Aerobic Rice Research Articles

Improving Resource Utilization Efficiency and Productivity in Rice-wheat Cropping System through Cutting Edge Technologies: An Overview

Rice-wheat cropping system is one of the major cropping system practiced in South Asia on 13.5 m hectares area, 10.3 million hectares of which are in the Indo-Gangetic Plains (IGP). The Indian Rice-Wheat Cropping System (RWCS) accounts for more than 70% of the country’s total grain production which is essential for ensuring national food security. Widely used RCT known as Zero Tillage (ZT) in which wheat is directly sown into the undisturbed soil after rice harvested. The Adoption of Furrow Irrigated Raised Bed System (FIRBS) in wheat production saves 30-40% water, seed use by 25-30% and nutrients use by 25% without reducing yield. The RCTs involve residue management (mainly residue retention), crop diversification and no- or minimum tillage with direct seeding and bed planting. AWD in rice save water by 10 to 30% while reducing seepage and deep drainage losses and Brown manuring is highly beneficial for weed control, water and soil conservation and nutrient supplementation. The cultivation of aerobic rice is a new system of growing in non-flooded, non-puddled soils, with high external inputs using innovative technique of aerobic rice that require less water than transplanted rice. A simple and inexpensive diagnostic tool leaf colour chart can be used for monitoring the relative greenness as a measure of the plant N status. Thus, it can be concluded that RCT adoption improving soil health, water use efficiency and nutrient use efficiency with higher sustained yields which leads to sustainable improvements in RWCS. By saving on labour, time, diesel, fertilisers, pesticides, and farm power, resource conservation technologies lower the cost of farming and also lessen environmental pollution.

Optimizing the lateral dripline spacing of drip-irrigated aerobic rice to increase water productivity and profitability under the water-limited condition

The potential use of drip irrigation to reduce water use without yield penalty in aerobic rice cultivation has not been fully explored in the tropics due to high investment costs. One major way to lowering this cost is by optimizing the lateral spacing to serve more rows of rice plants per dripline. This study evaluates the effects of lateral dripline spacing on the grain yield, water productivity, and the economic return in aerobic rice production. Field experiments were conducted for the period of two years (2020–2021) using three lateral dripline spacings (40-cm, 60-cm, and 80-cm) as treatments and surface flooding as the control. Grain yields, water use, water productivity, and economic benefits were evaluated. The drip-irrigated aerobic rice did not show significant differences with surface flooding except for a lower yield at 80-cm in 2021 dry season due to its low percent filled grains. Among treatments, the 60-cm lateral spacing consistently obtained the highest irrigation water productivity by up to 1.03 kg m-3 and 42% irrigation water savings relative to surface flooding. Increasing the spacing of the lateral dripline decreased the material costs (80 <60 <40 cm) by 10–36%. The 60-cm spacing produced the highest average net income by 41–75% among drip treatments and had comparative economic returns compared with surface flooding. The net present value and the benefit-cost ratio indicate that it is economically viable to invest in drip irrigation using a 60-cm lateral spacing. Thus, this study suggests that when there is insufficient water to grow surface flooding aerobic rice, drip irrigation using 60-cm lateral spacing is the best option for reducing irrigation water use and increasing water productivity; while having comparative yield and economic return as surface flooding method of aerobic rice cultivation.

Effect of Rice Establishment Methods and Nutrient Management Practices on Growth, Yield and Economics of Rice (Oryza sativa L.)

A field experiment was conducted at Rice Research Farm of Birsa Agricultural University, Ranchi, Jharkhand,during Kharif seasons of 2018 and 2019 to find out the effect of rice establishment methods and nutrientmanagement practices on growth, yield and economics of rice. The experiment was laid out in split plotdesign replicated thrice with rice variety Naveen as test crop. The treatments comprised of three differentrice establishment methods viz., normal transplanting, wet direct seeding using drum seeder and aerobicrice assigned to main plots and five nutrient management practices viz., RDF( 80:40:20 kg NPK/ha), 75%RDF + 25% N through FYM (60:30:15 kg NPK/ha + 20 kg N through FYM), RDF + 25% N through FYM(80:40:20 kg NPK/ha + 20 kg N through FYM) , LCC based nitrogen application and control (No fertilizer)assigned to sub plots. The soil was clay loam in texture and slightly acidic in reaction (6.2) having 4.3 g/kgorganic carbon, 230.00 kg/ha available soil nitrogen, 36.80 kg/ha available phosphorous, 161.20 kg/ha ofavailable potassium. Results revealed that wet direct seeding of rice using drum seeder recorded maximumgrain (42.19 q/ha) and straw yield (65.22 q/ha) which was comparable with transplanting method butwere significantly superior to aerobic rice. Among the nutrient management practices, application of RDF+ 25% N through FYM produced maximum grain (46.33 q/ha) and straw yield (71.53 q/ha) which wassignificantly better than rest of the treatments except LCC based N application. Among the differentestablishment methods, wet direct seeding of rice using drum seeder recorded maximum net return (58337`/ha) which was significantly higher than other establishment methods. The B:C ratio was also maximumwith wet direct seeding using drum seeder (2.00) which was statistically at par with aerobic rice (1.93).Among the nutrient management practices, LCC based N application gave the highest net return (64030 `/ha) and B:C ratio (2.28).

