Search Results (349)

During vegetative growth, plants undergo various morphological and physiological changes in the transition from the juvenile phase to the adult phase. In terms of stress resistance, it has been suggested that plants gain or reinforce disease resistance during the process of maturation, which is recognized as adult plant resistance or age-related resistance. While much knowledge has been obtained about changes in disease resistance as growth stages progress, knowledge about changes in plant responses to pathogens with progressing age in plants is limited. In this study, we experimentally compared rice blast resistance in rice leaves sampled from plants at different growth phases. The results indicate differential infection progression and fungal status depending on growth stage. Transcriptome analysis following blast fungus infection revealed that several genes involved in the defense response were upregulated in both the juvenile and intermediate stage, but the expression changes of many genes were growth phase-specific. These findings highlight differences in rice leaf stress responses to blast infection at different growth stages. Full article

The coastal regions of Bangladesh host a rich diversity of Aman rice landraces, which are crucial for local agriculture but are highly vulnerable to natural disasters like cyclones and floods. Specifically, local landraces often experience flooding during grain filling and maturation stages, and sprouts in the field lead to a severe loss of yield. Seed dormancy, which delays germination, is a key trait for escaping sprouting in the field during harvesting. However, there is lack of information on genetic variability in the existing rice landraces grown in the coastal area of Bangladesh. This study evaluated the seed dormancy of 28 local Aman rice landraces, plus four varieties from the Bangladesh Institute of Nuclear Agriculture and Bangladesh Rice Research Institute. Germination tests were conducted under controlled conditions, and an electrical conductivity (EC) test was used to assess seed vigor. The results showed that Bari Mota, Tulsimala, Chinigura, Dishari, and Birindi exhibited the highest dormancy rates, i.e., 100%, 100%, 99%, 99%, and 99%, respectively, while BINA Dhan 10, Nona Bokra, and BINA Dhan 8 had the lowest dormancy rates, with values of 11%, 16%, and 24%, respectively. Priming treatments enhanced germination rates in some varieties; however, others, such as Bari Mota and Tulsimala, remained dormant, underscoring the variability in seed dormancy levels. Compared to non-priming, a significant improvement of germination was recorded in BRRI dhan 41 (85.3% vs. 9%), Motha mota (84% vs. 8%), Lal chikon (74.6% vs. 1%), Sadamota (74.6% vs. 5%), and Bashful (53.3% vs. 3%). Altogether, our results suggest that local landraces are diverse in seed dormancy, and genotypes with high dormancy, such as Bari Mota and Tulsimala, can potentially be grown in the disaster-prone coastal areas. In contrast, these genotypes can be used for future breeding programs. Therefore, this study carries significant implications for rice cultivation in the coastal areas of Bangladesh. Full article

Inefficient phosphorus (P) fertilizer application often accumulates soil P, wasting valuable phosphate resources and contributing to environmental pollution. Given the suboptimal P fertilizer use efficiency (PUE), understanding soil P dynamics and selecting appropriate fertilizers is crucial. Fluvo-aquic soil and yellow-cinnamon soils were used in a rice pot trial to compare five P fertilizer types: single superphosphate (SSP), diammonium phosphate (DAP), calcium magnesium phosphate (CMP), triple superphosphate (TSP), and ammonium polyphosphate (APP), alongside a no P, control (CK). In fluvo-aquic soil, TSP and APP significantly increased rhizosphere P availability at anthesis, while SSP increased yield and shoot P accumulation at maturity. In yellow-cinnamon soil, DAP had the highest rhizosphere P availability at anthesis, while APP significantly increased shoot P accumulation at anthesis and shoot P accumulation and grain yield at maturity. Moreover, PUE was highest with SSP and CMP in fluvo-aquic soil and APP and TSP in yellow-cinnamon soil. Throughout the experiment, increased soil alkaline phosphatase activity promoted NaOH-Po conversion to NaHCO₃-Pi, increasing rice shoot P uptake, yield, and PUE in both soils. Based on the above findings, it is recommended to apply SSP and TSP to fluvo-aquic soil and APP and TSP to yellow-cinnamon soil to achieve higher yield and PUE, which can be further confirmed by subsequent field-scale studies. Full article

