Rice Nutrient Research Articles

Hydrus-1D Model for Simulating Potassium Transport in Rice Crop Irrigated with Alternate Wetting and Drying Practice

ABSTRACT Potassium (K) is one of the essential nutrients that play a crucial role in rice fields; however, its availability, transport, and balance components can be influenced by alternating wetting and drying (AWD) irrigation practice. This study used the Hydrus-1D solute transport model to simulate K transport and balance components in AWD irrigated rice fields. Thirty lysimeter field experiment plots with three different irrigation treatments (No: no soil water stress, MS: mild soil water stress (400 cm), and SS: severe soil water stress (750 cm)) were used for rice cultivation. Daily measurements of soil matric potential head (SMPH) and ponding water depth (PWD) were recorded. Throughout the rice-growing season, leachate water samples from the surface (ponding water) and soil profiles were collected to measure K content. Using the lysimeter field experiment data, the Hydrus-1D model simulated K transport in the AWD rice field. The simulation results indicate that the K distribution predominantly occurred within the top puddled soil layer (0–20 cm) in AWD practice. This suggests that the recommended K fertilizer dose with a 4–5 cm PWD and SMPH of 400 cm optimizes K availability for rice while limiting K leaching loss. The Hydrus-1D model proves to be a valuable management tool, aiding in determining optimal K application rates and ponding water depths for AWD irrigation, ensuring sufficient K nutrients for rice, and controlling K loss for sustainable rice production.

Predicting the geospatial distribution of Chinese rice nutrient element in regional scale for the geographical origin—A case study on the traceability of Japonica rice

AbstractEffective geographical origin discrimination of Chinese rice requires a large database of samples to ensure sufficient data for origin verification at a regional scale. In this study, environmental similarity was used to establish a spatial database of rice nutrient element, and then the validity of the database was verified using the back propagation artificial neural networks modeling (BPNN). The spatial distribution model of 14 rice nutrient element (Al, Ba, Ca, Cu, Cr, Fe, K, Mg, Mn, Mo, Na, Ni, Rb, and Zn) on regional scale was built using an environmental similarity method for the first time. Elemental concentrations of 692 samples were used to build a simulated geographical origin prediction model for northeastern (N‐E), middle to lower Yangtze River plain (Y‐R), southwestern (S‐W), and southeastern (S‐E) in China. The results indicated that the performance of the environmental similarity model for these four growing regions was S‐W > N‐E > S‐E > Y‐R based on the lowest ranking root mean square error (RMSE) for each region. For example, the RMSEs of Zn in S‐W, N‐E, S‐E, and Y‐R regions were 2.0, 2.4, 2.7, and 3.7 mg/kg, respectively. A case study on the traceability of Japonica rice was shown that Japonica rice could be discriminated with higher origin accuracy using a simulated database (91.8%) than by the actual database (87.0%) using the BPNN model. This indicates that a simulated rice element database could improve the accuracy of geographical origin discrimination for Chinese rice and potentially be applied to other large national‐scale crop datasets.

Mitigation of uranium toxicity in rice by Sphingopyxis sp. YF1: Evidence from growth, ultrastructure, subcellular distribution, and physiological characteristics

Uranium (U) contamination of rice is an urgent ecological and agricultural problem whose effective alleviation is in great demand. Sphingopyxis genus has been shown to remediate heavy metal-contaminated soils. Rare research delves into the mitigation of uranium (U) toxicity to rice by Sphingopyxis genus. In this study, we exposed rice seedlings for 7 days at U concentrations of 0, 10, 20, 40, and 80 mg L−1 with or without the Sphingopyxis sp. YF1 in the rice nutrient solution. Here, we firstly found YF1 colonized on the root of rice seedlings, significantly mitigated the growth inhibition, and counteracted the chlorophyll content reduction in leaves induced by U. When treated with 1.1 × 107 CFU mL−1 YF1 with the amendment of 10 mg L−1 U, the decrease of U accumulation in rice seedling roots and shoots was the largest among all treatments; reduced by 39.3% and 32.1%, respectively. This was associated with the redistribution of the U proportions in different organelle parts, leading to the alleviation of the U damage to the morphology and structure of rice root. Interestingly, we found YF1 significantly weakens the expression of antioxidant enzymes genes (CuZnSOD,CATA,POD), promotes the up-regulation of metal-transporters genes (OsHMA3 and OsHMA2), and reduces the lipid peroxidation damage induced by U in rice seedlings. In summary, YF1 is a plant-probiotic with potential applications for U-contaminated rice, benefiting producers and consumers.

