Yield Penalty Research Articles

A machine learning interpretation of the contribution of foliar fungicides to soybean yield in the north\u2010central United States

Foliar fungicide usage in soybeans in the north-central United States increased steadily over the past two decades. An agronomically-interpretable machine learning framework was used to understand the importance of foliar fungicides relative to other factors associated with realized soybean yields, as reported by growers surveyed from 2014 to 2016. A database of 2738 spatially referenced fields (of which 30% had been sprayed with foliar fungicides) was fit to a random forest model explaining soybean yield. Latitude (a proxy for unmeasured agronomic factors) and sowing date were the two most important factors associated with yield. Foliar fungicides ranked 7th out of 20 factors in terms of relative importance. Pairwise interactions between latitude, sowing date and foliar fungicide use indicated more yield benefit to using foliar fungicides in late-planted fields and in lower latitudes. There was a greater yield response to foliar fungicides in higher-yield environments, but less than a 100 kg/ha yield penalty for not using foliar fungicides in such environments. Except in a few production environments, yield gains due to foliar fungicides sufficiently offset the associated costs of the intervention when soybean prices are near-to-above average but do not negate the importance of disease scouting and fungicide resistance management.

Characterization and Evaluation of Transgenic Rice Pyramided with the Pi Genes Pib, Pi25 and Pi54

BackgroundEmergence of new pathogen strains of Magnaporthe oryzae is a major reason for recurrent failure of the resistance mediated by a single resistance gene (Pi) in rice. Stacking various Pi genes in the genome through marker-assisted selection is thus an effective strategy in rice breeding for achieving durable resistance against the pathogen. However, the effect of pyramiding of multiple Pi genes using transgenesis still remains largely unknown.ResultsThree Pi genes Pib, Pi25 and Pi54 were transferred together into two rice varieties, the indica variety Kasalath and the japonica variety Zhenghan 10. Transgenic plants of both Kasalath and Zhenghan 10 expressing the Pi transgenes showed imparted pathogen resistance. All the transgenic lines of both cultivars also exhibited shorter growth periods with flowering 2–4 days early, and shorter plant heights with smaller panicle. Thus, pyramiding of the Pi genes resulted in reduced grain yields in both rice cultivars. However, tiller numbers and grain weight were generally similar between the pyramided lines and corresponding parents. A global analysis of gene expression by RNA-Seq suggested that both enhancement and, to a lesser extent, inhibition of gene transcription occurred in the pyramided plants. A total of 264 and 544 differentially expressed genes (DEGs) were identified in Kasalath and Zhenghan 10, respectively. Analysis of the DEGs suggested that presence of the Pi transgenes did not alter gene expression only related to disease resistance, but also impacted many gene transcriptions in the pathways for plant growth and development, in which several were common for both Kasalath and Zhenghan 10.ConclusionPyramiding of the Pi genes Pib, Pi25 and Pi54 via transgenesis is a potentially promising approach for improving rice resistance to the pathogen Magnaporthe oryzae. However, pleiotropic effects of the Pi genes could potentially result in yield loss. These findings support the idea that immunity is often associated with yield penalties. Rational combination of the Pi genes based on the genetic background may be important to balance yield and disease resistance.

An act of defiance? Measuring farmer deviation from personalised extension recommendations in Zambia

AbstractGiven the recognised role of blanket extension advice in the low uptake of productivity‐enhancing technologies among developing country farmers, personalised or site‐specific extension approaches are gaining attention. Focusing on the case of the plant clinic extension model which provides personalised crop protection services to smallholder farmers, we investigate to what extent and how accurately farmers adopt personalised extension advice, and the implications for agricultural productivity. We combine a unique database of personalised integrated pest management (IPM) recommendations provided to 420 plant clinic attendees in Zambia with survey data on the actual IPM practices implemented by these same clinic attendees. We find that more than 80% of the sample farmers deviated from the personalised IPM recommendations they received from plant clinics. Based on the degree of deviation from the personalised recommendations, we identify five categories of adopters of IPM practices and show their heterogeneous effects on maize productivity. For example, our multi‐valued treatment effect estimates suggest an 82% yield penalty for non‐adopters compared to full adopters of recommended IPM practices, while the yield gain for full adopters is more than double that of partial adopters, as well as that of those who adopted additional practices beyond what was recommended. Our findings have important implications for the promotion of personalised extension services and for the measurement of the impact of complex agricultural technologies.

