Agricultural Sciences: Techniques and Innovations Vol. 12

Heterotic Grouping in Maize: Critical Narrative Review of Conceptual Foundations, Classification Methods and Genomic Prospects

2026-08-20T11:34:30+00:00

Heterotic grouping is central to maize hybrid breeding because it structures parental pools, guides tester choice and concentrates crossing effort on combinations with a higher probability of superior performance. Yet the term is frequently used imprecisely, and molecular clusters, pedigree classes and combining-ability groups are often treated as interchangeable even though they capture different biological and operational signals. This critical narrative review evaluates the conceptual basis, regional development, classification methods and genomic future of heterotic grouping in maize. Literature published principally from 1990 to 31 May 2026 was selected through live searches of accessible scholarly indexes and DOI metadata sources, supplemented by citation chaining and verification against official article records. The evidence indicates that a heterotic group is best understood as a breeding population defined by repeatable cross-performance relationships, not as a taxonomic unit or a neutral-marker cluster. Long-established temperate patterns, including Stiff Stalk versus non-Stiff Stalk in North American dent maize and Dent versus Flint in Europe, show comparatively strong alignment among pedigree, genomic differentiation and hybrid performance because recurrent selection and germplasm recycling have reinforced those divisions. In tropical, subtropical and recently assembled breeding material, agreement is weaker: genetic distance can describe ancestry and avoid close relatives, but it does not consistently predict heterosis or specific combining ability. Testcross evidence remains the most direct basis for operational assignment, although results depend on tester choice, target environment, maturity, stress regime and trial precision. Heterotic group-specific and general combining ability methods can improve classification in some populations, while genomic prediction generally offers greater practical value than simple marker distance when adequate training relationships and multi-environment data are available. The most defensible strategy is therefore integrative and dynamic: combine pedigree and genomic structure with replicated testcross performance, update assignments as programmes evolve, and manage within-group diversity as deliberately as between-group divergence.

Ecological Management of the Brinjal Insect-Pest Complex: Integrating Natural Enemies and Plant Diversification

2026-08-20T11:38:29+00:00

Brinjal, or eggplant, supports a persistent insect-pest complex in which internal feeders, sap feeders, mites and defoliators impose different ecological and operational demands on pest management. The fruit and shoot borer is usually the principal yield-limiting species in South Asian production, but whiteflies, leafhoppers, aphids, thrips, mites and leaf-feeding beetles can become locally dominant, particularly when insecticide use disrupts natural regulation. This critical narrative review evaluates how natural enemies and plant diversification can be combined to build more durable pest management rather than applied as isolated components. Literature was selected through transparent searches of accessible scholarly indexes and verified journal records, with emphasis on field evidence, mechanistic relevance, methodological quality and consistency across production systems. The evidence indicates that plant diversification can reduce pest colonisation, alter host-finding, provide food and refuge for beneficial arthropods, and improve yield stability; nevertheless, outcomes depend strongly on companion identity, spatial arrangement, crop ratio, phenology and landscape context. Natural enemies contribute most reliably when interventions are matched to pest biology: parasitoids and egg-stage tactics must act before fruit and shoot borer larvae enter plant tissue, whereas predator-parasitoid assemblages can exert stronger continuous pressure on exposed sucking pests. Higher natural-enemy abundance does not automatically produce lower pest density or damage, and broad-spectrum insecticides, intraguild interactions, alternative prey, poor synchrony and inadequate habitat resources can weaken expected benefits. The strongest strategy is therefore an adaptive architecture that couples sanitation, monitoring and selective interventions with purpose-designed intercrops, flowering resources, semi-natural habitat and compatible biological products. Current evidence is limited by short experimental durations, small plots, inconsistent outcome reporting and geographical concentration. Future research should use factorial, multi-season and landscape-aware trials that measure pest suppression, natural-enemy function, yield, profitability, pesticide displacement and farmer feasibility together.

Nutrient Delivery to Woody Plants by Stem Injection: A Critical Appraisal of Transport Mechanisms, Agronomic Efficacy and Physiological Cost

