Maximum Tillering Stage Research Articles

Genetic Diversity Analysis of Rice (Oryza sativa L.) Genotypes for Yield and Sheath Blight Screening

Sheath blight disease, caused by Rhizoctonia solani Kühn, is considered the second most important disease affecting rice, causing yield reduction globally. In the present study thirty diverse rice genotypes were inoculated with fungal mycelia during the maximum tillering stage to assess the genetic diversity of rice genotypes for sheath blight reactions. Mahalanobis D2 statistics was performed for grain yield and yield contributing features under sheath blight stress to calculate the genetic divergence between the genotypes. Four clusters were formed from the genotypes. Cluster III has the highest number of genotypes (nine). The highest inter-cluster distance was noticed between cluster I and cluster IV (11.41) and minimum between cluster III and cluster IV (6.50). The intra-cluster distances were lower, indicating the homogeneity of the genotypes within the clusters. Maximum intra-cluster D2 value was recorded in cluster IV (6.32) and minimum in cluster II (5.36). Cluster I showed high genetic divergence from all other clusters. Hence, the genotypes from cluster I could be used for hybridization with the genotypes of other clusters to develop high yielding sheath blight resistant rice varieties.

Effect of Crop Establishment Method, Residue and Nutrient Management on Productivity of Rice-Wheat Cropping System at Rupandehi, Bhairahawa, Nepal

The puddling operation and multiple tillage operations done in traditional rice-wheat system have negative impact on soil resulting into low productivity of rice - wheat system. A field experiment was conducted to find the alternate practices for enhancing the productivity of rice-wheat system at National Wheat Research Program, Bhairahawa during 2018/19. Three crop establishment methods: surface seeded wheat (SSW) followed by (fb) unpuddled transplanted rice (U-TPR), zero tilled wheat (ZTW) fb zero tilled direct seeded rice (ZT-DSR) and conventionally tilled wheat (CTW) fb puddled transplanted rice (PTR) were tested in two levels of residue management: residue removed (R0) and residue retention (R50). Three levels of nutrient management: recommended dose of NPK (F100), 25% higher dose of NPK (F125) and farmer’s practice (FP) were assigned in wheat. Strip-split plot design with 3 replications was used in wheat while strip-plot design with 9 replications was used in rice. Crop establishment methods (CSM) were assigned in vertical strips; residue management in horizontal blocks and nutrient management were assigned in subplots. The number of tillers at maximum tillering stage, maximum leaf area index, effective tiller per square meter and number of grains per spike of wheat were significantly affected by CSM, where ZTW had shown better results (413.7 tillers, 2.12 LAI, 224.1 effective tiller per square meter and 34.27 grains per spike) than SSW and CTW but the CSM had no significant effect on grain yield of both rice and wheat crop. R0 had produced significantly higher straw yield than R50 of both rice and wheat, whereas, R50 had produced significantly higher harvest index than R0 in rice. The application of 25% more nutrients than the recommended dose resulted in the significantly better growth, yield attributes, and yield of wheat. The ZTW fb ZT-DSR had produced significantly higher system yield than SSW fb U-TPR where, CTW fb PTR was statistically at par with both systems. The recommended dose of nutrients (F100) and 25% higher than F100 (F125) had produced significantly higher system yield than farmer’s practice (FP) dose. Research results revealed that ZTW fb ZT-DSR system can be suggested instead of traditional CTW fb PTR system without significant yield differences.

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.

Estimating SPAD, Nitrogen Concentration, and Chlorophyll Content in Rice Leaves using Calibrated Smartphone Digital Image

Laboratory analysis is commonly used to determine nitrogen and chlorophyll content. However, smartphones can serve as rapid, mobile, and non-destructive tools for this purpose. An equation can be created to calculate nitrogen and chlorophyll content by analyzing color parameters from digital images of rice leaves. An examination was performed on 86 rice leaf samples from the maximum tillering and mature stages. Rice leaf photos were taken with a smartphone in natural outdoor lighting. Color calibration with Spydercheckr was needed to adjust for lighting conditions. Uncalibrated and calibrated image data were analyzed to determine RGB values converted into CIELAB color space. The L*, a*, and b* values had a significant correlation with SPAD parameters, nitrogen concentration, chlorophyll a, b, and total chlorophyll content. This connection was higher after image calibration. The study found that smartphone images could predict SPAD values with 87.9% to 92.3% precision, depending on color space. Using a smartphone digital picture of L* and a* values, N content could be estimated with 84.7% and 81.9% accuracy. Average accuracy for chlorophyll a, b, and total chlorophyll content was 65% to 76%. This study shows smartphone images can estimate rice leaf SPAD and nitrogen content.

