High-yielding Rice Research Articles

Generation of Two-Line Restorer Line with Low Chalkiness Using Knockout of Chalk5 through CRISPR/Cas9 Editing.

Chalkiness is an important grain quality trait in rice. Chalk5, encoding a vacuolar H+-translocating pyrophosphatase, is a major gene affecting both the percentage of grains with chalkiness (PGWC) and chalkiness degree (DEC) in rice. Reducing its expression can decrease both PGEC and DEC. In this study, the first exon of Chalk5 was edited in the elite restorer line 9311 using the CRISPR/Cas9 system and two knockout mutants were obtained, one of which did not contain the exogenous Cas9 cassette. PGWC and DEC were both significantly reduced in both mutants, while the seed setting ratio (SSR) was also significantly decreased. Staggered sowing experiments showed that the chalkiness of the mutants was insensitive to temperature during the grain-filling stage, and the head milled rice rate (HMRR) could be improved even under high-temperature conditions. Finally, in the hybrid background, the mutants showed significantly reduced PGWC and DEC without changes in other agronomic traits. The results provide important germplasm and allele resources for breeding high-yield rice varieties with superior quality, especially for high-yield indica hybrid rice varieties with superior quality in high-temperature conditions.

Genetic improvement of phosphate-limited photosynthesis for high yield in rice

Low phosphate (Pi) availability decreases photosynthesis, with phosphate limitation of photosynthesis occurring particularly during grain filling of cereal crops; however, effective genetic solutions remain to be established. We previously discovered that rice phosphate transporter OsPHO1;2 controls seed (sink) development through Pi reallocation during grain filling. Here, we find that OsPHO1;2 regulates Pi homeostasis and thus photosynthesis in leaves (source). Loss-of-function of OsPHO1;2 decreased Pi levels in leaves, leading to decreased photosynthetic electron transport activity, CO2 assimilation rate, and early occurrence of phosphate-limited photosynthesis. Interestingly, ectopic expression of OsPHO1;2 greatly increased Pi availability, and thereby, increased photosynthetic rate in leaves during grain filling, contributing to increased yield. This was supported by the effect of foliar Pi application. Moreover, analysis of core rice germplasm resources revealed that higher OsPHO1;2 expression was associated with enhanced photosynthesis and yield potential compared to those with lower expression. These findings reveal that phosphate-limitation of photosynthesis can be relieved via a genetic approach, and the OsPHO1;2 gene can be employed to reinforce crop breeding strategies for achieving higher photosynthetic efficiency.

A Novel Function of GW5 on Controlling the Early Growth Vigor and its Haplotype Effect on Shoot Dry Weight and Grain Size in Rice (Oryza sativa L.)

Strong early growth vigor is an essential target in both direct seeded rice breeding and high-yielding rice breeding for rice varieties with relatively short growth duration in the double-cropping region. Shoot dry weight (SDW) is one of the important traits associated with early growth vigor, and breeders have been working to improve this trait. Finding stable QTLs or functional genes for SDW is crucial for improving the early growth vigor by implementing molecular breeding in rice. Here, a genome-wide association analysis revealed that the QTL for SDW, qSDW-5, was stably detected in the three cultivation methods commonly used in production practice. Through gene-based haplotype analysis of the annotated genes within the putative region of qSDW-5, and validated by gene expression and knockout transgenic experiments, LOC_Os05g09520, which is identical to the reported GW5/GSE5 controlling grain width (GW) and thousand grain weight (TGW) was identified as the causal gene for qSDW-5. Five main haplotypes of LOC_Os05g09520 were identified in the diverse international rice collection used in this study and their effects on SDW, GW and TGW were analyzed. Phenotypic comparisons of the major haplotypes of LOC_Os05g09520 in the three subpopulations (indica, japonica and aus) revealed the same patterns of wider GW and higher TGW along with higher SDW. Furtherly, the haplotype analysis of 138 rice varieties/lines widely used in southern China showed that 97.8% of the cultivars/lines carry Hap2LOC_Os05g09520. These results not only provide a promising gene source for the molecular breeding of rice varieties with strong early growth vigor, but also elucidate the effect of the LOC_Os05g09520 haplotypes on SDW, GW, and TGW in rice. Importantly, this study provides direct genetic evidence that these three traits are significantly correlated, and suggests a breeding strategy for developing high-yielding and slender grain-shaped indica cultivars with strong early growth vigor.