Despite the successful breeding of hybrid japonica rice by the new strategy (the female parent with a restorer line containing an appropriate proportion of indica rice genes) in China, it remains unclear whether these cultivars exhibit a similar yield performance with the traditional high-yield hybrid cultivars in the Yangtze River region. Therefore, two field experiments were conducted in Fenghua City and Yuyao City, China, during the two growing seasons in 2019 and 2020. Six japonica hybrid rice cultivars and one control indica–japonica hybrid rice cultivar (Yongyou1540 [YY1540]) were chosen as the experimental materials in each year, and the seedling quality, grain yield, and yield components were evaluated. The results showed that the grain yield of YY1540 was 13.9 t ha⁻¹ and 14.5 t ha⁻¹ in 2019 and 2020, respectively, which was the highest among all cultivars in both years. However, the japonica hybrid rice cultivars CHY83 in 2019 and CHY112 in 2020 also achieved high yield performance with 13.7 t ha⁻¹ and 14.0 t ha⁻¹, respectively, which were not significantly difference from YY1540. The japonica hybrid cultivars with a high grain yield typically exhibited more spikelets per panicle, more spikelets per m², and a higher harvest index than those with a lower grain yield. Increasing the total growth duration had a limited impact on the grain yield of japonica hybrid rice. However, the post-heading daily grain yield was significantly positively correlated with grain yield in japonica hybrid rice cultivars. Moreover, significant quadratic relationships were observed between plant height at maturity and grain yield and between seedling dry weight and grain yield. The optimal plant height at maturity and seedling dry weight for achieving a high grain yield in japonica hybrid rice were approximately 130 cm and 300 mg plant⁻¹, respectively. This study provides useful information for breeding high-yield japonica hybrid cultivars. Full article

The starch content in rice grains is a key factor in determining their quality. An optimal starch level not only ensures grain fullness, improving storage stability, but also enhances the stickiness and viscosity of cooked rice, thereby boosting its palatability and nutritional value. However, traditional methods for monitoring starch content are expensive and lack the capability to provide rapid spatial distribution information across large areas. To address this limitation, this study focuses on mature rice grains in the Yingjiang region, leveraging multispectral data from the Sentinel-2 satellite. First and second derivative transformations were applied to the multispectral reflectance data, followed by the use of three feature selection algorithms to identify key spectral bands. BP neural networks and ELM neural network regression models were then integrated to quantitatively estimate starch content across the study area. As a result, high-precision spatial distribution maps of starch content were generated, providing a novel and efficient method for large-scale rapid monitoring. The results demonstrate that, compared to full-band data, the use of SPA feature selection significantly improved the predictive accuracy of both BP and ELM models, despite a slight increase in the models’ MSE. Similarly, CARS feature selection also contributed substantially to enhancing the accuracy of the BP and ELM models. In contrast, UVE feature selection significantly reduced the MSE of the BP model, improving predictive precision, with the model achieving an R² of 0.8061 and an MSE of 0.3896. This study highlights that the inversion method, which combines feature selection algorithms with machine learning models, can effectively enhance the predictive accuracy of starch content estimation. Among the tested approaches, the combination of UVE feature selection and BP neural networks delivered the best performance. These findings confirm the feasibility of utilizing Sentinel-2 satellite multispectral data for the quantitative inversion of agronomic parameters across large agricultural areas, providing robust technical support for precision agriculture. Full article

This study aimed to investigate the impact of nitrogen (N) fertilizer on bacterial community composition and diversity in the rhizosphere and endosphere of rice at different growth stages. Two treatments, N0 (no N application) and N1 (270 kg N ha⁻¹), were implemented, with samples collected during the jointing, tasseling, and maturity stages. High-throughput sequencing was used to analyze the structure and composition of bacterial communities associated with Huaidao No. 5 (japonica conventional rice). The findings indicated that root zone location was the primary factor influencing the diversity and composition of rice root-associated bacterial communities. Further analysis revealed that nitrogen fertilizer primarily influenced rhizosphere bacterial diversity, while endosphere bacterial diversity was more significantly affected by growth stages. Rice recruited distinct beneficial bacteria in the rhizosphere and endosphere depending on the growth stage. Additionally, the relative abundance of functional genes related to nitrogen metabolism in root-associated bacteria was not significantly influenced by nitrogen application at 270 kg N ha⁻¹. These findings offer valuable insights into how nitrogen fertilizer affects plant root bacterial communities across different growth stages. Full article