Effect of Soil Texture on Soil Nutrient Status and Rice Nutrient Absorption in Paddy Soils

Soil texture affects rice nutrient uptake and yield formation by influencing soil structure, microbial activity, and soil nutrient supply capacity. Analyzing the relationship between soil texture, nutrient content, and rice agronomic traits is of great significance for precise and efficient fertilizer application. The tillage layer (0–20 cm) of 31 paddy fields in China’s main rice-producing areas was collected to perform rice pot experiments, and soil texture characteristics, physicochemical properties, microbial-related indicators, and rice agronomic traits were measured and analyzed. The results showed that these soils could be classified into four types of soil texture: loamy sandy soil, sandy loam soil, silty loam soil, and silty soil. Analysis of variance showed that the available nitrogen (AN), available potassium (AK), and available phosphorus (AP) contents were the highest in silty loam, silty, and sandy loam soils, respectively, and silt loamy soil had the highest CEC. Principal component analysis (PCA) also showed that soil physicochemical properties can be distinguished to a certain extent according to soil texture types. For the relationship of soil texture parameters and soil physicochemical properties, soil organic matter (OM), total nitrogen (TN), AN, ammonium nitrogen (NH4+-N), and microbial carbon (MBC) contents were positively correlated with soil clay content, AK was positively correlated with silt content, and soil phosphorus status was significantly related to pH. Mantel’s test revealed significant correlations between rice N, P, and K nutrient status, dry matter accumulation, and yield, and soil available nutrient content, MBC, pH, and soil texture parameters. Structural equation modeling (SEM) indicated that sand affected soil available nutrients by regulating pH, while clay can positively influence soil available nutrients by affecting soil organic matter mineralization and microbial activity, thus influencing nutrient absorption and yield formation in rice. Overall, in rice production, the silty and silty loam paddy soil with fine texture and higher clay content facilitates the mineralization of soil organic matter and the activity of soil microbes, resulting in more available soil nutrients, which benefits the rice absorption and accumulation of nutrients. Furthermore, a higher content of clay also promotes the distribution of dry matter to the panicle, thereby promoting rice yield formation.

Effect of milling degree on vitamin B1 stability in rice: A perspective on cooking-induced component interactions

To investigate the influence of degrees of milling (DOM) on the stability of rice nutrients, this study focused on vitamin B1 (VB1)'s stability during rice cooking and digestion at different DOMs. The results showed VB1's stability in brown rice (DOM 0%), moderately-milled rice (DOM 8.06%), and white rice (DOM 12.82%) after cooking were 92.91%, 84.54%, and 94.57%, respectively, and after digestion were 84.82%, 67.64%, and 95.97%. Considering the variation of VB1's bound content, there was an interaction between VB1 and rice components during cooking, which affected VB1's stability. Analysis of ultraviolet spectroscopy, thermodynamics, molecular structure changes, and intermolecular forces confirmed the non-covalent forces between VB1 and other nutrients, among which starch had the strongest affinity for VB1, compared with protein and dietary fiber. These results reveal the mechanism that milling altered VB1's stability by changing the composition of components that interact with VB1 in the rice matrix.

Himalayas farmer participatory evaluation of balanced application of nutrients in rice (Oryza sativa)–wheat (Triticum aestivum) system in Kumaon hills