OsCKq1 Regulates Heading Date and Grain Weight in Rice in Response to Day Length

BackgroundPhotoperiod sensitivity is among the most important agronomic traits of rice, as it determines local and seasonal adaptability and plays pivotal roles in determining yield and other key agronomic characteristics. By controlling the photoperiod, early-maturing rice can be cultivated to shorten the breeding cycle, thereby reducing the risk of yield losses due to unpredictable climate change. Furthermore, early-maturing and high-yielding rice needs to be developed to ensure food security for a rapidly growing population. Early-maturing and high-yielding rice should be developed to fulfill these requirements. OsCKq1 encodes the casein kinase1 protein in rice. OsCKq1 is a gene that is activated by photophosphorylation when Ghd7, which suppresses flowering under long-day conditions, is activated.ResultsThis study investigates how OsCKq1 affects heading in rice. OsCKq1-GE rice was analyzed the function of OsCKq1 was investigated by comparing the expression levels of genes related to flowering regulation. The heading date of OsCKq1-GE lines was earlier (by about 3 to 5 days) than that of Ilmi (a rice cultivar, Oryza sativa spp. japonica), and the grain length, grain width, 1,000-grain weight, and yield increased compared to Ilmi. Furthermore, the culm and panicle lengths of OsCKq1-GE lines were either equal to or longer than those of Ilmi.ConclusionsOur research demonstrates that OsCKq1 plays a pivotal role in regulating rice yield and photoperiod sensitivity. Specifically, under long-day conditions, OsCKq1-GE rice exhibited reduced OsCKq1 mRNA levels alongside increased mRNA levels of Hd3a, Ehd1, and RFT1, genes known for promoting flowering, leading to earlier heading compared to Ilmi. Moreover, we observed an increase in seed size. These findings underscore OsCKq1 as a promising target for developing early-maturing and high-yielding rice cultivars, highlighting the potential of CRISPR/Cas9 technology in enhancing crop traits.

Vermicompost application enhances soil health and plant physiological and antioxidant defense to conferring heavy metals tolerance in fragrant rice

Cadmium (Cd) contamination in agricultural soils and its accumulation in plant organs have become a global issue due to its harmful effects on human health. The in-situ stabilizing technique, which involves using organic amendments, is commonly employed for removing Cd from agricultural soils. Thus, the current study investigated the effect of vermicompost (VC) on soil properties and plant physio-biochemical attributes, leaf ultrastructure analysis, antioxidant defense mechanisms, and grain yields of two different fragrant rice cultivars, Xiangyaxiangzhan (XGZ) and Meixiangzhan-2 (MXZ-2), under Cd-stress conditions. The results showed that Cd toxicity deteriorates soil quality, the plant’s photosynthetic apparatus, and the plant’s antioxidant defense mechanism. Moreover, under Cd stress, both cultivars produced significantly lower (p < 0.05) rice grain yields compared to non-Cd stress conditions. However, the VC application alleviated the Cd toxicity and improved soil qualitative traits, such as soil organic carbon, available nitrogen, total nitrogen, phosphorus, and potassium. Similarly, VC amendments improved leaf physiological activity, photosynthetic apparatus function, antioxidant enzyme activities and its related gene expression under Cd stress These enhancements led to increased grain yields of both fragrant under Cd toxicity. The addition of VC mitigated the adverse effects of Cd on the leaf chloroplast structure by reducing Cd uptake and accumulation in tissues. This helped prevent Cd-induced peroxidation damage to leaf membrane lipids by increasing the activities of antioxidant enzymes such as ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD). On average across the growth stages, the Pos-Cd + VC3 treatment increased SOD, APX, CAT, and POD activities by122.2 and 112.5%, 118.6, and 120.6%, 44.6 and 40.6%, and 38.6 and 33.2% in MXZ-2 and XGZ, respectively, compared to the plants treated with Pos-Cd treated alone. Enhancements in leaf physiological activity and plant antioxidant enzyme activity strengthen the plant’s antioxidant defense mechanism against Cd toxicity. In addition, correlation analysis showed a strong relationship between the leaf net photosynthetic rate and soil chemical attributes, suggesting that improved soil fertility enhances leaf physiological activity and boosts rice grain yields. Of the treatments, Pos-Cd + VC3 proved to be the most effective treatment in terms of enhancing soil health and achieving high fragrant rice yields. Thus, the outcomes of this study show that the addition of VC in Cd-contaminated soils could be useful for sustainable rice production and safe utilization of Cd-polluted soil.

