Parbodh C. Sharma

Agronomic improvements can make future cereal systems in South Asia far more productive and result in a lower environmental footprint

South Asian countries will have to double their food production by 2050 while using resources more efficiently and minimizing environmental problems. Transformative management approaches and technology solutions will be required in the major grain-producing areas that provide the basis for future food and nutrition security. This study was conducted in four locations representing major food production systems of densely populated regions of South Asia. Novel production-scale research platforms were established to assess and optimize three futuristic cropping systems and management scenarios (S2, S3, S4) in comparison with current management (S1). With best agronomic management practices (BMPs), including conservation agriculture (CA) and cropping system diversification, the productivity of rice- and wheat-based cropping systems of South Asia increased substantially, whereas the global warming potential intensity (GWPi) decreased. Positive economic returns and less use of water, labor, nitrogen, and fossil fuel energy per unit food produced were achieved. In comparison with S1, S4, in which BMPs, CA and crop diversification were implemented in the most integrated manner, achieved 54% higher grain energy yield with a 104% increase in economic returns, 35% lower total water input, and a 43% lower GWPi. Conservation agriculture practices were most suitable for intensifying as well as diversifying wheat-rice rotations, but less so for rice-rice systems. This finding also highlights the need for characterizing areas suitable for CA and subsequent technology targeting. A comprehensive baseline dataset generated in this study will allow the prediction of extending benefits to a larger scale.

Assessing soil properties and nutrient availability under conservation agriculture practices in a reclaimed sodic soil in cereal-based systems of North-West India

ABSTRACT Soil quality degradation associated with resources scarcity is the major concern for the sustainability of conventional rice-wheat system in South Asia. Replacement of conventional management practices with conservation agriculture (CA) is required to improve soil quality. A field experiment was conducted to assess the effect of CA on soil physical (bulk density, penetration resistance, infiltration) and chemical (N, P, K, S, micronutrients) properties after 4 years in North-West India. There were four scenarios (Sc) namely conventional rice-wheat cropping system (Sc1); partial CA-based rice-wheat-mungbean system (RWMS) (Sc2); CA-based RWMS (Sc3); and CA-based maize-wheat-mungbean (Sc4) system. Sc2 (1.52 Mg m−3) showed significantly lower soil bulk density (BD). In Sc3 and Sc4, soil penetration resistance (SPR) was reduced and infiltration was improved compared to Sc1. Soil organic C was significantly higher in Sc4 than Sc1. Available N was 33% and 68% higher at 0–15 cm depth in Sc3 and Sc4, respectively, than Sc1. DTPA extractable Zn and Mn were significantly higher under Sc3 and Sc4 compared to Sc1. Omission study showed 30% saving in N and 50% in K in wheat after four years. Therefore, CA improved soil properties and nutrient availability and have potential to reduce external fertilizer inputs in long run.

Can productivity and profitability be enhanced in intensively managed cereal systems while reducing the environmental footprint of production? Assessing sustainable intensification options in the breadbasket of India

Highlights • Higher cereal productivity can be achieved with lower environmental footprint through conservation agriculture.• Wheat productivity and profitability can be increased by zero-tillage and early sowing.• Kharif maize appears to be a suitable and profitable alternative to rice in northwest India.• Productivity and resource efficiency of transplanted rice can be improved by BMPs.• Directly sown rice has potential to save water, energy and global warming potential compared to transplanted rice.

Crop residue degradation by fungi isolated from conservation agriculture fields under rice–wheat system of North-West India

PurposeIn North West-Indo Gangetic Plains (NW-IGP) of India in situ burning of crop residues is practiced by majority of farmers’ which deteriorates soil and environmental quality. Fungi have the potential for lignocellulose degradation and can be used for the in situ decomposition of crop residues. Lignocellulose degrading fungal spp. were isolated and evaluated for the activity of lignocellulolytic enzymes.MethodThe lignocellulose degrading fungi were isolated by appearance of zone on carboxy methyl cellulose (CMC) agar media and tannic acid (TA) media. Carboxy methyl cellulase, filter paperase, cellobiase, xylanase and laccase activity were estimated in submerged, as well as solid state fermentation using a mixture of rice and wheat straw in the ratio of 4:1. rice–wheat straw as substrate. The residue left after solid state fermentation was evaluated for carbon/nitrogen ratio, dry mass loss, and loss of cellulose, hemicellulose and lignin. Selected potential isolates were further tested in pot experiment for their effect on wheat plants. The interaction among isolates was also studied.ResultAfter primary screening, 19 out of a total of 72 fungal isolates were selected based on their enzymatic activity profile and potential to degrade lignocellulosic residues in submerged fermentation. Out of these 19 isolates, 11 were further selected based on their enzymatic secretions in solid state fermentation. All the 11 strains were identified morphologically. Four fungal isolates (RPW 1/3, RPW 1/6, RPWM 2/2 and RZWM 3/2) showed higher enzymatic activities and more loss of dry mass and cell wall constituents over the other isolates. These isolates were identified by ITS region sequencing as Aspergillus flavus, Aspergillus terreus, Penicillium pinophilum and Alternaria alternata.ConclusionThis study revealed that fungal isolates may be used for managing crop residues in conservation agriculture based rice–wheat system of NW-IGP to eliminate ill effects of residue burning.