To screen rice varieties with high storage stability for eating quality and elucidate their traits, 34 widely grown rice varieties were selected to examine the changes in the eating quality of their grains after natural storage for one year. A hierarchical analysis, normalization method, and cluster analysis were used to identify the rice varieties that maintained their eating quality during storage. Meanwhile, the yield and its components, panicle traits, grain size, grain major component content, physiological indicators (such as antioxidant enzyme activity), and key growth stages were analyzed at rice maturity. The results showed that after storage, the values of the appearance, texture, and taste of the cooked rice decreased by 18.7%, 19.1%, and 14.2%, respectively. The storage stability of the eating quality of rice was evaluated using a hierarchical analysis based on the storage stability scores of the appearance, texture, and taste of the cooked rice. A judgment matrix was established, where the corresponding weights of the appearance, texture, and taste of the cooked rice were identified to be 0.105, 0.259, and 0.637, respectively. Based on a cluster analysis and the normalization method, these varieties were classified into three categories regarding the storage stability of their eating quality: high storage stability, intermediate storage stability, and low storage stability, accounting for 14.7%, 52.9%, and 32.4%, respectively. Finally, five rice varieties with high storage stability were screened. These varieties exhibited storage stability scores of the appearance, texture, and taste of cooked rice that were 215%, 219%, and 340% higher than those of the low storage stability type, respectively. The correlation analysis revealed that the storage stability of the eating quality of the rice was significantly and negatively correlated with amylose starch content, peroxidase activity, and malondialdehyde content. The amylose starch content, peroxidase activity, and malondialdehyde content of the high storage stability type were 12.4%, 35.9%, and 6.42% lower than those of the low-storage-stability variety, respectively. Therefore, the major features of rice varieties with high storage stability included low amylose starch content, diminished peroxidase activity, and low malondialdehyde content. This study provides valuable theoretical insights into the safe storage of rice grains and the selection and breeding of rice varieties with high storage stability. Full article

As rice yield rises, the issue of broken axis windings in mature rice threshing drums is becoming increasingly severe. To disclose the winding characteristics and signal traits of the drums during the threshing process of mature rice, this paper undertakes an analysis of the winding characteristics and signals of the drums in rice with the assistance of a vibration test and analysis system. Since rice can lead to drum winding and shaft breakage, this paper alters the driving mode of the drums to exhibit the influence of rice on them. Firstly, the transfer characteristics of the frame need to be studied and analyzed, followed by subsequent research. The test results indicate that the horizontal displacement of the cylinder axial trajectory rises with the growth of the transmission chain, while the vertical displacement drops with the growth of the transmission chain. Additionally, to investigate the effect of mature rice on the threshing performance of horizontal axis II and horizontal axis III, a control variable method was employed. This approach allowed for the observation of how mature rice influences the threshing roller by systematically adjusting both the threshing gap and the rotational speed of the roller. It can be discerned from the test results that with the reduction of the threshing gap of affected mature rice, the unstripped rate gradually declines, while the entrainment loss rate gradually increases. As the rotational speed of horizontal shaft roller III increases, the rate of uncleared material gradually decreases, while the rate of entrainment loss progressively rises. The research findings can furnish a reference for the winding characteristics of rice on rollers and the enhancement of vehicle driving comfort. Full article