A study was conducted by involving 24 farmers in their fields during 2011–13 in lower Kumaon hills, to study the response of rice (Oryza sativa L.)–wheat (Triticum aestivum L.) system to balanced nutrient application. The highest mean grain yields of rice (7.21 t/ha) and of wheat (5.14 t/ha) were recorded with the recommended doses of nitrogen, phosphorus and potassium (120, 60 and 40 kg/ha respectively, to both the crops) applied along with the sulphur @ 20 kg/ha followed by recommended NPK alone without micronutrients (7.01 and 5.01 t/ha, respec tively, for rice and wheat). During both the years, grain yields of rice and wheat under the farmers’ practice of nu trient application were significantly lower than the other treatments except control and N alone. In rice crop, appli cation of recommended doses of N, P and K provided additional mean grain yield of 1.50 t/ha over the farmers’ practice, whereas it was 1.04 t/ha in wheat. Application of sulphur @ 20 kg/ha over the recommended dose of NPK to both the crops resulted in additional grain yield of rice and wheat by 200 and 130 kg/ha, respectively, it also resulted in the highest production efficiency (45.4 kg/ha/day). The highest net returns were found under the treatment receiving recommended dose of NPK along with sulphur @ 20 kg/ha ( 150.15 × 103/ha) and it was 54.8% higher over the farmers’ practice of fertilizer application. The soil fertility status after harvesting of wheat in rice–wheat cropping system revealed that highest available nitrogen (298 kg/ha), phosphorus (16.9 kg/ha) and po tassium (200 kg/ha) were observed with recommended doses of N, P and K along with sulphur @ 20 kg/ha to rice and wheat crops in sequence.

Optimal Soil, Climate, and Management Factors for Maximizing Crop Yield and Soil Nutrients in a Rice–Oilseed Rotation System with Straw Return

Straw return (SR) has been widely recommended as a conservation agricultural practice in China. However, the effects of SR on crop yield and soil properties are inconsistent across studies of rice–oilseed rape cropping systems in China. This study aimed to investigate the effects of SR on crop yield and soil nutrient content in a rice–oilseed rotation system, and to understand the mechanism of straw return on the difference in yield increases between rice and oilseed rape. Additionally, suitable climate factors, soil properties, and agricultural practices were identified to achieve maximum increases in yield and soil nutrients in a rice–oilseed rotation under SR. This paper is based on a meta-analysis of 1322 observations from 83 peer-reviewed studies to evaluate the effects of climate, initial soil conditions, and agricultural management practices on rice and oilseed rape yields and soil nutrients under SR. The results showed that the responses of oilseed rape and rice yield remained positive, with 12.37% and 6.54% increases, and were significantly higher under SR than the control (no SR). Moreover, SR significantly increased the contents of several soil nutrients (soil organic carbon (SOC), total nutrients, available nutrients) and microbial biomass carbon (MBC) and nitrogen (MBN). Interestingly, the increase in crop yields was attributed to the increase in SOC, total nitrogen, and available potassium. Additionally, the increase in yields was mainly affected by climate factors, initial soil properties, and agronomic practices. For example, both mean annual temperature (MAT) and mean annual precipitation (MAP) had a positive correlation with crop yield increases under SR (p < 0.01). Initial soil conditions such as low SOC and total nitrogen content were more suitable for increased rice yield under SR, while the opposite was true for increased oilseed rape yield. Without fertilization, the SR did not significantly improve crop yield and soil nutrients, while it was more pronounced with N fertilization at 150–180 kg hm−2. The positive effect of SR on crop yields is more evident with plowing tillage, whereas the SR caused the highest increase in soil nutrients with the no-tillage condition. These findings have important implications for further improving crop yield, SOC, and soil nutrients in the Chinese rice–oilseed cropping system through straw return.

Fertilization enhances rice productivity by promoting phosphorus uptake and altering soil microbiota

Fertilization can enhance crop yield and improve soil health. However, its effects on nutrient uptake, soil microbiota, and rice yield remain unclear. Herein, we designed a double-cropping system with different fertilization treatments to determine their contributions to paddy soil agroecosystem and rice yield. Soil samples were collected before planting the early rice, after harvesting early rice, and after harvesting the late rice. Soil physicochemical properties, and rice yield, and rice nutrient (total nitrogen, phosphorus, and potassium contents) were determined. Variation of soil microbiota were also determined by high-throughput sequencing. We found that soil potassium content significantly improved during the planting process (P < 0.05), while rice phosphorus displayed significant variation under fertilization (P < 0.05). Notably, late rice yield was significantly higher than early rice yield (P < 0.001) after fertilization treatment. Furthermore, rice yield was positively correlated with available soil phosphorus (P < 0.05), indicating that fertilization promoted phosphorus uptake. Organic fertilizer altered the soil microbiota and increased Chloroflexi phyla abundance, while organic fertilizer combined with a compound microbial agent increased the diversity of soil microbial communities. A partial least squares path model revealed that fertilizer treatment directly positively affected rice yield by influencing phosphorus uptake and Shannon index (P < 0.01). Collectively, this study demonstrates that organic fertilization with compound microbial agents can stabilize soil nutrients, increase soil microbial diversity, and improve rice yield, thereby offering a guide for enhancing fertilizer utilization and improving agroecosystems.

