Rice Production Research Articles

Insights from a 19-year field study: optimizing long-term nutrient supply strategies for enhanced crop productivity and nutritional security in rice–wheat systems

What nutrient supply options can ensure maximum productivity and optimize the nutrient uptake of rice–wheat system (R-W system)? an experiment started in the year 1998 (19-year-old) to examine the impact of optimal nutrient supply (NS) strategies to maximize crop productivity and nutritional security in R-W system. To determine the best nutrient management strategies (BNMS), seven different NS methods were tested. These included (organic and mineral fertilizers), as well as combinations such as integrated plant nutrition system (IPNS), IPNS + B (berseem), and IPNS + C (cowpea), with the aim of enhancing the productivity and nutrient absorption of R-W system. Results showed that rice grain yield notably wide-ranging from 1.61 to 5.81 t ha−1 under different NS options and highest rice grain yield (mean of 19 years) was observed at IPNS + C (5.81 t ha−1), which was at par with IPNS (5.79 t ha−1), STCR (soil test crop response) (5.76 t ha−1) and IPNS + B (5.67 t ha−1) followed by 100% recommended dose fertilizer NPK (4.41 t ha−1), which equality with OF (organic farming) (4.04 t ha−1) and lowest was recorded in control plot (1.61 t ha−1). Wheat grain yield varied significantly from 1.43 to 5.86 t ha−1 under different NS options. The highest yield (mean of 19 years) was observed in treatments IPNS + B (5.86 t ha−1), IPNS (5.77 t ha−1), IPNS + C (5.48 t ha−1), and STCR (5.45 t ha−1), followed by OF at 4.49 t ha−1, NPK at 3.76 t ha−1, with the lowest in the control plot at 1.43 t ha−1. Additionally, total phosphorus and sulfur accumulation in rice (grain: 8.41 to 39.09 kg ha−1; straw: 6.02 to 23.54 kg ha−1) varied significantly across nutrient supply treatments. Overall, adoption of IPNS integration with legumes (IPNS + B and IPNS + C), can significantly improve productivity and nutrient accumulation in R-W systems. Incorporating legumes into farming practices is advised for sustained productivity and nutritional benefits.

The microRNA399d-PHOSPHATE2 module alters rice sensitivity to rice ragged stunt virus by manipulating phosphate uptake.

Rice (Oryza sativa L.) production frequently faces threats from biotic and abiotic stressors, with rice ragged stunt virus (RRSV) as a substantial biotic factor. The relationship between inorganic phosphorus (Pi) content and susceptibility to RRSV is crucial yet poorly understood. This study investigates how phosphorus metabolism influences rice resistance to RRSV, focusing on genetic manipulations that modulate this relationship. The RRSV infection increased phosphate (Pi) content in the aerial parts of rice plants by enhancing Pi uptake and transport. Furthermore, the upregulation of microRNA399d (miR399d) and the suppression of its target gene OsPHOSPHATE2 (OsPHO2) enhanced Pi accumulation, increasing rice susceptibility to RRSV infection. Additionally, elevated Pi levels, which are associated with altered ROS dynamics, reduced ROS activity and potentially dampened the plant's innate immune response to viral infection. The miR399d-PHO2 module was identified as pivotal in mediating phosphate uptake and influencing susceptibility to RRSV through modulations in the phosphorus and ROS pathways. This study shed light on the regulatory mechanisms of phosphorus nutrition in rice, revealing a critical interaction between phosphorus metabolism, ROS dynamics, and viral defense. The findings suggest potential strategies for manipulating Pi levels to enhance plant resistance against viruses, opening avenues for agricultural improvements and disease management in rice.

Context-dependent agricultural intensification pathways to increase rice production in India

Yield gap analysis is used to characterize the untapped production potential of cropping systems. With emerging large-n agronomic datasets and data science methods, pathways for narrowing yield gaps can be identified that provide actionable insights into where and how cropping systems can be sustainably intensified. Here we characterize the contributing factors to rice yield gaps across seven Indian states, with a case study region used to assess the power of intervention targeting. Primary yield constraints in the case study region were nitrogen and irrigation, but scenario analysis suggests modest average yield gains with universal adoption of higher nitrogen rates. When nitrogen limited fields are targeted for practice change (47% of the sample), yield gains are predicted to double. When nitrogen and irrigation co-limitations are targeted (20% of the sample), yield gains more than tripled. Results suggest that analytics-led strategies for crop intensification can generate transformative advances in productivity, profitability, and environmental outcomes.

