Hybrid Maize Varieties Research Articles

Molecular mechanisms of heterosis under drought stress in maize hybrids Zhengdan7137 and Zhengdan7153.

Maize is one of the most successful crops in utilizing heterosis which significantly improves maize stresses resistance and yield. Drought is a destructive abiotic stress that significantly reduces crop yield, particularly in maize. Drought stress and re-watering frequently occur during the growth and development of maize; however, the molecular mechanisms of heterosis under drought stress and re-watering have rarely been systematically investigated. Zhengdan7137 and Zhengdan7153 are two maize hybrid varieties with robust heterosis, and separately belongs to the SS×NSS and Reid×Tangsipingtou heterotic groups. 54 transcriptomes of these two hybrids and their parental inbred lines were analyzed under well-watering (WW), water-deficit (WD), and re-watering (RW) conditions using RNA-Seq. In this study, we identified 3,411 conserved drought response genes (CDRGs) and 3,133 conserved re-watering response genes (CRRGs) between Zhengdan7137 and Zhengdan7153. When comparing CDRGs and CRRGs to overdominance and underdominance genes, we identified 303 and 252 conservative drought response overdominance genes (DODGs) and underdominance genes (DUDGs), respectively, and 165 and 267 conservative re-watering response overdominance genes (RODGs) and underdominance genes (RUDGs), respectively. DODGs are involved in stress response-related processes, such as L-phenylalanine metabolism, carbohydrate metabolism, and heat response, whereas DUDGs are associated with glucose metabolism, pentose-phosphate shunt, and starch metabolism. RODGs and RUDGs contribute to the recovery of hybrids from drought stress by upregulating cell propagation and photosynthesis processes, and repressing stress response processes, respectively. It indicated overdominant and underdominant genes conservatively contributed to hybrid heterosis under drought stress. These results deepen our understanding of the molecular mechanisms of drought resistance, uncover conservative molecular mechanisms of heterosis under drought stress and re-watering, and provide potential targets for improving drought resistance in maize.

Revolutionizing plant breeding: a historical perspective from cross-pollination to gene editing

The history of plant breeding can be broadly divided into four eras: the Pre-Mendelian era (before 1900), the Mendelian era (1900-1920), the post-Mendelian era (1921-1950), and the Modern era (after 1950). Significant milestones include the release of the first hybrid maize varieties in 1961, the first sorghum hybrid (CSH-1) in 1964, the first bajra hybrid (HB-1) in 1965, and the first pigeon pea hybrid (ICPH-8) in 1991. Achieving a world with zero hunger requires a sustainable increase in food production and distribution and elimination of poverty. This goal demands scientific, logistical, and humanitarian approaches to ensure food security from farmers and breeders to policymakers and governments. Conventional breeding techniques alone are insufficient to meet the challenges posed by climate change, biotic and abiotic stress, and the growing global population projected to reach 10 billion by 2050. Novel plant breeding techniques, such as genome editing, speed breeding, and omics technology integration, offer precise, cost-effective, and less time-consuming solutions. These techniques enable the editing of agriculturally significant genes, promoting hybrid seed production, induced apomixis, and resistance to biotic and abiotic stress. Genome editing technologies have evolved, with CRISPR/Cas9 and its variants, base editing (BE), and prime editing (PE) playing pivotal roles in generating transgene-free plants. These advancements have significant implications for crop improvement, meeting food and nutrition security, and catering to regional preferences. Syngenta's initiative to open rights to CRISPR-based technologies through the Shoots by Syngenta platform exemplifies the collaborative efforts needed to drive agricultural innovation and sustainability. The review discusses the current regulatory regimes governing genome-edited crops, prospects of new tools such as DNA-free editing systems and nanotechnology, and their applicability in crop improvement. A multidisciplinary approach involving political, social, economic, and scientific stakeholders is essential for the successful adoption of genome editing technologies, which will ultimately make agriculture a lucrative profession and attract youth to the field.

