‘Sikkim Primitive’ (SP) maize locally known as ‘murali makkai’ in Sikkim is a unique genetic resource exhibiting prolificacy and excellent popping capacity. Status of SP has reached extinction level due to its very small population size and neglected conservation efforts in-situ. In an initial effort to conserve and revive this landrace, characterization and documentation was carried out with 31 morphologically assayed traits recorded at different growth stages along with molecular characterization with simple-sequence repeat (SSR) markers. Plants exhibited prolificacy (5–6 cobs/plant) and excellent popping capacity along with other distinct traits. Plants were tall with thin stem, loose drooping tassel with anthocyanin coloration present at the base of glumes and in brace roots. Cobs were medium sized carrying small seeds with low test weight (87.90 g). A total of 22 SSR markers show amplification in murali makkai with markers bnlg1083, umc1353, umc1128, bnlg1017, bnlg2077, umc2298 and umc2373 amplified unique amplicons ranging from 100 to 800 bp. The characterized set of traits and molecular characterization for murali makkai will facilitate in utilization for genetic improvement and maintenance of genetic purity.

Artifacts, including ceramics, ground stone, and soil samples, as well as dental calculus, recovered from sites in the eastern North American central Plains were submitted to multiple laboratories for analysis of microbotanical remains. Direct accelerator mass spectrometer (AMS) dates of 361–197 cal BC provide evidence for the earliest use of maize (Zea mays ssp. mays) in this region. Squash (Cucurbita sp.), wild rice (cf. Zizania spp.), and palm (Arecaceae sp.) microremains were also found. This research adds to the growing evidence of the importance of microbotanical analysis in documenting plant use and in the identification of early maize. The combined data on early maize from the eastern Plains adds to our understanding of the timing and dispersal of this crop out of the American Southwest. Alternative explanations for the adoption and early use of maize by eastern central Plains communities include its value as a secondary resource, as an addition to an existing farming strategy, or as a component of Middle Woodland rituals.

The Meadowcroft Rockshelter in southwestern Pennsylvania is best known for its pre-Clovis occupation. Potentially important for later times is the recovery of maize macrobotanical remains from higher strata dating as early as the 4th century BC based on radiometric radiocarbon (14C) dates on wood charcoal. These remains have been considered to be potentially as old as the earliest microbotanical evidence for maize in Michigan, New York and Québec recovered from directly dated charred cooking residues adhering to pottery. The results of accelerator mass spectrometry (AMS) dating 17 samples from maize specimens from all Meadowcroft strata producing maize, indicate that the specimens originated from historical use of the shelter, most likely after AD 1800. These results further emphasize the need to obtain direct dates on maize macrobotanical remains recovered from early contexts prior to the development and common use of AMS dating.

The spatio-temporal variation of leaf chlorophyll content is an important crop phenotypic trait that is of great significance for evaluating crop productivity. This study used a soil-plant analysis development (SPAD) chlorophyll meter for non-destructive monitoring of leaf chlorophyll dynamics to characterize the patterns of spatio-temporal variation in the nutritional status of maize (Zea mays L.) leaves under three nitrogen treatments in two cultivars. The results showed that nitrogen levels could affect the maximum leaf SPAD reading (SPADmax) and the duration of high SPAD reading. A rational model was used to measure the changes in SPAD readings over time in single leaves. This model was suitable for predicting the dynamics of the nutrient status for each leaf position under different nitrogen treatments, and model parameter values were position dependent. SPADmax at each leaf decreased with the reduction of nitrogen supply. Leaves at different positions in both cultivars responded differently to higher nitrogen rates. Lower leaves (8th–10th positions) were more sensitive than the other leaves in response to nitrogen. Monitoring the SPAD reading dynamic of lower leaves could accurately characterize and assess the nitrogen supply in plants. The lower leaves in nitrogen-deficient plants had a shorter duration of high SPAD readings compared to nitrogen-sufficient plants; this physiological mechanism should be studied further. In summary, the spatio-temporal variation of plant nitrogen status in maize was analysed to determine critical leaf positions for potentially assisting in the identification of appropriate agronomic management practices, such as the adjustment of nitrogen rates in late fertilization.

