Sweet Maize Research Articles

Multispectral UAV-Based Disease Identification Using Vegetation Indices for Maize Hybrids

In the future, the cultivation of maize will become more and more prominent. As the world’s demand for food and animal feeding increases, remote sensing technologies (RS technologies), especially unmanned aerial vehicles (UAVs), are developing more and more, and the usability of the cameras (Multispectral-MS) installed on them is increasing, especially for plant disease detection and severity observations. In the present research, two different maize hybrids, P9025 and sweet corn Dessert R78 (CS hybrid), were employed. Four different treatments were performed with three different doses (low, medium, and high dosage) of infection with corn smut fungus (Ustilago maydis [DC] Corda). The fields were monitored two times after the inoculation—20 DAI (days after inoculation) and 27 DAI. The orthomosaics were created in WebODM 2.5.2 software and the study included five vegetation indices (NDVI [Normalized Difference Vegetation Index], GNDVI [Green Normalized Difference Vegetation Index], NDRE [Normalized Difference Red Edge], LCI [Leaf Chlorophyll Index] and ENDVI [Enhanced Normalized Difference Vegetation Index]) with further analysis in QGIS. The gathered data were analyzed using R-based Jamovi 2.6.13 software with different statistical methods. In the case of the sweet maize hybrid, we obtained promising results, as follows: the NDVI values of CS 0 were significantly higher than the high-dosed infection CS 10.000 with a mean difference of 0.05422 *** and a p value of 4.43 × 10−5 value, suggesting differences in all of the levels of infection. Furthermore, we investigated the correlations of the vegetation indices (VI) for the Dessert R78, where NDVI and GNDVI showed high correlations. NDVI had a strong correlation with GNDVI (r = 0.83), a medium correlation with LCI (r = 0.56) and a weak correlation with NDRE (r = 0.419). There was also a strong correlation between LCI and GNDVI, with r = 0.836. NDRE and GNDVI indices had the correlation coefficients with a CCoeff. of r = 0.716. For hybrid separation analyses, useful results were obtained for NDVI and ENDVI as well.

Monitoring Helicoverpa armigera Damage with PRISMA Hyperspectral Imagery: First Experience in Maize and Comparison with Sentinel-2 Imagery

The cotton bollworm (CBW) poses a significant risk to maize crops worldwide. This study investigated whether hyperspectral satellites offer an accurate evaluation method for monitoring maize ear damage caused by CBW larvae. The study analyzed the records of maize ear damage for four maize fields in Southeast Hungary, Csongrád-Csanád County, in 2021. The performance of Sentinel-2 bands, PRISMA bands, and synthesized Sentinel-2 bands was compared using linear regression, partial least squares regression (PLSR), and two-band vegetation index (TBVI) methods. The best newly developed indices derived from the TBVI method were compared with existing vegetation indices. In mid-early grain maize fields, narrow bands of PRISMA generally performed better than wide bands, unlike in sweet maize fields, where the Sentinel-2 bands performed better. In grain maize fields, the best index was the normalized difference of λA = 571 and λB = 2276 (R2 = 0.33–0.54, RMSE 0.06–0.05), while in sweet maize fields, the best-performing index was the normalized difference of green (B03) and blue (B02) Sentinel-2 bands (R2 = 0.54–0.72, RMSE 0.02). The findings demonstrate the advantages and constraints of remote sensing for plant protection and pest monitoring.