Effects of Phosphorus and Potassium Supply on Photosynthetic Nitrogen Metabolism, Nitrogen Absorption, and Nitrogen Utilization of Hydroponic Rice

Phosphorus (P) and potassium (K) stress significantly affect the growth, physiological characteristics, and nutrient uptake of rice plants. This study investigated the photosynthetic nitrogen (N) metabolism, N uptake, and N utilization of plants under varied P and K supplies. Two local conventional high-yield rice varieties (Shennong 265 and Liaojing 294) were used. These varieties were subjected to the following hydroponic experimental treatments: HPHK (normal P and K concentrations), HPLK (normal P and 1/20 normal K concentration), LPHK (normal K and 1/20 normal P concentration), and LPLK (1/20 normal P and K concentrations). The results showed that the mesophyll cells had a relatively complete nuclear and chloroplast structures, and the antioxidant enzymes of the plants were significantly reduced under the HPHK treatment. Compared to the LP treatments (LPHK and LPLK), the HPHK treatment was found to have the following potential effects: effectively optimize plant configuration; promote leaf development (Pn, E, Ci, and Tr, chlorophyll, and leaf area index); significantly increase the N-metabolism-related enzyme activity of leaves and roots and the accumulation of N in the plant in the main growth stages; and significantly increase the rice yield and N-related efficiency. In conclusion, the HPHK treatment was found to be beneficial in improving the plant configuration, promoting photosynthetic N metabolism, and increasing grain yield and N-related utilization efficiency.

Deciphering the genetic basis of agronomic, yield, and nutritional traits in rice (Oryza sativa L.) using a saturated GBS-based SNP linkage map

Developing high-yielding rice varieties that possess favorable agronomic characteristics and enhanced grain Zn content is crucial in ensuring food security and addressing nutritional needs. This research employed ICIM, IM, and multi-parent population QTL mapping methods to identify important genetic regions associated with traits such as DF, PH, NT, NP, PL, YLD, TGW, GL, GW, Zn, and Fe. Two populations of recombinant inbred lines consisting of 373 lines were phenotyped for agronomic, yield and grain micronutrient traits for three seasons at IRRI, and genotyped by sequencing. Most of the traits demonstrated moderate to high broad-sense heritability. There was a positive relationship between Zn and Fe contents. The principal components and correlation results revealed a significant negative association between YLD and Zn/Fe. ICIM identified 81 QTLs, while IM detected 36 QTLs across populations. The multi-parent population analysis detected 27 QTLs with six of them consistently detected across seasons. We shortlisted eight candidate genes associated with yield QTLs, 19 genes with QTLs for agronomic traits, and 26 genes with Zn and Fe QTLs. Notable candidate genes included CL4 and d35 for YLD, dh1 for DF, OsIRX10, HDT702, sd1 for PH, OsD27 for NP, whereas WFP and OsIPI1 were associated with PL, OsRSR1 and OsMTP1 were associated to TGW. The OsNAS1, OsRZFP34, OsHMP5, OsMTP7, OsC3H33, and OsHMA1 were associated with Fe and Zn QTLs. We identified promising RILs with acceptable yield potential and high grain Zn content from each population. The major effect QTLs, genes and high Zn RILs identified in our study are useful for efficient Zn biofortification of rice.

Amino acid permease OsAAP12 negatively regulates rice tillers and grain yield by transporting specific amino acids to affect nitrogen and cytokinin pathways

Amino acids are necessary nutrients for the growth of Oryza sativa (rice), which can be mediated by amino acid transporter; however, our understanding of these transporters is still limited. This study found that the expression levels of amino acid permease gene OsAAP12 differed between indica and japonica rice. Altered expression of OsAAP12 negatively regulated tillering and yield in transgenic rice lines. Subcellular localization revealed that OsAAP12 was primarily localized to the plasma membrane. Moreover, it was indicated that OsAAP12 transported polar neutral amino acids asparagine (Asn), threonine (Thr), and serine (Ser) through experiments involving yeast heterologous complementation, fluorescence amino acid uptake, and amino acid content determination. Additionally, exogenous application of amino acids Asn, Thr, and Ser suppressed axillary buds outgrowth in OsAAP12 overexpression lines compared with wild-type ZH11. Conversely, the opposite trend was observed in CRISPR mutant lines. RNA-seq analysis showed that the expression patterns of genes involved in the nitrogen and cytokinin pathways were generally altered in OsAAP12 modified lines. Hormone assays indicated that OsAAP12 mutant lines accumulated cytokinins in the basal part of rice, whereas overexpression lines had the opposite effect. In summary, CRISPR mutant of OsAAP12 boosted rice tillering and grain yield by coordinating the content of amino acids and cytokinins, which has potential application value in high-yield rice breeding.

