Theory gaps in Agriculture

Representative open questions

Showing 30 of 54 — one per source paper, highest-quality first.

• Development and research trends of stay-green biology in legumes: a bibliometric and visual analysis over three decades (2026) · doi

  Basic themes such as stay-green syndrome in the context of geminivirus and hemiptera alydidae pest resistance show foundational importance but lack cohesive conceptual development. The molecular basis linking stay-green phenotypes to disease and pest resistance mechanisms requires integrated transcriptomic and physiological investigation.

• Evaluation of the effects of hydrogel and glycine betaine application on growth, physiological characteristics and yield of peanut under water deficit (2026) · doi

  Although the study found that combined hydrogel and GB application produced more significant increases in peanut growth and yield than either treatment alone, the physiological basis for this synergistic interaction was not mechanistically explored. Research should investigate whether synergistic effects operate through improved osmolyte accumulation, enhanced ion homeostasis regulation, or better soil water availability when both amendments are applied simultaneously to peanut.

• Rapid fertilizer turnover and dominant soil N mineralization in a cool-climate vineyard revealed by 15N tracing, biological N availability, and N exposure (2026) · doi

  A severe overwinter frost between 2021 and 2022 caused 95% reproductive bud mortality and markedly altered soil N dynamics (20–26% increase in total N, 77–106% increase in biological N availability in 0–30 cm layer). Future studies should systematically investigate the mechanisms and magnitude of frost-induced root mortality, freeze-thaw cycle effects on N immobilization in microbial biomass, and sap bleeding contributions to labile N pools using 15N isotope tracing across multiple freeze-thaw cycles.

• Dynamic regulation of secondary metabolites and agarwood aroma compounds in Aquilaria sinensis by the endophytic fungus NSZJ-CX-22 revealed through metabolomics and GC–MS (2026) · doi

  Alkaloid biosynthesis pathways (represented by atherosperminine and ergometrine) showed consistently low enrichment and weak significance across all culture stages, yet specific alkaloid compounds were identified as top VIP differential metabolites in mid-late cultivation. The regulatory mechanisms controlling alkaloid biosynthesis activation despite low pathway enrichment scores require dedicated investigation.

• Deciphering Trichoderma viride-mediated cadmium stress alleviation in wheat: morphological, physiological and biochemical insights (2026) · doi

  Conflicting results exist regarding the effect of Trichoderma species on proline and glycine betaine accumulation during cadmium stress—T. viride increased these osmoregulatory components in wheat, while T. harzianum reduced proline levels in V. radiata; comparative mechanistic studies across different Trichoderma strains and host plant species are needed to clarify the strain-specific and species-specific responses.

• Integrating combining ability and multivariate analysis for the selection of superior tomato hybrids (2026) · doi

  The SST/TA (soluble solids content to titratable acidity) variable showed non-significant GCA and SCA effects, attributed to proximity of genetic parameters among inbred lines sharing the same gene pool. The specific genetic architecture controlling sensory quality traits in tomato requires investigation using broader germplasm diversity beyond the current gene pool.

• Phytoremediation As An Eco-Friendly Remediation Method For Reducing Contamination Of Heavy Metals From Contaminated Soil In Aligarh (2026) · doi

  Plant-microbe interactions and their role in enhancing heavy metal mobilization and plant uptake in phytoremediation are mentioned as an innovative research area but lack experimental characterization; the specific microbial consortia and their mechanisms for improving phytoremediation performance have not been investigated.

• COMPOST-MEDIATED MODULATION OF CHLORPYRIFOS RESIDUES: IMPACTS ON SOIL PROPERTIES AND HUMAN HEALTH RISKS FROM YAM (Dioscorea rotundata) CONSUMPTION (2026) · doi

  The contradiction between Singh et al. (2024) findings—that organic amendments increase microbial chlorpyrifos degradation but do not reduce plant uptake—and this study's incomplete understanding of why compost-treated soils (T7-T9) still showed elevated yam tuber residues (0.080-0.440 mg/kg) requires investigation of chlorpyrifos speciation in amended soils. Specifically, the study lacks analysis of bound residues, soil sorption isotherms, and root exudate-mediated desorption kinetics that could explain persistent plant bioavailability despite enhanced soil degradation pathways.

• Soil and Environmental Chemistry: Exercises (2017) · doi

  The retardation factor estimation for Alachlor transport assumes linear partitioning behavior, but nonlinear isotherm behavior evident in Tables 17-18 at low dissolved concentrations (<0.07 mg·dm−3) suggests potential site-limited sorption mechanisms that are not accounted for in the standard retardation coefficient model applied to chloroacetanilide herbicides.

