Challenges and opportunities in productivity and sustainability of rice cultivation system: a critical review in Indian perspective

Empowering rice breeding with NextGen genomics tools for rapid enhancement nitrogen use efficiency

As rice has no physiological capacity of fixing nitrogen in the soil, its production had always been reliant on the external application of nitrogen (N) to ensure enhanced productivity. In the light of improving nitrogen use efficiency (NUE) in rice, several advanced agronomic strategies have been proposed. However, the soared increase of the prices of N fertilizers and subsequent environmental downfalls caused by the excessive use of N fertilizers, reinforces the prerequisite adaptation of other sustainable, affordable, and globally acceptable strategies. An appropriate alternative approach would be to develop rice cultivars with better NUE. Conventional breeding techniques, however, have had only sporadic success in improving NUE, and hence, this paper proposes a new schema that employs the wholesome benefits of the recent advancements in omics technologies. The suggested approach promotes multidisciplinary research, since such cooperation enables the synthesis of many viewpoints, approaches, and data that result in a comprehensive understanding of NUE in rice. Such collaboration also encourages innovation that leads to developing rice varieties that use nitrogen more effectively, facilitate smart technology transfer, and promotes the adoption of NUE practices by farmers and stakeholders to minimize ecological impact and contribute to a sustainable agricultural future.

Ecology and diversity of arbuscular mycorrhizal fungi (AMF) in rice (Oryza sativa L.) in South India: an ecological analysis of factors influencing AMF in rice fields

AIMS

This study examined the diversity of arbuscular mycorrhizal fungi (AMF), mean spore density (MSD), and root colonization in relation to factors such as agroclimatic zones, rice varieties and soil types in paddy fields of South India. The aim was to understand how these factors influence AMF association in rice, facilitating their effective use as a biological tool in paddy cultivation.

METHODS AND RESULTS

AMF were identified through light microscopy of spores, while MSD and percentage-root-length colonization (PRLC) were measured using standard methods. Correlation and principal component analyses were performed to explore the interrelationships between AMF characteristics and various environmental, soil, and plant variables. Sixteen AMF species were identified across 29 rice varieties from three agroclimatic zones, 6 soil orders, and 18 soil series over 2 seasons. Notably, 70% of chemicalized rice fields lacked AMF spores, and only 50% exhibited root colonization. This study offers new insights into the role of AMF in rice cultivation.

CONCLUSION

The AMF diversity and root colonization in relation to environmental variables underscore their significant impact on AMF in particular crop fields.

Enhancing aromatic rice production through agronomic and nutritional management for improved yield and quality

To meet the growing international demand for aromatic rice, this study, conducted at Uttar Banga Krishi Viswavidyalaya in Cooch Behar, West Bengal, aimed to enhance the yield and quality of the 'Tulaipanji' rice cultivar through advanced establishment methods and the use of organic nutrients over two years. The research tested three planting techniques: mechanical transplanting, wet direct seeding (using a drum seeder), and traditional methods, alongside four nutrient management strategies: vermicompost, farmyard manure, a mix of both, and conventional fertilizers. Findings revealed that mechanical transplanting significantly increased yield by over 31.98% and 71.05% compared to traditional methods and wet direct seeding, respectively. Using vermicompost alone as a nutrient source not only boosted yields by 21.31% over conventional fertilizers but also enhanced the rice's nutritional value and cooking quality. Moreover, soils treated with vermicompost showed higher dehydrogenase activity, indicating better soil health. Economically, mechanical transplanting with vermicompost was the most beneficial, yielding the highest net returns and benefit-cost ratios in both years studied. This approach presents a viable model for improving the sustainability of aromatic rice production globally, emphasizing the economic and environmental advantages of adopting mechanical planting techniques and organic fertilization methods.

Exploring the potential of Bacillus for crop productivity and sustainable solution for combating rice false smut disease