Optimizing phosphate application to improve soil quality and reduce phosphorus loss in rice-wheat rotation

How to determine the optimal dosage of phosphorus (P) fertilizer input for an agricultural field is important to maintain soil quality and crop production while minimizing environmental impact. In this study, we set up a 5-year rice-wheat rotation with contrasting P fertilization treatments (0, 25, 50, 75, 100, and 150 kg P2O5 ha−1, hereafter, P0, P25, P50, P75, P100, and P150, respectively) per season to explore the relationship between the amount of P input and crop yield, P use efficiency (PUE), balance of P accumulation and loss, ecosystem multifunctionality (EMF), and soil quality. Our results indicate that increased P amounts significantly boosted rice and wheat production of both straw and grain, but the tendency slowed down when the input was over 75 kg P2O5 ha−1. The PUE declined with increased P input and soil P balance of 50 kg P2O5 ha−1 for wheat and 100 kg P2O5 ha−1 for rice. Runoff emerges as the main pathway for soil P loss and escalates with higher P application rates. We emphasize increasing ridge height and controlling water input for basal fertilizer to minimize P loss. The application of P fertilizer increased the soil P pool, with labile P (L-P) and moderately labile P (M-P) increasing by 13–114 % and 23–111 %, respectively, compared to P0. The transformation of M-P to L-P in paddy soil is associated with an increased abundance of Actinobacteria. Low P applications (P25 and P50) increased EMF by 3.27 and 3.58 times, while high P applications (P75, P100, and P150) decreased EMF. Furthermore, P application significantly improved the soil quality index (SQI) compared to P0. The impact of abiotic factors on yield and P loss is more significant than that of biotic elements, with the SQI serving as a dependable indicator for predicting yield. Central to minimizing P loss while maximizing yield is the reduction of Resin-P content and the maintenance of NaOH-Pi levels, suggesting that organic materials may be a good alternative strategy. These findings provide valuable data and theoretical support for optimizing P application in rice-wheat cropping systems, promoting a mutually beneficial scenario for agricultural production and ecological protection.

Salicylic Acid and Melatonin Synergy Enhances Boron Toxicity Tolerance via AsA-GSH Cycle and Glyoxalase System Regulation in Fragrant Rice.

Background: Boron is an essential micronutrient for plant growth and productivity, yet excessive boron leads to toxicity, posing significant challenges for agriculture. Fragrant rice is popular among consumers, but the impact of boron toxicity on qualitative traits of fragrant rice, especially aroma, remains largely unexplored. The individual potentials of melatonin and salicylic acid in reducing boron toxicity are less known, while their synergistic effects and mechanisms in fragrant rice remain unclear. Methods: Thus, this study investigates the combined application of melatonin and salicylic acid on fragrant rice affected by boron toxicity. One-week-old seedlings were subjected to boron (0 and 800 µM) and then treated with melatonin and salicylic acid (0 and 100 µM, for 3 weeks). Results: Boron toxicity significantly impaired photosynthetic pigments, plant growth, and chloroplast integrity while increasing oxidative stress markers such as hydrogen peroxide, malondialdehyde, methylglyoxal, and betaine aldehyde dehydrogenase. Likewise, boron toxicity abridged the precursors involved in the 2-acetyl-1-pyrroline (2-AP) biosynthesis pathway. However, individual as well as combined application of melatonin and salicylic acid ameliorated boron toxicity by strengthening the antioxidant defense mechanisms-including the enzymes involved during the ascorbate-glutathione (AsA-GSH) cycle and glyoxalase system-and substantially improved 2-AP precursors including proline, P5C, Δ1-pyrroline, and GABA levels, thereby restoring the 2-AP content and aroma. These findings deduce that melatonin and salicylic acid synergistically alleviate boron toxicity-induced disruptions on the 2-AP biosynthesis pathway by improving the 2-AP precursors and enzymatic activities, as well as modulating the physio-biochemical processes and antioxidant defense system of fragrant rice plants. Conclusions: The findings of this study have the potential to enhance rice productivity and stress tolerance, offering solutions to improve food security and sustainability in agricultural practices, particularly in regions affected by environmental stressors.

Multisite Mutagenesis of 4-Hydroxyphenylpyruvate Dioxygenase (HPPD) Enhances Rice Resistance to HPPD Inhibitors and Its Carotenoid Contents.