Marker-assisted forward and backcross breeding for improvement of elite Indian rice variety Naveen for multiple biotic and abiotic stress tolerance.

The elite Indian rice variety, Naveen is highly susceptible to major biotic and abiotic stresses such as blast, bacterial blight (BB), gall midge (GM) and drought which limit its productivity in rainfed areas. In the present study, a combined approach of marker-assisted forward (MAFB) and back cross (MABC) breeding was followed to introgress three major genes, viz., Pi9 for blast, Xa21 for bacterial blight (BB), and Gm8 for gall midge (GM) and three major QTLs, viz., qDTY1.1, qDTY2.2 and qDTY4.1 conferring increased yield under drought in the background of Naveen. At each stage of advancement, gene-based/linked markers were used for the foreground selection of biotic and abiotic stress tolerant genes/QTLs. Intensive phenotype-based selections were performed in the field for identification of lines with high level of resistance against blast, BB, GM and drought tolerance without yield penalty under non-stress situation. A set of 8 MAFB lines and 12 MABC lines with 3 to 6 genes/QTLs and possessing resistance/tolerance against biotic stresses and reproductive stage drought stress with better yield performance compared to Naveen were developed. Lines developed through combined MAFB and MABC performed better than lines developed only through MAFB. This study exemplifies the utility of the combined approach of marker-assisted forward and backcrosses breeding for targeted improvement of multiple biotic and abiotic stress resistance in the background of popular mega varieties.

Are portable polyethylene tents reliable for imposing heat treatments in field-grown wheat?

Environmental variability has increased in recent decades and there are high expectations that heat waves will affect wheat productivity. Therefore, methods to quantify the effects of high temperature on wheat growth, yield, and yield-related traits under field conditions are greatly needed. In this opinion paper, we first describe the different approaches to quantify these effects, briefly highlighting their pros and cons. Portable polyethylene tents over the plots are cost-effective and convenient when relatively large plots are preferred and/or when there is no access to electricity in the field. This method shares a drawback with other approaches due to the tent reducing light intensity and altering other environmental factors like wind, humidity and evapotranspiration. We discuss to what degree there is an actual confounding effect (incorrectly assigning changes to heat effects that might be in part due to lower radiation). In that context, we not only discuss the issue theoretically, but also present results from a field experiment comparing a control (open uncovered plot), and a “roof-only” treatment (covering the plot with a polyethylene roof alone; thus impacting incoming radiation but not temperature). These treatments were imposed at either booting or the onset of grain filling, and testing two wheat cultivars having contrasting grain numbers per m2 and average grain weight. Supporting a theoretical framework that this reduced radiation would be compensated by increased radiation use efficiency, we show empirically that the roof-only treatment (which reduced incoming photosynthetically active radiation by 10.7 ± 0.2 % at noon on sunny days, but did not alter the temperature at any time of the day) did not result in any yield penalty with respect to the uncovered control plots. Thus, portable polyethylene tents are a reliable method to impose heat treatments in field experiments. Although other methods are more sophisticated and may be perceived as having fewer confounding factors, portable polyethylene tents are ideally suited to irrigated field experiments where electricity is not available, where relatively large plots are needed, and for research carried out on a limited budget.

Agronomic and physiological traits facilitating better yield performance of japonica/indica hybrids in saline fields