Rice false smut, which is caused by the soil-borne fungal pathogen Ustilaginoidea virens (U. virens), is one of the most threatening diseases in most of the rice-growing countries including India that causes 0.5-75% yield loss, low seed germination, and a reduction in seed quality. The assessment of yield loss helps to understand the relevance of disease severity and facilitates the implementation of appropriate management strategies. This study aimed to mitigate biotic stress in rice by employing a rhizobacterial-based bioformulation, which possesses diverse capabilities as both a plant growth promoter and a biocontrol agent against U. virens. Rhizobacteria were isolated from the soil of the rice rhizospheres from the healthy plant of the false smut affected zone. Furthermore, they were identified as Bacillus strains: B. subtilis (BR_4), B. licheniformis (BU_7), B. licheniformis (BU_8), and B. vallismortis (KU_7) via sequencing. Isolates were screened for their biocontrol potential against U. virens under in vitro conditions. The antagonistic study revealed that B. vallismortis (KU_7) inhibited U. virens the most (44.6%), followed by B. subtilis BR_4 (41.4%), B. licheniformis BU_7 (39.8%), and B. licheniformis BU_8 (43.5%). Various biochemical and plant growth promoting attributes, such as phosphate and Zn solubilization, IAA, ammonium, siderophore, and chitinase production, were also investigated for all the selected isolates. Furthermore, the potential of the isolates was tested in both in vitro and field conditions by employing talc-based bioformulation through bio-priming and root treatment. The application of bioformulation revealed a 20% decrease in disease incidence in plants treated with B. vallismortis (KU_7), a 60.5% increase in the biological yield, and a 45% increase in the grain yield. This eco-friendly approach not only controlled the disease but also improved the grain quality and reduced the chaffiness.

Enhancing physiological metrics, yield, zinc bioavailability, and economic viability of Basmati rice through nano zinc fertilization and summer green manuring in semi-arid South Asian ecosystem

During the summer and rainy seasons (April-October) of 2020 and 2021, two consecutive field experiments were conducted at the research farm of the ICAR-Indian Agricultural Research Institute, New Delhi, India. In this study, we examined the effects of summer green manuring crops (GM) and a variety of zinc fertilizers (ZnF) on Basmati rice (Oryza sativa L.) growth, physiological development, yield response, zinc nutrition and economic returns. A combination of GM residues and nano zinc fertilization helped significantly enhancing Basmati rice's growth and its physiological development. Following the incorporation of Sesbania aculeata (Sesbania), successive Basmati rice physiological parameters were significantly improved, as well as grain, straw, biological yields, harvest index and economic returns. The highest Zn content of 15.1 mg kg -1 and the lowest of 11.8 mg kg -1 in milled rice grain were recorded in Sesbania green manuring (G2) and control i.e., in the fallow (G1), respectively. Coating onto urea with 0.2% nano zinc oxide (NZnCU) was observed to be more effective than other zinc sources in terms of growth parameters, yield attributes, zinc nutrition, grain and straw yields for succeeding Basmati rice crop; however, the effects were comparable to those of bulk zinc oxide-coated urea (BZnCU) of 1%. The highest Zn content of 15.1 mg kg -1 was recorded with the application of 1% BZnCU and the lowest of 11.96 mg kg -1 with the soil application of 5 kg Zn ha -1 through bulk ZnO in the milled rice grain. Application of 1% BZnCU led to a 26.25% increase in Zn content of milled rice grain compared to soil application of 5 kg Zn ha -1 through bulk ZnO. As a result, the combination of inclusion of Sesbania aculeata (Sesbania) residue and 0.2% NZnCU was identified as the most effective treatment, for Basmati rice growth and physiological development. A combination of nano Zn fertilization in conjunction with the incorporation of green manure can be advocated for better growth, physiological performance, zinc dense grains, and higher profitability of Basmati rice for farmers and consumers.

Incidence of Sheath Blight in Irrigated Rice and Associated Yield Losses in Northern India

Rice-growing districts in Uttar Pradesh, India, were surveyed during the months of July and October to record the frequency of occurrence and disease incidence of sheath blight caused by Rhizoctonia solani in paddy. A total of 180 paddy fields were surveyed at the block level of 21 districts, where almost all the rice varieties were found highly susceptible to R. solani and exhibited severe yield loss compared with low-infested fields. The district Muzaffarnagar had the highest rate of disease occurrence, while maximum disease severity was recorded in the district Saharanpur. This district also had the highest soil population of R. solani, followed by Mathura, Muzaffarnagar, Barabanki, Aligarh, Sultanpur, Mainpuri, and Rampur. The greatest relative yield loss attributed to sheath blight infestation was recorded in Mathura (40%). The yield loss was linearly correlated with soil population of R. solani and disease incidence. Disease occurrence, incidence, severity, and yield loss to paddy were all significantly greater in the area which experienced relatively higher temperatures (25 to 38°C) and relative humidity (49 to 100%) during the months of June to August. Furthermore, the fields applied with a total dose of 250 to 280 kg nitrogen/ha exhibited higher disease severity (2.9 to 3.3 score) compared with fields that received a moderate dose of 140 to 180 kg N/ha (0.9 to 1.8 disease severity score). The rice nursery fields were found almost free from the sheath blight, but the disease was quite prevalent in the paddy fields with 7.2 to 38.9% disease incidence which resulted in 14.3 to 39.7% yield loss to rice.