Oviposition behaviour and larval attraction of the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) to different maize plant varieties for pest management in Nigeria

Phytophagous insects likely select suitable host plants for oviposition based on olfactory and tactile cues. However, details of how insects differentiate among different plant varieties are often unclear. The fall armyworm (Spodoptera frugiperda J. E. Smith) is a highly destructive pest on maize, but little is known about the attraction and oviposition preference of S. frugiperda to different maize varieties, particularly in the context of sub-Saharan Africa, where the insect is a major threat to maize production. We determined the oviposition preference of S. frugiperda females on six different maize plant varieties three of which were hybrid varieties and three were open-pollinated varieties, in multiple-choice and no-choice assays. We also evaluated the attraction preference of S. frugiperda larvae on these maize varieties, using an olfactometer bioassay. We found that S. frugiperda females oviposited significantly less egg masses on the hybrid varieties DEKAIB and 30Y87 than on the other varieties tested and that females oviposited less on the hybrid maize varieties compared to the open-pollinated maize varieties overall. Additionally, we found that S. frugiperda larvae were more attracted to the open-pollinated variety LMFP than to clean air, which was not the case for any of the other maize varieties tested. Taken together, our results show that S. frugiperda responds differentially to the different maize varieties and that hybrid maize varieties seem less attractive. Further investigating the chemistry of hybrid maize varieties like DEKAIB might yield clues on how to breed maize varieties with increased resistance against S. frugiperda infestation.

Farmers’ attitude towards modern maize production in Dinajpur Sadar upazila

The vital determination of the study was to determine the farmers’ attitudes towards modern maize production. The study was carried out in the Chehelgazi unions of Sadar upazila under Dinajpur District. Ninety-two farmers were selected as sample from an updated list of 920 farmers involved in maize production. Data were collected by a pre-tested interview schedule during September to October 2017. Simple and direct questions with different scales were used to obtain information. The co-efficient of correlation (r) was computed to explore the relationships between the nine selected characteristics of the farmers and their attitude towards modern maize production. About three-fourths (73.9%) of the farmers had highly favorable attitude towards modern maize production, while 26.1% moderately favorable attitude and none of them had slightly favorable attitude towards modern maize production. Correlation analyses indicated that among nine selected characteristics, education, farm size, cosmopoliteness, and extension media contact of the farmers had significant positive relationships with their attitude towards modern maize production. However, age, family size, area under maize production, annual income and training received had no significant relationships with their attitude towards modern maize production. ‘Cost of modern maize production is high than other crops’ (78.3%) emerged as the 1st ranked problem and last ranked (25.0%) perceived problem mentioned by the farmer was ‘Lack of knowledge on hybrid maize variety’ expressed by the farmers. The vital (56.5%) suggestion cited by the farmers was ‘organizing more training program for the farmers’ and ‘Application of IPM technique’ (28.3%) was last suggestion. Int. J. Agril. Res. Innov. Tech. 14(1): 96-103, June 2024

Phytochrome B interacts with LIGULELESS1 to control plant architecture and density tolerance in maize

Over the past few decades, significant improvements in maize yield have been largely attributed to increased plant density of upright hybrid varieties rather than increased yield per plant. However, dense planting triggers shade avoidance responses (SARs) that optimize light absorption but impair plant vigor and performance, limiting yield improvement through increasing plant density. In this study, we demonstrated that high-density-induced leaf angle narrowing and stem/stalk elongation are largely dependent on phytochrome B (phyB1/B2), the primary photoreceptor responsible for perceiving red (R) and far-red (FR) light in maize. We found that maize phyB physically interacts with the LIGULELESS1 (LG1), a classical key regulator of leaf angle, to coordinately regulate plant architecture and density tolerance. The abundance of LG1 is significantly increased by phyB under high R:FR light (low density) but rapidly decreases under low R:FR light (high density), correlating with variations in leaf angle and plant height under various densities. In addition, we identified the homeobox transcription factor HB53 as a target co-repressed by both phyB and LG1 but rapidly induced by canopy shade. Genetic and cellular analyses showed that HB53 regulates plant architecture by controlling the elongation and division of ligular adaxial and abaxial cells. Taken together, these findings uncover the phyB-LG1-HB53 regulatory module as a key molecular mechanism governing plant architecture and density tolerance, providing potential genetic targets for breeding maize hybrid varieties suitable for high-density planting.

Plot-level satellite imagery can substitute for UAVs in assessing maize phenotypes across multistate field trials.