2026-08-20T11:43:26+00:00

Nutrient disorders in perennial woody crops and amenity trees are frequently refractory to soil fertilisation because calcareous or alkaline substrates immobilise applied micronutrients, and to foliar sprays because several elements move poorly once deposited on the leaf surface. Stem injection, the direct introduction of solutions into functional xylem through a port in the trunk, has been proposed for more than nine decades as a way of bypassing both bottlenecks. Interest has intensified as injection hardware developed for pesticide and antibacterial delivery has become commercially available, yet the nutritional application has never been subjected to the same critical scrutiny as the plant-protection application. This review examines the physiological basis, delivery technology, agronomic evidence and physiological cost of stem injection used specifically for nutrient delivery. Literature was identified through structured searching of scholarly bibliographic indexes accessible during preparation, supplemented by backward citation searching, and appraised for design adequacy, controls, measurement validity and generalisability rather than scored with a formal instrument. Four conclusions emerge with differing degrees of confidence. Correction of iron deficiency chlorosis by injected ferrous sulphate is the best-supported application, replicated across several genera and reported to persist for more than one season, although most trials are small, short and conducted on severely chlorotic trees. Evidence for zinc, manganese and boron is thinner, is often confounded with co-injected fungicidal compounds, and includes documented failures to reach critical leaf concentrations. Macronutrient delivery is constrained by a mass-balance problem that no reported injection protocol resolves, and the single well-documented magnesium trial found the approach ineffective. Injection ports impose a reproducible wound whose consequences depend on host compartmentalisation capacity, dose and pressure, and are rarely followed for long enough to quantify cumulative cost under repeated annual use. The dominant unresolved question is not whether injected nutrients enter the tree, which is well established, but whether the delivered dose reaches deficient tissue in a spatially uniform and physiologically meaningful quantity at acceptable cost to the stem.

Polyhalite and Soil Health: Mechanisms, Evidence Boundaries and Implications for Sustainable Agriculture

2026-08-20T11:47:01+00:00

Polyhalite is a naturally occurring hydrated sulphate mineral that supplies potassium, sulphur, calcium and magnesium in a fixed stoichiometric association. Its increasing agronomic use has generated claims extending from balanced crop nutrition to improved soil health and lower environmental impact. This critical narrative review evaluates those claims by separating demonstrated nutrient-delivery effects from plausible but incompletely tested soil-health mechanisms. Literature published from 1 January 1991 to 5 June 2026 was identified through accessible scholarly indexes, bibliographic databases, journal platforms, institutional repositories and citation searching, with foundational mineralogical studies included where necessary. Evidence was appraised for comparator adequacy, nutrient-rate equivalence, duration, soil and crop representativeness, measured soil-health domains, independence of funding and consistency across studies. Polyhalite is an effective source of potassium and sulphate sulphur, while its calcium and magnesium can contribute to crop uptake and exchangeable pools under responsive conditions. Its slower dissolution than highly soluble potassium salts can moderate nutrient-release peaks, but release remains strongly dependent on particle form, moisture, soil texture and rainfall. Crop responses are generally positive relative to nutrient-omission controls, yet superiority over balanced conventional fertilisation is inconsistent. Direct evidence for durable improvement of soil structure, organic carbon, biodiversity or multifunctionality remains limited; most studies assess post-harvest nutrient concentrations, pH, electrical conductivity or short-term enzyme and microbial indicators. The product’s chloride-free composition is useful for chloride-sensitive crops and some salinity contexts, but does not establish universal agronomic or environmental superiority. A substantial share of the evidence base involves manufacturer funding or authorship, reinforcing the need for independent, long-term, nutrient-balanced trials. Polyhalite can support sustainable agriculture when selected through soil testing, crop demand, rainfall risk and whole-rotation nutrient budgets, preferably as part of blended and adaptive nutrient management rather than as a stand-alone soil-health intervention.

Synthetic Seed and Encapsulation Technologies for Plant Propagules: A Critical Review of Biological Design, Storage Performance and Translational Readiness

2026-08-20T11:52:36+00:00

Synthetic seed technology seeks to convert clonally propagated plant material into discrete, handleable propagules that can be stored, transported and established with some of the operational advantages of true seed. The concept began with encapsulated somatic embryos but has expanded to shoot tips, axillary buds, nodal segments, microshoots, protocorm-like bodies and other regenerable tissues. This critical narrative review evaluates how that expansion has altered the biological meaning, engineering requirements and practical expectations of the technology. Literature from 1982 to 10 June 2026 was identified through accessible scholarly sources and citation tracing, with emphasis on peer-reviewed studies whose bibliographic identity and relevance could be verified. Evidence indicates that calcium-alginate encapsulation remains the dominant platform because ionotropic gelation is mild, inexpensive and readily adjustable, yet a capsule that is morphologically satisfactory is not necessarily biologically competent. Conversion depends jointly on propagule developmental state, matrix composition, mineral nutrition, plant growth regulator history, gas and water exchange, storage environment and the need for post-encapsulation rooting. Somatic embryos retain the closest functional analogy to zygotic seeds, whereas non-embryogenic propagules broaden genotype coverage but frequently preserve dependence on tissue-culture steps. Short- to medium-term storage is feasible in many species, but optimum temperature is not consistently low, and long-duration retention of conversion capacity remains strongly species- and protocol-dependent. Molecular-marker studies generally report clonal similarity after encapsulation, although reliance on limited RAPD or ISSR sampling constrains conclusions about genomic and epigenomic stability. The principal translational weakness is therefore not the ability to form beads, but the absence of standardised quality attributes linking capsule mechanics, physiological state, conversion probability, storage life, sanitation and cost. Future progress requires quality-by-design experiments, sensitive stability assays, non-sterile or direct-sowing validation, automation, and multi-laboratory performance testing. Synthetic seeds are best regarded as a configurable clonal propagule-delivery system rather than a universal replacement for botanical seed.

