Maize Grain Research Articles

Insecticidal toxicity of essential oil of Nepalese Acorus calamus (Acorales:Acoraceae) against Sitophilus zeamais (Coleoptera:Curculionidae)

Maize weevil (Sitophilus zeamais) (Coleoptera:Curculionidae) is an economic stored grain pest that causes significant damage to various stored products, including maize (Zea mays). In this study, we extracted essential oil from the rhizome of sweet flag (Acorus calamus) (Acorales:Acoraceae) by hydro-distillation and tested insecticidal property of the oil at 7 concentrations (10, 5, 2.5, 1.25, 0.625, 0.3125, 0.15625 and control) against maize weevil (Sitophilus zeamais) at the National Entomology Research Center, Nepal Agricultural Research Council in the year 2020/2021. Three different experiments were conducted: scintillating vial bioassay, repellency test, and exposing weevils to oil treated maize grains. Scintillating vial bioassay showed that higher the concentration of essential oil, lower the time required to cause 50 % maize weevil mortality. Median lethal concentration (LC50) at 3 and 24 h was calculated as 2.29 and 0.16 % of oil concentration in scintillating vial bioassay. When oil is treated to maize grain, LC50 for 10 and 16 days was calculated as 2.77 and 0.23 % of oil concentrations. In the same way, at 10 % concentration maize weevil showed highest repellent activity (98.75 %) as compared to 5, 2.5 and 1.25 % concentrations after 24 h of treatment. Weight loss and grain damage were significantly less in the oil treatments than the control. However, from the perspective of health benefits, Acorus calamus treated maize is still questionable for feed and food purpose. As β asarone has carcinogenic effects at certain level, it needs further residue tests of treated maize to know allowable maximum residue limit (MRL) before consumption as food or feed.

Comparison of different machine learning algorithms for predicting maize grain yield using UAV-based hyperspectral images

Comparison of different machine learning algorithms for predicting maize grain yield using UAV-based hyperspectral images

EFFECT OF DRIP IRRIGATION WITH FOLIAR DRESSING OF MINERAL FERTILIZER KRISTALON AND THEIR IMPACT ON MAIZE GRAIN YIELD IN SOUTHERN KAZAKHSTAN

Nowadays, drip irrigation is a promising technology for optimizing plant development conditions and allowing the introduction of necessary nutrients to plants. The study aimed to establish the effects of drip irrigation with various levels of foliar dressing of mineral fertilizer Kristalon on maize (Zea mays L.) and achieve its maximum genetic potential for grain yield to enhance overall production. A field experiment implies exploratory research and quantifies the effects of drip irrigation with foliar Kristalon dressing to validate and introduce scientific achievements in agricultural production. Various technological methods applied to corn cultivation sought to increase its green mass and yield. In the experimental treatments, the corn crop irrigation engaged drip irrigation with different foliar dressings of Kristalon in the phases of the 5th and 11th tillering leaf and stem elongation with the norms of 2, 4, and 6 kg Kristalon ha-1, respectively, in comparison with the control treatment (no Kristalon foliar dressing). Corn foliar treatment with fertilizer Kristalon preparation with a norm of 2, 4, and 6 kg ha-1 produced grain yields of 11.43, 12.27, and 12.33 t ha-1, respectively, compared with the control treatment (9.67 t ha-1). The fertilizer Kristalon at 2, 4, and 6 kg ha-1 produced 18.2%, 26.9%, and 27.5% more grain yield than the control. However, the Kristalon foliar dressing at 6 kg ha-1 did not significantly increase the maize grain yield, and there was an increase of 0.6% compared with the 4 kg ha-1 level. Therefore, corn foliar dressing with fertilizer Kristalon at 4 kg ha-1 is an option for better production under the environmental conditions of South Kazakhstan.

Do intercropping and mineral nitrogen fertilizer affect weed community structures in low-input maize-based cropping systems?