Microbial ureolysis and ammonium oxidation in rice (Oryza sativa) rhizosphere: Impact of different fertilizers

Nitrogen is a crucial nutrient for rice (Oryza sativa L.) productivity, and chemical N fertilizers are often applied to enhance rice production. However, the response of soil microbial activity and corresponding functional genes to chemical fertilization remains unclear. The present study was carried out during rainy (kharif) seasons of 2019 and 2020 at the research farms of ICAR-Indian Agricultural Research Institute, New Delhi to study in the microbial responses to different concentration of nitrogen and fertilizers applied to the soil of rice fields. Study included a microcosmic experiment with 3 N concentrations (0, 10, and 100 mM), and treatment included were T1, RDF; T2, 50% N as urea and KNO3 at 75:25 with PK; T3, 50% N as urea and KNO3 at 75:25 with PK and ammonium oxidizing microbial consortium. Nitrogen addition at 10 and 100 mM increased urease activity by 19–26%, potential ammonium oxidation (PAO) by 16–49%, and ureC gene copies by 10–22%. Indeed, treated soils possessed 1.2 to 6.5 folds’ higher copies of archaeal- and bacterial amoA. In the field experiments, the rhizosphere of T1 showed the highest urease and PAO activities while having the lowest activity of ammonification. The abundance of ureC, archaeal-, and bacterial amoA genes ranged from 2.9×106 to 2.0×107, 4.6×103 to 2.4×104, and 2.3 to 9.4×106 copies/g soil, respectively. The ureC gene copies were more abundant in T1, while archaeal and bacterial amoA genes exhibited the highest copies in T3. Urease activity and ureC copies were highest during the vegetative stage, while PAO, and archaeal- and bacterial amoA gene copies were enriched during the flowering stage. The gene abundance and associated enzymatic activities showed a strong correlation, implying that structural changes in the microbial community due to different combinations of fertilizers might alter the nutrient turnover in soil. Our results showed that N-fertilizers could significantly alter the structure and activities of microbial communities, and appropriate N fertilization is necessary for improving the sustainability of rice cultivation.

Silicon Supplements Potentially Reduce the Sheath Blight Incidence and Severity of Rice (Oryza sativa L.)

Sheath Blight is a disease causing up to 50% yield losses of rice depending on severity. Silicon (Si) is a beneficial nutrient for rice having the ability to protect against diseases. So, a pot experiment was carried out at the Bangladesh Institute of Nuclear Agriculture Headquarters Farm, Mymensingh from July 2021 to November 2021 with artificial inoculation of Rhizoctonia solani to study the effect of different Si supplements and their doses on rice ShB incidence and severity. The test crop used in the study was Chinigura aromatic rice variety. The experiment was laid out in a completely randomized design (CRD) with three replications. Among the nine treatments, except control, Si was applied from K2SiO3, CaSiO3, and MgSiO3 with three concentrations viz., 2, 4, and 6 mM Si respectively through the foliar spray. The application of different Si supplements showed a significant positive effect on the growth, yield contributing characters, and yield of rice. The highest yield was found at the application of Si as CaSiO3 6 mM. Disease incidence and severity matrix were significantly reduced due to the application of different Si supplements. The minimum disease incidence and severity matrix were found at T6 (CaSiO3 6 mM) treatment. The maximum disease incidence and severity matrix reduction was 35.27% and 54.3%, respectively at T6 (CaSiO3 6 mM) treatment over control (without Si application) which was statistically identical to T3 (K2SiO3 6 mM), T7 (MgSiO3 2 mM), and T8 (MgSiO3 4 mM). The overall disease incidence and severity matrix reduction over control was 24.68% and 35.59%, respectively due to different Si supplement applications. Again, the highest nutrient concentration was found in different Si supplement treatments over control. So, Si supplement applications such as K2SiO3, CaSiO3, and MgSiO3 may be an advisable option for the management of sheath blight disease of rice for successful crop production.

A Preliminary Study of the Impacts of Duckweed Coverage during Rice Growth on Grain Yield and Quality.