Compound Microbial Agent Improve Soil Redox Status to Reduce Methane Emissions from Paddy Fields

Paddy fields are considered as a major source of methane (CH4) emissions. Aerobic irrigation methods have proved to be efficacious in mitigating CH4 emissions in paddy cultivation. The promising role of compound microbial agents in refining the rhizospheric ecosystem intimates their potential as novel agents in reducing CH4 emissions from paddy fields. To explore a new way of using compound microbial agents to reduce CH4 emissions, we conducted pot and field experiments over the period of 2022‒2023. We measured CH4 flux, the redox potential (Eh) of the soil, the concentration of dissolved oxygen (DO) in the floodwater, and the activity of both methanogens (mcrA) and methanotrophs (pmoA). The results showed that the application of the compound microbial agent led to a significant increase in the DO levels within the floodwater and an increase of 9.26% to 35.01% in the Eh of the tillage soil. Furthermore, the abundance of pmoA increased by 31.20%, while the mcrA/pmoA ratio decreased by 25.96% at the maximum tillering stage. Applying 45−75 kg/hm2 of the compound microbial agent before transplanting resulted in a reduction of cumulative CH4 emissions from paddy fields by 17.49% in single- cropped rice and 43.54% to 50.27% in double-cropped late rice during the tillering stage. Correlation analysis indicated that CH4 flux was significantly negatively correlated with pmoA gene abundance and soil Eh, and positively related to the mcrA/pmoA ratio. Additionally, soil Eh was significantly positively correlated with pmoA gene abundance, suggesting that paddy soil Eh indirectly affected CH4 flux by influencing the pmoA gene abundance. In conclusion, the pre-planting application of the compound microbial agent at a rate of 45‒75 kg/hm2 can enhance the Eh in the rhizosphere and increase the abundance of the pmoA gene, thereby reducing CH4 emissions from paddy fields during the tillering stage of rice growth.

Dissecting root system architecture traits in durum wheat–goatgrass (Triticum durum–Aegilops speltoides) backcross introgression lines

AbstractA well‐developed root system is essential for efficient nutrient and water uptake. We phenotyped a set of 172 Triticum durum–Aegilops speltoides backcross introgression lines (BILs) for various root architecture traits during 2019–2020 and 2020–2021 cropping seasons. The roots were sampled at the maximum tillering stage, and data on various root architecture traits were recorded. The quantitative trait loci (QTL) mapping was carried out using 5672 polymorphic SNPs obtained from genotyping‐by‐sequencing. A total of 21 QTLs were detected for various root architecture traits on chromosomes 1A, 2A, 2B, 3B, 5A and 6B. Stable QTLs were detected for total root length, number of root tips and root dry weight over the two seasons. Candidate genes were identified by scanning the physical interval corresponding to the linkage disequilibrium (LD) decay flanking the SNPs linked to the stable QTLs. In silico expression studies of postulated candidate genes revealed root‐specific upregulation of some of the genes. These QTLs can be used in breeding programmes after the development and validation of suitable marker assays.

Agronomic biofortification of basmati rice (Oryza sativa L.) through iron and boron under varying seedling densities