Recent trends in nitrogen cycle and eco-efficient nitrogen management strategies in aerobic rice system.

Rice (Oryza sativa L.) is considered as a staple food for more than half of the global population, and sustaining productivity under a scarcity of resources is challenging to meet the future food demands of the inflating global population. The aerobic rice system can be considered as a transformational replacement for traditional rice, but the widespread adaptation of this innovative approach has been challenged due to higher losses of nitrogen (N) and reduced N-use efficiency (NUE). For normal growth and developmental processes in crop plants, N is required in higher amounts. N is a mineral nutrient and an important constituent of amino acids, nucleic acids, and many photosynthetic metabolites, and hence is essential for normal plant growth and metabolism. Excessive application of N fertilizers improves aerobic rice growth and yield, but compromises economic and environmental sustainability. Irregular and uncontrolled use of N fertilizers have elevated several environmental issues linked to higher N losses in the form of nitrous oxide (N2O), ammonia (NH3), and nitrate (NO3–), thereby threatening environmental sustainability due to higher warming potential, ozone depletion capacities, and abilities to eutrophicate the water resources. Hence, enhancing NUE in aerobic rice has become an urgent need for the development of a sustainable production system. This article was designed to investigate the major challenge of low NUE and evaluate recent advances in pathways of the N cycle under the aerobic rice system, and thereby suggest the agronomic management approaches to improve NUE. The major objective of this review is about optimizing the application of N inputs while sustaining rice productivity and ensuring environmental safety. This review elaborates that different soil conditions significantly shift the N dynamics via changes in major pathways of the N cycle and comprehensively reviews the facts why N losses are high under the aerobic rice system, which factors hinder in attaining high NUE, and how it can become an eco-efficient production system through agronomic managements. Moreover, it explores the interactive mechanisms of how proper management of N cycle pathways can be accomplished via optimized N fertilizer amendments. Meanwhile, this study suggests several agricultural and agronomic approaches, such as site-specific N management, integrated nutrient management (INM), and incorporation of N fertilizers with enhanced use efficiency that may interactively improve the NUE and thereby plant N uptake in the aerobic rice system. Additionally, resource conservation practices, such as plant residue management, green manuring, improved genetic breeding, and precision farming, are essential to enhance NUE. Deep insights into the recent advances in the pathways of the N cycle under the aerobic rice system necessarily suggest the incorporation of the suggested agronomic adjustments to reduce N losses and enhance NUE while sustaining rice productivity and environmental safety. Future research on N dynamics is encouraged under the aerobic rice system focusing on the interactive evaluation of shifts among activities and diversity in microbial communities, NUE, and plant demands while applying N management measures, which is necessary for its widespread adaptation in face of the projected climate change and scarcity of resources.

Effect of Precision Water and Nitrogen Management on Yield Attributes and Yield of Aerobic Rice under Drip System

