Yield Components Of Rice Research Articles

Effects of rice stalks mulching combined with green manure (<italic>Astragalus smicus </italic>L.) incorporated into soil and reducing nitrogen fertilizer rate on rice yield and soil fertility

<p id="C3">Planting green manure and straw retention is an effective measure to improve soil fertility. Two-year field experiment were conducted to assess the effects of reduced nitrogen rate under the rice straw mulching combined with planting green manure (<italic>Astragalus sinicus </italic>L.) at full bloom stage on rice yield, yield components, and soil nutrient availability in Hantai district, Hanzhong city, Shaanxi province from 2018 to 2020. Five treatments were assigned: (1) CK, winter fallow, no straw mulching, no fertilization; (2) NPK, winter fallow, no straw mulching, conventional nitrogen fertilizer rate; (3) GRN1, planting green manure in winter, rice straw mulching with conventional N fertilizer rate; (4) GRN2, planting green manure in winter, rice straw mulching with 80% conventional N rate; (5) GRN3, green manure planting in winter, rice straw mulching with 70% conventional N rate. The results showed that: (I) rice yield (Quanxiangyou 1521) of GRN1 was 10,047 kg hm^-2, which was higher 6.7% than that of NPK, and GRN2 and GRN3 had marginal effects in 2019. Moreover, the yield (Huanghuazhan) of GRN2 and GRN3 were significantly higher than that of NPK by 6.6% and 5.8% in 2020, respectively. Compared with CK and NPK, the rice straw mulching combined with planting green manure significantly enhanced the rice yield by 67.9%-83.0% and 2.8%-6.7%, respectively. (II) Planting green manure combined with rice straw mulching increased soil organic carbon content and available P content in 0-20 soil layer. Compared with NPK treatment, soil organic carbon and available P content of GRN2 increased 6.8%-13.2% and 9.9%-12.6%, respectively. Correlation analysis indicated that rice yield was significantly correlated with plant height, fresh weight per plant, fresh root stubble weight, filled grain number per panicle, and 1000-grain weight. Compared with NPK, GRN2 significantly increased effective panicle, effective grain number per panicle by 13.0%-29.3% and 4.5%-14.3%, respectively. Meanwhile, GRN2 significantly increased plant height, fresh weight per plant, and root fresh weight by 10.4%, 23.6%, and 30.0%, respectively. In conclusion, rice stalks mulching combined planting green manure with 20% reduced nitrogen rate can improve rice yield and agronomic performance, enlarge soil carbon sequestration capacity, and increase soil nutrients availability, which is a green rice cultural practice adapted to Hanzhong area.

Improved nitrogen use efficiency, carbon sequestration and reduced environmental contamination under a gradient of manure application

The challenge of reducing the environmental contamination related to agricultural practices to improve nitrogen (N) use efficiency (NUE), carbon (C) sequestration, and crop yield, requires efficient N fertilization and management strategies. We carried out a field experiment from 2016 to 2018 exploring the effect of the gradual replacement of mineral N with organic manure N on soil properties, soil organic C storage, soil total N storage, rice grain yield and yield components, N uptake and C accumulation of rice, and NUE. Moreover, we explained the relationship among the proportions of manure added to fertilizers, soil properties, rice grain yield and yield components, and aboveground N uptake and C accumulation of rice after harvest. Compared to mineral fertilization, 50% manure improved NUE and increased the effective panicle, seed setting rate, grain yield, and straw yield. However, in comparison to mineral fertilization, 100% manure decreased the effective panicle, the number of spikelets per panicle, grain yield, and straw yield and decreased partial factor productivity (PFP), N agronomic efficiency (AEN), and N recovery efficiency (REN). Moreover, in comparison with mineral fertilization, 50% manure increased the aboveground N uptake and C accumulation of rice, decreased the N surplus by 61.5%, and increased the apparent accumulated N recovery efficiency by 10.7%. In comparison to mineral fertilization, manure percentages exceeding 25% increased the total and available N, phosphorus, potassium, and organic C contents in soil. According to redundancy analysis, aboveground C accumulation and N uptake of rice jointly contributed to the variation in grain yields and yield components by 27.9%. In conclusion, 50% manure is a promising ecologically friendly strategy that improves the grain yield, N uptake, C sequestration, and NUE of rice and improves soil fertility. Simultaneously, 50% manure decreases the risk of environmental contamination.