Pre-Treatment of Rice Plants with ABA Makes Them More Tolerant to Multiple Abiotic Stress

Multiple abiotic stress is known as a type of environmental unfavourable condition maximizing the yield and growth gap of crops compared with the optimal condition in both natural and cultivated environments. Rice is the world's most important staple food, and its production is limited the most by environmental unfavourable conditions. In this study, we investigated the pre-treatment of abscisic acid (ABA) on the tolerance of the IAC1131 rice genotype to multiple abiotic stress after a 4-day exposure to combined drought, salt and extreme temperature treatments. A total of 3285 proteins were identified and quantified across the four treatment groups, consisting of control and stressed plants with and without pre-treatment with ABA, with 1633 of those proteins found to be differentially abundant between groups. Compared with the control condition, pre-treatment with the ABA hormone significantly mitigated the leaf damage against combined abiotic stress at the proteome level. Furthermore, the application of exogenous ABA did not affect the proteome profile of the control plants remarkably, while the results were different in stress-exposed plants by a greater number of proteins changed in abundance, especially those which were increased. Taken together, these results suggest that exogenous ABA has a potential priming effect for enhancing the rice seedlings' tolerance against combined abiotic stress, mainly by affecting stress-responsive mechanisms dependent on ABA signalling pathways in plants.

A review on co-pyrolysis of agriculture biomass and disposable medical face mask waste for green fuel production: recent advances and thermo-kinetic models

The Association of Southeast Asian Nations is blessed with agricultural resources, and with the growing population, it will continue to prosper, which follows the abundance of agricultural biomass. Lignocellulosic biomass attracted researchers' interest in extracting bio-oil from these wastes. However, the resulting bio-oil has low heating values and undesirable physical properties. Hence, co-pyrolysis with plastic or polymer wastes is adopted to improve the yield and quality of the bio-oil. Furthermore, with the spread of the novel coronavirus, the surge of single-use plastic waste such as disposable medical face mask, can potentially set back the previous plastic waste reduction measures. Therefore, studies of existing technologies and techniques are referred in exploring the potential of disposable medical face mask waste as a candidate for co-pyrolysis with biomass. Process parameters, utilisation of catalysts and technologies are key factors in improving and optimising the process to achieve commercial standard of liquid fuel. Catalytic co-pyrolysis involves a series of complex mechanisms, which cannot be explained using simple iso-conversional models. Hence, advanced conversional models are introduced, followed by the evolutionary models and predictive models, which can solve the non-linear catalytic co-pyrolysis reaction kinetics. The outlook and challenges for the topic are discussed in detail.

Influence of tillage and residue management practices on productivity, sustainability, and soil biological properties of rice-barley cropping systems in indo-gangetic plain of India

Introduction

Conservation agriculture is a sustainable system of farming that safeguard and conserves natural resources besides enhancing crop production. The biological properties of soil are the most sensitive indicator to assess the short term impact of management practices such as tillage and residue incorporation.

Methods

Nine treatments of tillage and residue management practices [Reduced till direct seeded rice-zero till barley (RTDSR–ZTB); RTDSR–ZTB–green gram residue (Gg); Zero till direct seeded rice–zero till barley–zero till green gram (ZTDSR–ZTB–ZTGg); RTDSR–ZTB + rice residue at 4 t ha 1 (RTDSR–ZTBRR4); RTDSR–ZTBRR6; un-puddled transplanted rice (UPTR)–ZTB–Gg; UPTR–ZTBRR4; UPTR–ZTBRR6, and puddled transplanted rice (PTR)–RTB] executed under fixed plot for five years on crop productivity and soil biological properties under rice-barley production system.

Results

The shifting in either RTDSR or ZTDSR resulted in yield penalty in rice compared to PTR. The PTR recorded highest pooled grain yield of 3.61 ha−1. The rice grain yield reduced about 10.6% under DSR as compared to PTR. The ZTB along with residue treatments exhibited significantly higher grain yield over ZTB, and the RTDSR-ZTBRR6 registered highest pooled grain yield of barley. The system productivity (12.45 t ha−1) and sustainable yield index (0.87) were highest under UPTR-ZTBRR6. Biological parameters including microbial biomass carbon, soil respiration, microbial enzymes (Alkaline phosphatase, nitrate reductase and peroxidase), fluorescein diacetate hydrolysis, ergosterol, glomalin related soil proteins, microbial population (bacteria, fungi and actinobacteria) were found to be significantly (p < 0.05) effected by different nutrient management practices. Based on the PCA analysis, Fluorescein diacetate hydrolysis, microbial biomass carbon, soil respiration, nitrate reductase and fungi population were the important soil biological parameters indicating soil quality and productivity in present experiment. The results concluded that UPTR-ZTBRR6 was a more suitable practice for maintaining system productivity and soil biological health.