A Field experiment was conducted at Indian Institute of Rice Research (IIRR) during Rabi season of 2020 and 2021, with an objective to study the effect of precision water and nitrogen management on yield attributes and yield of aerobic rice under drip system. Treatments included three precision irrigation management methods- {I1 (DRIP irrigation 1.5 Epan in Flat bed system); I2 (DRIP irrigation 1.5 Epan in Raised bed system) and I3 {Surface irrigation (up to saturation)}} and four precision nitrogen management practices- N1 {Recommended practice (RDF)-(120:60:40 N P K kg ha-1)}; N2 {Green seeker (Optical sensor) based N application}; {N3 (LCC based N application) and N4­­ (No Nitrogen)} replicated thrice. Results of experiment shows that, the performance of aerobic rice was better when it was managed with precision ‘N’ management tools like LCC based ‘N’ application with surface method of irrigation in terms of recording higher yield attributes and yield. Among irrigation methods, higher values of yield attributes such as no of panicles m-2 (144), length of panicle (21.7 cm), panicle weight (3.4 g), filled grains panicle-1 (109.3), total grains panicle-1 (128.7), test weight (21.6 g), grain yield (4171 kg ha-1) and lowest sterility percentage (15.6%) were observed under surface irrigation followed by drip irrigation with raised beds during both years (mean). Significantly higher values for above parameters were recorded under LCC based N application (148, 21.7 cm, 3.5 g, 114.5, 132.4, 21.5 g, 4230 kg ha-1 and 13.7%) followed by recommended practice among nitrogen management practices. The experimental data revealed that, cultivating rice under aerobic ecosystem with drip irrigation along with precision nitrogen management tools like LCC and greenseeker aids in recording high yield and yield attributes besides saving water and nutrients.

Energy Dynamics of Aerobic Rice Cultivation in India

Aerobic rice needs 30% less total water for land preparation, 50% saving on labour requirement and 50% less GHG emission compared to transplanted rice. Energy use efficiency of aerobic rice cultivation also varies due to varieties. However, a detailed study on various energy inputs components of aerobic rice cultivation (variety, water management, spacing, fertilizer dose and weed management) is lacking. To confirm the energy dynamics of aerobic rice cultivation, a combined study was taken up to find out the energy input, output and energy use efficiency of aerobic rice cultivation consisting of various trials conducted at research farm of ICAR-Indian Institute of Rice Research and few other trials conducted at other places. Gayatri variety performed well in terms of higher energy use efficiency at eastern part of India. Further higher energy use efficiency (output/input ratio) was recorded at 100% RFD. Crop spacing also affects the total energy output of aerobic rice. It was seen that the total output energy is highest at optimum spacing of 20 x 10 cm compared to 25 x 10 and 30 x 10 cm. Apart from need based hand weeding, Pendimethalin 1.0 kg /ha + Bispyribac sodium 35 g/ha resulted higher energy use efficiency (2.75) compared to those of other chemical weed management practices. It was observed that aerobic rice based systems maintained higher productivity and profitability in comparison to transplanting based rice cropping systems. The study revealed that varieties, fertilizer dose and spacing played crucial role in enhancing the energy use efficiency of aerobic rice cultivation. So, farmers have to strike a balance among the input resources specially variety, water, fertilizer to achieve higher energy use efficiency in aerobic rice based cropping systems.

Effect of drought stress and its mitigating chemicals on aerobic rice (Oryza sativa L.) cultivation

Aerobic rice cultivation is a method of growing rice in well-drained, non-puddled and non-saturated soils using specifically developed varieties. It is the process of growing a crop from dry seeds put in the ground rather than transplanting seedlings from a nursery. Rice production is severely limited by drought stress during reproductive phase, which causes significant economic losses. Enhancing agricultural yield in the drought-prone rainfed areas has become necessary in consideration of the present and projected global food demand. A field experiment was conducted during summer 2022 at Tamil Nadu Agricultural University, Coimbatore, to study the effect of drought stress at reproductive stage and its growth and yield of aerobic rice. The experiment was laid out in split plot design with three replications. In main plot irrigation interval viz., irrigation @ IW/CPE 1.0 (M1), withholding irrigation for 8 days from heading (M2), with holding irrigation for 12 days from heading (M3) was adopted. In sub plot stress mitigating chemicals viz., salicylic acid @ 100 ppm (S2), sodium selenate @ 20 ppm (S3), Pink Pigmented Facultative Methylotroph @ 1 per cent (S4) in comparison with control no spray (S1). The results revealed that irrigation @ IW/CPE 1.0 with foliar application of sodium selenate @ 20 ppm recorded higher grain yield (4146 kg ha-1) which was followed by drought stress for 8 days from heading with foliar spray of sodium selenate @ 20 ppm recorded the grain yield of 3461 kg ha-1. The application of sodium selenate @ 20 ppm at heading stage which results to mitigate the drought stress up to 8 days and the yield reduction is noticed only 16 per cent when compared to without drought stress.