Partial Substitution of Nitrogen Fertilizer with Biogas Slurry Increases Rice Yield and Fertilizer Utilization Efficiency, Enhancing Soil Fertility in the Chaohu Lake Basin.

To investigate the effects of biogas slurry substitution for fertilizer on rice yield, fertilizer utilization efficiency, and soil fertility, a field experiment was conducted on rice-wheat rotation soil in the Chaohu Lake Basin for two consecutive years, with the following six treatments: no fertilization (CK), conventional fertilization (CF), optimized fertilization (OF), biogas slurry replacing 15% of fertilizer (15% OFB), biogas slurry replacing 30% of fertilizer (30% OFB), and biogas slurry replacing 50% of fertilizer (50% OFB). The field experiment results showed that, compared with CF treatment, OF treatment in 2022 and 2023 significantly increased (p < 0.05) rice yield, promoted the uptake of nitrogen (N), phosphorus (P), and potassium (K) by grains and straws, improved fertilizer utilization efficiency, and increased the contents of soil organic C (SOC), NH4+-N, NO3--N, hydrolysable N, and available P. The 15% OFB and 30% OFB treatments significantly increased (p < 0.05) rice grain and straw yields compared with CF treatment, and rice grain and straw yields were the highest in the 30% OFB treatment. Compared with CF and OF treatments, 30% OFB treatment significantly increased (p < 0.05) the N, P, and K uptake of grains and straws and increased the fertilizer utilization efficiency. Compared with CF treatment, the grain yield of 50% OFB treatment was significantly decreased (p < 0.05) in 2022, and there was no significant difference in 2023, which may be because the biogas slurry was applied before planting in 2023 to provide more nutrients for early rice growth. Compared with CF treatment, 30% OFB treatment significantly increased (p < 0.05) the contents of SOC, NH4+-N, available K, and hydrolysable N. In summary, optimizing N and K topdressing methods can increase rice yield and improve the fertilizer utilization efficiency and soil fertility. The 30% OFB treatment resulted in the highest rice yield, fertilizer utilization efficiency, and improved soil fertility, indicating that biogas slurry replacing 30% of fertilizer was the best application mode for rice in this region.

Straw Incorporation with Exogenous Degrading Bacteria (ZJW-6): An Integrated Greener Approach to Enhance Straw Degradation and Improve Rice Growth.

Rice straw is an agricultural waste, the disposal of which through open burning is an emerging challenge for ecology. Green manufacturing using straw returning provides a more avant-garde technique that is not only an effective management measure to improve soil fertility in agricultural ecosystems but also nurtures environmental stewardship by reducing waste and the carbon footprint. However, fresh straw that is returned to the field cannot be quickly decomposed, and screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. This study aimed to reveal the potential mechanism of influence exerted by exogenous degradative bacteria (ZJW-6) on the degradation of straw, growth of plants, and soil bacterial community during the process of returning rice straw to the soil. The inoculation with ZJW-6 enhanced the driving force of cellulose degradation. The acceleration of the rate of decomposition of straw releases nutrients that are easily absorbed by rice (Oryza sativa L.), providing favorable conditions for its growth and promoting its growth and development; prolongs the photosynthetic functioning period of leaves; and lays the material foundation for high yields of rice. ZJW-6 not only directly participates in cellulose degradation as degrading bacteria but also induces positive interactions between bacteria and fungi and enriches the microbial taxa that were related to straw degradation, enhancing the rate of rice straw degradation. Taken together, ZJW-6 has important biological potential and should be further studied, which will provide new insights and strategies for the appropriate treatment of rice straw. In the future, this degrading bacteria may provide a better opportunity to manage straw in an ecofriendly manner.

DWARF AND LESS TILLERS ON CHROMOSOME 3 promotes tillering in rice by sustaining FLORAL ORGAN NUMBER 1 expression.