The overuse and misuse of fertilizers have been causing duckweed outbreaks in irrigation ditches and paddy fields in many rice-growing areas. However, how duckweed coverage in a paddy field affects the rice yield and grain quality is under debate because duckweed may act as either a weed, competing with rice for mineral nutrients, or a "nutrient buffer", providing significant ecological and economic benefits. To understand the effects of duckweed coverage throughout rice growth on the yield and quality of rice grains, an experiment with three Japonica rice cultivars was conducted with fertile lotus-pond bottom soil as a growth medium to provide sufficient mineral nutrients for both the duckweed and rice. Averaged across three rice cultivars, duckweed coverage decreased the panicle density but increased the spikelet density and grain weight, resulting in no significant change in the rice yield. Duckweed coverage had no impact on the processing and appearance quality in general, but significant duckweed-by-cultivar interactions were detected in the head rice percentage and grain chalkiness, indicating different sensitivities of different cultivars in response to the duckweed treatment. The decrease in breakdown and increase in setback values in the rapid visco analyzer (RVA) profile of rice flour suggested that duckweed coverage during rice growth worsened the cooking quality of the rice. However, no significant change in the palatability of the cooked rice was found. The most profound change induced by the duckweed was the nutritional quality; duckweed coverage increased the protein concentration but decreased the concentrations of Mg, Mn, Cu, and Zn in rice grains. This preliminary study suggested that duckweed coverage during rice growth has profound effects on the rice nutrient uptake and grain nutritional quality under the circumstances, and further research on the responses of the rice quality to the duckweed coverage in paddy fields in multiple locations and years is needed.

Insights into Recent Updates on Factors and Technologies That Modulate the Glycemic Index of Rice and Its Products.

Rice is a staple food and energy source for half the world's population. Due to its quick digestion and absorption in the gastrointestinal tract, rice is typically regarded as having a high or medium-high glycemic index (GI); however, this can vary depending on the variety, nutrient compositions, processing, and accompanying factors. This report included a table of the glycemic index for rice and rice products in different countries, which could give an overview and fundamental information on the recent GI of different rice varieties. In addition, latest updates about the mechanism effects of rice nutritional profiles and processing techniques on GI were also provided and discussed. The influence of state-of-the-art GI regulation methods was also evaluated. Furthermore, the effectiveness and efficiency of applied technologies were also given. Furthermore, this review offered some aspects about the potential nutraceutical application of rice that food scientists, producers, or consumers might consider. Diverse types of rice are grown under various conditions that could affect the GI of the product. The instinct nutrients in rice could show different effects on the digestion rate of its product. It also revealed that the rice product's digestibility is process-dependent. The postprandial glucose response of the rice products could be changed by modifying processing techniques, which might produce the new less-digestive compound or the inhibition factor in the starch hydrolysis process. Because of the significant importance of rice, this paper also concluded the challenges, as well as some important aspects for future research.

Metabolomics and machine learning technique revealed that germination enhances the multi-nutritional properties of pigmented rice

Enhancing the dietary properties of rice is crucial to contribute to alleviating hidden hunger and non-communicable diseases in rice-consuming countries. Germination is a bioprocessing approach to increase the bioavailability of nutrients in rice. However, there is a scarce information on how germination impacts the overall nutritional profile of pigmented rice sprouts (PRS). Herein, we demonstrated that germination resulted to increase levels of certain dietary compounds, such as free phenolics and micronutrients (Ca, Na, Fe, Zn, riboflavin, and biotin). Metabolomic analysis revealed the preferential accumulation of dipeptides, GABA, and flavonoids in the germination process. Genome-wide association studies of the PRS suggested the activation of specific genes such as CHS1 and UGT genes responsible for increasing certain flavonoid compounds. Haplotype analyses showed a significant difference (P < 0.05) between alleles associated with these genes. Genetic markers associated with these flavonoids were incorporated into the random forest model, improving the accuracy of prediction of multi-nutritional properties from 89.7% to 97.7%. Deploying this knowledge to breed rice with multi-nutritional properties will be timely to address double burden nutritional challenges.

Rhizoactinobacteria Enhance Growth and Antioxidant Activity in Thai Jasmine Rice (Oryza sativa) KDML105 Seedlings under Salt Stress.