Effect of polymer seed coating with pendimethalin on germination percentage and growth characters of aerobic rice

Weeds are the major constraints in aerobic rice cultivation which provides stronger competition for essential growth factors. As one of the weed control techniques, we used polymer seed coating with herbicide as a seed treatment before sowing as an alternative to pre-emergence application of herbicide. The present investigation was carried to study the effect of polymer seed coating with pendimethalin on germination percentage and growth characters of rice in Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore. The experiment comprised of pot culture studies and germination test. Initially the seed were treated with polymer @ 3ml/kg of seed, this base layer provided a surface for adhesion of herbicide and added the pendimethalin with different concentrations ranging from 0.4 to 1.0 kg a.i./ha. The results revealed that Polymer seed coating with pendimethalin had negative effect on emergence of paddy seeds due to its phytotoxicity and the seed coating with polymer alone does not have any effect on the emergence and development of rice.

Liquid Bioformulation Regulates Soil Microbial and Enzymatic Activities, and Nutrient Dynamics in Drip-Irrigated Aerobic Rice

ABSTRACT The use of liquid formulations―prepared from naturally available farm wastes―has increasingly gained popularity in recent years; however, it remains unclear how these amendments influence the rhizosphere soil biochemistry, particularly in aerobic rice. In this study, we reformulated the traditional liquid manure (Jeevamrutha) with microbial consortia as liquid bioformulation (LBF), and evaluated its potential effect (when applied with or without NPK-fertilizers) on soil biochemical properties and nutrient availability at different stages of crop growth. Six treatments were tested: (i) absolute control, (ii) conventional practice (CP), LBF applied twice at 2000 L ha–1 with (iii) 100% recommended dose of fertilizer (RDF) through a multi-split fertigation (LBF+NPK100), (iv) 75% RDF (LBF+NPK75), (v) 50% RDF (LBF+NPK50), and (vi) LBF alone. The results showed that soil microbial biomass carbon, total bacterial and fungal load, dehydrogenase, urease, and acid phosphatase activities were significantly (p < .05) higher in the LBF co-applied plots, particularly at the panicle initiation and maturity stages of rice. However, actinomycetes and alkaline phosphatase showed an irregular trend with the growth stages. The rhizosphere soil microbial index (RSMI) values were significantly higher under LBF co-applied treatments over the CP, signifying the improvement of soil quality. Grain yield with LBF+NPK75 increased by 30.3−37.8% and 19.3−32.4% for the summer and rainy seasons, respectively, compared with the CP. Combining LBF with NPK-fertigation had more long-lasting effect on soil N and P availability. Therefore, our findings suggest that substituting about half of RDF with LBF could bring promising agronomic and soil ecological benefits to the rice production under aerobic conditions.

Effect of drip irrigation regimes and nitrogen levels on growth, yield and economics of aerobic rice (Oryza sativa L.)

Water supply to agriculture especially rice will be affected in the future because of climate change and increased demand of water for non-agricultural use. To sustain rice production, focus should be on water saving rice production systems such as aerobic rice, which may further reduce water requirement when combined with drip irrigation. Hence, a field experiment to study the influence of drip irrigation regimes and nitrogen levels on growth, yield and economics of aerobic rice was conducted at Tirupati, Andhra Pradesh, during the rabi seasons of 2019-20 and 2020-21. Four main plot treatments consisting of irrigation regimes based on pan evaporation i.e., drip irrigation at 1.25 Epan, 1.50 Epan, 1.75 Epan, 2.00 Epan and four sub plot treatments comprising of four doses of nitrogen i.e., 75 % RDN (90 kg N ha-1), 100 % RDN (120 kg N ha-1), 125 % RDN (150 kg N ha-1) and 150 % RDN (180 kg N ha-1) were tested in split plot design replicated thrice. Significantly higher plant height, number of tillers, yield attributes, grain yield, straw yield and gross returns were recorded with drip irrigation regime of 2.0 Epan over other irrigation regimes, but was comparable with drip irrigation at 1.75 Epan. While, higher net returns and B:C ratio were recorded with drip irrigation regime of 1.75 Epan which was at par with 2.0 Epan and 1.5 Epan. Aerobic rice grown with 180 kg N ha-1 proved to be superior with respect to plant height, number of tillers m-2, panicle weight, grain yield, straw yield, gross returns and net returns which was however comparable with 150 kg N ha-1 in case of panicle number, filled grains per panicle, test weight and B:C ratio. Among the interaction combinations, drip irrigation regime of 2.0 Epan along with 180 kg N ha-1 resulted in superior plant height, tillers m-2, yield attributes, grain yield, straw yield, gross returns, net returns and B:C ratio which was statistically at par with drip irrigation regime of 1.75 Epan along with 180 kg N ha-1 except in case of tiller number.