Acacia dealbata Link is one of the main invasive species in southwestern Europe and a resource with potential value for agriculture. Our objective was to assess the value of A. dealbata vegetative aerial biomass used as green manure and as a tool for weed control in maize crops through three sequential experiments. In 2017, an experiment was carried out with acacia green manure vs inorganic fertilization of pots sown with a field corn and a sweet corn hybrid with strong and weak nutrient demand, respectively. Nutrients were not released from acacia green manure at an appropriate timing, and maize suffered nutrient deficit. In 2018, a pot experiment was made outdoors incorporating acacia green manure at different times before maize sowing, and we found that a 4-month period was required for maximum nutrient release from acacia green manure. In 2019, an early and a late-field experiments were performed by incorporating acacia green manure 4 months before maize sowing. Physiological and agronomic data were recorded in maize, along with soil data, for all years, and weed data the last year. Altogether, most effects and interactions between genotype or environment and fertilization treatment were not significant, and some deficiencies caused by acacia green manure fertilization depend on genotype and environment. Incorporation of acacia green manure 4 months before maize sowing partially controlled weeds and replaced inorganic fertilization. However, deficiencies should be corrected with additional weed control practices and fertilization treatments, according to the nutrient demand of the crop and the soil environment.

The potential yield of improved maize varieties usually cannot be fully realised mainly due to inappropriate soil nutrient management practices in most parts of Ethiopia. Site-specific fertiliser recommendations are rarely used in the farming systems of Ethiopia. There is also a lack of data to develop or validate decision support tools for targeting specific crop production. A study was conducted for three consecutive rainy seasons (2016–2018) in the maize belt of the north-western parts of the Amhara National Regional State of Ethiopia. The objectives were to obtain the maximum achievable yield potential of maize, determine the most yield-limiting nutrients and create a database of maize responses to applied nutrients so that decision support tools could be developed for the study areas. Treatments were individual nutrients (nitrogen (N), phosphorus (P) and potassium (K)) and combinations of the three. In some treatments, NPK was also combined with sulphur, zinc, lime and compost. Two hybrid maize varieties (BH-540 and BH-660) adaptable to the study areas were used. BH-540 was used for the Mecha district, while BH-660 was used for the south Achefer, Jabitahnan–Burrie–Womberma districts. Maize yield increased by more than 50% due to fertiliser applications compared to without fertiliser. The study showed that the possibility of increasing maize productivity to more than 12 t ha-1 for the study sites. The most yield-limiting nutrient in the study sites was N, followed by P; K was not a yield limiting. Without N the yield of both varieties was non-significant from the control (without added nutrients). Maize grain yield did not respond to application of lime, compost, zinc and sulphur. The result also showed very high variability across sites, indicating that it is important for policymakers, farmers and investors to consider site-specific fertiliser recommendations. Finally, a database containing intensive plant response to NPK for maize was generated and could be used as input in site-specific decision support tools development.

The establishment of plants in an ecosystem is limited by the availability of seeds and the availability of suitable sites for establishment. Describing plant population dynamics through the relative strength of seed and establishment limitation is an important concept in the study of natural ecosystems. To date, it is unclear whether this concept can be applied to describe populations of annual weeds in agricultural fields. Using a recruitment function, we show that limitation parameters prove valuable in describing seedling recruitment in weed populations. We conducted a seed addition experiment in three cornfields (Zea mays L.) and recorded seedling recruitment in populations of the economically important weed barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.]. Seed predation, competition with other weeds, and seed burial were prevented. We estimated the strength of seed and establishment limitation in the population with two parameters: n, which is the number of microsites, and b, which is the suitability of those sites to support a seedling. We further estimated the relative proportions of density-dependent and density-independent establishment limitation in the seedling population. Recruitment rates of E. crus-galli ranged from 31% to 36% across all evaluated seed densities and fields, which is high compared with results from other seed addition studies. Two of the three monitored populations were predominantly establishment limited at the highest evaluated seed density of 2,400 added seeds m−2. Further knowledge about the relative strength of limitations in other weed populations will provide important information on how effective different weed management strategies can be.