Three key factors determine yield in rice (Oryza sativa): panicle number, grain number, and grain weight. Panicle number is strongly associated with tiller number. Although many genes regulating tillering have been identified, whether Dof proteins are involved in controlling plant architecture remains unknown. The dwarf and less tillers on chromosome 3 (dlt3) rice mutant produces fewer tillers than the wild type. We cloned DLT3, which encodes a Dof protein that interacts with MONOCULM 3 (MOC3) in vivo and in vitro and recruits MOC1, forming a DLT3-MOC3-MOC1 complex. DLT3 binds to the promoter of FLORAL ORGAN NUMBER 1 (FON1) to activate its transcription and positively regulate tiller number. The overexpression of MOC1, MOC3, or FON1 in the dlt3 mutant increased tiller number. Collectively, these results suggest a model in which DLT3 regulates tiller number by maintaining the expression of MOC1, MOC3, and FON1. We discovered that DLT3 underwent directional selection in the Xian/indica and Geng/japonica populations during rice domestication. To provide genetic resources for breeding varieties with optimal panicle numbers, we performed large-scale diversity sequencing of the 1,080-bp DLT3 coding region of 531 accessions from different countries and regions. Haplotype analysis showed that the superior haplotype, DLT3H1, produced the most tillers, while haplotype DLT3H6 produced the fewest tillers. Our study provides important germplasm resources for breeding super high-yielding rice varieties with combinations of superior haplotypes in different target genes, which will help overcome the challenge of food and nutritional security in the future.

Balancing Greenhouse Gas Emissions and Yield through Rotational Tillage in the Cold Rice-Growing Region

Tillage practices are of critical importance in maintaining soil quality on cropland and for food production, with rice cultivation representing a significant portion of the world’s food production and greenhouse gas (GHG) emissions. While numerous studies have examined the effects of reduced and no-tillage on soil GHG emissions and rice yields, the impact of adopting a rotational approach to tillage practices on the rice cultivation cycle remains uncertain. In this study, we conducted a four-year (2017–2020) field experiment in a single rice-growing area in Northeast China with the aim of investigating the effects of different tillage practices on GHG emissions from paddy fields and rice yields under full straw return conditions. We set up three experimental treatments: rotary tillage, plowing, and rotational tillage (i.e., a combination of one year of plowing and one year of rotary tillage). The results showed that averaged across all treatments, average methane (CH4, 302.6 ± 51.1 kg ha−1) and nitrous oxide (N2O, 0.86 ± 0.361 kg ha−1) emissions and rice yield (9.0 ± 0.9 t ha−1) did not exhibit significant inter-annual variability during the entire experimental period and were comparable to the average for the region. The ranking of GHG emissions during the rice-growing season was as follows: rotary tillage &gt; plowing &gt; rotational tillage. Across the experimental period, CH4 and N2O emissions were 9.1% and 8.5% lower in the plowing treatment and 21.2% and 13.1% lower in the rotational tillage treatment compared to the rotary tillage treatment. During the experimental period, there was no significant effect of tillage treatments on rice yield. This reduction in emissions may be attributed to changes in soil penetration resistance. In the rotational and plowing treatments, soil penetration resistance was in a range more adapted to rice growth and GHG emissions reduction compared to the rotary tillage treatment. The yield-scale GHG emission intensity was reduced by 12.7% and 26.1% in the plowing and rotational tillage treatments, respectively, in comparison to the rotary tillage treatment. This suggests that rotational tillage is a management practice that can achieve greenhouse gas emission reductions in paddy fields and stabilize or possibly increase rice yields. Consequently, the results demonstrated that a rotational alternation of multiple tillage practices is a synergistic strategy for achieving low carbon and high yield in rice in the cold rice-growing region of Northeast China.

Inferior spikelet filling is affected by T6P/SnRK1-mediated NSC remobilization in large-panicle rice (Oryza sativa L.).