Methane emission, methanogenic and methanotrophic communities during rice-growing seasons differ in diversified rice rotation systems

Appropriate crop rotation in rice field is an important measure to maintain soil fertility and rice productivity. However, the effects of different rice rotation systems on methane (CH4) emission and the underlying mechanisms, as well as rice grain yields have not been well assessed. Here, a 2-year field study involving three rice rotation systems (Wh-PR: wheat-flooded rice rotation, Ra-PR: rapeseed-flooded rice rotation, Ra-UR: rapeseed-aerobic rice rotation) was conducted. CH4 emissions, methanogenic and methanotrophic communities and rice grain yields were measured during rice growing seasons to determine which rice rotation pattern can reduce CH4 emissions and improve rice grain yields. The average cumulative CH4 emission was 136.19 kg C ha−1 in Ra-PR system, which was significantly higher than that in Wh-PR and Ra-UR systems by 60.6 % and 14.6-fold, respectively. These results were mainly attributed to the low soil dissolved organic carbon in Wh-PR system and the well aerated soil condition in Ra-UR system, as compared with Ra-PR system. Rice grain yields exhibited no significant differences among the three rotation systems in 2019 and 2020. The abundances of methanogens in Ra-PR system were obviously higher than those in Wh-PR and Ra-UR systems. While the abundances of methanotrophs were comparable between Ra-PR and Wh-PR systems, which exhibited significantly lower abundances than that in Ra-UR system. CH4 fluxes showed markedly positive relations to the abundances of methanogens, while exhibited no relationship with the abundances of methanotrophs. Both methanogenic and methanotrophic community compositions differed considerably in Wh-PR and Ra-UR systems in comparison with Ra-PR system. Specifically, the relative low abundances of Methanothrix and Type I methanotrophs occurred in Wh-PR and Ra-UR systems, whereas Methanosarcina, Methanocella, Methanomassiliicoccus and type II methanotrophs (Methylocystis and Methylosinus) were found in higher relative abundances in Wh-PR and Ra-UR systems. Overall, changing the preceding upland crop types or introducing aerobic rice to substitute flooded rice in rice-based rotation systems could diminish CH4 emissions, mainly by regulating soil properties and eventually changing soil methanogenic and methanotrophic communities.

Resource Use, Profitability and Externality in Aerobic vis-à-vis Conventional Rice Cultivation in Karnataka

The study was undertaken to analyze resource use, the economics of cultivation and the externality associated with Aerobic Rice Cultivation (ARC) compared to Conventional Rice Cultivation (CRC) in the Eastern Dry Zone of Karnataka. The Snowball sampling technique was adopted to collect primary data from 50 farmers, each practising ARC and CRC. The per hectare gross returns were higher in CRC (`1,16,827 per ha) compared to aerobic rice cultivation (`1,00,664 per ha) since the grain yield was higher in CRC. The aerobic rice cultivation (ARC) was profitable as it generated higher net returns (`24,653 per ha) compared to conventional paddy cultivation (`11,046 per ha) because of the lower cost of cultivation. ARC was sustainable compared to the conventional method as resources were optimally used. In addition, ARC resulted in positive externality to the tune of `7714 per hectare over CRC. Human labour was the major cost component in both ARC and CRC. Among the costs in ARC, human labour cost accounted for nearly 40 per cent because of the high labour requirement for weeding. The imputed irrigation cost was higher in CRC than in ARC, where water requirement was saved up to 63 per cent. The analysis revealed the superiority of ARC over CRC in terms of cost, net returns and positive externality. Hence, the study will help policymakers and stakeholders to promote the technology extensively.

Improving Nitrogen Use Efficiency in Aerobic Rice Based on Insights Into the Ecophysiology of Archaeal and Bacterial Ammonia Oxidizers.