At present, we have adequate production of rice to fulfill the needs of humans. Now it is time to produce biofortified rice, whose grains contain enough amounts of nutrients like iron and boron. Two field experiments were carried out in Kharif 2019 and 2020 at Meerut (Uttar Pradesh), India, to find the effect of iron and boron nutrition on rice with different planting densities. The main plot treatment consists of three planting densities, and the subplot treatment consists of five foliar applications of micronutrients. They were tested in a split-plot design (SPD) with three replications. The results revealed that the rice transplanted with one seedling/hill gave the highest iron and boron content in grains and/or the crop fortified with iron and boron at 0.1 and 0.04% applied at the maximum tillering (MT) and panicle initiation (PI) stages of rice, respectively. The higher values of yield-contributing characters such as effective tillers/m2, panicle length (cm), grain weight/panicle (g), and test weight (g), as well as quality parameters such as nutrient content in grain (mg/kg), volume expansion ratio, protein content in grains (%), and amylose content (%) of rice were noticed in one seedling/hill except effective tillers/m2 during the first and second years. Application of Fe and B at the MT and PI stages of rice improved almost all the yield attributes and quality parameters. Planting density of two and three seedlings/hill was recorded at par values of grain yield, followed by one seedling/hill. Rice transplanted with three seedlings/hill obtained an average of 10.1 and 10.6% more grain yield than one seedling/hill during the first and second years, respectively. However, the application of Fe at 0.1% and B at 0.04% during both stages through foliar spray resulted in the highest seed yield and showed parity with the application of iron at 0.1% at the MT stage and boron at 0.04% at the PI stage. Economics revealed that the planting density of three seedlings/hill gave the maximum net returns of 61,585 and 66,752 ₹/ha with a benefit–cost ratio of 2.12 and 2.19 during 2019 and 2020, respectively. Furthermore, the highest net returns (62,188 and 67,938 ₹/ha) and benefit–cost ratio (2.15 and 2.23) were observed from the treatment of iron at 0.1% and boron at 0.04% at the MT and PI stages during the first and second years, respectively.

Zinc fertilization effect on macro and micro-nutrients concentrations and uptake in wheat (Triticum aestivum) varieties

A field experiment was conducted during the winter (rabi) seasons of 2013–14 and 2014–15 at New Delhi, to find out the effect of zinc (Zn) fertilization on concentration and uptake of macro and micro-nutrients in high-yield ing wheat (Triticum aestivum L.) varieties. Treatments comprised 6 high-yielding varieties of wheat in the main plots and 5 Zn management treatments as sub-plots. Results indicated that nitrogen (N), phosphorus (P) and po tassium (K) content in different parts of wheat varieties was found in the order of grain > straw > spike straw, grain > spike straw > straw and straw > spike straw > grain, respectively. However the concentration of iron (Fe) and manganese (Mn) was found in order of straw > spike straw > grain and straw > grain > spike straw respectively. With respect to nutrients, the highest N (2.28%), P (3,711.6 mg/kg), K (0.48%), Zn (40.6 mg/kg), Fe (124.8 mg/kg) and Mn (33.7 mg/kg) contents were registered in grain of ‘HD 2967’, ‘HD 2967’, ‘HD 2687’, ‘HD 2851’, ‘HD 2687’ and ‘HD 2894’, respectively. The concentration of macro and micro-nutrients were recorded statistically identical in different treatments of Zn fertilization. However, significant increase in macro and micro-nutrients uptake was registered due to Zn fertilization and the highest uptake of nutrients was recorded with application of 1.25 kg Zn/ha through Zn-EDTA + 0.5% foliar spray of Zn-EDTA at maximum tillering and booting stages. Thus, soil (1.25 kg Zn/ ha) + foliar (0.5%) application of Zn-EDTA was found superior with respect to macro and micro-nutrients uptake.

Effect of Drought Periods on Rice Lines Growth and Yield

Numerous variables, such as drought period, growth stage, and varieties, influence rice growth and yield in response to drought. This study was conducted to determine the effect of drought periods on the growth and yields of several rice lines and varieties as well as to select drought-tolerant lines. Using a split-plot design with three replications, the pot experiment was carried out in the greenhouse from December 2015 to April 2016 at the Sukamandi Experimental Site of Indonesian Center for Rice Research (BB Padi). Drought periods were treated as the main-plot, while the rice lines/varieties were treated as sub-plots. The main-plot consists of four levels: control, drought at the maximum tillering stage, drought at the primordia stage, and drought at the grain filling stage. The rice lines used are expand lines of rainfed lowland rice and upland rice from the BB Padi breeding program. The results showed that of the 36 rice lines and 6 varieties tested, drought periods during maximum tillering and primordia affected plant height, while the tiller number was not affected by all drought periods. From the yield characters, drought periods increased unfilled grain percentage and decreased 1000 grains weight and also grain weight per plant. Jatiluhur is consistently tolerant and has the highest yield. There are 8 rice lines with consistent tolerance and not significantly different yields with Jatiluhur: B13650E-TB-80-2, B14168E-MR-6, B14168E-MR-10, B14168E-MR-11, B14168E-MR-12, B14168E-MR-13, B12480D-MR-7-1-1, and B12056F-TB-1-29-1. Keywords: Drought periods, Rice lines, Growth, Yield