While frequently used herbicides display limited efficacy against herbicide-resistant weeds, it becomes imperative to explore novel herbicides that ensure both effective weed management and environmental safety. Though 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitory herbicides like mesotrione are prevalent in maize weed management, their integration into rice production is hindered due to the inherent sensitivity of rice HPPD (OsHPPD). In this study, a mutant allele of OsHPPD featuring six amino acid substitutions, termed OsHPPD-6M, maintains enzymatic activity in 200 μm mesotrione while the wild type can only withstand 1 μm. Enzymatic assays in vitro indicated that the HPPD activity of OsHPPD-6M surpassed that of the WT by 2-fold through enhanced substrate-binding. Its overexpression in transgenic rice conferred greater tolerance to mesotrione, topramezone, and isoxaflutole by 36.7-, 41.6-, and 37.1-fold relative to that in the WT rice. Interestingly, these 6M-OE plants demonstrated substantially elevated contents of carotenoids compared to WT plants without a significant impact on agronomic traits.

Surfactins and Iturins Produced by Bacillus velezensis Jt84 Strain Synergistically Contribute to the Biocontrol of Rice False Smut

Rice false smut, caused by the plant pathogenic fungus Ustilaginoidea virens, is widespread in rice-growing regions globally, severely compromising rice quality and production. Employing Bacillus spp. to control rice false smut represents an effective and environmentally sustainable strategy for disease management. The lipopeptides produced by Bacillus velezensis Jt84 demonstrated robust inhibitory effects against U. virens, resulting in abnormal mycelial morphology and spore germination. Iturins were identified as essential for the antifungal activity against U. virens, as confirmed by mutagenesis experiments that suppressed iturin biosynthesis. The surfactin-deficient mutant exhibited inhibitory effects against U. virens comparable to the wild-type, indicating that the absence of surfactins did not diminish its antifungal activity. Both the Jt84∆srf and Jt84∆itu mutants displayed reduced biofilm formation capabilities compared to the wild-type, with the Jt84∆srf mutant being particularly impaired and unable to form a complete biofilm. Regarding swarming motility, the ∆srf mutant exhibited a significant reduction compared to the wild-type, whereas the Jt84∆itu mutant showed a modest increase. Colonization experiments revealed that the Jt84∆srf mutant strain had significantly lower colonization on rice leaf surfaces than the wild-type strain, highlighting the critical role of surfactins in the colonization of B. velezensis Jt84 on rice leaves. In conclusion, our research demonstrated that surfactins and iturins have distinct functionalities and act synergistically to contribute to the biocontrol of rice false smut in B. velezensis Jt84. This synergy is achieved through their potent antifungal effects, biofilm formation, and successful colonization.

Analysis of characteristics of rice tillering dynamics influenced by sowing dates based on DTM

To quantitatively analyze the regularity and characteristics of tillering dynamics of rice at different sowing dates. In this paper, the whole process of rice tillering was decomposed into two aspects: tiller occurrence and tiller extinction, and two Logistic functions were used to describe them respectively, so as to establish a dynamic tillering model in rice based on double Logistic function (Dynamic Tillering Model, DTM). Then, according to DTM, dynamic tillering indexes (DTIs) were defined and their calculation formulas were derived. Finally, the characteristics and laws of rice tillering dynamic response to sowing dates were analyzed using DTM and DTIs with the observed tillering data of three rice varieties, (Hui-Liangyou 898 (HLY898), Y-Liangyou 900 (YLY900) and Y-Liangyou 911 (YLY911)), in six sowing dates (March 15, March 20, March 25, March 30, April 5, April 10). The results show that: 1. The model fits well. The normalized RMSE (RMSEn) of the DTM fitted to the observed tillering data of different rice varieties sown at different times were all less than 10 %, and their mean values were less than 5 %. 2.The variation degree of DTIs under the influence of sowing dates had certain consistency among the three rice varieties. the inherent rate of tillering (Rit), the maximum tillering rate (Rmt), the maximum tillers extinction rate (Rme) and the duration of tillering (Dt) varied greatly, while the total number of grow tillers (Ng), the peak time of tillering (Tpt), the peak time of tillers extinction (Tpe) and the end time of tillering (Tet) had smaller variation. 3. The eight DTIs, the inherent rate of tillering (Rit), the duration of tillering (Dt), the maximum tillering rate (Rmt), the number of retained tillers (Nr), the peak time of tillering (Tpt), the end time of tillering (Tet), the start time of tillers extinction (Tse) and duration of tillers extinction (De), had a consistent linear response to the sowing dates among the three rice varieties. 4. Under different sowing dates, the dynamic characteristics of tillering of YLY900 and YLY911 were relatively close, while HLY898 had great differences from YLY900 and YLY911. In this paper, the evolution process of the number of tillers of rice was accurately described by the DTM, and the regularity and characteristics of tillering dynamics of rice were deeply revealed using the DTIs, with agronomic experiment of three varieties with six sowing dates. Therefore, it has important theoretical value to deeply understand the law of the tillering dynamic of rice affected by sowing dates and has important practical significance for guiding accurate planting and fine management of rice production from the perspective of grasping tillering dynamics.