The abundance and structural composition of nitrogen (N) transformation-related microbial communities under certain environmental conditions provide sufficient information about N cycle under different soil conditions. This study aims to explore the major challenge of low N use efficiency (NUE) and N dynamics in aerobic rice systems and reveal the agronomic-adjustive measures to increase NUE through insights into the ecophysiology of ammonia oxidizers. Water-saving practices, like alternate wetting and drying (AWD), dry direct seeded rice (DDSR), wet direct seeding, and saturated soil culture (SSC), have been evaluated in lowland rice; however, only few studies have been conducted on N dynamics in aerobic rice systems. Biological ammonia oxidation is majorly conducted by two types of microorganisms, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). This review focuses on how diversified are ammonia oxidizers (AOA and AOB), whose factors affect their activities and abundance under different soil conditions. It summarizes findings on pathways of N cycle, rationalize recent research on ammonia oxidizers in N-cycle, and thereby suggests adjustive agronomic measures to reduce N losses. This review also suggests that variations in soil properties significantly impact the structural composition and abundance of ammonia oxidizers. Nitrification inhibitors (NIs) especially nitrapyrin, reduce the nitrification rate and inhibit the abundance of bacterial amoA without impacting archaeal amoA. In contrast, some NIs confine the hydrolysis of synthetic N and, therefore, keep low NH4+-N concentrations that exhibit no or very slight impact on ammonia oxidizers. Variations in soil properties are more influential in the community structure and abundance of ammonia oxidizers than application of synthetic N fertilizers and NIs. Biological nitrification inhibitors (BNIs) are natural bioactive compounds released from roots of certain plant species, such as sorghum, and could be commercialized to suppress the capacity of nitrifying soil microbes. Mixed application of synthetic and organic N fertilizers enhances NUE and plant N-uptake by reducing ammonia N losses. High salt concentration promotes community abundance while limiting the diversity of AOB and vice versa for AOA, whereas AOA have lower rate for potential nitrification than AOB, and denitrification accounts for higher N2 production. Archaeal abundance, diversity, and structural composition change along an elevation gradient and mainly depend on various soil factors, such as soil saturation, availability of NH4+, and organic matter contents. Microbial abundance and structural analyses revealed that the structural composition of AOA was not highly responsive to changes in soil conditions or N amendment. Further studies are suggested to cultivate AOA and AOB in controlled-environment experiments to understand the mechanisms of AOA and AOB under different conditions. Together, this evaluation will better facilitate the projections and interpretations of ammonia oxidizer community structural composition with provision of a strong basis to establish robust testable hypotheses on the competitiveness between AOB and AOA. Moreover, after this evaluation, managing soils agronomically for potential utilization of metabolic functions of ammonia oxidizers would be easier.

Screening of Herbicides for Rice Seedling Safety and Echinochloa colona Management under Australian Conditions

Different herbicides are currently required for sustainable weed management in aerobic rice. Three pot experiments were conducted using different herbicides to evaluate rice safety and for the control of Echinochloa colona, a major weed of aerobic rice. Among the pre-emergence (PRE) herbicides, it was found that pendimethalin (594 g ai ha−1) and flumioxazin (60 g ai ha−1) were relatively safe herbicides for rice and provided 100% control of E. colona. All other PRE herbicides, such as atrazine, cinmethylin, clomazone, dimethenamid-P, isoxaflutole, metribuzin, prosulfocarb + S-metolachlor, pyroxasulfone, trifluralin, and S-metolachlor reduced the biomass of rice compared with the non-treated control. Dose-response studies revealed that flumioxazin and pendimethalin even at low doses (30 g ai ha−1 for flumioxazin and 294 g ai ha−1 for pendimethalin) provided excellent control (&gt;95%) of E. colona. Post-emergence (POST) application of paraquat (360 g ai ha−1) at the time of rice emergence caused toxicity in the crop, but also provided excellent control of E. colona. When applied just after crop emergence (11 days after sowing), Pendimethalin was found to be safe for rice (2% mortality) and reduced the biomass of E. colona by 88% compared with the non-treated control. It is quite possible that the rice variety Reiziq used in this study may have a tolerance to flumioxazin, which needs further investigation involving more rice varieties. This study suggests that flumioxazin can be used as an alternative to pendimethalin for the sustainable management of E. colona in aerobic rice.

Effect of Organic and Inorganic Sources of Nutrients on Yield Attributes and Yield of Maize in Aerobic Rice- Zero Till Maize Cropping System Under Sandy Clay Loam Soils in Southern Telangana Agro-Climatic Zone

Continuous growing of rice –rice mono-cropping over the years and excessive dependence on chemical fertilizers alone has led to decrease in soil fertility and productivity. Rice–maize double cropping is gaining popularity in many Asian countries including India. fertilizer need of a crop in a system is strongly influenced by the preceding crops and the amount of fertilizers applied to them. Cropping with two nutrient intensive cereals like rice-maize would remove a substantial quantity of plant nutrients from soil during continued agriculture round the year, envisaging the need for adoption of efficient nutrient management practices for sustained soil health and improving system productivity. A field experimentt was carried out to study the residual effect of organic nutrient sources and inorganic fertilizer levels on yield attributes and yield of zero till maize. The experiment was laid out in split plot design with four organic sources of nutrients applied to preceding rice as main plots viz: M1: Neem leaf manure @ 6 t ha-1; M2: Vermicompost @ 2 t ha-1; M3: Goat manure @ 5 t ha-1; M4: Microbial consortia [seed treatment @ 4 g kg-1 + soil application @ 4 kg ha-1] and four subplots with graded doses of fertilizers viz: S1: Control; S2: 50% RDF; S3: 75% RDF and S4: 100% RDF (180:60:60). The study revealed that various organic nutrient sources and graded fertilizer doses exerted a remarkable effect on plant height, LAI, dry matter production and Days to 50% silking which resulted in significantly higher grain, stover yield and harvest index of zero till maize.