In the face of declining crop yields, inefficient fertilizer usage, nutrient depletion, and limited water availability, the efficiency of conventional NPK fertilizers is a critical issue in India. The hypothesis of this study posits that nano-nitrogen could enhance growth and photosynthetic efficiency in crop plants compared to conventional fertilizers. For this, a randomized block design (RBD) field experiment was conducted with six treatments: no nitrogen (T1), 100% N through urea (T2), and varying levels of N replacement with nano-nitrogen (33%: T3; 50%: T4; 66%: T5; and 100%: T6). Morphological and physiological traits and yield attributes were measured at physiological maturity, and yield attributes were measured at harvest. Results showed that 33% nitrogen replacement with nano-nitrogen (T3) outperformed conventional urea (T2) in physiological traits and achieved higher grain yields (3789 kg/ha for rice and 4206 kg/ha for wheat) compared to T2 (3737 kg/ha for rice and 4183 kg/ha for wheat with 100% urea). Although T4 and T5 showed statistically similar yields, they were lower than T2 and T3 for rice, while 50%, 66%, and 100% replacements reduced wheat yield by 2.49%, 8.39%, and 41.26%, respectively, compared to T2. Key enzymes of N metabolism decreased with higher nano-nitrogen substitution. Maximum nitrogen availability was observed in T2 and T3. This study concludes that nano-nitrogen is an effective strategy to enhance growth, balancing productivity and environmental sustainability. Full article

Rice is the staple diet for most of the world’s population and is considered a major staple crop in China. Anhui province of China is among the leading provinces for rice production, consumption, and commodities; it is well-known as the “land of fish and rice”. Japonica rice cultivation in Anhui Province is mainly categorized into late-maturing medium, early-maturing medium, and early-maturing late japonica. This review explores the suitable ecological zone distribution and corresponding climate characteristics of the three types of japonica rice in Anhui Province. Data on japonica rice varieties approved in the province over the past twenty years were collected, illustrating the development process of japonica rice varieties in the province and their quality and resistance to rice blast disease. The review shows that the yield is positively and significantly correlated with agronomic traits, such as the number of effective panicles and the total number of grains per panicle, plant height, etc. In addition, it elucidates the major problems faced by Anhui’s japonica rice breeding and cultivation, such as frequent events of high temperatures, rice blast disease, and medium to low soil fertility levels. Considering the existing issues in breeding japonica rice varieties in Anhui Province, this review proposes a strategy for breeding high-yield and disease-resistant japonica rice varieties, particularly varieties adaptable to medium and low fertility soil conditions. In brief, this article provides a theoretical basis and practical recommendations for the sustainable development of japonica rice in the Anhui Province of China. Full article

Rice is a water-intensive crop, conventionally grown under submerged conditions, with standing water for about 80% of its growth period. There is an urgent need for water-saving technologies to address challenges associated with conventional irrigation techniques for rice. The alternate wetting and drying (AWD) technique is one of these water-saving techniques; however, it requires continuous monitoring of water levels in the field. The implementation of real-time, electronic sensor-based precision irrigation technology may address the problems associated with conventional irrigation systems and AWD leading to high water use efficiency. Therefore, a study was undertaken to develop a suitable sensor-based automated irrigation system to maintain optimal water levels in rice fields. This study conceptualized an electronic sensor-based automated irrigation system for rice cultivated under the AWD technique. In this method, the rice field is initially flooded to a maximum depth of 5 cm. Irrigation is reapplied once the water level reduces to 10 cm below the soil surface. This developed system helps address water scarcity by regulating water levels, preventing excess ponding. It uses magnetic float-based sensors and electronic circuits to detect water levels, converting them into electronic signals transmitted wirelessly via radio frequency (RF) to a controller. The controller has been programmed for different growth stages that need to be set manually during the cropping period. The system is designed primarily for the AWD method but includes an option for continuous ponding (CP), needed during the flowering stage. The maximum water level at full maturity is set at 5 cm above the soil surface, while irrigation with the AWD method begins when the water level falls 10 cm below the soil surface. The developed system was tested during the Kharif season of 2018–19; the irrigation water productivity was 6.15 kg ha⁻¹mm⁻¹ with the automated system, compared to 3.06 kg ha⁻¹mm⁻¹ in the control (continuous ponding). Total water productivity was 4.80 kg ha⁻¹mm⁻¹ for the automated system and 2.63 kg ha⁻¹mm⁻¹ for the control. The automated system achieved 36% more water savings over the control, which used continuous ponding as farmers practice. The developed system supports AWD, a proven water-saving technique in rice cultivation. Full article