• JIH exhibited yield superiority over IH not only in non-saline fields, but also in saline fields. • Limited shoot and root growth were responsible for the yield penalty of rice under saline field conditions. • The improved agronomic and physiological traits of JIH facilitated superior grain yield over IH in saline fields. It is of great interest to utilize saline fields to promote rice production in China. Previous studies reported greater yield productivity of japonica/indica hybrids (JIH) over indica hybrids (IH) under nonsaline fields. It has still not been established how salinity stress intervenes with rice yield and whether JIH would exhibit superior grain yield than IH under saline field conditions. This study investigated three JIH and three IH cultivars grown at the two sites that differed significantly in soil salinity, namely, nonsaline (Wulie, abbreviated as WL) and saline (Tiaozini, abbreviated as TZN) fields, in Yancheng, Jiangsu, China. The panicles per m 2 , spikelets per panicle, filled-kernel percentage, and kernel weight of JIH and IH were reduced, and a 36.0 %–43.5 % loss in grain yield was observed with salinity stress at TZN compared with WL. For JIH and IH, the shoot biomass and leaf area index (LAI) at jointing, heading, and maturity were all reduced at TZN compared to those at WL; similar results were also detected for root biomass, root length and volume, and root bleeding rate after heading. Compared with IH, JIH produced a 24.8 % higher grain yield under saline field conditions at TZN across two years. Four agronomic and physiological traits were summarized for superior grain yield of JIH compared to that of IH with salinity stress under field conditions. First, JIH had an enlarged sink size potential of a greater number of spikelets per panicle. Second, a synergistically increased biomass accumulation and harvest index of JIH, supported by higher biomass accumulation and LAI at the main growth stages and improved NSC remobilization after heading. Third, JIH had an improved stay-green characteristic, indicated by a higher leaf area per plant, SPAD values, and leaf photosynthetic rate after heading. Fourth, JIH exhibited a better root morpho-physiology than that of IH after heading, showing a larger and deeper root structure and higher root bleeding rate. These results indicated that the limited shoot and root growth were responsible for the yield penalty of rice under saline field conditions. JIH's improved agronomic and physiological traits facilitated superior yield performance over IH with salinity stress under field conditions.

Vessel- and ray-specific monolignol biosynthesis as an approach to engineer fiber-hypolignification and enhanced saccharification in poplar.

Lignin is one of the main factors determining recalcitrance to processing of lignocellulosic biomass towards bio-based materials and fuels. Consequently, wood of plants engineered for low lignin content is typically more amenable to processing. However, lignin-modified plants often exhibit collapsed vessels and associated growth defects. Vessel-specific reintroduction of lignin biosynthesis in dwarfed low-lignin cinnamoyl-CoA reductase1 (ccr1) Arabidopsis mutants using the ProSNBE:AtCCR1 construct overcame the yield penalty while maintaining high saccharification yields, and showed that monolignols can be transported between the different xylem cells acting as 'good neighbors' in Arabidopsis. Here, we translated this research into the bio-energy crop poplar. By expressing ProSNBE:AtCCR1 into CRISPR/Cas9-generated ccr2 poplars, we aimed for vessel-specific lignin biosynthesis to: (i) achieve growth restoration while maintaining high saccharification yields; and (ii) study the existence of 'good neighbors' in poplar wood. Analyzing the resulting ccr2 ProSNBE:AtCCR1 poplars showed that vessels and rays act as good neighbors for lignification in poplar. If sufficient monolignols are produced by these cells, monolignols migrate over multiple cell layers, resulting in a restoration of the lignin amount to wild-type levels. If the supply of monolignols is limited, the monolignols are incorporated into the cell walls of the vessels and rays producing them and their adjoining cells resulting in fiber hypolignification. One such fiber-hypolignified line had 18% less lignin and, despite its small yield penalty, had an increase of up to 71% in sugar release on a plant base upon saccharification.

Marker-Assisted Pyramiding of Downy Mildew-Resistant Gene Ppa3 and Black Rot-Resistant Gene Xca1bo in Popular Early Cauliflower Variety Pusa Meghna

Cauliflower is an important extensively grown cool season vegetable in India. Black rot and downy mildew are major devastating diseases reducing yield and quality of the crop. To tackle these through host plant resistance, a marker-assisted backcross breeding method was followed to pyramid a black rot-resistant gene (Xca1bo) and a downy mildew-resistant gene (Ppa3) from donors BR-161 and BR-2, respectively, into the background of Pusa Meghna cauliflower cultivar. Marker-assisted backcross breeding was followed up to BC2 generation using SCAR marker ScOPO-04833 and SSR marker BoGMS0624 for black rot and downy mildew resistance genes in foreground selection, respectively. In background selection, at each stage of backcrossing, 47 parental polymorphic SSR markers were used. The graphical genotyping of the five two-gene (Xca1boXca1boPpa3Ppa3) homozygous BC2F2 plants showed an average recovery of 85.44% of the Pusa Meghna genome with highest genome recovery of 91.7%. The genome contribution of donor parents (BR-161 and BR-2) was 8.26 with 6.34% of residual heterozygousity. The backcross derived pyramided lines BC2F2:3-7-16 and BC2F2:3-7-33 showed high resistance to both the diseases and exhibited higher yield and vitamin C content as compared with recipient parent Pusa Meghna. It is, therefore, evident from this study that resistant genes can be introgressed successfully into a Pusa Meghna cultivar without any yield penalty, benefitting farmers with reduced input cost and consumers with chemical residue free produce. Besides, the pyramided lines carrying dominant resistant genes can be exploited in a hybridization programme to develop hybrid(s) in cauliflower.