• Evaluación comparativa de frameworks de visión artificial para el conteo automatizado y monitoreo de especies menores en sistemas pecuarios (2026) · doi

  YOLOv12 and RT-DETRv2 are recent architectures (2024-2025) with limited scientific literature; the long-range attention mechanisms and transformer-based detection approaches need empirical validation specifically on minor species in high-density occlusion scenarios. Future studies should evaluate whether attention mechanisms generalize to guinea pig and rabbit detection with partial occlusion patterns.

• Foliar potassium–calcium nutrition enhances fruit yield, quality and mitigates cracking in guava (Psidium guajava L.) under humid subtropical conditions (2026) · doi

  The study identifies that potassium nitrate at 2.0% outperformed sulphate-based treatments, but the mechanistic basis for why nitrate forms provide additional benefits through nitrogen supply during critical growth stages in guava reproductive development remains uncharacterized. Future work should isolate the independent contributions of nitrate versus potassium ions on leaf physiological status and fruit sink performance across defined phenological stages.

• Robust apple leaf disease diagnosis for sustainable horticulture: overcoming background noise with a multilayer transformer-based approach (2026) · doi

  The paper demonstrates that VGG-16 and ResNet models experience non-monotonic convergence patterns with accuracy downfalls around 10 epochs followed by recovery at 40 epochs, but does not systematically analyze the relationship between model depth, background noise learning, and convergence instability. Investigating whether deeper architectures are inherently prone to noise feature learning during apple leaf disease diagnosis would inform architectural design choices.

• Mastering feed efficiency for a sustainable operation in poultry industry (2026) · doi

  Understanding of host-microbiome interactions directly influencing nutrient utilization and feed efficiency in poultry under diverse production environments remains mechanistically unclear. Targeted nutritional and microbial interventions to consistently improve feed efficiency require deeper knowledge of how microbiota composition and function vary across different management systems and their specific interactions with genetics and diet.

• Soil Chemistry (2012) · doi

  The mechanisms by which liming agents such as CaCO3 improve soil structure beyond neutralization remain unclear. Future research should investigate the specific physicochemical pathways through which lime amendments alter soil aggregate stability, porosity, and water retention in acid soils across different soil types and pH ranges.

• Classification of Walnut Leaf Images Using a Hybrid CNN-Based Deep Learning Approach (2026) · doi

  The paper mentions that prior walnut classification studies used very few varieties (e.g., 3 varieties achieving 93.3% accuracy); the specific threshold number of walnut varieties at which hybrid CNN-GLCM approaches outperform traditional feature extraction methods, and how classification accuracy scales with increasing variety complexity, has not been systematically analyzed.

• Effect of Applying GA3 Treatment on Vitis vinifera Agronomical Traits and Embryo Germination Rate (2026) · doi

  The study demonstrates that GA3 application before flower cup induces seedlessness and embryo abortion, but the specific molecular mechanisms underlying GA3-induced embryo viability loss in both seeded ('Rizamat') and seedless ('Toyfi', 'Qora Kishmish') cultivars remain unexplored. Investigation of GA signaling pathways and differential gene expression during GA3-induced embryo abortion is needed.

• Model test on longitudinal differential settlement of operational shield tunnel under localized surface loading (2026) · doi

  The study investigated soil pressure distribution at the crown position under different burial depths (H=1D, H=2D, H=3D), but did not examine behavior at depths greater than H=3D or determine the exact threshold depth beyond which surface loads become negligible. Future research should establish the critical burial depth at which surface loading effects on shield tunnels become negligible across different soil compositions.

• Biodiminution of lithium in forest floor food webs (2026) · doi

  The study examines lithium biodiminution in forest floor food webs but does not specify quantitative thresholds for lithium concentration levels at which bioaccumulation becomes physiologically significant in arthropods and other detritivores. Future work should establish dose-response relationships for lithium uptake across different arthropod taxa in forest soil ecosystems.

• Performance of Spring Wheat Genotypes for Quality, Yield, and Related Reproductive Traits under Different Production Systems (2026) · doi

  The paper identifies that Radmira achieves superior protein and gluten content under high-intensive production due to strong nitrogen uptake efficiency, but does not characterize the specific physiological or genetic mechanisms driving differential nitrogen use efficiency among the three genotypes. Detailed investigations into nitrogen uptake kinetics, remobilization patterns, and genetic markers associated with nitrogen use efficiency in these cultivars are absent.