Weeds are a major threat to crop growth in sub-Saharan Africa (SSA), particularly in low-input cropping systems. We investigated the effect of different cropping systems and nitrogen fertilizer on weed infestation during the 2017/18 and 2018/19 cropping seasons in Goromonzi district, Zimbabwe. The objectives of this study were to (1) determine if and how weed composition and structure are affected by intercropping maize with either an improved or landrace cowpea variety compared to sole crops of maize and of improved or landrace cowpea; (2) if and how weed composition and structure are affected by nitrogen fertilization; and (3) how the subsequent changes in weed infestation affect grain yield. Weed parameters were measured at different dates during the cropping cycle, and grain yield was measured at harvest. Significant differences were observed for the density of the 21 weed species collected in two seasons; seven of these weed species had a relative density exceeding 5%. Significantly more weeds were recorded in sole maize compared to sole cowpea. Intercropping significantly reduced the density of C. benghalensis. In sole crops, application of mineral nitrogen fertilizer significantly affected weed density, diversity, richness, and groundcover. Maize grain yield was independent of weed biomass and density, in both sole crops and intercrops. However, increase in weed biomass significantly reduced cowpea yield. Our results suggest that growing sole cowpea reduces weed infestation, therefore, cowpea should be considered as one of the options for effective weed control in subsistence farming communities, where access to herbicides is lacking.

EFFECTS OF ELEVATED PLANT DENSITY AND REDUCED NITROGEN ON AGRONOMIC AND YIELD ATTRIBUTES OF MAIZE INBRED LINES AND THEIR DIALLEL CROSSES

Elevating plant density and improving N fertilizer rate for high density-tolerant genotype can maximize maize (Zea mays L.) grain productivity per unit land area. This investigation’s objective sought to evaluate the effects of stresses resulting from increasing plant density combined with reducing N application rate on traits of eight inbred lines and their diallel F1 crosses. Choosing eight maize inbred lines differing in tolerance to low N and high density (D) were samples for diallel crosses. Parents and crosses’ evaluation ensued in the 2020 and 2021 seasons under three plant densities: low (47,600), medium (71,400), and high (95,200) plants/ha, and three N fertilization rates: low (95 kg N/ha), medium (285 kg N/ha), and high (476 kg N/ha). Elevating plant density from 47,600 to 71,400 and 95,200 plants/ha caused a significant decrease in grain yield/plant by 25.43% and 30.15% for inbred parents and 17.92% and 25.65% for F1 crosses, respectively. This reduction correlated with significant decreases in all yield components but caused a notable increase in grain yield/ha by 13.69% and 27.33% for inbreds and 20.99% and 44.69% for F1 crosses, respectively. The best combination of plant population density and N level for giving the highest grain yield/ha was high N (476 kg N/ha) × high density (95,200 plants/ha) for all inbreds and all F1 crosses.

Effects of planting date, environments and their interaction on grain yield and quality traits of maize hybrids

Maize is one of the most important staple food crops for most low-income households in the Southern African region. Erratic and inconsistent rainfall distribution across maize-growing areas is a major threat to maize production. Late rains in recent years have forced farmers to plant later than the optimal planting dates, leading to poor maize quality being reported by industry, which raised the question of the influence of later planting dates on grain yield and quality traits of maize. Three yellow and three white maize hybrids were evaluated at three planting dates in three different production environments for three consecutive seasons using a randomized complete block design with three replications. The second and third planting dates caused a significant yield decrease of 23.37 % and 53.73 % from the first planting date across environments, respectively. Planting date three was associated with decreased grain yield, starch content, and increased protein but no significant change in fat and fiber content. Some hybrids yielded relatively well at all planting dates. In conclusion, the early planting date was the most suitable for maize grain yield and starch production in the maize-growing areas of the country. However, planting in January should be avoided at all costs, as it leads to very low yield and poor grain quality.

Phytochemicals reduced growth, sporulation and conidial dimensions of Fusarium verticillioides, cause of fumonisin contamination in maize grains

The objective of the study was to evaluate the effectiveness of methanolic extracts of plants against radial growth and spore dimensions of Fusarium verticillioides. Leaf extracts of 25 plants were tested against the fungus. Of which, thirteen extracts were potent against the fungus and evaluated using food poising technique. Growth was evaluated on PDA medium amended with the extracts at 5 mg ml–1. Control treatments included plates without (negative) extracts and with synthetic (positive) fungicide. Spore dimension was determined using PDB. The results showed T. vulgaris extract completely inhibited mycelial growth of the fungus as equivalent as the fungicide. Similarly, G. parviflora, C. citratus, R. officinalis, R. chalepensis, and Agave sp. also recorded growth reductions ranging from 71.04 to 81.35 % at day seven. In addition, extracts of Agave sp., C. citratus and T. vulgaris did not support sporulation. Overall, the results indicate that T. vulgaris extracts could be safe source of bioactive chemicals to control F. verticillioides.