The effects of foliar application of zinc and phosphorous on the morphology and yield of the dominant Iranian rice variety (Hashemi)

Deficiencies of phosphorus (P) and zinc (Zn) cause the most important nutrient disorders in the world’s paddy fields. This study characterized the effect of Zn and P foliar application on morphology, grain yield and its yield components. The two factors factorial experiment was conducted using a randomized complete block design with three replications in 2017–2018. The analysis of variance indicated that most treatments influenced morphological characters, yield, and yield components. The results also revealed that the foliar application of Zn and P at 1 week before flowering and grain filling increased the fertile tiller number (15%), panicle length (20%), filled and unfertile grain number (23 and 13%). Also, the separate foliar application of Zn and P increased grain yield by about 12 and 7%, respectively. Both the straw and biological yield were increased by Zn and P foliar application about 10 and 7%, respectively. The results indicate that both P and Zn foliar application was able to improve the rice yield components and physiological characteristics toward higher yield.

Assessment of Seedling Rate per Hill for Irrigated Rice in a Wet Sub-Tropical Condition of Bhutan

A field experiment was conducted at the research farm of the Agriculture Research and Development Centre (ARDC) Samtenling in Sarpang district of Bhutan in 2020 to assess the effects of transplanting different numbers of seedlings per hill on grain yield and yield components of rice under irrigated conditions. A widely adopted rice variety, Bhur Kambja-1, was used for the study with one to seven seedlings per hill transplanted at 20×20 cm spacing. The experiment was laid out in a randomized complete block design with three replications. The results of the experiment revealed that the number of seedlings per hill had a significant effect on number of tillers per hill and grain yield. In terms of rice grain yield, a significant difference was observed only between three and seven seedlings per hill with a recorded yield of 3.9 and 2.7 t ha-1, respectively. However, no significant effect was established on other yield components, such as the plant height, panicle length, number of grains per panicle, and unfilled grains per panicle. Therefore, this study recommends transplanting three seedlings hill-1 for cultivation of Bhur Kambja-1 rice variety in the wet-subtropical condition of Bhutan as three seedlings per hill yielded significantly higher productivity and could potentially reduce the seed rate.

Effects of Textile Wastewater on Growth and Yield Components of Rice (Oryza Sativa L.)

An experiment was conducted to study the effect of textile wastewater on growth and yield components of rice (Oryza sativa L.). The treatments wereT1: Control, T2: Sole RDF (Recommended Dose of Fertilizer) + FW (Fresh Water), T3: 50% RDF + 25% TWW (Textile Waste Water), T4: 50% RDF + 50% TWW, T5: 50% RDF + 75% TWW, T6: 50% RDF + 100% TWW. The highest plant height (134.1 cm), tiller number at maturity stage (344/m2), straw yield (6.94 t/ha),grain yield (4.25 t/ha), panicle number (306/m2), panicle length (24.57cm), number of grain/ panicle (118.5), percent of filled grain/panicle (85.07%) and 1000-grain weight (13.77gm) were found inT2. And the second highest plant height (124.2 cm), tiller number at maturity stage (342/m2), grain yield (3.97 t/ha), panicle number (301/m2), panicle length (24.12cm), number of grain per panicle (117.2), percent of filled grain/panicle (84.17%) and 1000-grain weight (13.37gm) were found in T4.And T5 gave the second highest yield of straw (6.05 t/ha). Although highest values were found in T2, but statistically the achievements indicate that there was little difference between the T2 and T4 treatments. The overall findings of this study indicated that where fresh water is scarce application of 50% RDF along with 50% TWW irrigation may be a good indicator to achieve better growth and yield of rice. Dhaka Univ. J. Biol. Sci. 31(1): 147-157, 2022 (January)

Effect of organic sources of nutrients on growth physiology and yield components of scented rice (Oryza sativa L.)