Genotype by year interaction for selected traits in sweet maize (Zea maize L.) hybrids using AMMI model

This study investigated genotype × environment interactions for the stability of expression of four productivity traits (cobs yield, cobs I class trade share, lend of cobs and fulfilment of cobs) of sweet maize hybrids (Zea mays L.). The additive main effects and multiplicative interaction (AMMI) model was employed to assess genotype × environment interaction. AMMI stability value was used to evaluate both stability and genotype. The genotype selection index was calculated for each hybrid, incorporating both the average trait value and the stability index. Ten sweet maize hybrids were evaluated: Golda, GSS 1453, GSS 3071, GSS 5829, GSS 8529, Overland, Noa, Shinerock, Sindon, and Tessa. Trials were ran conducted over four vegetative seasons at a single location in the Wielkopolska region using replicated field experiments. The AMMI model revealed significant genotypic and environmental effects for all analyzed traits. Based on their superior stability and favorable average trait values, both the Golda cultivar and the GSS 3071 hybrid are recommended for further breeding program inclusion.

Maize Pharmacy of Sweet Corn (Zea mays L. convar. saccharata var. Rugosa)

Sweet maize (Zea mays L. convar. saccharata var. Rugosa) is unique in sweet-taste, and pleasant flavour, hence the need to increase its usefulness and commercial values by enhancing its shelf-life and control of post-harvest losses. This preliminary study therefore simulated the traditional, natural, non-alcoholic, field-corn fermentation method for freshly-harvested yellow sweet corn into ògì, a fermented gruel or porridge food. Lactobacillus casei, Lactobacillus fermentum, Lactobacillus plantarum, and Saccharomyces cerevisiae predominated the naturally fermented ògì sample from sweet maize, with pH of 5.0–5.3. Observable characteristics of yellow sweet maize-fermented ògì were similar to those of yellow, field corn-fermented ògì. Present study is the first to report fermentation of sweet corn to ògì, indicative of sweet maize as a high potential plant substrate for health-promoting and nutritious fermented human diet, especially as prebiotics and probiotics, for lactating nursing mothers, convalescents, aged, and as weaning-food for infants or complementary food for children and adults.

Nitrogen substitution practice improves soil quality of red soil (Ultisols) in South China by affecting soil properties and microbial community composition

Substituting synthetic nitrogen (N) fertilizer with organic amendments is considered an effective practice to improve soil quality. However, information on the effects of N substitution practices on soil quality in the red soil area in South China is still limited. In this study, therefore, four kinds of organic materials, including maize straw, cow manure, biochar and biogas residue, were applied to sweet maize farmland for six consecutive cropping seasons to substitute 20% synthetic N fertilizer in the Pearl River Delta Plain, which is a typical red soil area in South China. We compared the effects of different N substitution practices with conventional fertilization (CK) on the soil physical, chemical and biological properties and the microbial community structure. A minimum dataset method was utilized to calculate the soil quality index (SQI) under different treatments. The results demonstrated that the N substitution practice improved the SQI by 55%−70% compared to the CK in the red soil of South China by improving the soil physicochemical properties and biological characteristics. Meanwhile, the N substitution practice showed positive effects on changing the microbial community structure. Cow manure substitution showed the best effect due to the increased relative abundance of beneficial phyla in the soil microbiota, such as Proteobacteria, Chloroflexi and Ascomycota, and the decreased relative abundance of Basidiomycota. Finally, the structural equation model illustrated that the N substitution practice greatly improved the SQI in red soil by improving the soil bulk density, pH, β-glucosidase activity, urease activity and microbial community composition. Collectively, all four N substitution practices significantly improved soil quality, and cow manure substitution was the most effective way to improve soil microbial community composition and soil quality. This study provides a research basis for improving soil quality in the red soil region in South China and valuable information for the development of clean agricultural production in typical subtropical areas in East Asia.