Bird-of-paradise, thorn apple and maize pollens are promising alternative diets for the long-term rearing of predatory mite Amblyseius swirskii (Acari: Phytoseiidae)

Pollen grains can provide important nutrients for reproduction of different predators such as phytoseiid mites. Since mass rearing of phytoseiid predatory mites may be facilitated by feeding on alternative diets, the current study evaluated the utility of plant pollen as diet for mass rearing of the predatory mite Amblyseius swirskii Athias-Henriot, which is a commercially available biocontrol agent of phytophagous mites and insects. Demographic parameters of A. swirskii fed on pollens of bird-of-paradise (Caesalpinia gilliesii), thorn apple (Datura stramonium), and maize (Zea mays) were determined over 10 continuous generations. In addition, the pollens of common hibiscus (Hibiscus syriacus), and velvetleaf (Abutilon theophrasti) were assessed, but the predatory mite was unable to reach adulthood when fed on these pollens, and most of them died in nymphal stages. This study also evaluated the preying ability of A. swirskii on the natural prey Tetranychus urticae Koch before and after 10 generations. All experiments were conducted in the laboratory under controlled conditions of 25±1°C, 60±5% RH, and a photoperiod of 16:8 (L: D) h. According to the life table parameters, the pollen grains of bird-of-paradise, followed by maize and thorn apple, were shown to be promising diets for the long-term rearing of A. swirskii. Furthermore, the study found that A. swirskii reared on bird-of-paradise pollen had a high predation capability, with a mean of 677 prey per generation after 10 generations. Overall, it is concluded that while bird-of-paradise pollen was the most suitable alternative diet for the predatory mite, both maize and thorn apple pollen grains were also found to be promising diets for A. swirskii. These diets can be used for mass rearing of this predatory mite.

Maize-legume intercropping and botanical Piper mitigating effect on pest populations while enhancing the yield of maize

Climate change poses a wave of pests, devastating crops and jeopardizing the quest to feed more than 8 billion people globally. This can be seen in fall armyworm and snails being a nightmare to maize productivity. Thus this study was set up to increase maize productivity by reducing maize pests (FAW and snails) in maize-legume intercropping with locally produced organic (botanical) insecticide and utilizing legume nitrogen-fixing ability for maize growth and production. This work was done at the University of Buea and had nine treatments, and each was replicated three times in a randomized complete block design. The main crop maize, was intercropped with beans and cowpea. Data on fall armyworm incidence and severity, snail incidence and severity, height of plant, leaf number, girth of stem, leaf area index, and maize grain dry weight were collected. Data was subjected to ANOVA, P < 0.05, using SPSSv26 and graphs drawn with excel. More damaged plants for FAW and snails occurred in control, 14, and 11 plants, respectively, and were significantly different (P < 0.05) among treatments. The most pests were recorded in control 4 FAW and 3 snails per plant which varied statistically (P <0.05). Maize growth parameters (height of plant, leaf number, girth of stem, leaf area index) differed significantly (P < 0.05) across treatments, with control recording the least (206 cm, 13, 7.4 cm and 641 cm2 respectively). The best results were obtained with an intercrop of maize and cowpea along with synthetic or Piper pesticide. (236.4 cm, 16, 10.6 cm and 730.6 cm2 respectively) with no statistical difference. The highest maize yield was recorded in maize+cowpea intercrop coupled with Piper or synthetic insecticide (6.13 and 5.93 t/ha, respectively), with significant (P < 0.05) difference. Plant damage was connected adversely with yield (r = −0.90 for FAW, r = −0.94 for snail) and favourably with the number of pests (r = 0.70 for FAW, r = 0.86 for snail). ConclusionIntercropping and Piper emulsion effectively managed maize pests, while boosting maize output. As a result, farmers can utilize this maize-dwarf bean and maize-cowpea intercrop, as well as the organic Piper emulsion approach, as a sustainable crop protection and fertilizer management strategy to increase production.