Salinity is one of the most devastating abiotic stresses hampering the growth and production of rice. Nine indole-3-acetic acid (IAA)-producing salt-tolerant plant-growth-promoting rhizobacteria (ST-PGPR) were inoculated into Thai jasmine rice (Oryza sativa L.) variety Khao Dawk Mali 105 (KDML105) seedlings grown under different concentrations of NaCl (0, 50, 100, and 150 mM). The ST-PGPR strains significantly promoted the growth parameters, chlorophyll content, nutrient uptake (N, P, K, Ca, and Mg), antioxidant activity, and proline accumulation in the seedlings under both normal and saline conditions compared to the respective controls. The K+/Na+ ratio of the inoculated seedlings was much higher than that of the controls, indicating greater salt tolerance. The most salt-tolerant and IAA-producing strain, Sinomonas sp. ORF15-23, yielded the highest values for all the parameters, particularly at 50 mM NaCl. The percentage increases in these parameters relative to the controls ranged from >90% to 306%. Therefore, Sinomonas sp. ORF15-23 was considered a promising ST-PGPR to be developed as a bioinoculant for enhancing the growth, salt tolerance, and aroma of KDML105 rice in salt-affected areas. Environmentally friendly technologies such as ST-PGPR bioinoculants could also support the sustainability of KDML105 geographical indication (GI) products. However, the efficiency of Sinomonas sp. ORF15-23 should be evaluated under field conditions for its effect on rice nutrient uptake and growth, including the 2AP level.

Identification of rice leaf diseases and deficiency disorders using a novel DeepBatch technique.

Rice is one of the most widely consumed foods all over the world. Various diseases and deficiency disorders impact the rice crop's growth, thereby hampering the rice yield. Therefore, proper crop monitoring is very important for the early diagnosis of diseases or deficiency disorders. Diagnosis of diseases and disorders requires specialized manpower, which is not scalable and accessible to all farmers. To address this issue, machine learning and deep learning (DL)-driven automated systems are designed, which may help the farmers in diagnosing disease/deficiency disorders in crops so that proper care can be taken on time. Various studies have used transfer learning (TL) models in the recent past. In recent studies, further improvement in rice disease and deficiency disorder diagnosis system performance is achieved by performing the ensemble of various TL models. However, in all these DL-based studies, the segmentation of the region of interest is not done beforehand and the infected-region extraction is left for the DL model to handle automatically. Therefore, this article proposes a novel framework for the diagnosis of rice-infected leaves based on DL-based segmentation with bitwise logical AND operation and DL-based classification. The rice diseases covered in this study are bacterial leaf blight, brown spot, and leaf smut. The rice nutrient deficiencies like nitrogen (N), phosphorous (P), and potassium (K) were also included. The results of the experiment conducted on these datasets showed that the performance of DeepBatch was significantly improved as compared to the conventional technique.

Improvement of Yield, Yield Components and the Concentration of Some Nutrients in Rice Leaves by Using Rice Straw and Its Biochar

Improvement of Yield, Yield Components and the Concentration of Some Nutrients in Rice Leaves by Using Rice Straw and Its Biochar

OsMADS5 interacts with OsSPL14/17 to inhibit rice root elongation by restricting cell proliferation of root meristem under ammonium supply.

Nitrogen (N) is a vital major nutrient for rice (Oryza sativa). Rice responds to different applications of N by altering its root morphology, including root elongation. Although ammonium ( ) is the primary source of N for rice, is toxic to rice roots and inhibits root elongation. However, the precise molecular mechanism that -inhibited root elongation of rice is not well understood. Here, we identified a rice T-DNA insert mutant of OsMADS5 with a longer seminal root (SR) under sufficient N conditions. Reverse-transcription quantitative PCR analysis revealed that the expression level of OsMADS5 was increased under compared with supply. Under conditions, knocking out OsMADS5 (cas9) produced a longer SR, phenocopying osmads5, while there was no significant difference in SR length between wild-type and cas9 under supply. Moreover, OsMADS5-overexpression plants displayed the opposite SR phenotype. Further study demonstrated that enhancement of OsMADS5 by supply inhibited rice SR elongation, likely by reducing root meristem activity of root tip, with the involvement of OsCYCB1;1. We also found that OsMADS5 interacted with OsSPL14 and OsSPL17 (OsSPL14/17) to repress their transcriptional activation by attenuating DNA binding ability. Moreover, loss of OsSPL14/17 function in osmads5 eliminated its stimulative effect on SR elongation under conditions, implying OsSPL14/17 may function downstream of OsMADS5 to mediate rice SR elongation under supply. Overall, our results indicate the existence of a novel modulatory pathway in which enhancement of OsMADS5 by supply represses the transcriptional activities of OsSPL14/17 to restrict SR elongation of rice.