Soil bacterial diversity under conservation agriculture-based cereal systems in Indo-Gangetic Plains

In Indo-Gangetic plains (IGP) of India, natural resources (soil, water, and environment) are degrading under the conventional–till (CT)-based management practices in rice–wheat cropping system. A long-term field experiment was conducted to understand the soil bacterial diversity and abundance under different sets of management scenarios (Sc). The study comprised of four scenarios, namely, -Sc.I CT-based rice–wheat system (farmers’ practice); Sc.II, partial conservation agriculture (CA) based in which rice is under CT—wheat and mungbean under zero-tillage (ZT); Sc.III, full CA-based in which rice–wheat–mungbean are under ZT and Sc.IV, where maize–wheat–mungbean are under ZT. These scenarios varied in cropping system, tillage, and crop residue management practices. Using Illumina MiSeq sequencing technology, the variable regions V3–V4 of 16S rRNA were sequenced and the obtained reads were analyzed to study the diversity patterns in the scenarios. Results showed the presence of 53 bacterial phyla across scenarios. The predominant phyla in all scenarios were Proteobacteria, Acidobacteria, Actinobacteria, and Bacteroidetes which accounted for more than 70% of the identified phyla. However, the rice-based systems (Sc.I, Sc.II, and Sc.III) were dominated by phylum Proteobacteria; however, maize-based system (Sc.IV) was dominated by Acidobacteria. The class DA052 and Acidobacteriia of Acidobacteria and Bacteroidetes of Bacteroidia were exceptionally higher in Sc.IV. Shannon diversity index was 8.8% higher in Sc.I, 7.5% in Sc.II, and 2.7% in Sc.III compared to Sc.IV. The findings revealed that soil bacterial diversity and abundance are influenced by agricultural management practices as bacterial diversity under full CA-based management systems (Sc.III and Sc.IV) was lower when compared to farmer’s practice (Sc.I) and partial CA (Sc.II) scenarios.

Current Trends in Salinity and Waterlogging Tolerance

Soil salinity and waterlogging together impair crop production on at least one-fourth of the irrigated land worldwide and cause yield loses ranging from 15 to 80%. Much has been reported on plant accumulation to waterlogging and salinity in terms of physiological, biochemical and anatomical modifications. Genome-level profiling coupled with systematic genetic analysis is the need of the hour to understand the underlying mechanism regulating stress tolerance. The accumulation of organic osmolytes and proteins from the late embryogenesis abundant (LEA) superfamily adds on to maintenance of low intracellular osmotic potential of plants. A significant upregulation of several other pathways including calcium signalling, sulphur assimilation and ROS detoxification is associated with salinity stress response. Salinity stress induces widespread proteome modification in crop plants, and study of proteome has proved to be a very efficient approach to study plant salt stress tolerance. Approaches like metabolic fingerprinting, metabolite profiling and targeted analysis are gaining wide importance to investigate salinity stress tolerance of crops. Plants respond to low oxygen condition in three distinct stages. These are signal transfer (Stage a, 0–4 h), metabolic reprogramming (Stage b, 4–24 h) and morphological transformations brought about by the first two stages (Stage c, 24–48 h). Genomic studies have classified genes activated under waterlogging stress into three categories: low oxygen-sensing and cell signalling-involved genes, metabolic adjustment genes and genes that maintain plant internal microenvironments. Search for quantitative trait loci (QTLs) controlling vital traits linked to waterlogging tolerance has gained momentum in recent years. Integration of all the key omics approaches should be another vital target to research groups working across the globe to further progress towards the ultimate goal of developing salt tolerant crop varieties without compromising yield.