Screening of Rice Genotypes for Resistance Against Bacterial Blight Disease

A study was undertaken at V. C. Farm, Mandya, Karnataka, India during 2020 to screen the genotypes against BLB under natural field conditions. Host Plant resistance is an important component of an integrated management program for this disease. Among the 102 rice genotypes screened under natural epiphytotic condition at Zonal Agricultural Station, V. C. Farm, Mandya, none of them were found immune against bacterial leaf blight. So, in the study, plants were assessed by measuring disease severity (% of leaf diseased) and area under the disease progress curve (AUDPC). The pathogenicity of Xoo was tested on IRRI rice cultivars, inoculation was conducted at the maximum tillering stage, and the lesion length was measured after 14 days of inoculation. An attempt was made to phenotypically characterize a set of 102 Genotypes from IRRI for BLB resistance by artificially inoculaton using clipping method. Out of the 102 genotypes and two checks tested, it was observed that five entries viz., IRGC 125853, IRGC 126264, IRGC 132357, IRGC 122088 IRGC 125658 and Improved Samba Mahsuri were highly resistant with score of 1. Only one entry (IRGC 125754) was resistant with score of 3, 33 lines being moderately resistant with score of 5 and 43 lines were susceptible with score of 7. 20 lines and also the susceptible check Jyothi-PTB 39, had the highest susceptibility with a phenotypic score of 9.

Effect of planting density and micronutrient application on growth, physiological parameters and yield of rice (Oryza sativa)

The field experiments were conducted during the rainy (kharif) seasons of 2019 and 2020 at crop research centre (CRC) of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, Uttar Pradesh to study the effect of seedling density and micronutrient application on growth, physiological parameters and yield of basmati rice (Oryza sativa L). Three planting densities, viz. 1 seedling per hill, 2 seedlings per hill and 3 seedlings per hill and 5 foliar application of micronutrient [MN0-control; MN1, B @0.04% and Fe @0.1% at maximum tillering (MT) stage; MN2, B @0.04% and Fe @0.1% at panicle initiation (PI) stage; MN3, Fe @0.1% at maximum tillering stage (MT) and B @0.04% at panicle initiation (PI) stage and MN4, B @0.04% and Fe @0.1% at maximum tillering (MT) and panicle initiation (PI) stages] were tested in a split plot design, keeping as main plots and sub plots, respectively with 3 replications. The growth, physiological traits and yield of basmati rice were significantly influenced by varying planting density and micronutrients application through leaves, as indicated by the outcomes of the experiments. Growth and physiological parameters such as dry matter accumulation, leaf area index, plant height, chlorophyll content, crop growth rate and relative growth rate increased through the application of boron and iron, being highest in foliar spray of 0.04% B and 0.1% Fe at both the stages (MT and PI). Of the different seedling densities, 3 seedlings per hill resulted in significantly higher grain yield (5.0 and 5.1 t/ha) during 1st and 2nd year, respectively. In both the years, the highest grain and straw yield were observed by using 3 seedlings per hill along with a foliar application of 0.04% B and 0.1% Fe during the MT and PI stages.