• Chemistry of the pedosphere (2012) · doi

  Table 6.5 presents cation-exchange capacity (CEC) values for individual soil minerals and humus, but the paper does not specify how to calculate or predict the effective CEC of natural soil mixtures containing multiple minerals with different exchange sites and pH-dependent charge properties.

• Traditional medicinal uses, diversity, and conservation status of Malagasy aromatic plants: a review (2026) · doi

  Introduced/invasive aromatic plant species documented with traditional medicinal uses in Madagascar (Eucalyptus citriodora, Eucalyptus globulus, Eclipta prostrata, Daucus carota) are listed with identical therapeutic properties to their uses in origin regions, yet no evidence is provided that Malagasy endemic populations independently developed these uses or simply adopted introduced European/Asian ethnomedicinal knowledge. Ethnographic studies distinguishing indigenous discovery versus knowledge transfer are needed for non-endemic aromatic species.

• Comparative Effects of Different Light Intensities on Performance and Egg Quality in Japanese Quails (2026) · doi

  While the paper demonstrates that light intensity affects feed conversion ratio and growth performance without altering total feed intake, the underlying metabolic and hormonal mechanisms—specifically which growth-regulating hormones (GH, IGF-1, thyroid hormones) are modulated by 15 lux illuminance in Japanese quails—remain unexplored and require direct measurement.

• Comparative Effects of Organic and Inorganic Fertilizers on the Nutritional Profile and in Situ Digestibility of Alfalfa (Medicago sativa L.) in Cannulated Buffalo Bulls (2026) · doi

  While the T5 treatment (100% urea) showed the highest digestion rate and lowest lag time, the paper does not investigate the mechanistic basis of why inorganic nitrogen specifically accelerates fiber fermentation or whether there are optimal nitrogen concentration thresholds beyond 100% urea that could further enhance in situ digestibility in alfalfa.

• Influence of Wheat Bran, Maize Bran and Soya Hulls Supplementation on Milk Yield, Composition and Physiological Responses in Cholistani Cattle (2026) · doi

  The study tested soya hulls, wheat bran, and maize bran supplementation at only 25% inclusion level in Cholistani cattle diets. The mechanism by which soya hulls improve or depress milk yield remains unexplained, as Het-land et al. (2001) reported increased milk yield with higher SH levels but did not elucidate the physiological pathway, while Bergeron (2002) attributed decreased yield to low starch content without mechanistic validation.

• Shrub Age and Water Dynamics Influence Primary Production, Carbon, and Nitrogen Stocks in a Coastal Environment (2024) · doi

  The study does not quantify how vegetation-microclimate feedbacks specific to woody plant encroachment in the coastal setting alter soil organic carbon accumulation rates or modify the partitioning of water between differently sized shrubs and potential groundwater recharge.

• JA-mediated H2O2 and ABA signaling enhances root hydraulic conductance in cotton under partial root-zone irrigation (2026) · doi

  The proposed model identifies JA as a systemic master signal translocated from leaves to hydrated roots under PRI, but the specific mechanisms governing JA synthesis induction by signals from the drying root zone and its long-distance translocation remain uncharacterized. Direct measurement of JA biosynthesis regulation and xylem/phloem transport kinetics during the PRI cycle is needed to validate this leaf-to-root signaling pathway.

• Temperature dependent immunological responses of Spoladea recurvalis exposed to entomopathogenic fungi (2026) · doi

  The study examined the interaction between temperature, fungal isolates, and time on total hemocyte density and hemocyte types, but did not investigate whether specific bacterial taxa identified in the gut microbiome (via PCoA and Jaccard dissimilarity) correlate with changes in hemocyte populations or larval mortality across temperature treatments. Establishing mechanistic links between microbiome composition shifts and immunological response phenotypes in Spoladea recurvalis would require integrated analysis of microbiome-hemocyte interactions.

• Stabilization of Expansive Clay Using Calcium Lignosulfonate for Subgrade Application (2026) · doi

  While the optimum stabilizer content was determined at 4%, the mechanism of why excess chemical (beyond 4%) reduces CBR values is not fully explained.

• Remote Sensing for Within-Plot Soil Variability Assessment Using NDVI Dispersion Metrics (2026) · doi

  The first two principal components explained only 37.33% of the total variance, reflecting the complexity of the system and the diversity of variables considered, indicating that substantial unexplained variance remains in the relationships among soil properties, terrain attributes, and crop indicators.

• Phosphate-solubilizing inoculants induce stage-specific rhizosphere microbiome shifts and enhance chickpea symbiosis under low P availability (2026) · doi

  The mechanisms by which fungal diversity directly influences nodulation and N2 fixation efficiency require further mechanistic investigation beyond correlational observations.