Poor grain filling in inferior spikelets (IS), which is influenced by the remobilization of nonstructural carbohydrates (NSC) stored in the sheath and internode of rice plants, limits the expected high yield of large-panicle rice. NSC remobilization from the sheath to the panicle is regulated by the T6P/SnRK1 pathway. However, in large-panicle rice, it is unclear whether IS grain filling is related to the NSC remobilization mediated by T6P/SnRK1 signaling. In this study, two large-panicle cultivars-W1844 and CJ03-with distinct differences in IS grain filling were used to explore the physiological mechanism mediating IS development. Compared to W1844, CJ03 IS showed lower expression of the genes related to sucrose uploading, later sucrose peaking, and delayed starch accumulation. In the CJ03, low OsSUTs expression and NSC output, transport rate, and contribution rate were detected in the sheaths and internodes. These results suggest that poor NSC remobilization results in insufficient assimilate supply for the IS, and consequently, poor IS grain filling. Furthermore, poor NSC remobilization coincided with the increased T6P content and decreased SnRK1 activity during grain filling in CJ03 IS. The expression levels of genes related to T6P metabolism and those encoding the catalytic subunit of SnRK1 were consistent with the observed T6P content and SnRK1 activity in the sheaths and internodes. Therefore, IS grain filling is potentially affected by T6P/SnRK1 signaling-mediated NSC remobilization in large-panicle rice.

Comparative seed yields of lowland rice (Oryza sativa L.): evaluating seeds sources and fertilizers

Abstract The use of high-quality seeds from high-yielding rice varieties (HYV) is crucial for enhancing grain yield. Yet, the supply of certified seed meets only 57.3% of the total rice seed demand, leading some farmers to plant non-certified local rice seeds. A study examining the effects of seed sources and fertilization on seed yields was conducted in Bogor Village, Sukra District, Indramayu Regency during the Dry Season of 2019. The treatments consisted of two factors: A. Seed sources (Local non-certified seed (Local-NC), HYV non-certified seed (HYV-NC), and HYV-certified seed) and B. Fertilization methods (Recommended Fertilizer (RF), RF+BioF, RF+P as top dressing, and RF+N as top dressing). These were designed in a Complete Block Design with three replications. Results showed that Local-NC was more susceptible to BPH and RSB than HYV varieties. Additionally, Local-NC had the highest percentage of off-type plants and produced the lowest grain and seed yields. The addition of P or N fertilizer to RF during the heading stage notably improved the panicle number per hill, 1000-grain, seed yields and rendement. Our findings suggest that optimal rice seed yields can be achieved by planting HYV– certified seeds and applying either RF + 18 kg P ha−1 or RF + 11.5 kg N ha−1 as top dressing.

Multi-trait genome-wide association studies reveal novel pleiotropic loci associated with yield and yield-related traits in rice

Rice yield is a complex trait affected by many related traits. Traditional single-trait genome-wide association studies (GWAS) have limitations when studying complex traits, as they cannot account for the genetic relationships among multiple traits. Multi-trait GWAS, which can consider the relationships among multiple traits and identify pleiotropic loci, is more suitable for complex traits such as rice yield than single-trait GWAS. In this study, we conducted a multi-trait GWAS on 11 two-trait combinations of yield and yield-related traits with 575 hybrid rice varieties across two environments. All of these yield-related traits showed significant genetic correlation with yield (YD), including filled grains per panicle (FGPP), kilo-grain weight (KGW), tillers per plant (TP), primary branch number (PB), secondary branch number (SB) and main panicle length (MPL). In total we identified 44 pleiotropic quantitative trait loci (pQTLs), including 29 new pQTLs not found in single-trait GWAS. We then screened 23 pQTLs showing common effects in two traits as key pQTLs. These key pQTLs were subsequently analyzed for haplotype analysis and identified 13 pleiotropic candidate genes. Finally, we identified two optimal yield-enhancing allele combinations by pyraming superior haplotypes: GS3-GL3.1-OsCIPK17 for the YD-KGW combination and GNP12 for the YD-FGPP and YD-SB combinations. This study provides pleiotropic candidate genes and allele combinations that exhibit superior differences in both yield and yield-related traits, offering valuable information for future high-yielding rice breeding.

Assessing the productive potential of high-yielding rice varieties on acid sulfate soils in the tidal swampland of Central Kalimantan

Abstract Tidal swampland holds significant agricultural potential including cultivating rice. Farmers in these regions typically cultivate local rice varieties. Breeding rice techniques have led to the development of superior rice well-suited to thrive in tidal swamplands. This research was conducted on acid sulfate soil within a tidal swampland located in Terusan Karya Village, Kapuas Regency, Central Kalimantan, during the 2021 dry season. The study employed a completely randomized block design with two replications. The experimental treatments comprised nine high-yielding rice varieties: Inpari IR Nutri Zinc, Cakrabuana Agritan, Inpari 3, Inpari 32, Inpari 42, Inpari 47, Inpara 2, Inpara 8, and Inpara 10. The parameters were observed, including plant height, panicle number per hill, panicle length, and grain yield. The high-yielding varieties of rice planted in acid sulfate tidal swamplands exhibit varying growth and yield performances. Grain yields of rice ranged from 5.45 to 7.30 t ha−1 of dry-milled grain. The highest grain yield was shown by Inpari 3 (7.30 t ha−1) and Inpari 32 (7.04 t ha−1). High heritability values are indicated by the traits of dry harvest and milled grains, while wide variability is shown by characters such as plant height, panicle length, grain dry harvest, and dry milled.