Nitrogen regimes affect agro-physiology, carbon assimilation and sink behavior of scented rice

Agro-physiology, C-assimilation & its contribution in sink development; and crop yield can be augmented through N regimes for higher productivity of scented rice (aromatic and basmati). Being scented rice sink limited crop; we loomed to enhance sink capacity by augmenting leaf area index (LAI) though nitrogen (N) regimes in new environment. In order to establish N-relationship with sink capacity (SC) & filling efficiency (SFE) and to determine N-related agro-physiological behavior a field experiment for two years conducted in middle IGP. Four N levels (control, low, moderate and high) tested for two aromatic and two basmati rice varieties under split plot design. The basmati rice varieties reported 37.81-52.13% higher grain yield (GY) with lesser N over short grained aromatic varieties. Dry matter, its translocation and pre-anthesis contribution, tiller number and physiological traits at growth stages were also comparatively higher in HUBR 10–9 over short grained HUR 917 and comprehended parity level with HUR 4–3. The SFE was negatively correlated with SC and LAI across nitrogen dose and varieties. Higher LAI at moderate N produced larger sink; higher SFE was at low N. On contrary to short grained HUR 917; BS varieties (HUBR 10–9 & HUBR 2–1) produced larger sink. Economic N was lower for BSV’s (126.48–131.52 kg N ha−1) with GY potential of 5.11–6.01 Mg ha−1.

A novel method for rice identification: Coupling Raman spectroscopy with Fourier spectrum and analyzing with deep learning

The development of detection methods for food adulteration is of great significance for promoting innovation and development in food safety supervision technology. In this study, we proposed a novel model: Raman-Fourier-BiLSTM-CNN (RFBC), which combines Raman spectroscopy with deep learning to achieve precise identification of seven brands of japonica rice in the northeastern region of China. This model focuses on revealing the worth of the Fourier spectrum of Raman spectra. The raw Raman spectra and their Fourier spectra are cleverly coupled through a Bi-directional Long Short-Term Memory (BiLSTM) connection structure, and the resulting composite features are deeply analyzed by a Convolutional Neural Network (CNN). Compared to traditional algorithms, RFBC exhibits superior feature extraction capabilities. To further evaluate the recognition performance of RFBC, this study compared it with the RFBC model containing only the original Raman spectrum branch, as well as with machine learning models based on Principal Component Analysis (PCA), including Support Vector Machine (SVM), Random Forest (RF), K-Nearest Neighbor (KNN), and eXtreme Gradient Boosting (XGBoost). The results show that, compared with the other five models, RFBC can accurately identify different brands of japonica rice, with significant advantages in accuracy, precision, recall, and other aspects. RFBC achieves a classification accuracy of 97.1 %, macro precision of 97.2 %, macro recall of 97.1 %, and macro F1-score of 97.2 %. The system proposed in this study can more accurately identify brands of japonica rice, providing strong technical support for combating counterfeit japonica rice products.

Determination of Optimum Nitrogen Level for Maximizing Yield of Two HYV Boro Rice Varieties in Bogura Region, Bangladesh

Application of N fertilizer is very crucial for rice, but both excessive and mild reduced productivity. A field experiment was conducted during the Boro 2021-2022 season to find out the optimum dose of N fertilizer for higher yield. The trial was conducted in a factorial RCBD design with three replications. Factor A: Two varieties of rice viz. BRRI dhan89 and BRRI dhan100 and B: Five Nitrogen levels i.e., 0, 90, 120, 150, and 180 Kg ha−1. Yield and yield-contributing traits varied significantly with N levels. BRRI dhan89 outyielded BRRI dhan100 due to its varietal potential and longer life cycle. The highest tiller number hill−1, panicle number hill−1, panicle length, filled grain panicle−1, grain yield, biological yield and harvest index and lowest spikelet sterility were obtained from 120 kg N ha−1 irrespective of variety. The result revealed that the combination of both varieties with 120 kg N ha−1 followed by 90 Kg N ha−1 in maximizing rice productivity while avoiding excess use of N fertilizer. Bangladesh Agron. J. 2024, 26(2): 41-48