A field experiment was conducted to evaluate the effect of different organic sources of nutrientson growth physiology and yield components of scented rice, variety KetekiJoha at Regional Agricultural Research Station, AAU, Titabor during 2017 and 2018. Eight treatments were evaluated in randomized block design with three replications. The results revealed that the application of different proportion of organic sources of nutrients significantly improved the growth physiology and yield parameters of scented rice over the control. Among the treatments,the application of green manure (2.5 t ha-1) + Vermicompost (2.5 t ha-1) + Azolla (20 kg ha-1) + biofertilizer consortium (4 kg ha-1 seedling) as root dip + rock phosphate (17 kg ha-1) recorded the highest grain yield (38.05 qha-1) with significant increase in yield components of the crop.Application of green manure + Vermicompost + Azolla + biofertilizer consortium as root dip + rock phosphate significantly produced higher plant height (78.5cm), leaf area index (4.3), flag leaf area (35.3cm-2), total Chlorophyll content (3.5mgg-1fwt), panicles m-2 (304.3), panicle length (28.2 cm), grains panicle-1(108.4),panicle weight (2.7 g), harvest index (35.2 %) and 1000 grain weight(23.6 g). The organic treatments also significantly enhanced the growth physiology viz., crop growth rate, specific leaf weight, and net assimilation rate of the plant.

Effect of organic sources of nutrients on growth physiology and yield components of scented rice (Oryza sativa L.)

A field experiment was conducted to evaluate the effect of different organic sources of nutrientson growth physiology and yield components of scented rice, variety KetekiJoha at Regional Agricultural Research Station, AAU, Titabor during 2017 and 2018. Eight treatments were evaluated in randomized block design with three replications. The results revealed that the application of different proportion of organic sources of nutrients significantly improved the growth physiology and yield parameters of scented rice over the control. Among the treatments,the application of green manure (2.5 t ha-1) + Vermicompost (2.5 t ha-1) + Azolla (20 kg ha-1) + biofertilizer consortium (4 kg ha-1 seedling) as root dip + rock phosphate (17 kg ha-1) recorded the highest grain yield (38.05 qha-1) with significant increase in yield components of the crop.Application of green manure + Vermicompost + Azolla + biofertilizer consortium as root dip + rock phosphate significantly produced higher plant height (78.5cm), leaf area index (4.3), flag leaf area (35.3cm-2), total Chlorophyll content (3.5mgg-1fwt), panicles m-2 (304.3), panicle length (28.2 cm), grains panicle-1(108.4),panicle weight (2.7 g), harvest index (35.2 %) and 1000 grain weight(23.6 g). The organic treatments also significantly enhanced the growth physiology viz., crop growth rate, specific leaf weight and net assimilation rate of the plant.

Effect of water stress on growth, yield and yield components of rice (Oryza sativa L.) genotypes

This study aimed to examinate effects of drought stress on rice agronomical traits and identify rice genotypes and elite lines that are tolerant to drought. Twenty genotypes consisting of seventeen inbred lines, two parental lines (IR64 and B6144F-MR) and drought tolerant variety APO were evaluated in a split plot design with four replications in experiment with and without water stress. Analysis of variance results indicated that the effects of genotype and drought stress were highly significant for day to 50% flowering, panicle leaf length, panicle leaf width, plant height, panicles number per m2, 1000 grains yield and grains yield. Genotype, drought stress, and Genotype × drought interaction was highly significant for day to 50% flowering, plant height and grains yield. Number of tillers m2, panicle leaf length, plant height, 1000 grains weight, biomass and grains yield were decreased with increasing water stress level; however, day to 50% flowering and panicles number per m2 were increased. Responses of the rice genotypes in water stress varied significantly. There had been different degree of reduction to the yield contributing characters for the stress. From the findings of this study genotypes APO, IRB-MR-412 and B6144F-M showed best drought tolerant level, as these genotypes gave significantly higher yield than the other genotypes under study.

Genetic diversity reveals synergistic interaction between yield components could improve the sink size and yield in rice

AbstractIntensive breeding programs have increased rice yields, strongly contributing to increasing global food security during the post‐green revolution period. However, rice productivity has reached a yield barrier where further yield improvement is restricted by inadequate information on the association of yield components, and morphological and physiological traits with yield. We conducted a field experiment to evaluate (i) the contribution of morphological and physiological traits to yield and (ii) quantify the trade‐off effect between the yield components in rice, using a mini‐core collection of 362 rice genotypes comprising geographically distinct landraces and breeding lines. Our data point towards multiscale coordination of physiological and morphological traits associated with yield and biomass. Considerable trait variations across the genotypes in yield ranging from 0.5 to 78.5 g hill−1and harvest index ranging from 0.7% to 60.7% highlight enormous diversity in rice across the globe. The natural elimination of trade‐off between yield components revealed the possibility to enhance rice yield in modern cultivars. Furthermore, our study demonstrated that genotypes with larger sink sizes could fix more carbon to achieve a higher yield. We propose that the knowledge thus generated in this study can be helpful for (a) trait‐based modeling and pyramiding alleles in rice‐breeding programs and (b) assisting breeders and physiologists in their efforts to improve crop productivity under a changing climate, thus harnessing the potential for sustainable productivity gains.