Rice (Oryza sativa) plays a pivotal role in global food security. Understanding the genetics of rice cultivation is crucial, particularly for traits such as viviparous germination, which significantly influences germination and yield. Our research aimed to elucidate the genetic and molecular mechanisms by which the Sdr4 gene influences viviparous germination and to develop novel molecular markers for this gene to enhance breeding strategies against viviparous germination. In all, 683 rice cultivars and 100 F₂ plants were used for viviparous germination and genetic analysis using KASP (Kompetitive Allele-Specific PCR) and agarose gel-based markers related to viviparous germination tolerance. We developed and used a polymorphic agarose gel-based marker and a KASP marker targeting the Sdr4 gene. A genetic analysis of field-grown rice cultivars and the F₂ population revealed that the two markers on Sdr4 were functional for the genomic selection of SNPs and InDels related to dormancy. The Pearson correlation coefficient (r = 0.74, p-value = 3.31 × 10⁻⁸) between the Sdr4-IND KASP marker genotype and viviparous germination rate demonstrated a significant positive correlation, supporting the marker’s utility for selecting rice varieties with diminished viviparous germination. This insight serves as a critical theoretical foundation for breeding strategies for developing early-maturing rice varieties with enhanced resistance to viviparous germination, addressing pivotal challenges in rice cultivation, and ensuring food security. Full article

The carbon and nitrogen (N) metabolism of rice under different mid-stage N compensation timings is unclear. Two Japonica super rice cultivars were examined under four N compensation timings (N1-N3: N compensation at mid-tillering, panicle initiation, and spikelet differentiation. N0: no N compensation) and CK with no N application. Mid-stage N compensation increased the N concentrations of various tissues, and N2 showed the highest plant N uptake at both the heading stage, maturity, and the grain filling period. Among the treatments, N2 showed the highest N utilization efficiency. With delayed compensation timing, there was a gradual decrease in soluble sugar and starch concentrations in each tissue, accompanied by a decline in the non-structural carbohydrate (NSC) concentration. Specifically, N2 treatment exhibited the highest NSC accumulation and the remobilized NSC reserve, but NSCs per spikelet decreased with delayed compensation timing. The highest yield was also obtained with N2, exhibiting a 4.5% increase compared to the N0 treatment, primarily due to an improvement in spikelets per panicle. Conclusively, N compensation at the panicle initiation stage is a reasonable N management strategy that can coordinate the improvement of carbon and N metabolism, enhance N accumulation with efficient utilization and NSC accumulation, and ultimately increase the yield. Full article

Aroma is a crucial determinant of rice taste quality, with volatile organic compounds (VOCs) playing a key role in defining this characteristic. However, limited research has explored the dynamic changes in these aromatic substances during the ripening stages of rice grains. In this study, we analyzed VOCs in rice grains across four ripening stages post-flowering using headspace solid-phase microextraction combined with gas chromatography–mass spectrometry (HS-SPME-GC-MS). A total of 417 VOCs were identified, among which 65 were determined to be key aroma-active compounds based on relative odor activity value (rOAV) analysis. Most of these aroma-active compounds exhibited an accumulation pattern as the grains matured. Notably, 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone and 2-Methyloxolan-3-one had the largest rOAV values. Additionally, (Z)-6-nonenal, (Z,Z)-3,6-nonadienal, 2-thiophenemethanethiol, 5-methyl-2-furanmethanethiol, 2,2,6-trimethyl-cyclohexanone, and 3-octen-2-one were identified as potential key markers for distinguishing rice-grain maturity stages. Moreover, 2-acetyl-1-pyrroline (2-AP), heptanal, and 1-nonanol were identified as marker metabolites differentiating aromatic from non-aromatic brown rice. These findings contribute to a deeper understanding of the dynamic variation and retention of aroma compounds during rice-grain ripening, and they offer valuable insights into the improvement of fragrant rice varieties. Full article