Abstract Accurate genotype-specific early yield estimates at fields and plots offer potential benefits to farmers in optimizing their agronomic practices, breeders in screening thousands of varieties, and policymakers in decision-making contributing to the improvement of agriculture and food production systems. Effective approaches to track plant growth and predict yield require large datasets of remote sensing and ground truth data collected across multiple environments. Low-altitude drone flights are increasingly being used to collect data from field evaluations of new crop varieties, while satellite imagery is being explored to track yield and management practices at the regional scales. Despite their lower spatial resolution, satellite platforms exhibit logistical and technical advantages in scalability and accessibility, and could facilitate plot-level predictions, especially with steadily improving spatial resolution. However, genotype-specific, plot-level, high-resolution satellite images from multiple environments with ground truth measurements are not yet publicly available. Here we generated, described, and evaluated over 20,000 plot-level images of over 80 hybrid maize varieties grown across the US corn belt under various management practices collected from (near simultaneous) satellite and drone flights integrated with ground truth yield measurement. Of the six baseline models examined, models employing data collected from satellite images often matched or exceeded the performance of models employing drone images for both within and cross-environment yield prediction. Large, multi-environment, genetically diverse datasets such as those generated in this study, along with more complex models could help unlock the power of satellite imagery as an important addition to the tool of farmers, plant geneticists, breeders, and policymakers.

Phenology and Climate Indices of Maize Hybrids under North Western Himalayan Region of Temperate Kashmir

In the Kharif season of 2021, a field experiment was conducted at the crop research farm of the Division of Agronomy, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir. The primary objective of the study was to investigate the phenology of maize hybrids in relation to agrometeorological indices. The experimental design included two factors: Factor A, representing different irrigation regimes at various growth stages (I1 to I6), and Factor B, consisting of two maize hybrid varieties (Shalimar Hybrid-2 and Shalimar Hybrid-3). The irrigation treatments ranged from early vegetation stage to rainfed conditions. The experiment followed a split plot design with three replications. Results indicated that the treatment I5 (Irrigation at IW/CPE ratio of 0.8) and Shalimar Hybrid-3 exhibited the highest values for key agrometeorological indices, including GDD, HTU, PTU, and HYTU. These findings provide valuable insights into optimizing irrigation practices and selecting suitable maize hybrids for enhanced phenological performance.

Response differences of two maize hybrid varieties to the application of bioagent-ameliorant and chicken manure in fertile soil

To ensure adequate nutrition for the growth of maize (Zea mays L.) in sustainable agriculture, it is necessary to apply bio-agent soil conditioner and manure. This study aims to determine the effect of doses of bioagent-ameliorant and chicken manure on growth and yield components. The research was conducted in highland with an altitude 800 m above sea level. This study used an experimental method with two sets of experiments, namely experiments using one and two-cobs maize cultivars. The experiment used a randomized block design (RBD) with two treatment factors and three replications. The first treatment factor was the dose of bioagent ameliorant, which consisted of 3 levels, namely 0, 7.5, and 15 kg/ha, while the second factor was the dose of chicken manure, which consisted of 3 levels, namely 0.5 and 10 tons/ha. The observed growth components were plant height and number of leaves, while the yield components observed were cob length, cob diameter, cob weight per plant, and cob weight per plot. In research on two-cob maize experiment, there was no interaction effect between doses of soil conditioner and chicken manure, while the interaction effect on plant height occurred in one-cob maize experiment. The single effect of ameliorant doses could not increase all components of growth and yield, both in one and two-cob maize cultivars. The single effect of doses of chicken manure increased number of leaves, cob length, cob weight per plant, and cob weight per plot in one-cob maize cultivar, while increased plant height in two-cob maize cultivar.

Performance Evaluation of Drought Tolerant Hybrid Maize (Zea mays) Varieties in East Hararghe Zone, Ethiopia

Performance Evaluation of Drought Tolerant Hybrid Maize (Zea mays) Varieties in East Hararghe Zone, Ethiopia

Genetic analysis of phenotypic plasticity identifies BBX6 as the candidate gene for maize adaptation to temperate regions.

