Canopy ammonia (NH₃) exchange is a major contributor to agricultural NH₃ emissions and is closely linked to nitrogen-use efficiency. Glutamine synthetase (GS) mediates plant NH₃ assimilation, yet the specific roles of different GS isoenzymes in regulating wheat canopy NH₃ exchange remain unclear. This study aimed to clarify the functional differences of wheat TaGS isoenzymes in modulating canopy–atmosphere NH₃ exchange dynamics using two wheat cultivars (Yumai 49-198 and Xinong 509) under two nitrogen application levels (120 and 225 kg N ha⁻¹). Field experiments combined with FTIR-based NH₃ flux measurement, biochemical assays, and molecular analyses were conducted at anthesis and 16, 24, and 30 days after anthesis (DAA). Results showed that the leaf NH₃ compensation point, determined by apoplastic NH₄⁺ concentration, is a key factor influencing canopy NH₃ exchange. Leaf NH₃ sources exhibited distinct temporal specificity: photorespiration and nitrate reduction dominated at anthesis to 16 DAA, whereas nitrogenous compound degradation prevailed at 24–30 DAA. This temporal partitioning was highly coordinated with TaGS isoenzyme expression: TaGS2 was highest in early grain filling, potentially supporting assimilate NH₃ from photorespiration/nitrate reduction, while TaGS1;1 expression increased progressively, aligning with the scavenging of NH₃ from organic nitrogen degradation. These coordinated patterns suggest that the TaGS isoenzymes play differentiated roles in influencing wheat canopy NH₃ exchange. This study thus provides correlative insights that point to potential molecular targets for breeding nitrogen-efficient wheat cultivars and mitigating agricultural NH₃ emissions sustainably.

Nitrous oxide (N₂O) is a potent greenhouse gas and a major ozone-depleting substance of the nitrogen cycle. While global N₂O budgets focus on microbial soil sources, evidence suggests that living plants can also contribute to N₂O emissions. However, the origin of plant-associated N₂O fluxes is contested: measured emissions may arise from endogenous plant metabolism or merely from transport of soil-derived N₂O. In this review, we clarify these pathways and synthesize current findings from laboratory and field studies. Experimental evidence from ¹⁵N-tracer and axenic-culture studies supports N₂O formation linked to nitrate (NO₃⁻) and nitrite (NO₂⁻) in photosynthetic organisms, although mechanistic resolution varies among taxa. In angiosperms, proposed plastid/chloroplast and hypoxia-associated mitochondrial routes are linked to NO₃⁻/NO₂⁻ metabolism and NO formation, but the terminal NO-to-N₂O step remains unresolved and differs from the flavodiiron-dependent mechanism demonstrated in algae. We discuss key environmental and physiological controls (substrate availability, light, O₂ status, reductant supply) on these processes and highlight methodological challenges in source attribution (chamber artefacts, destructive sampling, isotope analysis). Our analysis suggests that plant-associated N₂O fluxes are real, but highly variable and context-dependent. Rather than assuming generic “plant emission factors”, we emphasize source-specific approaches that distinguish endogenous formation from soil-derived transport and microbial production. This framework can improve N₂O budgets and guide mitigation by indicating whether management should target soil N availability and microbial processes or physiological conditions favouring plant-associated N₂O formation.