Dynamics of carbon budget and meteorological factors of a typical maize ecosystem in Songnen Plain, China

Aim of study: Understanding the carbon budget and meteorological factor impacts of farmland ecosystems is helpful for scientific assessment of carbon budget and low-carbon agricultural production practices. Area of study: The Songnen Plain, NE China, in 2019. Material and methods: Based on eddy-related flux and soil heterotrophic respiration observations from a typical maize farmland ecosystem, using mathematical statistics and carbon balance equation methods, were analyzed. Main results: Soil respiration rate (Rs) and composition were influenced and controlled by the synergistic effect of surface soil temperature (Ts) and water content (Wcs). Ts played a leading role, while Wcs played an important role. Ts and Wcs had the greatest influence on the heterotrophic respiration rate (Rh), followed by Rs and autotrophic respiration rate (Ra). Daily variations of net ecosystem productivity were correlated with daily mean air temperature, latent heat flux, and sensible heat flux. Annual carbon revenue was 1139.67 g C m-2, annual carbon expenditure was 456.14 g C m-2, and annual carbon budget was -683.53 g C m-2 in 2019. While considering that maize grain yield (-353.44 g C m-2) was moved out of the field at harvest, the net ecosystem carbon balance was -330.09 g C m-2; then it was carbon sink in 2019. By fully utilizing climate resources and improving agricultural managements, carbon sink is increased in farmland ecosystems. Research highlights: Soil respiration rate and composition were influenced and controlled by the synergistic effect of soil temperature and water content; the maize farmland ecosystem is carbon sink.

Effects of conservation practices on rainfed maize yield, furrow water infiltration, and soil moisture for surface sealing loam soils in the Yazoo‐Mississippi Delta

AbstractDecades of intense tillage have created the problem of surface sealing in loam soils across the Mid‐South United States and beyond. These soils exhibit low organic matter, poor aggregate stability, and ultimately low infiltration rates that decrease rainfed crop productivity and increase irrigation water demand. This research quantified the effects of soil management practices on rainfed maize (Zea mays L.) yield, furrow water infiltration, and soil moisture in Commerce very fine sandy loam and silt loam near Stoneville, MS. The six treatments included conventional tillage (CT), cereal rye (CR; Secale cereale L.), furrow diking (FD), no‐till (NT), polyacrylamide (PAM), and subsoiling (SS). No other treatment achieved a significantly higher maize grain yield than the CT control treatment in both years consistently. Single‐ring infiltrometer results indicated no significant differences among CT, CR, PAM, and SS in 2022 and between CT and NT in 2021. Neutron attenuation found that total soil water within the top 1 m was not significantly different among CT, FD, and SS on any of the eight measurement dates throughout the 2022 maize reproductive period. However, soil moisture was numerically lower for FD in the late reproductive stages. These findings suggest that environmental factors and other agronomic operations may counteract conservation practices, limiting their effectiveness at reducing irrigation requirements to mitigate groundwater depletion in the Mississippi River Valley Alluvial Aquifer.

Subchronic feeding study of glyphosate-tolerant maize GG2 with the gr79-epsps and gat genes in Wistar Han RCC rats

The genetically modified (GM) maize GG2 contains gr79-epsps and gat genes, conferring glyphosate tolerance. The present study aimed to investigate potential effects of maize GG2 in a 90-day subchronic feeding study on Wistar Han RCC rats. Maize grains from GG2 or non-GM maize were incorporated into diets at concentrations of 25% and 50% and administered to Wistar Han RCC rats (n = 10/sex/group) for 90 days. The basal-diet group of rats (n = 10/sex/group) were fed with common commercialized rodent diet. Compared with rats fed with the corresponding non-GM maize and the basal-diet, no biologically relevant differences were observed in rats fed with the maize GG2, according to the results of body weight/gain, feed consumption/utilization, clinical signs, mortality, ophthalmology, clinical pathology (hematology, prothrombin time, urinalysis, serum chemistry), organ weights, and gross and microscopic pathology. Under the conditions of this study, these results indicated that maize GG2 is as safe as the non-GM maize in this 90-day feeding study.