Climate changes pose a significant threat to crop adaptation and production. Dissecting the genetic basis of phenotypic plasticity and uncovering the responsiveness of regulatory genes to environmental factors can significantly contribute to the improvement of climate- resilience in crops. We established a BC1F3:4 population using the elite inbred lines Zheng58 and PH4CV and evaluated plant height (PH) across four environments characterized by substantial variations in environmental factors. Then, we quantified the correlation between the environmental mean of PH (the mean performance in each environment) and the environmental parameters within a specific growth window. Furthermore, we performed GWAS analysis of phenotypic plasticity, and identified QTLs and candidate gene that respond to key environment index. After that, we constructed the coexpression network involving the candidate gene, and performed selective sweep analysis of the candidate gene. We found that the environmental parameters demonstrated substantial variation across the environments, and genotype by environment interaction contributed to the variations of PH. Then, we identified PTT(35-48) (PTT is the abbreviation for photothermal units), the mean PTT from 35 to 48 days after planting, as the pivotal environmental index that closely correlated with environmental mean of PH. Leveraging the slopes of the response of PH to both the environmental mean and PTT(35-48), we successfully pinpointed QTLs for phenotypic plasticity on chromosomes 1 and 2. Notably, the PH4CV genotypes at these two QTLs exhibited positive contributions to phenotypic plasticity. Furthermore, our analysis demonstrated a direct correlation between the additive effects of each QTL and PTT(35-48). By analyzing transcriptome data of the parental lines in two environments, we found that the 1009 genes responding to PTT(35-48) were enriched in the biological processes related to environmental sensitivity. BBX6 was the prime candidate gene among the 13 genes in the two QTL regions. The coexpression network of BBX6 contained other genes related to flowering time and photoperiod sensitivity. Our investigation, including selective sweep analysis and genetic differentiation analysis, suggested that BBX6 underwent selection during maize domestication. Th is research substantially advances our understanding of critical environmental factors influencing maize adaptation while simultaneously provides an invaluable gene resource for the development of climate-resilient maize hybrid varieties.

Thermotolerant PGPR consortium B3P modulates physio-biochemical and molecular machinery for enhanced heat tolerance in maize during early vegetative growth

BackgroundGlobal warming and irregular changes in temperature are a serious threat to plant growth with a significant negative impact on yield. Global maize productivity has decreased significantly due to sudden temperature fluctuations and heat waves especially in the regions severely hit by climate change.ResultsThe current study demonstrates the potential of beneficial bacteria for inducing heat tolerance in maize during early growth. Three Bacillus spp. AH-08, AH-67, SH-16, and one Pseudomonas spp. SH-29 showed the ability to grow and exhibited multiple plant-beneficial traits up to 45 ± 2 °C. At temperatures of 45 and 50 °C, Bacillus sp. SH-16 exhibited upregulation of two small heat shock proteins (HSP) of 15 and 30 kDa, while SH-16 and AH-67 showed upregulation of two large HSP of 65 and 100 kDa. Plant-inoculation with the consortium B3P (3 Bacillus + 1 Pseudomonas spp.) was carried out on six hybrid maize varieties pre-grown at 25 ± 2 ºC. Heat shock was applied to 10-day-old seedlings as: 3 h at 38ºC, 48 h recovery period, and then 48 h at 42ºC. The B3P treatment showed significant improvement in the overall plant growth (plant height, root & shoot fresh & dry weight, root and leaf area) with a higher level of CAT, POD, total chlorophyll, and carotenoids, while low concentration of MDA. A non-significant difference was observed in case of total cell protein and amino acids after B3P-treatment under stress. The expression of HSP1 and HSP18 in Malka and YH-5427 while HSP70 and HSP101 were higher in FH-1046 and Gohar as compared to non-inoculated treatment.ConclusionsThese findings indicate that heat-tolerant plant-growth promoting rhizobacteria (Ht-PGPR) exert versatile, multiphasic and differential response to improve plant growth and heat-tolerance in different maize varieties during seedling/ early vegetative growth. Subsequent research will be focused on the field evaluation of these PGPR to see the field and yield response of this consortium under natural temperature fluctuations in field.