Mapping Rice Area in the Cauvery Delta Zone of Tamil Nadu Using Sentinel 1A Synthetic Aperture Radar (SAR) Data

Since remote sensing based crop inventory provides accurate and timely information as compared to the conventional survey methods of estimating area, Multi-temporal Sentinel 1A Synthetic Aperture Radar data was used for the estimation of rice area during Samba season 2022 in the Cauvery delta zone comprising Thanjavur, Thiruvaru, Mayiladuthurai, and Nagapatnam districts of Tamil Nadu. SAR data was preferred over optical satellite data due to excess cloud cover during cropping the major season in Tamil Nadu. Temporal back-scatter (dB) signature of rice crop was generated from the multi-temporal processed SAR data utilizing the modules of a fully automated MAPscape software aiding the discriminating of the crop from others. The signatures revealed that the dB levels to be the lowest during agronomic floods, reached the highest during maximum tillering stage and started declining thereafter. Multi-temporal feature extraction module of Mapscape was used to estimate rice area and validated for accuracy using ground truth data collected during survey. A total of 3.05 lakh ha of rice area was estimated with an overall accuracy of 90.8 % and 0.82 kappa coefficient. Largest area of 1.12 lakh ha was recorded in Thanjavur followed by Thiruvarur and Mayiladuthurai with 0.95 and 0.51 lakh ha respectively.

Histopathological patterns and differential behavioural of Rhizoctonia solani causing sheath blight in rice (Oryza sativa L.)

AbstractSheath blight of rice caused by Rhizoctonia solani Kuhn [teleomorph: Thanatephorus cucumeris (Frank) Donk] is a significant threat to rice cultivation, accounting for up to 50% yield losses. The present investigation demonstrates the early pathogenesis events and R. solani pre‐ and post‐penetration activities on moderately resistant (MR) and highly susceptible (HS) lines under field conditions. A pure culture of R. solani isolate (R1965) was inoculated inside the sheath at the maximum tillering stage for different time intervals (24, 48, 72 and 96 hpi). R. solani exhibited more profuse, dense, closely contact around surface grooves, lobate appressoria‐like structures and greater microsclerotia development on the HS line compared to the MR one. Using fluorescent, optical, and scanning electron microscopy, it was noticed for the first time that R. solani could intercept sheath papillae and employ them for attachment or penetration in two ways: (a) direct penetration by lobate or runner hyphae, appressorium and infection cushion and (b) indirect stomatal penetration. Assays using in vivo plant inoculation showed that disease lesion length was higher in the HS line than the MR line. Intraxylary hyphal colonization could be seen using microtomy to understand the cellular spatial dynamics of xylem colonization by R. solani. The penetration mechanism along with penetration hyphae of the R. solani inside HS rice lines describe in this paper for the first time using optical ultrastructure. These results supported for better understanding of host–pathogen interaction, penetration mechanism and colonization of R. solani in rice.

Modeling The Uptake Of Cationic Micronutrients And Rice Grain Yield At Different Graded Dose Of Nitrogen Fertilization

The current study has been directed to find out a relationship whether such graded doses of nitrogen fertilizer can influence the pattern of micronutrient uptake and yield of the rice plant. The field experiment was carried out during the boro season of 2022 at Bidhan Chandra Krishi Viswavidyalaya, Nadia. The experiment was designed in a thrice replicated Randomized blocks with nitrogen fertilizer levels (0, 50, 100, 150 kg ha-1). A statistical analysis was carried out through Correlation- Regression studies which analyzed the relationship between nitrogen application and micronutrient uptake by rice. Correlation study of N uptake under graded doses of fertilizer application with the uptake of micronutrients followed the pattern Zn (r=0.985**)>Fe (r=0.962**)>Cu (0.953**)>Mn (r=0.947**) and Zn (r=0.980**)>Mn (r=0.948**)>Cu (0.944**)>Fe (r=0.939**) for rice grains and straw at harvest, respectively. The correlation of yield with grain N, straw N and N at maximum tillering stage also revealed a positive value. The Linear Regression (LR) models confirmed that incremental doses of N have a significant association with the uptakes of micronutrients. Thus, judicious management of N fertilizer can be a viable non-traditional approach for micronutrient nutrition in rice.