Seaweed extract effect on arbuscular mycorrhizae spore in soil engineered by earthworm, and the soil effect on upland rice growth

Seaweed extract is known to contain nutrients and growth-regulating substances that affect soil biota, and a source of protection against pests and diseases. Earthworm, which is an example of a soil biota and playing the role of ecosystem engineer, has the ability to produce suitable land biostructures, for the inhabitation of arbuscular mycorrhizal fungi (AMF), which has an impact on upland rice growth. Therefore, this study aims to determine, (i) the effect of seaweed extract on the population of earthworms and spores of arbuscular mycorrhizal fungi, and (ii) the impact of the engineered soil on the growth of local upland rice varieties. Furthermore, the extract of seaweed, such as Kappapychus alvarezii, was divided into five concentration levels, namely 0%, 20%, 40%, 60%, and 80%. Each treatment was drenched into the soil from the cogongrass vegetated area, mixed with 20 Pheretima sp., and maintained for 49 days in the greenhouse. The result showed that the total difference in the earthworms’ concentration treatments was not significant. It also showed that the total AMF spores in the engineered soil products of 20% concentration was the highest. Based on treatment with the earthworm engineered soil products, the highest and lowest vegetative growth and yield components of upland rice were observed at the concentrations of 80% and 0%, respectively. In conclusion, the application of seaweed extract to the soil did not significantly reduce the earthworm population. The extract concentration of 20% also increased the total AMF spore in the engineered soil. Moreover, highly treated engineered soil products increased the growth and yield components of upland Kambowa rice on cogongrass soils.

Yield Response of Upland Rice (&amp;lt;i&amp;gt;oryza sativa l.&amp;lt;/i&amp;gt;) Through Nutrient Omission Trial in Vertisols of Fogera Districts, North West Ethiopia

The experiment was conducted with the objectives of investigating the yield-limiting nutrients through nutrient omission trial on upland rice in 2020/2021 cropping season on the vertisols in Fogera District, Northwestern Ethiopia. The experiment was laid out in randomized complete block design with nine treatments and three replications. The treatments were Control, Recommended NP, NPKSZnB, PKSZnB (-N), NKSZnB (-P), NPSZnB (-K), NPKZnB (-S), NPKSB (-Zn) and NPKSZn (-B). Yield attributing characters of biomass yield, plant height, panicle length, effective tillers, grain and straw yields of rice were significantly influenced by the treatments. The highest grain yield (7.2 ton ha^-1) was recorded from NPKSZnB treatment which was not significant with NPKSZn (-B), NPKSB (-Zn) and NPSZnB (-K). The lowest grain yield of 2.2 ton ha^-1 was recorded from the control followed by omission of N, P and S nutrients. The omission of N, P and S reduced the grain and straw yields significantly over the treatment receiving all the nutrients. The omission of N reduced the grain yield by 46%, omission of P reduced the grain yield by 17% while S omission reduced grain yield by 11% over the treatment that received all nutrients. Based on percent grain yield reduction, the limiting nutrients were found in the order of N > P > S. Overall, this result shows that nitrogen phosphorus and sulfur were the most vibrant factors to increase the yield and yield component of rice.