Effects of Phosphate Application Rate on Grain Yield and Nutrition Use of Summer Maize under the Coastal Saline-Alkali Land

Saline-alkali soil is a major threat to global food security. Phosphorus (P) fertilizer is essential for crop growth and yield production. Nevertheless, the optimal phosphate fertilizer application rates for summer maize under coastal saline–alkali soil are still unclear. A field experiment with five phosphate application rates (0, 45, 90, 135, and 180 kg ha−1, referred to as T1, T2, T3, T4, and T5, respectively) was conducted during the 2018–2020 summer maize seasons study the effects of phosphate rates on the grain yield, biomass, and nitrogen (N), P and potassium (K) accumulation, and N, P, and K physiological efficiency (denoted as NPE, PPE and KPE, respectively). Results showed that P application notably improved maize grain and biomass yield, the total uptake of N, P, K, and NPE and KPE across three seasons. As the P addition increased to 135 kg ha−1, the grain yield achieved a maximum of 7168.4 kg ha−1, with an average NPE of 2.15 kg kg−1, PPE of 0.19 kg kg−1, and KPE of 1.49 kg kg−1. However, PPE continuously decreased with the input of phosphate. P application rates exceeding 135 kg ha−1 were not considered effective due to a decline in grain yield, nutrient uptake, and NPE. Furthermore, the effect of the planting season was significant on the total uptake of N and K, and the use efficiency of N, P, and K. TOPSIS revealed that a phosphate application rate of 90–135 kg ka−1 was the optimal pattern for maize production. These results may give a theoretical basis for the phosphate management of maize production in saline–alkali soil.

Combinations of Spent Grains as Sources of Valuable Compounds with Highly Valuable Functional and Microbial Properties

The potential of spent grains as a source of valuable compounds with various properties has gained attention. They are the by-product of the brewing process, typically resulting from the beer-making process. Five different mixed combinations of spent grains of barley, wheat, rice, maize and finger-millet were formulated and further analyzed and compared. Barley and wheat (BW), barley and rice (BR), barley and maize (BM), and barley and finger-millets (BF) were mixed in a ratio of 1:1 (w/w) and ground into a fine powder to study their techno-functional, phytochemical and in vitro properties. The techno-functional, phytochemical and in vitro properties of barley and maize (BM) were found to be the best choice, making it a promising candidate for applications in value-added products. The WAI (water absorption index) of BM (5.03 g/g) was the highest compared to BB (3.20 g/g), BF (3.56 g/g), BR (4.10 g/g) and BW (4.33 g/g), whereas the WSI (water solubility index) and OAC (oil absorption capacity) of BM (7.06% and 1.90 g/g, respectively) were lower than BW (7.60% and 2.24 g/g, respectively), BR (8.20% and 2.30 g/g, respectively), BF (9.67% and 2.57 g/g, respectively) and BB (10.47% and 2.70 g/g, respectively). A higher percentage of inhibition of DPPH (44.14%) and high phenolic and flavonoid contents (72.39 mg GAE/gm and 66.03 mg QE/gm, respectively) were observed in BM. It also showed higher in vitro properties like amylase and lipase inhibition assay (89.05% and 62.34%, respectively) than the other combinations. The present study provides valuable information about the differences between spent grain varieties and their combinations, with potential applications in various industries.

Evaluation of grain yield and quality in maize hybrids of various origin under the conditions of Primorsky Territory

Background. This study was dedicated to the evaluation and selection of maize hybrids of different origin for important agronomic traits and for protein and oil accumulation in grain under the conditions of Primorsky Territory, as well as for their possible use as source material for breeding.Materials and methods. Twenty-two grain maize hybrids of various geographic origin were studied at the Federal Scientific Center of Agricultural Biotechnology of the Far East named after A.K. Chaika” in 2017–2020. Useful agronomic characters and biochemical indications were assessed, correlations between parameters were established, and an integrated evaluation of maize hybrids was made. The hybrids were ranked relative to a predetermined ideal model.Results. Based on the results of the integrated assessment, maize hybrids Р 7709, Р 8688 and Р 8523 (Pioneer Corporation) and Si Rotango (Syngenta) had the highest scores for a set of important agronomic traits under the conditions of Primorsky Territory. Higher protein content levels were detected in maize grain when the combination of temperature and moisture was optimal (Selyaninov’s hydrothermal coefficient = 1.1). The highest oil content was observed at an enhanced level of soil moisture (HTC = 3.1). The Si Rotango hybrid had the maximum protein content. The NUR, Ladozhsky 181 MV and P 7054 hybrids showed the maximum in oil content. Strong direct correlations were discovered between the yield and the weight of 1000 kernels and one ear, and between grain yield and the height of the lower ear position. Weak reverse correlations were observed between biochemical parameters and yield, and between a FAO maturity group and grain yield.