Comparative Performance of Aerial RGB vs. Ground Hyperspectral Indices for Evaluating Water and Nitrogen Status in Sweet Maize

This study analyzed the capability of aerial RGB (red-green-blue) and hyperspectral-derived vegetation indices to assess the response of sweet maize (Zea mays var. saccharata L.) to different water and nitrogen inputs. A field experiment was carried out during 2020 by using both remote RGB images and ground hyperspectral sensor data. Physiological parameters (i.e., leaf area index, relative water content, leaf chlorophyll content index, and gas exchange parameters) were measured. Correlation and multivariate data analysis (principal component analysis and stepwise linear regression) were performed to assess the strength of the relationships between eco-physiological measured variables and both RGB indices and hyperspectral data. The results revealed that the red-edge indices including CIred-edge, NDRE and DD were the best predictors of the maize physiological traits. In addition, stepwise linear regression highlighted the importance of both WI and WI:NDVI for prediction of relative water content and crop temperature. Among the RGB indices, the green-area index showed a significant contribution in the prediction of leaf area index, stomatal conductance, leaf transpiration and relative water content. Moreover, the coefficients of correlation between studied crop variables and GGA, NDLuv and NDLab were higher than with the hyperspectral indices measured at the ground level. The findings confirmed the capacity of selected RGB and hyperspectral indices to evaluate the water and nitrogen status of sweet maize and provided opportunity to expand experimentation on other crops, diverse pedo-climatic conditions and management practices. Hence, the aerially collected RGB vegetation indices might represent a cost-effective solution for crop status assessment.

Fresh maize yield in response to nitrogen application rates and characteristics of nitrogen-efficient varieties

Efficient nitrogen management is crucial in developing sustainable strategies aimed at enhancing yield while mitigating negative environmental impacts. However, limited research has focused on this aspect in the production of fresh maize. Therefore, this study analyzed nitrogen application rates and yield for 40 sweet and 44 waxy maize varieties in Zhejiang Province, China from 2015 to 2019 across five sites. Nitrogen application rates were categorized as relatively high (RHN: >300 kg ha-1 for sweet maize, >320 kg ha-1 for waxy maize) or relatively low (RLN). An increase in nitrogen application rates for both sweet and waxy maize significantly reduced nitrogen fertilizer partial productivity (R2=0.616, P<0.01; R2=0.643, P<0.01), indicating that the optimum nitrogen application rate in this study might be the lowest values (160 kg ha-1 for sweet maize and 180 kg ha-1 for waxy maize). The kernel number per ear of sweet maize had a potentially more significant impact on fresh grain yield compared to the 1,000-fresh kernel weight both under RLN and RHN. In waxy maize, 1,000-kernel weight contributed more to fresh grain yield under RLN, and kernel number ear-1 and 1,000-kernel weight cooperatively affected yield under RHN. In this study, it was observed that sweet maize required taller plant and ear height, along with an optimal ear-plant height ratio, to enhance dry matter accumulation and increase source size, particularly under RLN, to achieve a higher fresh grain yield. In contrast, a lower ear height and ear-plant height ratio of waxy maize probably contributed more to increased kernel number and weight under RLN, likely due to a lower ear height can reduce the distance between sink and source, enabling more efficient photoassimilate allocation to the ear.

Genetic architecture of kernel-related traits in sweet and waxy maize revealed by genome-wide association analysis.

Maize (Zea mays L.) is one of the most important crops worldwide, the kernel size-related traits are the major components of maize grain yield. To dissect the genetic architecture of four kernel-related traits of 100-kernel weight, kernel length, kernel width, and kernel diameter, a genome-wide association study (GWAS) was conducted in the waxy and sweet maize panel comprising of 447 maize inbred lines re-sequenced at the 5× coverage depth. GWAS analysis was carried out with the mixed linear model using 1,684,029 high-quality SNP markers. In total, 49 SNPs significantly associated with the four kernel-related traits were identified, including 46 SNPs on chromosome 3, two SNPs on chromosome 4, and one SNP on chromosome 7. Haplotype regression analysis identified 338 haplotypes that significantly affected these four kernel-related traits. Genomic selection (GS) results revealed that a set of 10,000 SNPs and a training population size of 30% are sufficient for the application of GS in waxy and sweet maize breeding for kernel weight and kernel size. Forty candidate genes associated with the four kernel-related traits were identified, including both Zm00001d000707 and Zm00001d044139 expressed in the kernel development tissues and stages with unknown functions. These significant SNPs and important haplotypes provide valuable information for developing functional markers for the implementation of marker-assisted selection in breeding. The molecular mechanism of Zm00001d000707 and Zm00001d044139 regulating these kernel-related traits needs to be investigated further.