Effect of integrated nutrient management on the growth and productivity of four high-yielding rice varieties of Eastern India

Aim: To investigate the integrated nutrient management in agricultural fields using cow dung manure and poultry manure as organic, and NPK as inorganic fertilizer at varied ratios. Methodology: Four rice varieties were selected for the experiment viz., MTU 1010, IET 4786, IET 17430, and IET 9947 under nine organic manure and inorganic fertilizer combinations in different ratios with one control treatment. The cultivation was carried out in three replications in a randomized complete block design. The biometric observations were noted at 30, 55, and 80 days after transplant (DAT). Leaf Area Index (LAI), Crop Growth Rate (CGR), and grain yield were calculated for the varieties under varied treatments. Results: Biometric observation and growth indices confirmed that the treatment T3 showed the highest value among all other treatments for shoot length, dry matter, LAI and LAD for all varieties. Treatment T7 recorded the maximum root length. For CGR treatment T2 and T3 recorded highest value for different varieties. Soil nutrient results suggest that treatment T2-T4 and T6-T8 showed the highest N, P and K content. The results showed significant difference (p&lt;0.05) in grain yield for all the treatments in all varieties, where T3 recorded the highest value. Interpretation: The year experiment revealed that integrated nutrient application resulted in considerably greater growth and productivity compared to the control and 100% inorganic fertilizer-treated cultivation. Key words: Cow dung, Integrated nutrient management, Poultry manure, Plant growth indices, Rice productivity Aim: To investigate the integrated nutrient management in agricultural fields using cow dung manure and poultry manure as organic, and NPK as inorganic fertilizer at varied ratios. Methodology: Four rice varieties were selected for the experiment viz., MTU 1010, IET 4786, IET 17430, and IET 9947 under nine organic manure and inorganic fertilizer combinations in different ratios with one control treatment. The cultivation was carried out in three replications in a randomized complete block design. The biometric observations were noted at 30, 55, and 80 days after transplant (DAT). Leaf Area Index (LAI), Crop Growth Rate (CGR), and grain yield were calculated for the varieties under varied treatments. Results: Biometric observation and growth indices confirmed that the treatment T3 showed the highest value among all other treatments for shoot length, dry matter, LAI and LAD for all varieties. Treatment T7 recorded the maximum root length. For CGR treatment T2 and T3 recorded highest value for different varieties. Soil nutrient results suggest that treatment T2-T4 and T6-T8 showed the highest N, P and K content. The results showed significant difference (p&lt;0.05) in grain yield for all the treatments in all varieties, where T3 recorded the highest value. Interpretation: The year experiment revealed that integrated nutrient application resulted in considerably greater growth and productivity compared to the control and 100% inorganic fertilizer-treated cultivation. Key words: Cow dung, Integrated nutrient management, Poultry manure, Plant growth indices, Rice productivity

Deep tillage combined with straw biochar return increases rice yield by improving nitrogen availability and root distribution in the subsoil

ContextAfter over 20 years of practicing shallow rotary tillage combined with straw direct return in the middle and lower Yangtze regions of China, the yield potential has gradually disappeared, and new alternative tillage practices are required to continuously increase rice yield. ObjectiveThis paper investigates the yield effect and mechanism of deep tillage combined with straw return through two consecutive years of a field experiment. MethodsThree tillage depths (shallow tillage 6–7 cm, ST; medium tillage 12–14 cm, MT; and deep tillage 25–28 cm, DT) plus three straw management methods (no straw return, NR; straw direct return, SR; and straw biochar return based on the same amount of carbon input as SR, BR) were set up as experiment treatments. The aboveground and belowground growth traits of rice and soil nitrogen (N) status were determined. ResultsCompared with ST and MT, the DT enlarged rice root distribution and increased soil N content in the middle and lower soil layers (7–28 cm) and decreased the root–shoot ratio at the flowering stage, which was conducive to absorbing more soil nutrients from the subsoil and allocating more photosynthetic products to the aboveground parts and grain. The MT and DT increased spike number and rice yield compared with ST. Compared with NR, both SR and BR increased soil total and available N contents, and the remaining soil available N content at the harvest stage of BR was lower than that of SR. Straw return (SR and BR) improved rice yield by increasing spike number and kernels per spike, and the effect of BR on increasing rice yield was greater than that of SR. ConclusionsThe DT combined with BR increased root distribution and N content in the subsoil, promoted the utilization of subsoil's nutrients, and increased rice yield. It is therefore a promising tillage practice for achieving high rice yields.