The synergy between farmers’ declaration of qualitative and quantitative maize postharvest losses in the transition agroecological zone of Ghana

Maize is a vital staple food crop in Ghana, providing nutrition and income for millions of farm households. However, postharvest losses pose a significant threat to the maize value chain, limiting its impact on livelihoods. Besides, there are few empirical studies that examine the socio-economic and farm-level factors that influence maize postharvest losses at the farm level. This study aimed to assess maize post-harvest losses in Ghana using farmers’ declarations of their losses expressed as a quantity (kg/acre) and a percentage and, their determining factors. Survey questionnaire was used to collect data from 189 maize farmers on their perception of quantitative and qualitative postharvest losses at Atebubu-Amantin municipality in the 2021 production season. The data was analyzed using descriptive, seemingly unrelated regression (SUR) and multivariate ordered probit (MOP) models. The quantitative data shows higher postharvest loss of Gh₵362.19/acre (US$64.7) in the major season compared with the minor season (Gh₵240.9 or US$43.02/acre). Data on the qualitative estimation is similar to the quantitative losses as it also depicts higher perceived maize postharvest lost during the major production season compared with the minor season. Both methods of estimation further show increased postharvest losses associated with the drying and winnowing of maize grains, implying that adoption of modern technologies such as the solar dryer that effectively dry maize grains would be crucial towards reducing losses at the farm level. Likewise, the SUR and MOP models reveal that the main drivers of maize postharvest losses are age, sex, and the number of years in formal education and training. Production season, membership in farmer-based organisations, extension access, and credit access also appear as important factors influencing postharvest losses. The findings from these assessments provide valuable insights for policymakers, development practitioners, and farmers to develop effective strategies to reduce postharvest losses and improve food security in Ghana.

Mixed application of controlled-release urea and normal urea can improve crop productivity and reduce the carbon footprint under straw return in winter wheat-summer maize cropping system

An important goal of sustainable agriculture is reducing the environmental risk while also ensuring food security. The mixed application of controlled-release urea and normal urea (CRUNU) is a potential nitrogen (N) management strategy for achieving this goal. However, few studies have focused on whether optimizing the N application rate of CRUNU can balance crop yield and greenhouse gas emissions, especially when straw is returned. Thus, we conducted a five-year field experiment in a winter wheat–summer maize planting system in Northwest China to determine the effects of different N fertilizer types (NU: normal urea; CRUNU) and N application levels (low N, 135 kg ha–1; medium N, 180 kg ha–1; high N, 225 kg ha–1) with straw return on the crop yield and stability, N fertilizer partial factor productivity (NFPF), and soil organic carbon (SOC). Life cycle assessment was also conducted to quantify the GHG emissions from farmland and carbon footprint (CF). Compared with NU, CRUNU improved the winter wheat and summer maize grain yield, biomass, and NFPF at all three N application levels. The crop grain yields increased significantly as the N application level increased under NU, but the crop grain yields did not differ significantly between the medium and high N application levels under CRUNU (P > 0.05). The SOC contents increased as the duration of straw return increased. Compared with NU, CRUNU significantly increased the SOC content, and correlation analysis showed that this increase was related to the increased amount of returned straw. Compared with NU, CRUNU increased the GHG emissions in the production process but reduced the GHG emissions in the application process, as well as increasing soil CO2 fixation to ultimately reduce the total GHG emissions. CRUNU increased the crop grain yield while also reducing the total GHG emissions, and thus the CF decreased significantly by 14.53–23.03% compared with NU, especially at the medium N application level. Therefore, this comprehensive analysis of the crop productivity and GHG emissions indicates that CRUNU combined with an appropriate N application level can be used as a nitrogen fertilizer management strategy for sustainable winter wheat–summer maize cropping in Northwest China.

Effects of 6-Benzyladenine (6-BA) on the Filling Process of Maize Grains Placed at Different Ear Positions under High Planting Density.