Effect of Crop Establishment Methods and Microbial Inoculations on Augmenting the Energy Efficiency and Nutritional Status of Rice and Wheat in Cropping System Mode

A field experiment was conducted for two consecutive years with the aim to quantify the role of different nutrient management variables such as microbial inoculation, zinc (Zn) fertilization and optimal and sub-optimal fertilization of nitrogen and phosphorus on the energetic and nutritional status of the rice–wheat cropping system (RWCS). The said nutrient management variables were applied over six different crop establishment methods (CEMs) in RWCS viz. puddled transplanted rice (PTR), system of rice intensification (SRI) and aerobic rice system (ARS) in rice and conventional drill-sown wheat (CDW), system of wheat intensification (SWI) and zero-tillage wheat (ZTW) in wheat. Two microbial consortia viz. Anabaena sp. (CR1) + Providencia sp. (PR3) consortia (MC1) and Anabaena-Pseudomonas biofilmed formulations (MC2) were used in this study, while recommended dose of nitrogen (N) and phosphorus (P) (RDN) (120 kg N ha−1 and 25.8 kg P ha−1), 75% RDN and Zn fertilization (soil applied 5 kg Zn ha−1 through zinc sulphate heptahydrate) were the other variables. The contribution of microbial consortia, Zn fertilization and RDN (over 75% RDN) to net energy production of RWCS was 12.9–16.1 × 103 MJ ha−1, 10.1–11.0 × 103 MJ ha−1 and 11.7–15.3 × 103 MJ ha−1. Among the CEMs, the highest gross and net energy production was recorded in ARS–ZTW with lowest energy required for production of one tonne of system yield (2366–2523 MJ). The system protein yield varies from 494.1 to 957.7 kg ha−1 with highest protein yield in 75% RDN + MC2 + Zn applied ARS–ZTW. Among micronutrients, the uptake of Zn and iron (Fe) is sensitive to all studied variables, while manganese (Mn) and cupper (Cu) uptake was found significantly affected by CEMs alone. The combination of 75% RDN + MC2 + Zn in ARS–ZTW was found superior in all respects with 288.3 and 286.9 MJ ha−1 net energy production and 2320 and 2473 MJ energy required for production of one tonne system yield in the first and second year of study, respectively.

Genomic Regions and Floral Traits Contributing to Low Temperature Tolerance at Young Microspore Stage in a Rice (Oryza sativa L.) Recombinant Inbred Line Population of Sherpa/IRAT109.

Aerobic rice production (AP) consumes less water compared to flooded systems. Developing genotypes and identifying genomic regions associated with low temperature (LT) tolerance at the young microspore stage (YMS) is imperative for AP, particularly for temperate regions. Using a recombinant inbred line population derived from the Australian LT tolerant variety Sherpa, experiments were conducted to map and dissect quantitative trait loci (QTL) associated with spikelet sterility (SS) after exposure to LT and to investigate floral traits contributing to the development of lower SS. Significant genotypic variation for SS was observed in the population after exposure to LT at YMS. Three genomic regions associated with SS, qYMCT3, qYMCT4, and qYMCT8.1 were identified in chromosomes 3, 4, and 8 respectively, using multiple QTL models explaining 22.4% of the genotypic variation. Introgression of the favorable allele from qYMCT3 was estimated to reduce SS by up to 15.4%. A co-locating genomic region with qYMCT3, qDTHW3.1 was identified as the major QTL affecting days to heading and explained as much as 44.7% of the genotypic variation. Whole-genome sequence and bioinformatic analyses demonstrated OsMADS50 as the candidate gene for qYMCT3/qDTHW3.1 and to our knowledge, this was the first attempt in connecting the role of OsMADS50 in both LT and flowering in rice. Differential sets selected for extreme SS showed LT tolerant genotype group produced higher total pollen per spikelet resulting in a higher number of dehisced anthers and pollen on stigma and eventually, lower SS than THE sensitive group. The relationship between these key floral traits with SS was induced only after exposure to LT and was not observed in warm ideal temperature conditions. Identification of elite germplasm with favorable QTL allele and combinations, gene cloning, and pyramiding with additional high-value QTL for key traits should empower breeders to develop AP adapted genotypes for temperate growing regions, and ultimately produce climate-resilient rice.