Climate change shifts forward flowering and reduces crop waterlogging stress

Climate change will drive increased frequencies of extreme climatic events. Despite this, there is little scholarly information on the extent to which waterlogging caused by extreme rainfall events will impact on crop physiological behaviour. To improve the ability to reliably model crop growth and development under soil waterlogging stress, we advanced the process-basis of waterlogging in the farming systems model Agricultural Systems Production Systems sIMulator. Our new mathematical description of waterlogging adequately represented waterlogging stress effects on the development, biomass and grain yield of many commercial Australian barley genotypes. We then used the improved model to examine how optimal flowering periods (OFPs, the point at which long-term abiotic stresses are minimal) change under historical and future climates in waterlogging-prone environments, and found that climate change will reduce waterlogging stress and shift forward OFP (26 d earlier on average across locations). For the emissions scenario representative concentration pathway 8.5 at 2090, waterlogging stresses diminished but this was not enough to prevent substantial yield reduction due to increasingly severe high temperature stress (−35% average reduction in yield across locations, genotypes and sowing dates). It was shown that seasonal waterlogging stress patterns under future conditions will be similar to those occurring historically. Yield reduction caused by waterlogging stress was 6% and 4% on average across sites under historical and future climates. To adapt, both genotypic and management adaptations will be required: earlier sowing and planting waterlogging tolerant genotypes mitigate yield penalty caused by waterlogging by up to 26% and 24% under historical and future climates. We conclude that even though the prevalence of waterlogging in future will diminish, climate change and extreme climatic events will have substantial and perverse effects on the productivity and sustainability of Australian farms.

Drought and crop yield.

Episodes of water shortage occur in most agricultural regions of the world. Their durations and intensities increase, and their seasonal timing alters with changing climate. During the ontogenic cycle of crop plants, each development stage, such as seed germination, seedling establishment, vegetative root and shoot growth, flowering, pollination and seed and fruit development, is specifically sensitive to dehydration. Desiccation threatens yield and leads to specific patterns, depending on the type of crop plant and the harvested plant parts, e.g. leafy vegetables, tubers, tap roots or fruits. This review summarizes the effects of drought stress on crop plants and relates the dehydration-dependent yield penalty to the harvested organ and tissue. The control of shoot transpiration and the reorganization of root architecture are of core importance for maintaining proper plant water relationships. Upon dehydration, the provision and partitioning of assimilates and the uptake and distribution of nutrients define remaining growth activity. Domestication of crops by selection for high yield under high input has restricted the genetic repertoire for achieving drought stress tolerance. Introgression of suitable alleles from wild relatives into commercial cultivars might improve the ability to grow with less water. Future research activities should focus more on field studies in order to generate more realistic improvements to crops. Robotic field phenotyping should be integrated into genetic mapping for the identification of relevant traits.

Mitigation of magneto-Rayleigh-Taylor instability growth in a triple-nozzle, neutron-producing gas-puff Z pinch

The gas-puff Z-pinch is a well-known source of x-rays and/or neutrons, but it is highly susceptible to the magneto-Rayleigh-Taylor instability (MRTI). Approaches to MRTI mitigation include density profile tailoring, in which nozzles are added or modified to alter the acceleration trajectory, and axial pre-magnetization, in which perturbations are smoothed out via magnetic field line tension. Here, we present two-dimensional magnetohydrodynamic simulations of loads driven by an 850 kA, 160ns driver that suggest these mitigation strategies can be additive. The initial axial magnetic field, B_{z0}, to stabilize a 2.5-cm-radius Ne gas liner imploding onto an on-axis deuterium target can be reduced from 0.7T to 0.3T by adding a second liner with a radius of 1.25cm. Because MRTI mitigation tends to increasingly lower yield with higher B_{z0}, the use of a lower field is advantageous. Here, we predict a reduction in yield penalty from >100× with the single liner to <10× with a double liner. A premagnetized, triple nozzle gas puff could therefore be an attractive source for intense neutrons or other fusion applications.

A large-scale genomic association analysis identifies a fragment in Dt11 chromosome conferring cotton Verticillium wilt resistance.