Cadmium, arsenic, and mineral nutrients in rice and potential risks for human health in South China.

Rice (Oryza sativa L.) is one of the most important staple food crops worldwide. For people fed on rice, toxic elements cadmium (Cd) and arsenic (As) and mineral nutrients in rice are pivotal to evaluate potential risks of harmful element intake and malnutrition. We collected rice samples of 208 cultivars (83 inbred and 125 hybrid) from fields in South China and determined Cd, As, As species, and mineral elements in brown rice. Chemical analysis shows that the average content of Cd and As in brown rice were 0.26 ± 0.32 and 0.21 ± 0.08mg·kg-1, respectively. Inorganic As (iAs) was the dominative As species in rice. Rice Cd and iAs in 35.1% and 52.4% of the 208 cultivars exceeded rice Cd and iAs limits, respectively. Significant variations of rice subspecies and regions were found for Cd, As, and mineral nutrients in rice (P < 0.05). Inbred rice had lower As uptake and more balanced mineral nutrition than hybrid species. Significant correlation was observed between Cd, As versus mineral elements like Ca, Zn, B, and Mo (P < 0.05). Health risk assessment indicates that high risks of non-carcinogenic and carcinogenic of Cd and iAs, and malnutrition, in particular Ca, protein and Fe deficiencies, might be caused by rice consumption in South China.

A hybrid CNN-LSTM model for diagnosing rice nutrient levels at the rice panicle initiation stage

Nitrogen (N) and potassium (K) are two key mineral nutrient elements involved in rice growth. Accurate diagnosis of N and K status is very important for the rational application of fertilizers at a specific rice growth stage. Therefore, we propose a hybrid model for diagnosing rice nutrient levels at the early panicle initiation stage (EPIS), which combines a convolutional neural network (CNN) with an attention mechanism and a long short-term memory network (LSTM). The model was validated on a large set of sequential images collected by an unmanned aerial vehicle (UAV) from rice canopies at different growth stages during a two-year experiment. Compared with VGG16, AlexNet, GoogleNet, DenseNet, and inceptionV3, ResNet101 combined with LSTM obtained the highest average accuracy of 83.81% on the dataset of Huanghuazhan (HHZ, an indica cultivar). When tested on the datasets of HHZ and Xiushui 134 (XS134, a japonica rice variety) in 2021, the ResNet101-LSTM model enhanced with the squeeze-and-excitation (SE) block achieved the highest accuracies of 85.38 and 88.38%, respectively. Through the cross-dataset method, the average accuracies on the HHZ and XS134 datasets tested in 2022 were 81.25 and 82.50%, respectively, showing a good generalization. Our proposed model works with the dynamic information of different rice growth stages and can efficiently diagnose different rice nutrient status levels at EPIS, which are helpful for making practical decisions regarding rational fertilization treatments at the panicle initiation stage.

Validating algorithms designed for fertilization control in rice farming system

Rice yields in Rwanda seldom reach values expected for irrigated production, in part due to poor fertilization management. To adapt well-known best practices to local conditions, two fuzzy fertilization algorithms were designed for conditions of rice production in Rwanda. Fuzzy algorithms have a linguistic rule base of 183 IF THEN statements linking measurable field conditions to crop yield. Interviews with government agricultural experts and published knowledge of site conditions were used to create the rule base which incorporates the known nutrient requirements of the different growth stages of rice. Fuzzy algorithms are intended for use in an Internet of Things (IoT) system. To validate the algorithms, historical weather and field data are used to drive yield simulations for different plots during the first growing season of 2020 at sites in northeast Rwanda. Predicted yields are compared to measured yields for scenarios with different irrigation levels and fertilization amounts and with and without full Internet connectivity. Insights are provided on the potential of these fuzzy methods to improve rice nutrient management for increased yields in low-income countries are discussed.