Insect crop pests are a major threat to food security in sub-Saharan Africa. Configuration of semi-natural habitat within agricultural landscapes has the potential to enhance biological pest control, helping to maintain yields whilst minimising the negative effects of pesticide use. Fall armyworm (Spodoptera frugiperda, J. E. Smith) is an increasingly important pest of maize in sub-Saharan Africa, with reports of yield loss between 12 and 45%. We investigated the patterns of fall armyworm leaf damage in maize crops in Ghana, and used pitfall traps and dummy caterpillars to assess the spatial distribution of potential fall armyworm predators. Crop damage from fall armyworm at our study sites increased significantly with distance from the field edge, by up to 4% per m. We found evidence that Araneae activity, richness and diversity correspondingly decreased with distance from semi-natural habitat, although Hymenoptera richness and diversity increased. Our preliminary findings suggest that modifying field configuration to increase the proximity of maize to semi-natural habitat may reduce fall armyworm damage and increase natural enemy activity within crops. Further research is required to determine the level of fall armyworm suppression achievable through natural enemies, and how effectively this could safeguard yields.

Maize is one of the three staple foods in the world. The white variety represents 60% of the maize importation with a world consumption of 1125 million tons in 2019/2020. Currently, new technologies could contribute to the analysis of this seed, supporting quality control and improvement. This study aims to carry out the morphological and proteomic comparison between the hybrid MR2008 and its parental lines LUG03 and CML491 through mass spectrometry and bioinformatics analysis. Herein, we identified that 34.8% of the hybrid proteome differs from the parental proteome. Also, ontological and morphological analyses determined that the hybrid exhibits more characteristics related to CML491 than LUG03, for example, metabolic pathways and enzymes, such as anthocyanidin 3-O-glucosyltransferase (UniProt P16166). This analysis allowed the identification of dominant characters, metabolic pathways and confirms the utility of this methodology in agricultural practices, mainly in processes of selection and quality control of a crop.

The extent of the reduction of maize (Zea mays L.) kernel moisture content through drying is closely related to field temperature (or accumulated temperature; AT) following maturation. In 2017 and 2018, we selected eight maize hybrids that are widely planted in Northeastern China to construct kernel drying prediction models for each hybrid based on kernel drying dynamics. In the traditional harvest scenario using the optimal sowing date (OSD), maize kernels underwent drying from 4th September to 5th October, with variation coefficients of 1.0–1.9. However, with a latest sowing date (LSD), drying occurred from 14th September to 31st October, with variation coefficients of 1.3–3.0. In the changed harvest scenario, the drying time of maize sown on the OSD condition was from 12th September to 9th November with variation coefficients of 1.3–3.0, while maize sown on the LSD had drying dates of 26th September to 28th October with variation coefficients of 1.5–3.6. In the future harvest scenario, the Fengken 139 (FK139) and Jingnongke 728 (JNK728) hybrids finished drying on 20th October and 8th November, respectively, when sown on the OSD and had variation coefficients of 2.7–2.8. Therefore, the maize kernel drying time was gradually delayed and was associated with an increased demand for AT ⩾ 0°C late in the growing season. Furthermore, we observed variation among different growing seasons likely due to differences in weather patterns, and that sowing dates impact variations in drying times to a greater extent than harvest scenarios.

Dietary studies can offer insight into the effects of imperial rule on colonised populations. Inka expansion was associated with change in agricultural production and diet, including greater emphasis on maize. This article presents stable isotope analyses of ten individuals from two locations in Antofagasta de la Sierra, Argentina. AMS dating assigns one site to the start of the Inka period and one to the end. Despite diachronic changes in material culture, isotope analyses indicate that maize remained relatively unimportant in local diet. Given the symbolic value of maize in the Inka world, this lack of dietary change suggests limited imperial influence over local agricultural production and diet.

In the following response to Hart and colleagues (2021) we clarify our interpretations of the archaeological record for maize use from western Illinois. The robust archaeological record, newly obtained AMS dates, and evaluations of enamel apatite combine to support a late date for maize cultivation in this region. We reiterate that maize histories in the Eastern Woodlands may vary among different regions.

Accelerated mass spectrometry (AMS) and carbon isotope analyses provide strong tandem methodologies used by archaeologists to evaluate and reevaluate the histories of maize use in the Midwest. In this article, we present newly obtained AMS dates and carbon isotope assays of alleged maize samples from the Icehouse Bottom (40MR23) and Edwin Harness sites (22RO33). Based on original studies, samples were thought to date to the Middle Woodland period (ca. 300 BC–AD 400). The results show that samples either were not maize or date to post-AD 900. As of this finding, there are no longer any securely dated Middle Woodland macrobotanical remains of maize from the Eastern Woodlands of North America.