SummaryVerticillium wilt (VW) is a destructive disease that results in great losses in cotton yield and quality. Identifying genetic variation that enhances crop disease resistance is a primary objective in plant breeding. Here we reported a GWAS of cotton VW resistance in a natural‐variation population, challenged by different pathogenicity stains and different environments, and found 382 SNPs significantly associated with VW resistance. The associated signal repeatedly peaked in chromosome Dt11 (68 798 494‐69 212 808) containing 13 core elite alleles undescribed previously. The core SNPs can make the disease reaction type from susceptible to tolerant or resistant in accessions with alternate genotype compared to reference genotype. Of the genes associated with the Dt11 signal, 25 genes differentially expressed upon Verticillium dahliae stress, with 21 genes verified in VW resistance via gene knockdown and/or overexpression experiments. We firstly discovered that a gene cluster of L‐type lectin‐domain containing receptor kinase (GhLecRKs‐V.9) played an important role in VW resistance. These results proved that the associated Dt11 region was a major genetic locus responsible for VW resistance. The frequency of the core elite alleles (FEA) in modern varieties was significantly higher than the early/middle varieties (12.55% vs 4.29%), indicating that the FEA increased during artificial selection breeding. The current developmental resistant cultivars, JND23 and JND24, had fixed these core elite alleles during breeding without yield penalty. These findings unprecedentedly provided genomic variations and promising alleles for promoting cotton VW resistance improvement.

Important analyzing parameters in the assessment of salt tolerance in plants

Maximal crop performance potential and land area suitable for cultivation are usually restricted by adverse environmental conditions. Among the abiotic factors, salinity stress is considered as one of the main threats, which causes ionic toxicity, dehydration and oxidative stresses on the plants. Alarmingly, the impact of salinity is predicted to be more severe in the forthcoming years due to global warming. Therefore, development of new cultivars with better salinity resistance with mimimized yield penalty under the adverse condition, either by breeding or genetic engineering approach, has attracted a great attention from the scientists. In this review, important parameters used in evaluation of plant resistance ability against salinity stress are discussed, which highlights the necessity to obtain multi-sets of biological data ranging from analyses of morphological alterations to physiological, biochemical and molecular responses, as well as by performing -omics studies to find out network of salinity-responsive pathways. Literature review also demonstrates that the relevance of salinity condition setup in terms of concentration and duration is required in experimental design. Furthermore, recent investigations on genome duplication, activities of non-coding sequence or epigenetics also reveal their regulatory roles in shaping plant response and tolerance degree toward salinity stress. Collection of such data not only contributes to widen scientific understanding of plant response mechanisms and adaptation to this stress factor but also facilitates the identification of important genes associating with plant tolerance to salinity. Therefore, the presented information could be used as a reference for the salinity stress-related studies serving for crop innovation and transgene function characterization.

A Review of Irrigation Water Management Research Achievements of JARC

Crop production in Ethiopia is largely dominated by rain-fed agriculture, which is suffered by climate change, due to occurrence of erratic rain falls. Therefore, it should be supplemented with irrigation; unless it is difficult to supply food for extremely growing country’s food demands. To alleviate such problems, Jimma irrigation research departments conducted a number of experiments to improve crop productivity as well as water use efficiency with minimum yield penalty at the expense of water saving at different climatic condition of southwestern Ethiopia. Therefore, the objective of this review is to analyze best research findings and technologies that were checked at different locations. Among promising results, deficit irrigation, inducing moisture stress at different growth stages of crops, supplemental irrigation, integrated use of mulching with deficit irrigation, mineral fertilization (Phosphorous and Nitrogen) vis irrigation, and irrigation scheduling are the major one. Accordingly, optimum yield of maize was reported when it was irrigated at alternate furrow method, is preferably good when irrigation amount is not less than 75% ETc, which saved about 50% of water over conventional furrows 100% ETc. Then the saved water used to irrigate additional piece of land. The other irrigation strategy is skipping irrigation in less sensitive stage of crops, the report comes from Haru ( Gimbi area) indicated that skipping irrigation during initial and late season had minimum impacts on maize yields, with 50% water saving as compared to all stage irrigated maize. In addition to reducing the amount of water significantly, the cover crop could play significant role in reducing soil evaporation. For instance, the experiment conducted at Haru showed that alternate furrow mulched with plastic mulch provided highest potato yield over non-mulched. Most of time, the fertilizer recommendation made for rain fed agriculture does not work for irrigated agriculture. The full irrigation (100% ETc) combined with 46 kg/ha phosphorous in soybean provided highest yield. However, increasing the amount of phosphorous fertilizer beyond this level did not increase the yield even if the field receives enough moisture. Finally, the future research direction should focus on water saving together with optimized fertilization through liquid water, and integrated with water harvesting in areas with limited water source either physical or economical. Keywords: Deficit Irrigation, Moisture Stress and Irrigation Scheduling DOI: 10.7176/JRDM/78-01 Publication date: August 31 st 2021