Effect of Different Sources of Silicon on the Growth, Yield and Si Uptake in Aerobic Rice

A field experiment was conducted to study the different sources of silicon (Si) on plant growth and yield. The experiment was laid in randomized complete design (RCBD) with four treatments and four replications. The experiment results revealed that There was an increase in plant height and the number of tillers plant-1 with the application of different sources of Si over RDF (T1). At harvest RHB @ 4 t ha-1 recorded significantly higher plant height (106.05±1.23 cm) and the number of tillers hill-1 (15.25±2.75). Yield attributes like number of panicles hill-1 (13.23±0.49), Panicle length 23.43±0.29 cm), test weight (23.55±0.05 g), straw (7.15±0.59 t ha-1), grain (3.60±0.16 t ha-1) and total biomass yield (10. 75±1.01 t ha-1) was recorded in treatment receiving SA @ 4 mL L-1 (T3). Whereas, higher Si content and uptake in both straw and grain was significantly higher in the recorded in the with the application of the RHB @ 4 t ha-1. Thus, combined application of external Si sources and along with recommended dose of fertilizers found to increase the growth, yield and Si uptake in aerobic rice.

Rice performance as influenced by crop establishment methods, green organic mulches and rates of nitrogen fertilization along with liquid Azotobacter chroococcum

The effect of green organic mulches (Sesbania aculeata and Leucaena leucocephala) and nitrogen (N) levels on growth, yield, quality and nutrient uptake of rice (Oryza sativa L.) cultivar “Pusa Basmati 1509” was investigated in aerobic rice (AR) and transplanted rice (TPR). The levels of N were control (N0), 75% recommended dose of N (RDN); and 100% RDN) applied through Chemical fertilizer and Azotobacter chroococcum a liquid biofertilizer. A Field experiment was conducted in split plot design with four main-plot and 5 sub-plot treatments. The main plot consisted of bare soil, Sesbania mulch (10 Mg ha−1, fresh weight-FW), Leucaena mulch (10 Mg ha−1 FW), and TPR; and sub-plot consisted N0; 75% RDN, 100% RDN; 75% RDN+Azotobacter, and 100% RDN+Azotobacter. The highest grain, straw and biological yields (3.84, 6.74 and 11.6 Mg ha−1, respectively) and nutrient uptake were recorded with TPR followed by AR with Leucaena and Sesbania mulch. Grain, straw and biological yield of TPR over bare soil were increased by 31.9, 26.6 and 28.3%, respectively. Uptake of Fe, Zn, Mn and Cu by rice under TPR were 52, 33, 36 and 33% higher, respectively than AR under bare soil. The highest grain, straw, and biological yields (3.86, 7.79 and 11.7 Mg ha−1, respectively) of AR were obtained in 100% RDN + Azotobacter compared to the rest of the treatments. Therefore, the cultivation of AR with Leucaena/Sesbania mulch along with 100% RDN and Azotobacter biofertilizer can be most productive in the study area.

EFFECT OF WATER LEVEL MANAGEMENT ON YIELD OF LOWLAND RICE IN SOBARI SYSTEM

Research aimed to study effect of water level management on yield of lowland rice in System of Organic - Based on Controlled Aerobic Rice Intensification (SOBARI) had been conducted in lowland Group Farmers Sadang Mukti, Sadang Sari Baleendah, Bandung West Java with altitude of 668 m above sea level. The experiment was conducted since April 2013 until July 2013. Research used experimental methods, with Randomized Block design with three replications. The water level management treatment consisting of four water level managements, namely : A = moldy where re-filled when the soil water level had dropped to -15 cm below the soil surface, B = moldy where irrigation re-filled when the soil water level had dropped to -10 cm below the soil surface, C = moldy where irrigation re-filled when the soil water level had dropped to -5 cm below the soil surface, D = flooded water management 3-5 cm above the soil surface (conventional). The results showed that: to mitigate CH4 from rice field and increase the number of grain per panicle and yield of rice plants, the planting can be done with a water level management moldy, where irrigation re-filled when the soil water level had dropped to -5 cm below the soil surface.