain yield and economic returns. Compared with regional optimum N management, the new PNM strategy increased 4% grain yield, 3–10% N use efficiencies and 148 $ ha−1 economic returns across years and varieties. It is concluded that the new RapidSCAN sensor-based PNM strategy with two in-season N recommendations using NDVI and NDRE is suitable for guiding in-season N management in high-yield rice management systems. Future studies are needed to evaluate this RapidSCAN sensor-based PNM strategy under diverse on-farm conditions, as well as to integrate it into high-yield rice management systems for food security and sustainable development.

Ramifications of elevated temperature on the growth and yield performances of rice varieties incorporated with indigenous organic amendments

A field experiment was conducted at Chandipur of Keraniganj Upazilla in the district of Dhaka, Bangladesh to screen out the studied rice varieties of BR 3, BRRI dhan 28, Local BRRI dhan 29, and BRRI dhan 74 as influenced by the Rice Straw Compost – RSC, Mustard Meal – MM, and Trichocompost – TC (indigenous organic amendments), and elevated soil temperature of 3°C in relation to the growth and yield response of rice. The experiment was conducted using split plot design with elevated temperature in main plots and the different rates of organic amendments in subplots. The rates of organic amendments were 0. 4, 8 t ha-1 for RSC; 0, 3, 6 t ha-1 for MM; and 0, 2.5, 5 t ha-1 for TC. The soil temperature was raised by 3°C from the daily field temperature of 22-25°C. Grain and straw yields, 1000-grain weight, number of filled and fissured grains of rice were significantly (p≤0.05) enhanced with the increased rates of RSC, MM, and TC at elevated temperature of 3°C.The maximum grain (8.86 t ha-1) and straw (8.40 t ha-1) yields were recorded in the treatment RSC4HW26-28 and RSC8HW26-28, respectively in BRRI dhan 29 over control, which endorsed the lowest grain (3.42 t ha-1) and straw (2.68 t ha-1) yields. The RSC treatment was ranked first in order of the growth-yield and yield components (1000 – grain weight and No. of filled and fissured grain) of rice followed by MM and TC treatments. The aforesaid treatments were found to have significantly (p≤0.05) positive aftermath with the elevated soil temperature, regardless of rice varieties. Increased rice production by the elevated soil temperature might be due to the CO2 fertilization, which is a very important climatic issue at present day environment.&#x0D; Bangladesh J. Sci. Ind. Res.55(1), 53-64, 2020

Silicon enhances yield and nitrogen use efficiency of tropical low land rice

AbstractHigh nitrogen (N) rate often leads to low yield of rice due to lodging and mutual shading. This study was conducted to ascertain whether silicon (Si) could enhance yield response of rice to higher N rate by enhancing rigidity of plant parts and improving photosynthesis. The effects of Si and N on crop growth, photosynthesis, N use efficiencies and yield of rice were investigated during wet season (June to November) in sub‐humid tropical region of India. An increasing trend in crop growth rate with Si at all levels of N was observed. Silicon reduced the flag leaf angle making the leaf more upright and enhanced flag leaf N content. Leaf chlorophyll concentration and single leaf photosynthesis rate were higher with Si compared to without Si at flowering stage. Both N and Si significantly affected panicle number and grain filling. Application of 200 kg SiO2 ha−1 and 100 kg N ha−1 produced the highest number of panicle per square meter, filled grain per panicle and yield. Significant yield increases ranging from 8.2–16.9% were observed with Si compared to without Si. Both N and Si treatments had significant effects on N uptake and N use efficiency. Agronomic N use efficiency and N recovery efficiency were higher with Si compared to without Si. The highest physiological N use efficiency was recorded with 200 kg SiO2 ha−1 and 80 kg N ha−1. Silicon may enhance yield response of rice to higher N rate by improving source (photosynthetic) capacity and sink (reproductive organ) strength.

Lowland rice yield and profit response to fertilizer application in Rwanda

AbstractRice (Oryza sativa) production in Rwanda increased by 70% while yield ha−1 decreased during the past decade. Yield has biotic and abiotic constraints including inadequate nutrient supply. Yield response functions for N, P, and K were determined in eight marshlands grouped into four clusters. Additional treatment allowed for the diagnosis of response to Mg–S–Zn–B (MgSZnB). Rice grain yield with no fertilizer applied was 2.27 Mg ha−1. Mean yield increases were 2.35, 1.53, and 1.71 Mg ha−1 with N, P, and K application, respectively. The mean economically optimal rates (EOR) were 58 to &gt;150, 11–30, and 21–35 kg ha−1 for N, P, and K, respectively, depending on cluster and the cost of fertilizer. Yield responses to nutrient rates were similar across marshland clusters, and a single response function for each of P and K can serve all four clusters, while the response to N differed for Cluster B compared with A, BC, and C. Net returns to applied P and K were greater than for N, but the application of N is likely needed for such responses to P and K. The MgSZnB resulted in a mean grain yield increase of 1.72 Mg ha−1 with increases in all marshlands, but the information was not sufficient to determine which nutrients of MgSZnB were deficient or their optimal application rates. Fertilizer use can be very profitable for rice production in Rwanda. Profit can be enhanced with the application at less than EOR when fertilizer use is financially constrained.