Zero-tillage, residue management and precision nutrient management techniques are being promoted in the rice-wheat (RW) production system of Indo-Gangetic Plains (IGPs) to enhance climate change adaptation and increase food production. These management practices may also influence greenhouse gas emissions through their effects on various soil processes such as oxidation-reduction and nitrification-denitrification. We measured soil fluxes of CH 4 and N 2 O in RW system under three tillage and residue management systems layered with four nitrogen (N) management treatments. The tillage and residue management systems comprised: conventional tillage (CT), zero-tillage without residue retention (ZT − R) and ZT with full residue retention (ZT + R) for both the crops. The four N management treatments for rice were: (a) basmati cultivar with recommended dose of nitrogen (RDN) applied in three splits, (b) basmati cultivar with 80% RDN as basal dose followed by Green Seeker (GS) guided N application, (c) hybrid cultivar with RDN applied in three splits and (d) hybrid with 80% RDN as basal dose followed by GS guided N application. The four N management treatments for wheat comprised combinations of RDN with and without relay green gram (GG), and 80% of RDN as basal dose followed by GS guided N application with and without relay GG. We employed the static chamber method to collect gas samples from the experimental plots which were subsequently analysed using gas chromatograph. Significant CH 4 emissions were detected only in the CT rice system during the initial phase of continuous flooding, irrespective of N management strategies. N fertilization management affected the pattern of N 2 O emission with higher emission rates during crop establishment phase under 80% RDN as basal followed by GS guided N application than conventional RDN. In case of wheat, 80% RDN as basal followed by GS guided N application also induced higher cumulative N 2 O emissions than applying RDN at three regular splits. In rice, ZT-based RW system emitted more N 2 O than CT-based system. Overall ZT-based RW system reduced CH 4 emission but this benefit is counterbalanced by higher N 2 O production compared to CT-based RW system.

This study examines the effects of tillage, residue management and cropping system intensification through the inclusion of green gram on the performance of the rice-wheat (RW) system in NW India. We hypothesized that zero tillage (ZT) with residue retention provides a means of sustainably intensifying the RW system through lower production costs and higher economic profitability, whilst at the same time minimizing soil and environmental trade-offs. To test this hypothesis, we evaluated six combinations of tillage, residue management and green gram integration in RW rotation in northwest Indo-Gangetic Plains (IGP) of India. Treatments included in the study were: rice and wheat under conventional tillage (CT) with and without green gram (CTR-CTW, CTR-CTW+GG), both crops under zero-tillage (ZT) with and without green gram (ZTR-ZTW-R, ZTR-ZTW-R+GG) and both crops under ZT plus residues with and without green gram (ZTR-ZTW+R, ZTR-ZTW+R+GG). Based on two consecutive years of data, the net return from the RW system was significantly higher in the ZT than CT systems. Methane emissions were only observed under flooded conditions in CT rice plots; otherwise, emissions were negligible in all other treatment combinations. N 2 O emissions were dictated by N fertilizer application with no other treatment effects. Overall, ZT with residue retention resulted in the lowest global warming potential (GWP) ranging from −3301 to −823 kg CO 2-eq ha −1 year −1 compared to 4113 to 7917 kg CO 2-eq ha −1 year −1 in other treatments. Operational inputs (tillage, planting, and irrigation) and soil C sequestration had significant effects on total GWP. The water footprint of RW production system was about 29% less in CA-based system compared to CT-based systems. Our study concludes that ZTR-ZTW+R and ZTR-ZTW+R+GG in RW systems of northwestern IGP have the potential to be agronomically productive, economically viable with benefits also for the environment in terms of soil health and GHG emissions.

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Improved-Samba-Mahsuri (ISM), a high-yielding, popular bacterial blight resistant (possessing Xa21, xa13, and xa5), fine-grain type, low glycemic index rice variety is highly sensitive to low soil phosphorus (P). We have deployed marker-assisted backcross breeding (MABB) approach for targeted transfer of Pup1, a major QTL associated with low soil P tolerance, using Swarna as a donor. A new co-dominant marker, K20-1-1, which is specific for Pup1 was designed and used for foreground selection along with functional markers specific for the bacterial blight resistance genes, Xa21, xa13, and xa5. A set of 66 polymorphic SSR marker were used for the background selection along with a pair of flanking markers for the recombination selection in backcross derived progenies and in BC2F2 generation, 12 plants, which are homozygous for Pup1, all the three bacterial blight resistance genes and possessing agro-morphological traits equivalent to or better than ISM were selected and selfed to produce BC2F3s. They were evaluated in plots with low soil P and normal soil P at ICAR-IIRR, Hyderabad for their low soil P tolerance, and bacterial blight resistance and superior lines were advanced to BC2F6. One of the lines, when tested at multiple locations in India was found promising under both normal as well as low soil P conditions.

Castor (Ricinus communis L.) a chief non-edible oilseed crop has numerous industrial applications. Systematic genetic diversity analysis utilizing DNA based markers has been quick and reliable method that ensures selection of diverse parents for exploitation of higher levels of heterosis in breeding programs. From NCBI database, 63,852 EST sequences of castor were mined. One thousand one hundred and five (1105) EST-SSRs and 1652 repeat motifs sequences were identified from 20,495 non-redundant unigene sequences. Repeat motifs consisted of 29.7 % mono nucleotide repeats, 24.8 % di nucleotide repeats, 27.27 % tri nucleotide repeats and 3.94 % tetra nucleotide repeats. Twenty eight primer pairs were chosen from SSRcontaining ESTs to determine genetic diversity among 27 castor accessions. Twelve EST-SSRs showed polymorphism. Number of alleles detected were 2-3 with an average of 2.33 per locus. 150-400 bp was the size of an allele. Dendrogram analysis grouped the 27 accessions into two separate clusters. Genetic similarity coefficient of dendrogram ranged from 0.24 to 0.83. The polymorphic information content value of 0.28-0.49 revealed medium level of diversity in castor. Results of present study indicated that EST-SSRs to be efficient markers for genetic diversity studies. Knowledge on level of diversity existing in castor genotypes would be useful for breeders to plan efficient hybrid breeding programme.