Scanning the rice Global MAGIC population for dynamic genetic control of seed traits under vegetative drought

AbstractGrain size and shape are important yield components in rice (Oryza sativa L.), and their genetic control under adverse environmental conditions, such as drought stress, remains uncertain. This lack of knowledge is due to the laborious, time‐consuming phenotyping of seed attributes in large rice populations. We developed a new high‐throughput phenotyping method based on a desktop scanner and the open‐source package Plant Computer Vision (PlantCV). We used this method to investigate seed size and shape variability within the rice Global multi‐parent advanced generation intercross population, grown under well‐watered and vegetative drought conditions. Besides being affordable, rapid, and accurate, our method captured the phenotypic divergence between drought and well‐watered samples, expressed as 12 different traits, including new grain shape metrics. Our method facilitates the identification of outperforming genotypes under drought stress so is potentially very valuable for crop breeders seeking to make selection based on kernel attributes. We ran a marker–trait association analysis for the measured seed traits, demonstrating that our method also provides adequate phenotypes for genetic studies. We observed dynamic genetic control of seed‐related traits under vegetative drought stress, highlighting the importance of understanding the contribution of genotype × environment interactions on trait variation to develop resilient, high‐yielding rice cultivars.

Substituting nitrogen and phosphorus fertilizer with optimal amount of crop straw improves rice grain yield, nutrient use efficiency and soil carbon sequestration

Crop straw return after harvest is considered an important way to achieve both agronomic and environmental benefits. However, the appropriate amount of straw to substitute for fertilizer remains unclear. A field experiment was performed from 2016 to 2018 to explore the effect of different amounts of straw to substitute for fertilizer on soil properties, soil organic carbon (SOC) storage, grain yield, yield components, nitrogen (N) use efficiency, phosphorus (P) use efficiency, N surplus, and P surplus after rice harvesting. Relative to mineral fertilization alone, straw substitution at 5 t ha−1 improved the number of spikelets per panicle, effective panicle, seed setting rate, 1000-grain weight, and grain yield, and also increased the aboveground N and P uptake in rice. Straw substitution exceeding 2.5 t ha−1 increased the soil available N, P, and K concentrations as compared with mineral fertilization, and different amounts of straw substitution improved SOC storage compared with mineral fertilization. Furthermore, straw substitution at 5 t ha−1 decreased the N surplus and P surplus by up to 68.3 and 28.9%, respectively, compared to mineral fertilization. Rice aboveground N and P uptake and soil properties together contributed 19.3% to the variation in rice grain yield and yield components. Straw substitution at 5 t ha−1, an optimal fertilization regime, improved soil properties, SOC storage, grain yield, yield components, N use efficiency (NUE), and P use efficiency (PUE) while simultaneously decreasing the risk of environmental contamination.

Efectos de niveles de salinidad en Oryza sativa en diferentes estados fenológicos en condiciones de invernadero

In this research, the agronomic and yield components of rice were evaluated, subjected to different levels of salinity at different phenological stages. It was made on the greenhouse of the Faculty of Agricultural Sciences of the Technical University of Babahoyo, Ecuador. It was established an internally casualized delineation with an 8 X 3 factorial start with four repetitions, corresponding to only phenological phases of growth in three doses of salinity (dS.m-1). According to the results obtained, it is concluded that some agronomic characteristics are affected by high levels of salinity (7.0 dS.m-1), showing significant differences less than 0.05 between the treatments, as in the case of vigor whose level was 7.0 dS. m-1. In the same way, chlorophyll levels are significantly reduced between treatments, being a level of 7.0 dS.m-1 or more severe. It is evident that high levels of salinity are detrimental to yield variations, once at 7.0 dS.m-1, or weight of 1000 grains decreased by 54 %, in quantity or panicle compression by 68 %. Furthermore, it affects other phenophases such as flowering, development and pickling of its vegetative cycle, mainly in the phases of germination, molting, profile and growth of caule.

Effects of biochar and barley straw application on the rice productivity and greenhouse gas emissions of paddy field

To improve the agricultural environment, utilization of biochar and organic materials from paddy fields gaining importance. This is because the long-term use of inorganic fertilizers aggravates the soil environment, and also because rice paddy is a major source of CH4 and N2O emissions during rice cultivation which involves continuous flooding. Recently, the application of organic materials and biochar to the soil has received increasing attention due to their potential benefits related to soil quality, crop growth, and greenhouse gas emission. This study examines the influence of biochar and straw treatments on rice growth, soil physicochemical properties, and global warming potential in the paddy field. Five treatments were applied for the study: control (Cn), inorganic fertilizer (IF), barley straw biochar (BC), barley straw (BS), and BC + BS. Soil quality after rice harvesting improved in the BC treated group. The yield components of rice were also improved in the BC + BS, compared to other treatments. These effects resulted in increased rice yield and uptake of nutrient contents in the BC + BS treatment. Total fluxes of CH4 and N2O relative to global warming significantly decreased by 37.3% and 65.2% in the BC + BS group than in the IF treatment, respectively. Consequentially, a cropping system with BC and BS is an effective strategy to improve rice productivity and soil quality and also reduce GHG emissions from paddy fields, thereby alleviating global warming.