| Cereal crops have been the backbone of national agriculture for decades, as they are major staple food crops. Crop nutrients major sources are organic, inorganic and bio-fertilizers. Supplementation of beneficial microbes with organic and inorganic fertilizers is a feasible technology to improve wheat productivity. A field experiment was conducted to evaluate the impact of organic sources (OS) and inorganic N fertilizer (Urea) along with the application of bio-aab (beneficial microbes) on the wheat crop at the Agronomy Research Farm, The University of Agriculture Peshawar Pakistan, during 2020-2021. Two separate experiments were conducted (with and without bio-aab) in Randomized Complete Block Design each consisted of 10 treatments. Bio-aab treatments are T 1 : Poultry manure (PM) + 80 kg N + bioabb, T 2 : PM + 120 kg N + bio-aab, T 3 : PM + 160 kg N + bio-aab, T 4 : Farm yard manure (FYM) + 80 kg N + bioabb, T 5 : FYM + 120 kg N + bio-aab, T 6 : FYM + 160 kg N + bio-aab, T 7 : Maize residues (MR) + 80 kg N + bioabb, T 8 : MR + 120 kg N + bio-aab, T 9 : MR + 160 kg N + bio-aab, T 10 : Control), same treatments followed for without bio-aab. OS have applied accordingly to the plots one month before sowing, bio-aab solution (60 litres ha -1 ) was applied with first irrigation to one experiment before sowing to encourage microbial action necessary for manure decomposition, while half N was applied at sowing time and half after seven days of sowing with first irrigation. Statistical analysis was done combined over bio-aab. The principle beneficial microorganisms (BM) in bio-aab contain photosynthetic bacteria, lactic acid bacteria and yeast. These BM produced useful substances such as amino acids, nucleic acids, lactic acid, bioactive substances, hormones, enzymes and sugars. All these substances promote active cell and root division, plant growth, productivity, suppress harmful microorganisms, and enhance the decomposition of organic matter. Results showed that integrated use of PM and N (120 or 160 kg ha -1 ) along with the application of bio-aab significantly (P≤0.05) improved tillers m -2 (12%), grains spike -1 (15%), biological yield (31%) and grain yield (39%) as compared to control plots. Results of the bio-aab treated plots were found (8%) superior yield than without bio-aab.

Crop nutrient'smajor sources are organic, inorganic, and bio-fertilizers. Supplementation of beneficial microbes with organic and inorganic fertilizers is a feasible technology to improve wheat productivity. This study assessed the impact of Bioaabbiofertilizer (containing Rhodopseudomonas, Lactobacillus, and Saccharomycesspp.), nitrogen (N) rates (80, 120, 160 kg ha⁻¹), and organic amendments poultry manure (PM), farmyard manure (FYM), and maize residues (MR) on wheat growth and yield. Two field trials, with and without Bioaab, were conducted during the 2020–2021 winter season at The University of Agriculture, Peshawar, using a randomized complete block design with ten treatments (including a control), each replicated three times. In the Bioaab trial, 60 L ha⁻¹of the extended solution was applied via irrigation before sowing. Bioaab application and higher N levels significantly improved plant height, leaf area, dry matter, and yields. Compared to the control, plant height increased by 12.8% and 19.0%, and leaf area by 7.6% and 18.1% at 80 and 160 kg N ha⁻¹, respectively. Dry matter production rose by 16.2% at 160 kg N ha⁻¹. Among organic sources, PM showed the highest increase in plant height (18.8%), leaf area (17.3%), and dry matter (16.7%). FYM and MR also enhanced growth, though to a lesser extent. PM led to the highest biological (12,158 kg ha⁻¹) and grain yield (4,110 kg ha⁻¹), reflecting increases of 54.7% and 86.5% over the control, respectively. These results underscore the benefits of integrated nutrient management, particularly poultry manure combined with 120–160 kg N ha⁻¹, in boosting wheat productivity under semi-arid conditions.

Background and Aims: Straw return strengthens nutrient recycling in cereal rotations, yet its effects on phosphorus (P) and potassium (K) acquisition under contrasting tillage remain unclear. Method : A two-year split-plot experiment in northern China compared rotary tillage (RT) and moldboard plowing (MP) under no, half, full, and double straw return in a winter wheat–summer maize rotation. Soil and crop measurements covered four harvests; topsoil microbial communities were assessed after both maize harvests. Results : Full and double return increased grain yield and aboveground P accumulation in both crops, with higher maize yield under MP. Wheat K accumulation increased with straw return, whereas maize K accumulation showed no significant overall tillage or straw return effect. Estimated from additional uptake, apparent straw P recovery was higher under MP, while apparent K recovery increased with return rate. Maize P accumulation increased between years as K accumulation declined. MP and higher straw inputs generally increased topsoil organic matter, available P (AP), and available K (AK). Between maize harvests, AP increased while AK declined, indicating contrasting trajectories. AP correlated positively with maize P accumulation in both years (R² = 0.61–0.62), and AK with K accumulation in both crops. Microbial richness increased between years; combined analysis detected modest treatment differentiation for fungi but no significant differentiation for bacteria. Nutrient-associated taxa varied between years, providing candidates for functional investigation. Conclusion : Findings support separate P and K monitoring when integrating straw return with tillage; recommending double over full return requires evidence of additional agronomic and economic benefits.