Knowledge and Skills of Maize Farmers in Accessing Smartphone-Based Agricultural Information in Selected Districts of Tamil Nadu, India

2026-08-29T09:04:47+00:00

This cross-sectional ex post facto study assessed maize farmers’ knowledge and self-reported operational skills in accessing smartphone-based agricultural information in selected areas of Tamil Nadu, India. Data were collected in June 2023 from 120 maize farmers in Perambalur and Cuddalore districts. The districts, blocks, and villages were purposively selected on the basis of maize-cultivation area, after which 30 farmers per block were selected by simple random sampling from local administrative or extension-office lists. Knowledge was assessed using a 30-item dichotomous index, and skill was assessed using a 30-item three-point index. Frequencies, percentages, and exploratory Pearson correlations were used for analysis.

Overall knowledge was classified as low for 75.00% of respondents, medium for 23.30%, and high for 1.70%. Among the selected items, knowledge was higher for downloading applications through Google Play Store, using Google Pay, and identifying the Uzhavan App than for agriculture-specific marketing, diagnostic, transport, and maize-information services. Overall skill was classified as low for 43.30% of respondents, medium for 27.50%, and high for 29.20%. Skills in basic smartphone functions, including taking photographs or videos and sending or receiving messages, were more common than those involving agricultural marketing platforms, crop-advisory services, and online registration for government schemes.

Educational status, scientific orientation, smartphone-ownership pattern, familiarity with smartphone use, and smartphone-utilisation pattern were positively associated with overall knowledge, whereas age was negatively associated. Overall skill was positively associated with educational status, annual income, exposure to agricultural messages, scientific orientation, smartphone-ownership pattern, smartphone familiarity, smartphone utilisation, and WhatsApp-group membership; age and occupational status were negatively associated. Because these findings are cross-sectional and based on bivariate correlations, they should be interpreted as exploratory associations rather than causal effects. The results support practical, locally adapted digital-literacy initiatives that move beyond smartphone ownership to develop farmers’ capacity to use agriculture-specific digital services.

Constraints in the Adoption of Improved Cultivation Practices among Green Leafy Vegetable Growers in Kalaburagi District, Karnataka, India

2026-09-10T12:45:05+00:00

Green leafy vegetables are important components of household nutrition and farm income in vegetable-growing areas. The present study assessed the socio-economic characteristics, adoption of improved cultivation practices and major constraints experienced by vegetable growers in Kalaburagi district of Karnataka. The survey was conducted during 2023-24 and 2024-25 in six vegetable-growing villages, namely Gobbur, Malli, Kadaganchi, Narona, Ashtaga and Jambaga, covering Afzalpur and Aland taluks. A sample of 130 farmers was selected through proportionate random sampling. Data were collected using a structured and pre-tested schedule and analysed through frequency and percentage. The results indicated that 66.0% of respondents belonged to the 41-50 years age group, 39.5% were illiterate, 72.0% had small families and 48.5% were classified as big farmers. Borewell irrigation was the major water source, reported by about 67.0% of respondents. Adoption was higher for improved varieties (86.0%), irrigation management (80.0%), quality seed use (72.5%), nutrient management in the nursery (70.0%) and recommended FYM and chemical fertiliser use (66.0%). Lower adoption was observed for disease management (40.0%), insect pest management (32.1%) and improved nursery-raising practices (14.0%). The major technical, economic and marketing constraints were pest and disease incidence, non-availability of labourers, irregular power supply, high input and labour costs, limited access to bank loans, commission agents and lack of price information. The study highlights the need for improved extension support, input access, irrigation planning and local marketing infrastructure.

Plant Growth-Promoting Rhizobacteria: Laboratory Advances and Field Applications through Formulation, Commercialization and Deployment Challenges

2026-09-12T09:57:08+00:00

Plant growth-promoting rhizobacteria (PGPR) are beneficial root-associated bacteria that can enhance plant performance through direct and indirect mechanisms. Their functions include biological nitrogen fixation, mobilization of poorly available nutrients, phytohormone modulation, siderophore-mediated iron acquisition, antimicrobial activity, induced systemic resistance and stress mitigation. Despite extensive evidence under controlled conditions, field performance remains inconsistent because inoculant efficacy depends on strain–plant compatibility, root colonization, soil and climatic conditions, interactions with resident microbiota, formulation stability, storage and application practices. This narrative review integrates established mechanisms of PGPR action with evidence on formulation, field performance, commercialization and deployment. Particular attention is given to carrier-based and liquid formulations, encapsulation and emerging nano-enabled delivery systems, while distinguishing demonstrated benefits from technologies that remain primarily experimental. The review also examines biosafety, regulatory and adoption constraints and identifies priorities for developing PGPR products with reproducible field efficacy and practical value in sustainable agriculture.