A Study on the Specific Combining Ability in Several Inbred Lines of Maize

Maize is a cereal crop essential to fulfill the need for food and support global food security programs. Maize hybrid varieties play a very significant role in increasing maize production. Objectives of the research were to obtain a tester, which is consistent in identifying inbred lines with a high specific combining ability, and to obtain prospective crossed-hybrids that have the potential assembling to be maize hybrid varieties. The grain yield showed that the specific combining ability values ranged from -3682.2 to 5251.7. Crosses that have high and positive specific combining ability included lines of JG-11, JG-18, JG-34, JG-01, JG-40, JG-B0, JG-19, and JG-02 with a tester of JG-T00; lines of JG-20, JG-01, JG-03, JG-42, JG-02, JG-46, and tester of JG-T14; lines of JG-24, JG-08, JG-23, JG-26, JG-21, JG-07, and JG-06 with a tester of JG-T15; lines of JG-38, JG-40, JG-35, JG-36, JG-01, JG-51, JG-17, JG-B0, and JG-08 with tester of JG-T22; and lines of JG-07, JG-01, JG-26, JG-24, and JG-18 with tester of JG-T37. There were combinations of 9 crosses between inbred lines and the best testers, including JG-06XJG-T15, JG-51XJG-T22, JG-49XJG-T22, JG-B0XJG-T22, JG-35XJG-T22, JG-38XJG-T22, JG-17XJG-T22, JG-36XJG-T22, and JG-49XJG-37, which are potential as prospective maize hybrids that have high productivity.

Hyperspectral imaging combined with CNN for maize variety identification.

As the third largest food crop in the world, maize has wide varieties with similar appearances, which makes identification difficult. To solve the problem of identification of hybrid maize varieties, a method based on hyperspectral image technology combined with a convolutional neural network (CNN) is proposed to identify maize varieties. In this study, 735 maize seeds from seven half-parent hybrid maize varieties were regarded as the research object. The maize seed images in the range of 900 ~ 1700nm were obtained by hyperspectral image acquisition system. The region of interest (ROI) of the embryo surface was selected, and the spectral reflectance of maize seeds was extracted. After Savitzky-Golay (SG) Smoothing pretreatment, Maximum Normalization (MN) pretreatment was performed. The 56 feature wavelengths were selected by Competitive Adaptive Reweighting Algorithm (CARS) and Successive Projection Algorithm (SPA). And the 56 wavelengths were mapped to high-dimensional space by high-dimensional feature mapping and then reconstructed into three-dimensional image features. A five-layer convolution neural network was used to identify three-dimensional image features, and nine (SG+MN)-(CARS+SPA)-CNN maize variety identification models were established by changing the input feature dimension and the depth factor size of the model layer. The results show that the maize variety classification model works best, when the input feature dimension is 768 and the layer depth factor d is 1.0. At this point, the model accuracy of the test set is 96.65% and the detection frame rate is1000 Fps/s in GPU environment, which can realize the rapid and effective non-destructive detection of maize varieties. This study provides a new idea for the rapid and accurate identification of maize seeds and seeds of other crops.

Agronomic Characteristics of Maize Grown in Paddy Soil, Along with Root Zone Soil Chemical Properties and Soil Bacterial Numbers

Maize is being considered as an alternative crop for off-season rice production in Thailand due to increasing water scarcity. The objective of this study was to evaluate the agronomic characteristics and root-zone soil properties of 4 hybrid maize varieties grown in paddy soil during off-season rice cultivation, in order to assess their growth and development after the flooded-rice harvest and the associated soil microorganisms. The randomized complete block design with 4 treatments and 4 replications was used. The 4 treatments were 2 new maize varieties (Suwan 5731 and Suwan 5819), 1 check variety (Suwan 4452), and 1 local use variety (PAC 789). Suwan 5819 showed significantly higher plant height than Suwan 4452, Suwan 5731 and PAC 789, with the highest plant height recorded for Suwan 5819 (221 cm). Similarly, Suwan 5819 exhibited significantly higher estimated leaf area index than Suwan 4452, Suwan 5731 and PAC 789, with differences of 32.67, 42.57 and 29.29 % at VT, respectively. These superior performances of Suwan 5819 could be attributed in part to increased dry matter and nutrient accumulation at the VT stage. The grain yield for PAC 789 was 13.71 t ha–1, Suwan 4452 was 13.23 t ha–1, Suwan 5731 was 12.83 t ha–1, and Suwan 5819 was 12.25 t ha–1. However, there was no significant difference in the grain yields among the 4 varieties. The soil in the root zone of Suwan 5819 at VT was significantly less acidic (pH 5.08) than Suwan 4452 (pH 4.58), PAC 789 (pH 4.61) and Suwan 5731 (pH 4.75). The nitrogen-fixing bacteria were most abundant in PAC 789 (84 %), phosphate-solubilizing bacteria in Suwan 4452 (15 %), and potassium-solubilizing bacteria in Suwan 5819 (16 %). Overall, the study suggests that Suwan 5819 is a promising maize variety for agronomic performance in the tested region. HIGHLIGHTS Maize is a viable alternative to rice for off-season cultivation in water-scarce regions. One new maize hybrid (Suwan 5819) showed better growth and nutrient accumulation during the vegetative transition stage. Soil properties, including beneficial microorganisms, did not differ significantly among the four maize varieties studied. Suwan 5819 new maize hybrid had less acidic root zone soil conditions than the other tested varieties. Commercial maize hybrid had the highest counts of N-fixing and K-solubilizing bacteria in the root zone soil, but there was no significant difference in bacterial count compared to the Suwan maize GRAPHICAL ABSTRACT