Increasing grain weight under dense planting conditions can further improve maize yield. 6-BA is known to be involved in regulating grain development and influencing grain weight. Maize grain development is closely linked to starch accumulation and hormone levels. In this work, the effects of applying 6-BA at the flowering stage under high density on the grain filling characteristics, starch content, starch synthesis critical enzyme activity, and endogenous hormones levels of maize grains (including inferior grains (IGs) and superior grains (SGs)) of two high-yielding summer maize varieties widely cultivated in China were investigated. The findings indicated that applying 6-BA significantly improved maize yield compared to the control, mainly as a result of increased grain weight due to a faster grain filling rate. Additionally, the activities of enzymes associated with starch synthesis, including sucrose synthase (SuSy), ADP-glucose pyrophosphorylase (AGPase), granule-bound starch synthase (GBSS), soluble starch synthase (SSS), and starch branching enzyme (SBE), were all increased following 6-BA application, thus facilitating starch accumulation in the grains. Applying 6-BA also increased the zeatin riboside (ZR), indole-3-acetic acid (IAA), and abscisic acid (ABA) levels, and reduced the gibberellin (GA3) level in the grains, which further improved grain filling. It is worth noting that IG had a poorer filling process than SG, possibly due to the low activities of critical enzymes for starch synthesis and imbalanced endogenous hormones levels. However, IG responded more strongly to exogenous 6-BA than SG. It appears that applying 6-BA is beneficial in improving filling characteristics, promoting starch accumulation by enhancing the activities of critical enzymes for starch synthesis, and altering endogenous hormones levels in the grains, thus improving grain filling and increasing the final grain weight and yield of maize grown under crowded conditions. These results provide theoretical and technical support for the further utilization of exogenous hormones in high-density maize production.

Analysis of Linkage on Interaction of Main Aspects (Genotype by Environment Interaction, Stability and Genetic Parameters) of 1000 Kernels in Maize (Zea mays L.)

The assessment of 1000-kernel weight holds significant importance in determining maize grain yield, and elucidating its underlying genetic mechanisms is imperative for enhancing its overall performance. The material for the study consisted of 26 doubled-haploid (DH) maize lines obtained from crossing two cultivars with flint kernels. Lines were planted in the northern part of the Lower Silesia voivodship in Poland over ten years (2013–2022). The 1000-kernel weight was assessed. The purposes of the research were as follows: (1) to assess genotype by environment interaction (GEI by the additive main effects and multiplicative interaction (AMMI) model; (2) the selection of stable DH lines and environment-specific lines; and (3) the estimation of parameters related to additive and additive–additive gene interaction (epistasis). The results indicate the significant effects of genotype and environment, as well as the GEI, on the 1000-kernel weight. Estimates of additive gene action effects were statistically significant in every year of the study, except 2022. Estimates of epistasis (total additive-by-additive interaction) effects for 1000-kernel weight were statistically significant in 2013, 2015, and 2017 (positive effects), as well as in 2018 and 2020 (negative effects). The lines KN07 and KN10 are recommended for further inclusion in the breeding program due to their stability and highest average of 1000-kernel weight.

The Integrated Effects of Biostimulant Application, Mechanical Weed Control, and Herbicide Application on Weed Growth and Maize (Zea mays L.) Yield

A field trial was conducted (2020–2021) in a randomized complete block design arranged according to the split-plot design to evaluate the integrated effects of an alternative fertilization practice based on the application of a microbial biostimulant in combination with different weed control methods on weed growth and maize productivity. Two fertilization practices, conventional (CF) and alternative (AF), formed the main plots. The CF supplied maize with 160 kg N ha−1. The AF included a foliar application of the biostimulant NitroStim®, which contains N2-fixing bacteria (1 × 1012 colony forming units; CFU L−1) along with a 50% lower fertilizer incorporation rate (80 kg N ha−1). Four weed control treatments formed the subplots: one inter-row mechanical cultivation (M1), two inter-row mechanical cultivations (M2), tembotrione application (99 g a.i. ha−1; H), and an untreated control (CON). Combined over the years (p ≥ 0.05), fertilization, weed control, and their interactions affected (p ≤ 0.05) weed density and biomass, maize grain yield, and nitrogen partial factor productivity (PFPN). The AF reduced weed biomass by 28% compared to the CF. M1 resulted in a high value (389 g m−2). M2 and H reduced weed biomass compared to (M1 ≥ 70%). Weed biomass dropped below 35 g m−2 in the AF × H and AF × M2 subplots. Observations on weed density were similar. The AF resulted in 12 and 56% higher maize grain yield and PFPN than the CF, respectively. M2 increased grain yield by 18 and 25% compared to M1 and CON, respectively, and was not different from H. Moreover, AF × H and AF × M2 were the highest-yielding interactions (≥12,000 kg grain ha−1). AF × M2 increased PFPN by 56, 58, 64, and 67% compared to CF × H, CF × M2, CF × M1, and CF × CON, respectively, while AF × H resulted in similar PFPN.