Discussion

The understanding of the impact of different tillage and residue management practices on productivity, soil biological properties and soil quality index under rice-barley cropping system will help in determining the combination of best conservation agriculture practices for improved soil quality and sustainable production.

Challenges and technological interventions in rice-wheat system for resilient food-water-energy-environment nexus in North-western Indo-Gangetic Plains: A review

Rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system in north-western Indo-Gangetic Plains performed a crucial role in the national food security. However, the widespread and intensive cultivation of this system has led to serious problems such as declining groundwater table (~1 meter year-1) with sharp increase in number of districts under over-exploitation category, residue burning, higher greenhouse gases emission and herbicide resistance in weeds, causing stagnant crop productivity and lesser profitability. In this review article, an attempt has been made to discuss the major issues pertaining to intensive rice-wheat cultivation amidst climate vagaries and futuristic approach to address these challenges. Different tillage- and crop-specific recommendations such as adoption of direct seeded rice, diversification with lesser resource guzzling crops such as maize (Zea mays L.) at least on the periodic manner especially in light-medium soils, inclusion of summer legumes and alternative tillage systems (permanent beds and zero tillage with residue retention) have been suggested to address these issues. However, crop performance under these techniques has been found to be location, soil and cultivar specific. The absence of aerobic tailored genotypes and weeds have been identified as the major constraints in adoption of direct seeded rice. The integrated strategies of conservation tillage, crop breeding program and resource conserving region- and soil-specific agronomic measures with crop diversification would be helpful in tackling the sustainability issues. It requires future efforts on developing crop genotypes suited to conservation tillage, effective weed control strategies and trainings and demonstrations to farmers to switch from conventional rice-wheat system to alternative cropping systems.

Advancing Sowing Time and Conservation Tillage - The Climate-Resilient Approach to Enhance the Productivity and Profitability of Wheat

Field experiments consisting of two sowing time (early and timely), two tillage options (conventional tillage and conservation tillage) and ten genotypes were conducted with the aim to maximize the wheat productivity and profitability. The early sowing (second fortnight of October) produced 16.0% higher grain yield compared to timely sowing (mid-November) in northern Indian Plains. However, no significant yield differences were observed between conventional tillage (CT) and conservation tillage (CST) practices. Among genotypes, the better yielders were PBW 723, BISA 927 and HD 2967. The interaction of sowing time and genotype had a significant (p < 0.05) effect on wheat yield. However, the interaction of genotype and tillage did not produce any significant response on wheat yield. The experiments conducted at farmer's fields also demonstrated similar performance of wheat under CT and CST systems but CST offered the savings of more than Rs. 3500 (US $ 47) along with 125 kg ha^- 1 lesser CO₂ emissions over CT due to reduction in fuel consumption associated with tillage and seed bed operations. At farmers field also, early sown wheat yielded 5.5% higher over wheat sown in November. The results of present studies show that early sowing of high yielding wheat genotypes under CST practice enhanced the productivity and profitability of wheat under rice-wheat cropping system along with lesser noxious impact on the environment. Amidst climate vagary and its menace on the agriculture, the adoption of climate-resilient management practices such as advancing the sowing time and conservation tillage can improve the productivity of long duration wheat cultivars in sub-tropical humid conditions besides lesser deleterious consequences on the environment.

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.

Tracking Changes in the Spring Barley Gene Pool in Poland during 120 Years of Breeding

This study was undertaken to investigate the diversity and population structure of 83 spring barley (Hordeum vulgare L.) cultivars, which corresponded to 120 years of this crop's breeding in Poland. The analysis was based on 11,655 DArTseq-derived SNPs evenly distributed across seven barley chromosomes. Five groups were assigned in the studied cultivars according to the period of their breeding. A decrease in observed heterozygosity within the groups was noted along with the progress in breeding, with a simultaneous increase in the inbreeding coefficient value. As a result of breeding, some of the unique allelic variation present in old cultivars was lost, but crosses with foreign materials also provided new alleles to the barley gene pool. It is important to mention that the above changes affected different chromosomes to varying degrees. The internal variability of the cultivars ranged from 0.011 to 0.236. Internal uniformity was lowest among the oldest cultivars, although some highly homogeneous ones were found among them. This is probably an effect of genetic drift or selection during their multiplications and regenerations in the period from breeding to the time of analysis. The population genetic structure of the studied group of cultivars appears to be quite complex. It was shown that their genetic makeup consists of as many as eleven distinct gene pools. The analysis also showed traces of directed selection on chromosomes 3H and 5H. Detailed data analysis confirmed the presence of duplicates for 11 cultivars. The performed research will allow both improvement of the management of barley genetic resources in the gene bank and the reuse of this rich and forgotten variability in breeding programs and research.