Yield performance and agronomic characteristics of several candidate hybrid maize varieties on uncultivated land

Corn is currently a strategic and dominant national commodity used as raw material for animal feed. The increase in productivity was made possible by the continued assembly of hybrid corn which has a higher production per hectare with a wide or site-specific adaptation rate. Due to the wide utilization of maize, the main objective of all commercial maize breeding programs is to obtain new inbred and hybrids which will outperform the hybrids mainly on grain yield characteristics. This research was conducted in Bone Regency to know the yield potential of several hybrid maize on uncultivated land, using a randomized block design, 4 replications, a plot area of 3 x 5 m, and spacing of 70 x 20 cm. The material used consisted of 4 hybrids and 2 comparison varieties. The results showed that the hybrid G1603 (11.61 t/ha) showed the highest grain yield and was not significantly different from the comparison varieties. This result was supported by the character of the number of rows of seeds per ear, the length of the ear, and the diameter. These characteristics need to be considered to get hybrid corn with a high grain yield.

Distribution of chlorpyrifos residue in maize (Zea mays)

Chlorpyrifos is an organophosphate insecticide. It has low aqueous solubility, is volatile and non-mobile, moderately persistent in soil, highly toxic to mammals, and is an acetylcholinesterase inhibitor. The main use of chlorpyrifos is to control various types of agricultural pests. This study aims to determine the absorption of chlorpyrifos residues in maize plants. The study was conducted in July-December 2019. Experimental research was conducted at Jakenan experimental field on land contaminated with chlorpyrifos residue. The maize used was a hybrid maize variety NK 6172 Perkasa. Pesticide residue analysis was carried out at the Laboratory of the Agricultural Environmental Research Institute (IAERI). The results showed that the highest chlorpyrifos residue was in the stalks and leaf with a value of 0.0318-0.5682 mg kg−1 but still below the maximum residue limit (MRL) of 10 mg kg−1 recommended by The National Standardization Agency of Indonesia. The concentration of chlorpyriphos residue in maize grain is 0.0014-0.2203 mg kg−1 (MRL=0.05 mg kg−1). Chlorpyriphos residue in the soil is 0.0148-0.0786 mg kg−1 (MRL=3.2 mg kg−1), and the lowest was root (<0.0014 mg kg−1). Information on residue distribution on maize and soils can be helpful as an early warning about the use of insecticides and food safety measures.

Effect of Potassium Level on Growth, Yield, Nutrient Uptake and Economics of Hybrid Maize

Potassium is indeed one of the major essential nutrients required for optimal plant growth and development. It plays a crucial role in various physiological and biochemical processes within plants. In order to investigate the effect of different level of potassium on growth, yield, nutrient uptake and economics of hybrid maize a experiment was conducted at District Seed Farm of Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia and West Bengal, India. In experiment Randomized Block Design was employed and consisted of six treatment levels of potassium : T1 (0 kg K2O ha-1), T2 (30 kg K2O ha-1), T3 (60 kg K2O ha-1), T4 (90 kg K2O ha-1), T5 (120 kg K2O ha-1) and T6 (150 kg K2O ha-1) with recommended dose of nitrogen and phosphorus (120:60 N : P2O5 kg ha-1 ). Result indicated that plant height, grain yield, stover yield, net return and benefit : Cost ratio showed significant response upto 90 kg K20 ha-1. The total uptake of N, P and K showed significant response upto 90 kg K20 ha-1. Based on the results of the experiment, it was found that the application of potassium up to 90 kg K2O ha-1 is necessary to ensure a continuous supply of potassium to maize plants. This optimal potassium level was associated with higher maize yields and economic benefits, particularly when cultivating hybrid maize varieties.