Combined application of biochar and nitrogen fertilizer promotes the activity of starch metabolism enzymes and the expression of related genes in rice in a dual cropping system

BackgroundOveruse of chemical fertilizer highly influences grain filling rate and quality of rice grain. Biochar is well known for improving plant growth and grain yield under lower chemical fertilization. Therefore field trials were conducted in the early and late seasons of 2019 at Guangxi University, China to investigate the effects of combined biochar (B) and nitrogen (N) application on rice yield and yield components. There were a total of eight treatments: N1B0, 135 kg N ha− 1+ 0 t B ha− 1; N2B0,180 kg N ha− 1+ 0 t B ha− 1; N1B1,135 kg N ha− 1+ 10 t B ha− 1; N1B2,135kg N ha− 1+ 20 t B ha− 1; N1B3,135 kg N ha− 1+ 30 t B ha− 1; N2B1,180 kg N ha− 1+ 10 t B ha− 1; N2B2,180 kg N ha− 1+ 20 t B ha− 1; and N2B3,180 kg N ha− 1+ 30 t B ha− 1.ResultsBiochar application at 30 t ha− 1combined with low N application (135 kg ha− 1) increased the activity of starch-metabolizing enzymes (SMEs) during the early and late seasons compared with treatments without biochar. The grain yield, amylose concentration, and starch content of rice were increased in plots treated with 30 t B ha−1and low N. RT-qPCR analysis showed that biochar addition combined with N fertilizer application increased the expression of AGPS2b, SSS1, GBSS1, and GBSE11b, which increased the activity of SMEs during the grain-filling period.ConclusionOur results suggest that the use of 20 to 30 t B ha− 1coupled with 135 kg N ha− 1 is optimal for improving the grain yield and quality of rice.

Effects of biochar on water quality and rice productivity under straw returning condition in a rice-wheat rotation region

Straw returning is helpful to improve soil properties and realize the reutilization of agricultural waste. However, wheat straw returning may result in paddy water quality deterioration in rice-wheat rotation regions. This study conducted pot experiments of rice planting with different biochar application rates (0, 5, 20, and 40 t/hm2) under wheat straw returning conditions. The purposes are to investigate the applicability of biochar mixed with wheat straw returning to paddy fields and explore the effects of biochar on water quality, leaching losses of nitrogen (N) and phosphorus (P), and rice yield components. Results indicated that total straw returning reduced the water quality in paddy surface water and aggravated the leaching losses of N and P. Fortunately, the biochar application improved the negative effects caused by straw returning. 40 t/hm2 biochar mixed with straw returning significantly reduced the concentrations of COD and N in paddy surface water and N leaching loss than straw returning treatment (ST), decreased by 48.33%, 41.01%, and 45.73%, respectively. Meanwhile, applying biochar at a rate of 20 t/hm2 with straw returning is suitable to control the diffusion of P. In addition, the ST treatment had no significant effect on rice yield, while the proper application rate of biochar under straw returning condition can improve rice yield and promote N utilization. 20 t/hm2 biochar treatment is more effective to improving rice yield (16.89%) and N use efficiency (NUE) (10.14%). These findings can provide a new method to solve the negative effects of total straw returning on the water environment and rice growth and guide the utilization of straw resources in the rice-wheat rotation regions.