Influence Of Varietal Duration And Nitrogen Fertilization In Augmenting Micronutrient Uptake And Yield Of Rice

Lack of micronutrients in diet lead to health anomalies in human, to solve which diet-based availability can be looked upon. The goal of the current research is to ascertain how micronutrient uptake and yield of boro rice are influenced by the duration of the variety and graded doses of nitrogen fertilization. The field trial was conducted in the boro season of 2022 at Bidhan Chandra Krishi Viswavidyalaya, Gayeshpur, Nadia in a thrice replicated split plots with nitrogen fertilizer levels (0, 50, 100, 150 kg ha-1) in main plot and varieties (short duration-Satabdi, medium duration-Pratikshya and long duration-Swarna masuri) in sub-plots. At both maximum tillering and harvest stage, increase in nitrogen fertilization levels significantly increased the uptake of Zn, Cu, Fe and Mn and biomass yield significantly. However, while Fe and Mn concentrations were highest for N application at 150 kg ha-1, N application at 100 and 150 kg ha-1 statistically registered at par Zn and Cu values. Varietal influence on grain and straw yield as well as micronutrient uptake in harvest may be linked to their life cycle pattern where Partikshya considerably outperformed short duration Satabdi variety. Worst performance of Swarna Masuri variety may possibly be attributed to the inherent varietal characteristics and exposure to terminal moisture and heat stress at the months of May and June. Judicious management of nitrogen fertilizer may be a viable non- traditional approach for micronutrient nutrition in rice.

Changes in Wheat Rhizosphere Carbon Pools in Response to Nitrogen and Straw Incorporation

Large-scale burning of rice straw causes air pollution and deterioration of soil health, which challenges the sustainability of the rice–wheat system (RWS) in north-western India. In a field experiment on sandy loam (Typic Ustochrept) soil at Punjab Agricultural University, India, with split plot design, effects of four nitrogen (N) levels (0, 90, 120, and 150 kg N ha−1) in main plots and four levels of rice straw (RS) incorporation (0, 5, 7.5, and 10 Mg ha−1) in wheat in sub-plots were studied after 7 years on carbon (C) pools at maximum tillering (MT) and flowering (FL) stages of wheat and crop yields. Rice straw (RS) incorporation at 10 Mg ha−1 with N application at 120 kg N ha−1 in wheat not only increased labile C pools significantly especially at MT but also increased the wheat yield compared with no straw incorporation. Principal component analysis suggests that total polysaccharide carbon, basal soil respiration, and pH can be used as sensitive parameters for assessing soil quality in RWS.

Effect of Biofortified and Non-Biofortified Varieties and Zinc Fertilization Strategies on Growth, Productivity and Profitability of Rice

The field experiment was conducted in the rainy (Kharif, June to October) seasons of 2019 and 2020 at ICAR-Indian Agricultural Research Institute, New Delhi, India with the objective to appraise the effect of biofortified and non-biofortified varieties and zinc fertilization strategies on the growth, productivity and profitability of rice. The biofortified variety DRR Dhan 45 recorded a higher value of dry matter accumulation, leaf area index, and crop growth rate, and the non-biofortified variety Pusa 44 recorded higher effective tillers, panicle weight, filled grain weight per panicle, number of filled grains and total grains per panicle, fertility percentage and grain yield (5.2 t ha-1), though the performance of both varieties was statistically similar. But, the higher straw yield was recorded with the non-biofortified variety, Pusa Basmati 1121 (10.8 t ha-1). Pusa Basmati 1509 recorded higher cost of cultivation, gross returns, net returns and B:C. Among zinc fertilization strategies, soil application of 2.5 kg Zn ha-1 along with the foliar application of 0.5% ZnSO4.7H2O at maximum tillering and anthesis stages recorded higher growth parameters, yield, and yield attributes and better economics. On average, the soil+foliar Zn application increased grain yield by 14% and straw yield by 10.5%, and gross returns and net returns by 15.6% and 26.7%, respectively, than the control. Cultivation of rice varieties, Pusa 44 or DRR Dhan 45, along with soil+foliar Zn fertilization enhanced growth and productivity, while the aromatic variety, Pusa Basmati 1509 enhanced the profitability.