How can agricultural mechanization be accomplished in a sustainable and equitable way? This question has gained increased prominence in mechanization research over the past few years. In this study, we apply the question to mechanized maize shelling in Tanzania as a case in point. Data from a survey with 400 farmers and from semi-structured interviews with 21 key informants are combined for a gender analysis that relies on Kabeer's concept of four institutional sites (household, community, market and government). The findings reveal that although mechanization reduces men's and women's perceived drudgery of shelling, relief depends on gendered patterns of labor allocation and decision-making at the household level. As a result, the transformation of inequitable norms emerges as paramount. Key informants identified additional aspects that would make mechanized shelling more equitable and sustainable, such as mainstreaming gender and mechanization in comprehensive agricultural training, or the sensitization of mechanized input suppliers and manufacturers to farmers' preferences (including gender-sensitive machine design). Concerted efforts in multiple institutional sites are needed to achieve lasting change in respect of equity in mechanization.

The corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae), a specialist herbivore, is the cause of serious losses in maize yield for its capacity to transmit three important plant pathogens. They are also active phloem feeders, that insert stylets into the plant as they feed. Females place their eggs endophytically, totally inserted in the central midrib or the leaf blades, leaving conspicuous openings in the place where the ovipositor was inserted. In spite of the consequences that feeding and oviposition may have on the water status of the plant and the production of biomass, direct damage caused by the leafhopper has been only scarcely studied. In the present contribution, we measured biomass loss due to direct damage in maize plants under two watering regimes, with water supply ad libitum and with a watering restricted regime, emulating the most frequent field conditions. Moreover, we analyzed the effects of increasing densities of the vector on the biomass loss and plant mortality and the effects of females vs males. We observed that a density of 10 insects is sufficient to cause damage to 10-day-old seedlings, even in an ad libitum watering regime; however, in drought conditions, damage can be significantly greater, causing plant mortality. Also, females cause more damage than males, due to their oviposition habits.

Soil suppressiveness which is the natural ability of soil to support optimal plant growth and health is the resultant of multiple soil microbial components; which implies many difficulties when estimating this soil condition. Microbial benefits for plant health from repeated digestate applications were assessed in three experimental sites surrounding anaerobic biogas plants in an intensively cultivated area of northern Italy. A 2-yr trial was performed in 2017 and 2018 by performing an in-pot plant growth assay, using soil samples taken from two fields for each experimental site, of which one had been repeatedly amended with anaerobic biogas digestate and the other had not. These fields were similar in management and crop sequences (maize was the recurrent crop) for the last 10 yr. Plant growth response in the bioassay was expressed as plant biomass production, root colonization frequency by soil-borne fungi were estimated to evaluate the impact of soil-borne pathogens on plant growth, abundance of Pseudomonas and actinomycetes populations in rhizosphere were estimated as beneficial soil microbial indicators. Repeated soil amendment with digestate increased significantly soil capacity to support plant biomass production as compared to unamended control in both the years. Findings supported evidence that this increase was principally attributable to a higher natural ability of digestate-amended soils to reduce root infection by saprophytic soil-borne pathogens whose inoculum was increased by the recurrent maize cultivation. Pseudomonas and actinomycetes were always more abundant in digestate-amended soils suggesting that both these large bacterial groups were involved in the increase of their natural capacity to control soil-borne pathogens (soil suppressiveness).

The cover crops Mucuna pruriens var. utilis and Pueraria phaseoloides were introduced to African farmers to improve crop production on degraded soils, yet they appear not to be adopted at scale. In the humid forest zone of West and Central Africa, the dominant Acrisols and Nitisols are inherently poor even when not degraded through agriculture. In this zone, sole maize cropping and vegetable production systems are gaining importance, yet both suffer from nutrient deficiencies. Cover crops were often introduced along with a system change, requiring biomass retention, mainly for nutrient retention reasons. Farmers in the zone commonly use slash and burn systems due to added weed control and ease of operations on clean fields. This study evaluated mucuna and pueraria with and without burning the fallow biomass in an annual sole maize crop relay system against the burned and retained natural fallow. Over 14 consecutive years, biomass burning did not cause lower maize grain yields in any of the fallow types, on the contrary, the economically important marketable cob yields were higher when biomass was burned (mulched 2.10 cobs m−2 vs. 2.26 cobs m−2 when burned, p < 0.07). After cover crop fallow, maize grain yields were significantly higher than after natural fallow (1.92 Mg ha−1) over the 14 years, with maize yields in the pueraria treatment (2.63 Mg ha−1) out yielding those in the mucuna treatment (2.28 Mg ha−1). Maize produced 1.92 cobs m−2 in natural fallow, significantly less than in the mucuna (2.23 m−2, p < 0.013) and the pueraria (2.39 m−2, p < 0.001) fallow. Introducing mucuna or pueraria cover crops into slash and burn systems appears as a suitable measure to increase yields without changing the land preparation approach.