Path Coefficient Analysis of Growth and Yield Traits of Rice (Oryza sativa L.) at Bokolori, Talata Mafara, Sudan Savanna Ecological Zone, Nigeria

&#x0D; &#x0D; &#x0D; In order to determine the direct and indirect effects of yield and yield components of rice, a field experiment was conducted in each of the wet seasons of 2016 and 2017 at Irrigation Research Stations of the Institute for Agricultural Research, Bokolori, Talata Mafara, in the Sudan Savanna ecological zone of Nigeria (12° 34’ N; 06° 04’E). The treatment consisted of four (4) weed management practice (Oxadiazon at 1.0 kg a.i ha-1 [pre-emergence], Orizo-plus [proponil 360 g/l + 2,4-D 200 g/l] at 2.8 kg a.i ha-1[post emergence at 3 WAS], manual weeding [at 3 and 6 WAS] and weedy check [control]); three (3) each of seeding method (Drilling, Dibbling and Broadcast) and seed rate (40 kg ha-1; 70 kg ha-1; 100 kg ha-1). The experiment was laid in a split plot design replicated three times. Weed management practice was assigned to the main plots while the combination of seeding method and seed rate to the subplots. Data were collected on plant height, leaf area, crop dry matter, tillering ability, crop growth rate, harvest index (HI), panicle length, number of grains per panicle, 1000-grain weight and paddy yield. The result indicated that, the highest individual contribution of 25.04% to paddy yield was made by dry matter followed by 1000-grain weight (8.74%), tillering ability (8.46%), leaf area (3.13%), number of grains per panicle (1.03%) and the least was from panicle length (0.83%). The contribution of these growth and yield attributes to yield suggests that, priority be given to these traits when making selection for improvement.&#x0D; &#x0D; &#x0D;

Yield and Yield Components of Boro Rice as Influence by Nitrogen Application Methods and Weed Management

Two consecutive field experiments were conducted at the Suapur Union of Dhamrai Upazila, Dhaka, is located at 23088´N latitude and 90014´E longitude and AEZ-12, Bangladesh. The purpose of the experiment was to study the combine effect of nitrogen application methods and weed management for maximizing yield and yield components of boro rice (cv.BRRI dhan29).The experiment consisted of four nitrogen management methods and four weed managements. The experiment comprised two factors; Factor A: Nitrogen management (4 levels), N0: No urea (control), N1: Urea super granules-USG (77 kg N ha-1), N2: Prilled urea at recommended dose (150 kg N ha-1) and N3: ½ of the recommended dose (75 kg N ha-1); Factor B: Weed management (4 levels), W0: No weeding (control), W1: Two hand weeding (20 and 40 DAT), W2: Pre emergence herbicide (Butachor) and W3: Post emergence herbicide (Prityloclor). The experiment was laid out in a randomized complete block design with three replications. Data on different yield components and yield of BRRI dhan29 were recorded. Statistically significant variation was observed for their combined effect. The highest grain yield (6.80 t ha-1) was obtained from the interaction between urea super granules-USG (77 kg N ha-1) and pre emergence herbicide (Butachor), whereas whereas the lowest (3.85 t ha-1) from the interaction between no urea (control) and no weeding (control). From the results of the study it can be concluded that the application of urea super granules-USG (77 kg N ha-1) and pre emergence herbicide (Butachor) condition might be used for obtaining the best performance of BRRI dhan29.

Impact of tillage and crop establishment methods on rice yields in a rice-ratoon rice cropping system in Southwest China

Simplified cultivation methods for rice production offer considerable social, economic, and environmental benefits. However, limited information is available on yield components of rice grown using simplified cultivation methods in a rice-ratoon rice cropping system. A field experiment using two hybrid and two inbred rice cultivars was conducted to compare four cultivation methods (conventional tillage and transplanting, CTTP; conventional tillage and direct seeding, CTDS; no-tillage and transplanting, NTTP; no-tillage and direct seeding, NTDS) in a rice-ratoon rice system from 2017 to 2020. Main season yields for CTDS and NTDS were higher than for CTTP by 6.1% and 2.8%, respectively; whereas ratoon season yields for CTDS and NTDS were equal to or higher than for CTTP. Annual grain yields for CTDS and NTDS were higher than for CTTP by 4.4% and 3.2%, respectively. The higher CTDS and NTDS yields were associated with higher panicle numbers per m2 and biomass production. Rice hybrids had higher yields than inbred cultivars by 15.8–19.3% for main season and by 15.6–19.4% for ratoon season, which was attributed to long growth duration, high grain weight and biomass production. Our results suggest that CTTP can be replaced by CTDS and NTDS to maintain high grain yields and save labor costs. Developing cultivars with high grain weight could be a feasible approach to achieve high rice yields in the rice-ratoon rice cropping system in southwest China.