Landscape diversity influences the arthropod species diversity in the rice field

Landscape diversity is one of the key drivers for maintaining ecosystem services in agricultural production by providing vital habitats and alternative food sources for beneficial insects and pollinators within the agricultural landscapes. The landscape structure, land uses, and diversity differ between geographic locations. However, how the changes of landscape structure and land use diversity affect the arthropod diversity in a geographic area is poorly understood. Here, we tested the impact of landscape diversity on the rice locations in Bangladesh. Results ranged from highly diversified to very highly diversified in Chattogram (>7.9), to highly diversified (0.590.79) in Satkhira and moderately (0.390.59) to less diversified (0.190.39) in Patuakhali. These significant different landscape diversities influenced the arthropod diversity in rice fields. Arthropod species diversity increases with the increase in the Land Use Mix (LUM) index. The maximum tillering stage of rice growth harbored higher abundance and species diversity in rice fields. Moreover, we found that vegetation is the most important factor influencing the abundance of arthropods. Extensive agriculture and forest contributed substantially to predicting arthropod richness. Meanwhile, barren land and high-density residential land as well as intensive agriculture had large impact on species diversity. This study indicates that landscape diversity plays a vital role in shaping the species diversity in rice fields, providing guidelines for the conservation of arthropod diversity, maximizing natural pest control ecosystem service and more secure crop production itself.

QTL-Seq Approach Identified Pi63 Conferring Blast Resistance at the Seedling and Tillering Stages of Thai Indigenous Rice Variety “Phaladum”

Rice blast (BL) caused by Magnaporthe oryzae is a fungal disease causing significant yield losses in rice production worldwide. To overcome the breakdown of resistance by the rapid adaptation of pathogens, identifying resistance (R) genes or QTLs in indigenous rice, which harbors the R genes that co-evolved with the local pathogen race, is necessary. In this study, a recombinant inbred line (RIL) population derived from a cross between RD6 and Phaladum (PLD) was used to map quantitative trait loci (QTL) for BL resistance through a QTL-seq approach. A single QTL (qBLchr4) associated with BL resistance at the seedling and maximum tillering stages was mapped on the long arm of chromosome 4. Five genes, LOC_Os04g0616600, LOC_Os04g0617900 (OsGLP4-1), LOC_Os04g0619600 (OsRLCK161), LOC_Os04g0620800 (Pi63), and LOC_Os04g0621500, were considered the candidate genes representing qBLchr4. Subsequently, the Kompetitive Allele-Specific PCR (KASP) markers specific for the SNP variant and position of each gene were designed for validation in the mapping population. These markers showed the high phenotypic variance explained (PVE) values in all testing methods and/or environments, signifying the major effect of qBLchr4. Among these markers, the Pi63-KASP marker explained the highest and most stable phenotypic variation across all testing methods and/or environments, with 84.18%, 80.34%, and 23.43% in the upland short row (USR) method, Sila environment, and Mueang environment, respectively. Therefore, Pi63 was suggested to be the strongest candidate gene. These results represent the potential utility of future BL resistance breeding and/or pyramiding using marker-assisted selection (MAS).

Identification of quantitative trait loci for tillering, root, and shoot biomass at the maximum tillering stage in rice

Tillering and plant biomass are key determinants of rice crop productivity. Tillering at the vegetative stage is associated with weed competition, nutrient uptake, and methane emissions. However, little information is available on quantitative trait loci (QTLs) associated with tiller number (qTN), root biomass (qRB), and shoot biomass (qSB) at the active tillering stage which occurs approximately 6 weeks after planting. Here, we mapped tiller and biomass QTLs with ~ 250 recombinant inbred lines derived from a ‘Francis’ by ‘Rondo’ cross using data collected at the maximum tillering stage from two years of greenhouse study, and further compared these QTLs with those mapped at the harvest stage from a field study. Across these three studies, we discovered six qTNs, two qRBs, and three qSBs. Multiple linear regression further indicated that qTN1-2, qTN3-3, qTN4-1, qRB3-1, and qRB5-1 were significant at the maximum tillering stage while qTN3-2 was detected only at the harvest stage. Moreover, qTN3-1 was consistently significant across different developmental stages and growing environments. The genes identified from the peak target qTN regions included a carotenoid metabolism enzyme, a MYB transcription factor, a CBS domain-containing protein, a SAC3/GANP family protein, a TIFY motif containing protein, and an ABC transporter protein. Two genes in the qRB peak target regions included an expressed protein and a WRKY gene. This knowledge of the QTLs, associated markers, candidate genes, and germplasm resources with high TN, RB and SB is of value to rice cultivar improvement programs.