Green synthesis and characterization of silver nanoparticles and its efficacy against Rhizoctonia solani, a fungus causing sheath blight disease in rice.

Rice (Oryza sativa) stands as a crucial staple food worldwide, especially in Bangladesh, where it ranks as the third-largest producer. However, intensified cultivation has made high-yielding rice varieties susceptible to various biotic stresses, notably sheath blight caused by Rhizoctonia solani, which inflicts significant yield losses annually. Traditional fungicides, though effective, pose environmental and health risks. To address this, nanotechnology emerges as a promising avenue, leveraging the antimicrobial properties of nanoparticles like silver nanoparticles (AgNPs). This study explored the green synthesis of AgNPs using Ipomoea carnea leaf extract and silver nitrate (AgNO3), and also examined their efficacy against sheath blight disease in rice. The biosynthesized AgNPs were characterized through various analytical techniques such as UV-vis spectrophotometer, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Particle size analyzer, Zeta potential, Scanning Electron Microscope (SEM), Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM) for confirming their successful production and crystalline nature of nanoparticles. The results of UV-visible spectrophotometers revealed an absorption peak ranging from 421 to 434 nm, validated the synthesis of AgNPs in the solution. XRD, DLS, and TEM estimated AgNPs sizes were ~45 nm, 66.2nm, and 46.38 to 73.81 nm, respectively. SEM and FESEM demonstrated that the synthesized AgNPs were spherical in shape. In vitro assays demonstrated the significant inhibitory effects of AgNPs on mycelial growth of Rhizoctonia solani, particularly at higher concentrations and pH levels. Further greenhouse and field experiments validated the antifungal efficacy of AgNPs against sheath blight disease in rice, exhibiting comparable effectiveness to commercial fungicides. The findings highlight the potential of AgNPs as a sustainable and effective alternative for managing rice sheath blight disease, offering a safer solution amidst environmental concerns associated with conventional fungicides.

Bulked Segregant RNA-Seq Analysis of Pollinated Pistils Reveals Genes Influencing Spikelet Fertility in Rice

Prezygotic isolation is important for successful fertilization in rice, significantly affecting yield. This study focused on F5:6 generation plants derived from inter-subspecific crosses (Nipponbare × KDML105) with low (LS) and high seed-setting rates (HS), in which normal pollen fertility was observed. However, LS plants showed a reduced number of pollen grains adhering to the stigma and fewer pollen tubes reaching the ovules at 4‒5 h post-pollination, compared with HS plants. Bulked segregant RNA-Seq analysis of pollinated pistils from the HS and LS groups revealed 249 and 473 differentially expressed genes (DEGs), respectively. Kyoto Encyclopedia of Genes and Genomes analysis of the HS and LS- specific DEGs indicated enrichment in metabolic pathways, pentose and glucuronate interconversions, and flavonoid biosynthesis. Several of these DEGs exhibited co-expression with pollen development genes and formed extensive clusters of co-expression networks. Compared with LS pistils, enzyme genes controlling pectin degradation, such as OsPME35 and OsPLL9, showed similar expression patterns, with higher levels in HS pistils pre-pollination. Os02g0467600, similar to cinnamate 4-hydroxylase gene (CYP73), involved in flavonoid biosynthesis, displayed higher expression in HS pistils post-pollination. Our findings suggest that OsPME35, OsPLL9, and Os02g0467600 contribute to prezygotic isolation by potentially modifying the stigma cell wall (OsPME35 and OsPLL9) and controlling later processes such as pollen-stigma adhesion (Os02g0467600) genes. Furthermore, several DEGs specific to HS and LS were co-localized with QTLs and functional genes associated with spikelet fertility. These findings provide valuable insights for further research on rice spikelet fertility, ultimately contributing to the development of high-yielding rice varieties.