Exploring adaptation responses of maize to climate change scenarios in southern central Rift Valley of Ethiopia

In this study, we assessed responses of adaptation options to possible climate change scenarios on maize growth and yield by using projections of 20 coupled ensemble climate models under two representative concentration pathways (RCPs) 4.5 and 8.5 by means of a DSSAT model. Growth and yield simulations were made across present and future climate conditions using the hybrid maize variety (Shone). Subsequently, simulated yields were compared with farmer’ average and on-farm trial yields. Results showed that on-farm trial yield (5.1–7.3 t ha−1) lay in between farmers’ average yield (2.9–5 t ha−1) and water-limited potential yield (6.3–10.6 t ha−1). Maize yields achieved in farmers’ fields are projected to decline towards mid-century and further towards the end of the century regardless of the adaptation options compared with baseline in low potential clusters. Results of a combination of adaptation options including February planting, use of 64 kg ha−1 N and conservation tillage provided yield advantage of 5.8% over the 30 cm till under medium GHGs emission scenario during mid-century period at Shamana. Mulching with 5 t ha−1 was projected to produce a 4–5% yield advantage in the Hawassa cluster during the mid-century period regardless of changes in tillage or planting window. Under a high GHGs emission scenario, over 13.4% yield advantage was projected in the Bilate cluster due to conservation tillage and June planting during the mid-century period. In the Dilla cluster, the use of 10 t ha−1 mulch, conservation tillage and early planting (February) would result in a 1.8% yield advantage compared with the control either in medium or high GHGs emission scenarios. Thus, the most promising and least risky practices among simulated strategies were the use of nitrogen and mulching in combination with tillage or planting date adjustment. However, adaptation options remained least promising and highly risky if not integrated with mulching or nitrogen use. Hence, the negative impacts of future climate change and subsequent yield gaps would be reduced by optimizing the application of nitrogen, mulch and their interaction with planting date and tillage in high and low potential areas of maize production.

Morphological parameters, heritability, yield component correlation, and multivariate analysis to determine secondary characters in selecting hybrid maize

Abstract. Fadhli N, Farid M, Azrai M, Nur A, Effendi R, Priyanto SB, Nasruddin AD, Novianti F. 2023. Morphological parameters, heritability, yield component correlation, and multivariate analysis to determine secondary characters in selecting hybrid maize. Biodiversitas 24: 3750-3757. Direct selection for grain yield traits in maize (Zea mays L.) is often inefficient under specific conditions, necessitating the accurate determination of secondary traits to facilitate implementation and enhance selection precision. This study aimed to examine the morphological parameters, heritability, yield component correlations, and multivariate analysis of hybrid maize for determining potential secondary traits through indirect selection. The experimental design employed a randomized complete block design (RCBD) comprising 17 genotypes, including 15 hybrid maize lines and 2 hybrid maize varieties (RK 457 and RK 57). The results revealed that weight of harvested cob character and yield traits demonstrated significant correlations with production. Correlation values were further analyzed using biplot analysis and path analysis to identify potential secondary traits. The principal component biplot analysis results indicated four characters as effective secondary traits for selection, namely weight of harvested cob, yield, weight of 1000 seeds, and moisture content. MSM53/BCY as a parent of JHD 05 displayed superior performance compared to the two commercial hybrid varieties. Based on path analysis results, the weight of harvested cob character exhibited the highest direct effect on production with a value of 0.93, indicating that weight of harvested cob is the best secondary trait for selection.

Genotype by environment interaction and yield stability of hybrid maize varieties evaluated in three locations of mid altitudes of Rwanda (lay summary)

Genotype by environment interaction and yield stability of hybrid maize varieties evaluated in three locations of mid altitudes of Rwanda (lay summary)