The current study focused on characterization of the underlying genetic divergence in inbred lines developed from local landraces of North Eastern Hill Region of India – a designated Asiatic maize diversity centre – following six generations of inbreeding. Substantial genetic differentiation was indicated based on very high to moderate Fst values for 22 of the 38 simple sequence repeat markers studied. STRUCTURE analysis partitioned the subset into two distinct and one admixture subgroup (Populations I, II and III respectively) accompanied by a significant reduction in heterozygosity. Population II was further subdivided into subpopulations Pop-M9 and Pop-T9. Nei's pairwise genetic distance and population Fst values indicated that Populations I and II were more divergent with neighbour joining clustering analysis clearly defining landraces originating from the states of Tripura (Population II) and Sikkim (Population I) as most divergent. Principal coordinates analysis could explain 31.26% of the variation present in the subgroups wherein Population I was more variable. Analysis of molecular variance and Fst coefficients (P < 0.001) indicated 17% population structuring with 55% variation detected for individuals within populations. These results combined with the presence of phenotypic variability in the subgroups for yield traits supported by results of a preliminary partial diallel analysis strongly suggest the existence of distinct heterotic groups. Divergence studies are crucial for exploiting heterosis, and the current study would go a long way to help establish a germplasm base for developing varieties with improved agronomic performance and surer commercial prospects no reports of which are available thus far.

Polyhalite is a multi-nutrient mineral ore containing potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S). Historically, it has enjoyed minor use as a fertilizer, but the opening of a new mine in the UK will make larger quantities available. Therefore, an examination of the performance of crops fertilized with polyhalite, or selected commercial alternatives, was pertinent and is reported here.

Four field trials were carried out between 2013 and 2016 to investigate the response of winter barley (Hordeum vulgare L.) and forage maize (Zea mays L.) to different application rates of polyhalite, potassium chloride (muriate of potash, MOP) and potassium sulphate (sulphate of potash, SOP) fertilizers. Potassium and S nutrition were the focus of these trials as they limit field production more often than Mg and Ca.

Polyhalite was found to be an effective source of both K and S for crop production. In three out of four trials, application of polyhalite resulted in similar or greater K offtake compared with both MOP and SOP; MOP application resulted in greater K offtake in one trial. In three out of four trials, application of polyhalite resulted in similar or better S offtake compared with both MOP and SOP; SOP application resulted in greater S offtake in one trial. Polyhalite and MOP treatments produced similar total dry weight in all four trials, but were slightly inferior to SOP treatment.

Understanding the effects of crop management practices on weed survival and seed production is imperative in improving long-term weed management strategies, especially for herbicide-resistant weed populations. Kochia [Bassia scoparia (L.) A.J. Scott] is an economically important weed in western North American cropping systems for many reasons, including prolific seed production and evolved resistance to numerous herbicide sites of action. Field studies were conducted in 2014 in a total of four field sites in Wyoming, Montana, and Nebraska to quantify the impact of different crop canopies and herbicide applications on B. scoparia density and seed production. Crops used in this study were spring wheat (Triticum aestivum L.), dry bean (Phaseolus vulgaris L.), sugar beet (Beta vulgaris L.), and corn (Zea mays L.). Herbicide treatments included either acetolactate synthase (ALS) inhibitors effective on non-resistant B. scoparia or a non–ALS inhibiting herbicide effective for both ALS-resistant and ALS-susceptible B. scoparia. Bassia scoparia density midseason was affected more by herbicide choice than by crop canopy, whereas B. scoparia seed production per plant was affected more by crop canopy compared with herbicide treatment. Our results suggest that crop canopy and herbicide treatments were both influential on B. scoparia seed production per unit area, which is likely a key indicator of long-term management success for this annual weed species. The lowest germinable seed production per unit area was observed in spring wheat treated with non–ALS inhibiting herbicides, and the greatest germinable seed production was observed in sugar beet treated with ALS-inhibiting herbicides. The combined effects of crop canopy and herbicide treatment can minimize B. scoparia establishment and seed production.