Rice Disease Image Classification using MobileNetV2 Pretrained Model with AcivationAttention Visualization using Gradient-weighted Class Activation Mapping (Grad-CAM)

Rice diseases is one of the recurring factors of failed harvest and reduced rice production output and it is one of the biggest problems for Indonesia especially because of Indonesia’s population dependent of rice as it’s staple food. Pest control using fast dan early detection is one of the solutions to reduce the potential of failed harvest. Using a pretrained model of MobileNetV2, a model has been successfully built to detect for different types of rice diseases using convolutional neural network architecture and transfer learning method. The modelling process uses 7.077 image sample of rice infected by bacterial blight, blast, brown spot, and tungro. The model then can be accessed through website and has 99% of classification accuracy. Furthermore, using Gradient-Weighted Class Activation Mapping (Grad-CAM) rice disease can then be marked on top of the original image as a heat map, providing the users easier way to localize dan verify the classification result faster.

Sodium stress-induced oxidative damage and antioxidant responses during grain filling in Indica rice.

Sodium treatment caused the sodium ion accumulation at the milk stage of immature rice grains which in turn triggered the overproduction of reactive oxygen species and oxidative damage. The tolerant cultivar showed an enhanced antioxidative response and induced expressions of OsNHX and OsHKT ion-transporters. Sodium chloride-(NaCl) induced soil salinity is a major constraint hindering global rice production. Amongst its constituent ions, sodium (Na+) is known to be the main driver of toxicity under salt stress. The present investigation aims to measure the impacts of excess Na+ during rice grain filling using two Indica rice cultivars with opposite tolerances to salt (salt tolerant: Panvel-3, salt-sensitive: Sahyadri-3) mainly via oxidative and responsive antioxidative pathways. Plants were treated with Na+-specific treatments and NaCl with equimolar Na+ levels (100mM) at the initiation of the reproductive phase. Stressed and control plants were harvested at three different grain-filling stages- early milk, milk, and dough and assessed for ion accumulation and oxidative damage/antioxidant responses under Na+ stress. Na+ toxicity triggered reactive oxygen species (ROS) production and upregulated the responsive enzymatic antioxidants. Na+ stress also increased the nitric oxide (NO) levels and the activity of nitrate reductase in immature grains. Differential expression levels of OsNHX and OsHKT transporters were observed in response to Na+ stress. Mature grains displayed a high accumulation of Na+ along with reduced K+ content and elevated Na+/K+ under high Na+ availability. The alterations in mature grains' sugar, starch, and protein content were also observed in response to the Na+ stress. Overall, the salt-tolerant cultivar displayed higher antioxidant activities and a lower rate of ROS generation in response to the Na+ stress. Results suggested a link between Na+ accumulation, Na+-mediated stress responses via anti/-oxidant pathways, and the grain-filling process in both rice cultivars.

Consumers’ Evaluation of Vertebrates and Invertebrates through Price Premiums for Eco-Rice in Urban and Rural Japan

Balancing food production and biodiversity conservation is a big challenge around the world. Eco-friendly agriculture has the potential to overcome these challenges and achieve sustainability. Although some studies show the high valuation of flagship species (e.g., attractive birds and fish) in paddy land where eco-friendly rice is cultivated, limited research has been performed concerning non-specific species such as generalists inhabiting rice paddies that also contribute to agro-biodiversity and ecosystem services. Therefore, this study assesses the valuation of non-flagship vertebrates and invertebrates by applying a choice experiment to vertebrate- and invertebrate-friendly rice. To understand the spatial/regional heterogeneity of the valuation, a questionnaire survey was distributed to both urban and rural citizens in Japan. Our results demonstrated that almost all respondents expressed a desire to protect both vertebrates and invertebrates, with more appreciation for vertebrates than for invertebrates. The analysis also found regional heterogeneity between urban and rural areas in terms of vertebrate and invertebrate evaluations and purchasing intentions. Our findings indicate marketing potential in Japan to promote eco-friendly rice production in relation to vertebrate and invertebrate conservation.