Impact of management practices on weed infestation, water productivity, rice yield and grain quality in irrigated systems in Côte d'Ivoire

• AWD reduced weed biomass due to reduction of lowland and broad-leaved weeds. • AWD increased water productivity without yield penalty compared to CF. • Soil pH and N fertilization affected rice yield and water productivity in AWD fields. • Choice of rice variety largely determined grain quality. Management practices that simultaneously enhance rice yield, water productivity, labor productivity, and grain quality are needed for improving crop production and mitigating the negative impact of water scarcity on food security. The objectives of this on-farm study were to evaluate the effects of water management practices including the safe alternate wetting and drying (AWD) method of irrigation on rice yield, water productivity, weed biomass, and grain quality, and identify the factors associated with their variabilities in the fields with AWD. On-farm trials were conducted over two years in 30 fields within two irrigation schemes in the region of Bouake, central Côte d’Ivoire. Before rice cultivation, in each field, three plots consisting of water management practices were established: continuous flooding (CF), safe AWD, and farmers’ practice (FP). Lowland weeds were dominant in rice fields in this study area. Large variations in weed biomass, rice yield, and water productivity were found across fields for each water management practice. Weed biomass and irrigation water input were lower under safe AWD than CF due to higher soil drying while there was no significant difference in rice yield between safe AWD and CF. Water productivity was higher under safe AWD than CF and FP. Rice milling recovery, head yield, and chalkiness were not significantly different among water management practices. Higher rice yield and water productivity in the safe AWD fields were associated with higher soil pH and nitrogen (N) fertilizer rate and better congruence between nitrogen fertilizer application and crop N demand. Milling recovery, head yield, and chalkiness in the safe AWD fields were strongly affected by the choice of rice variety. Combination of safe AWD with varieties having good grain quality characteristics and improved nutrient management practices could be recommended to the smallholder rice farmers to improve rice yield, water productivity, and grain quality and reduce labour requirement for irrigation and weeding particularly in schemes where lowland weeds are dominant.

Pre-emptive Breeding Against Karnal Bunt Infection in Common Wheat: Combining Genomic and Agronomic Information to Identify Suitable Parents.

Wheat (Triticum aestivum L.) is the most widely grown cereal crop in the world and is staple food to half the world’s population. The current world population is expected to reach 9.8 billion people by 2050, but food production is not expected to keep pace with demand in developing countries. Significant opportunities exist for traditional grain exporters to produce and export greater amounts of wheat to fill the gap. Karnal bunt, however, is a major threat, due to its use as a non-tariff trade barrier by several wheat-importing countries. The cultivation of resistant varieties remains the most cost-effective approach to manage the disease, but in countries that are free of the disease, genetic improvement is difficult due to quarantine restrictions. Here we report a study on pre-emptive breeding designed to identify linked molecular markers, evaluate the prospects of genomic selection as a tool, and prioritise wheat genotypes suitable for use as parents. In a genome-wide association (GWAS) study, we identified six DArTseq markers significantly linked to Karnal bunt resistance, which explained between 7.6 and 29.5% of the observed phenotypic variation. The accuracy of genomic prediction was estimated to vary between 0.53 and 0.56, depending on whether it is based solely on the identified Quantitative trait loci (QTL) markers or the use of genome-wide markers. As genotypes used as parents would be required to possess good yield and phenology, further research was conducted to assess the agronomic value of Karnal bunt resistant germplasm from the International Maize and Wheat Improvement Center (CIMMYT). We identified an ideal genotype, ZVS13_385, which possessed similar agronomic attributes to the highly successful Australian wheat variety, Mace. It is phenotypically resistant to Karnal bunt infection (<1% infection) and carried all the favourable alleles detected for resistance in this study. The identification of a genotype combining Karnal bunt resistance with adaptive agronomic traits overcomes the concerns of breeders regarding yield penalty in the absence of the disease.

Genetic improvement of nitrogen use efficiency in crops.

Nitrogen (N) is an essential mineral nutrient for plant growth and development. N deficiency is the major factor limiting plant growth and crop production in most natural and agricultural soils. The green revolution of the 1960's boosted crop yields through cultivation of semi-dwarf plant varieties. However, green revolution wheat and rice varieties have relatively poor nitrogen use efficiency (NUE), require a high N fertilizer supply to achieve maximum yield potential, and this leads to an increase in production costs and environmental problem. Therefore, a major challenge for sustainable agriculture is whether improvement of NUE through the reduction of N fertilizer supply can be achieved without yield penalty. In this review, we summarize the recent advances in understanding of molecular mechanisms underlying the regulation of N-responsive plant growth, utilization and possibility for improvements of NUE in crops, and new breeding strategies through modulation of N-responsive growth-metabolism coordination for future sustainable agriculture.

Experimental comparison of continuous and intermittent flooding of rice in relation to methane, nitrous oxide and ammonia emissions and the implications for nitrogen use efficiency and yield

Intermittent flooding (IF) of rice has been encouraged as an approach to reduce water use and methane emissions compared with continuous flooding (CF), but may involve trade-offs. This study compared the contrasting effect of IF and CF flooding regimes on emissions of methane (CH4), nitrous oxide (N2O) and ammonia (NH3), nitrogen use efficiency (NUE) and yield. A split plot design was used which assessed the effects of four different fertiliser types. The results suggest that converting from CF to IF irrigation does lower CH4 emissions (by approximately 18%); however, this comes at a cost. IF irrigation resulted in a significant decrease in grain yield, regardless of fertiliser type (6.1% in this study) and also a significant decrease in NUE (a drop of 22.5% when compared to CF). IF irrigation also resulted in a small, but statistically significant (t-test p < 0.01) increase in N2O emissions. Difference in NH3 emission between the flooding regimes was not statistically significant. Our study concludes that conversion from CF to IF irrigation methods may well reduce overall global warming potential of greenhouse gas emissions from rice production; however, yield penalties and nitrogen pollution are likely to increase as a result. Leaf colour chart based application of Neem coated urea may lower the yield scaled GHG emissions under CF irrigation and NH3 loss in IF irrigation.

Farm robots: ecological utopia or dystopia?

Farm robots may lead to an ecological utopia where swarms of small robots help in overcoming the yield penalties and labor requirements associated with agroecological farming - or a dystopia with large robots cultivating monocultures. Societal discussions and policy action are needed to harness the potential of robots to serve people and the planet.

Plummeting global warming potential by chemicals interventions in irrigated rice: A lab to field assessment

Methane (CH4) emissions are responsible for the higher global warming potential of rice cultivation. There are scattered reports on the use of chemical interventions for reducing CH4 emissions from rice. A laboratory study was carried out to estimate the CH4 mitigation potential of oxygen releasing chemicals such as magnesium peroxide (MgO2) and calcium peroxide (CaCO2), chelating agent ethylene diamine tetra acetic acid (EDTA), nitrification inhibitors thiourea and neem oil, limus (urease inhibitors), phosphogypsum (PG) a byproduct of phosphate fertilizer industry and ammonium sulfate (AS). The cumulative CH4 emission from soil reduced by 2.0–32.3% under the different treatments during the 45 days’ incubation study. Subsequently, four chemicals having the highest CH4 reduction potential i.e. PG, EDTA, AS, and MgO2 were further evaluated for the mitigation of CH4 and their concurrent impact on nitrous oxide (N2O) emission in a two-year experiment growing rice. PG, EDTA, AS, and MgO2 significantly (p = 0.0025) decreased CH4 emissions by 9.3−27.5% as compared to the control. The cumulative N2O emission were significantly lower by 13.9% under PG as compared to control. The global warming potential decreased by 6.8% with MgO2 to 23.6% with PG. The grain yield increased by 3.1–11.2% under the different treatments. The greenhouse gas intensity (GHGI) was the highest in control (0.309 kg CO2 eq. kg-1 grain yield) and lowest in PG (0.212 kg CO2 eq. kg-1 grain yield). The findings suggest that PG, EDTA, AS, and MgO2 can be used to plummet the global warming potential of irrigated rice soils without any yield penalty. More research is required to be undertaken to evaluate the impact of these chemicals from the perspective of food security in the farmers’ fields.