How Farm Machinery Rental Services and Off-Farm Work Affect Household Income in China

(1) Background: Most nations struggle to close significant income gaps between high and low earners. While the adoption of farm machinery rental services and off-farm employment may be beneficial, it is unclear whether jointly applying both approaches can raise income levels in rural households or help narrow the income gap within the farm sector. This study investigated scenarios involving both participation in farm machinery rental markets and in off-farm work, analyzing their varied impacts on household incomes based on survey data from 1027 rice producers in rural China. (2) Methods: We employed a two-stage econometric procedure encompassing a bivariate ordered probit model with an endogeneity-corrected unconditional quantile regression model. (3) Results: Rice farmers often simultaneously rent farm machinery services and engage in off-farm work. Both activities positively affect their household incomes; however, these effects vary across different income levels. Renting farm machinery provides greater marginal benefits for lower-income households, while off-farm employment has a stronger impact on higher-income households. Farm machinery rental services appear to benefit disadvantaged households more than off-farm employment opportunities do. (4) Suggestions: To enhance the welfare of lower-income households, policymakers should focus on expanding access to farm machinery rental services.

Influence of Nitrogen Levels and Microbial Inoculation on Growth, Yield and Straw of Direct Seeded Basmati Rice (Oryza sativa L.)

Background: Rice, a staple cereal, serves as the primary food for almost 50% of the world¢s population. Nitrogen is the predominant mineral element found in crops and serves as the primary constraint on Rice production. Direct-seeded rice cultivation has emerged as a potential alternative to traditional transplanting method. The goal is to provide insights that may be used to build sustainable agricultural methods that are specifically designed for Basmati rice production. Methods: This study aim to evaluate the effect of different N application levels (M1: 0 kg ha-1, M2: 40 kg ha-1 and M3: 60 kg ha-1) options as first factor with four microbial inoculation treatments (S1-Control, S2-Azosprillum (618g/ha) + Streptomyces’s (618g/ha), S3- Consortium (1235 g/ha) and S4-AMF (1235 g/ha). The experiment was conducted using a split-plot design (SPD) with three replications. Result: The study revealed that the maximum yield and yield attributes viz. plant height (116.47 cm), effective tillers ( 354.13 m2),leaf area index (2.64), no. of grains per panicle(84.17), length of panicle (24.66 cm), no. of filled grains per panicle (125.0), grain yield (54.30 q ha-1), straw yield ( 80.42 q ha-1), biological yield (134.72 q ha-1) and 1000-grain weight (24.64 g), maximum protein content (%) in grains (8.73%), straw (5.78%) was recorded in M3S2 i.e. 60 kg N ha-1 with azosprillum (618 g/ha) + streptomyces's (618 g/ha) significantly highest compared to other nitrogen levels and microbial inoculation treatments. Hence, the application of N @ 60 kg ha-1 along with azosprillum (618 g/ha)+Streptomyces¢s (618 g/ha) can be suggested to achieve higher rice grain yield, yield attributes and nitrogen content in grain and straw in DSR.

Reduced Nitrogen Application with Dense Planting Achieves High Eating Quality and Stable Yield of Rice.

Rational nitrogen (N) application can enhance yield and improve grain eating quality in rice. However, excessive N input can deteriorate grain eating quality and aggravate environmental pollution, while reduced N application (RN) decreases rice yield. Reduced N application with dense planting (RNDP) is recommended for maintaining rice yield and improving N use efficiency. However, the effects of RNDP on the rice grain eating quality and starch structure and properties remain unclear. A two-year field experiment was conducted to investigate the effects of RNDP on the rice yield, grain eating quality, and starch structure and properties. Compared to conventional N treatment, RN decreased significantly the rice yield, while RNDP achieved a comparable grain yield. Both the RN and RNDP treatments improved significantly the rice eating quality. The high eating quality of RNDP was attributed to increased gel consistency, pasting viscosity, and stickiness after cooking as well as decreased protein content. A further analysis of starch structure and properties revealed that RNDP decreased the relative crystallinity, lamellar intensity, gelatinization enthalpy, and retrogradation enthalpy of starch. Therefore, RNDP achieved a stable rice yield and enhanced rice eating quality. These findings provide valuable insights into obtaining optimal quality and consistent yield in rice production under reduced N conditions.

Evaluating the effect of organic NPK granules on yield, nutrient uptake, post-harvest soil fertility and soil microbial population in rice (Oryza sativa L.)

Rice is the most important and staple food crop for more than two third of population of India. India is the second largest rice producing country in the world after China. Although, rice planted area in India is 40 per cent higher than in China, Indian rice production is 30 percent below Chinese production because of lower yields. Among several constraints of production, nutrient management plays a key role in realizing sustainable yield from any given cultivation practices. Integrated nutrient management system plays a vital role in balancing the soil fertility and plant nutrient supply to an optimum level through the judicious and efficient use of chemical fertilizers, green manure, FYM and biofertilizers leading to an eco-friendly approach and economically viable solution for this problem. Continuous integrated use of organic manures with chemical fertilizers would be quite promising in assessing the sustainability of a cropping system vis-à-vis monitoring the soil properties. To investigate further, a field experiment was conducted at the Experimental Farm, Department of Agronomy, Annamalai University, Annamalai Nagar, Cuddalore district of Tamil Nadu from June to September 2023 with a key objective of evaluating the effect of combined application of graded levels of conventional fertilizers along with organic NPK granules in lowland rice. The experiment was laid out in randomized block design with seven treatments comprised of different levels of conventional fertilizers along with organic NPK granules. Among the nutrient management evaluated, all the yield attributes of lowland rice viz., grain yield, straw yield, uptake of nutrients and post-harvest soil available nutrients were significantly influenced by the application of 70% NPK through synthetic fertilizers and 30% NPK through organic granules. Combining conventional fertilizers along with organic NPK granules improved nitrogen use efficiency via metabolite production, enzyme activity stimulation, and microbial rhizosphere interactions significantly enhancing the yield attributes and yield.

A Synthesis Analysis of the Relationship between Main and Ratoon Crop Grain Yields in Ratoon Rice

Ratoon rice represents a viable means to enhance rice production efficiency in terms of both area and time. Nonetheless, the development of specific varieties tailored for ratoon rice has been hindered by the complexity of trait considerations required during breeding/screening processes. A pivotal step towards advancing ratoon rice breeding programs involves reducing the dimensionality of selection traits. In this study, we performed a comprehensive analysis exploring whether the yield of the main crop could serve as a predictor for ratoon crop yield, thereby simplifying the selection process. Our findings revealed significant variability in the rice yields of both main and ratoon crops, with the ratoon crop yield averaging 51% of the main crop. Importantly, the correlation between grain yields of the main and ratoon crops did not deviate from the identity line, substantiating the feasibility of predicting ratoon crop yield based on the main crop yield. The number of panicles in the ratoon crops was found to be closely linked to that of the main crop; however, the size values of the panicles in the ratoon crops exhibited less of a dependency on the main crop’s panicle size. Additionally, a general decrease in grain weight was observed in the ratoon crops compared to the main crop. In summary, this study elucidates a pathway for the simplification of selection traits, thereby enhancing the efficiency of breeding high-yielding ratoon rice varieties, with the ultimate aim of fostering the sustainable development of ratoon rice.

Quantifying chlorophyll content index for efficient nitrogen management in rice (Oryza sativa L.)

Applying nitrogen fertilizer strategically enhances rice productivity in nitrogen-deficient soils. Splitting fertilizer doses across growth stages optimizes nutrient use efficiency. Monitoring chlorophyll levels correlates closely with leaf nitrogen content, crucial for assessing crop health. Non-destructive chlorophyll content meter techniques, such as the Chlorophyll Content Index (CCI), allow for precise nitrogen management adjustments in the field. However, its critical value may differ depending on crops and varieties. Hence, to find out the critical CCI value for rice cv. ADT 43, observational trials were conducted at the Experimental Farm of Annamalai University during two seasons Kuruvai (June-Oct 2023) and Navarai (Dec-March 2024). The pooled data of the present study indicated that the average LNC (maximum tillering, panicle initiation and booting stages) has a linear relationship (R2=0.8545) with the yield of rice crop. The corresponding higher yield ( greater than 7t/ha) coincided with LNC of 3.1%. Likewise, the average CCI has a linear relationship (R2=0.9031) with the LNC of rice plants. The corresponding LNC ( greater than 7t/ha) was matched with the CCI value of 29. This CCI value of 29 is considered as the critical CCI value. CCI can be used as a decision-support tool for N-fertilization of short duration rice crop, and when CCI reduced below this critical value the farmers can fertilise the field with adequate N.