Evaluation of growing of sweet maize varieties and hybrids as a repeated crop in different planting periods and schemes

In a comprehensive scientific study conducted in the Bukhara province, the cultivation of 12 varieties and hybrids of sweet (vegetable) corn was undertaken as a repeated crop in medium-saline meadow alluvial soils. Noteworthy varieties and hybrids evaluated in the study included "Zamin," "Mazza," "Megaton F1," and "Union F1," selected based on their suitability for the specific soil and climate conditions prevalent in the province. The research aimed to discern the optimal combinations of planting schemes and periods for maximizing yield in sweet corn production. Among the diverse planting schemes and periods tested, the study highlighted the effectiveness of the 60x30 and 70x25 cm schemes, identifying them as the optimal choices. Furthermore, the optimal planting period was pinpointed to be July 5, emphasizing the significance of timing in sweet corn cultivation in the region. The findings indicated that when varieties and hybrids like "Zamin," "Mazza," "Megaton F1," and "Union F1" were planted on July 5 using the 60x30 and 70x25 cm schemes, an impressive yield of 10.1-14.4 tons of vegetable cobs per hectare was achieved. This underscores the importance of meticulous selection of both planting schemes and periods to optimize sweet corn production in the specific agro-climatic conditions of the Bukhara province. The research outcomes contribute valuable insights for local farmers and agricultural practitioners, offering practical recommendations for enhancing crop productivity and ensuring sustainable sweet corn cultivation practices.

Pengaruh Kompos Tandan Kosong Kelapa Sawit dan Abu Cangkang Kerang Terhadap Serapan Unsur Fosfor dan Produksi Tanaman Jagung Manis di Tanah Ultisols

Utilization of Ultisols for sweet maize cultivation has several barriers, especially low of soil acidity, CEC, nutrient availability, organic matter and high of Al, Fe, and Mn consentration. This research was aimed to know the interaction of palm oil empty fruit compost and cockle shell ash on phosphorus uptake and yield of sweet maize in Ultisols. The experiment was carried out in screen house of Agriculture Faculty, Tanjungpura University. The research used factorial design arranged in a completely randomized design (CRD) consisting of two factors treatment (CRD). The first factor is palm oil empty fruit compost consisting control (T0), 670 g/polybag (T1), 1,030 g/polybag (T2) and 1,410 g/polybag (T3). The second factor is cockle shell ash consisting (A0), 3,3 g/polybag (A1), 4,4 g/polybag (A2), and 5,5 g/ polybag (A3). Each tretments was done in 3 replication. The parameters are soil pH, C-Oraganik, P-Available, phosphorus uptake, cob length, and cob weight. The results showed T0A3 can increase soil pH highest with the value 6.08. T3A2 can increase C-Organic with the value 2.31. T2A1 can increase P-Available with the value 26.96. T2 (1,030 g/polybag) significantly affected phosphorus uptake and cob weight.

Suitability of Satellite Imagery for Surveillance of Maize Ear Damage by Cotton Bollworm (Helicoverpa armigera) Larvae

The cotton bollworm (Helicoverpa armigera, Lepidoptera: Noctuidae) poses significant risks to maize. Changes in the maize plant, such as its phenology, influence the short-distance movement and oviposition of cotton bollworm adults and, thus, the distribution of the subsequent larval damage. We aim to provide an overview of future approaches to the surveillance of maize ear damage by cotton bollworm larvae based on remote sensing. We focus on finding a near-optimal combination of Landsat 8 or Sentinel-2 spectral bands, vegetation indices, and maize phenology to achieve the best predictions. The study areas were 21 sweet and grain maze fields in Hungary in 2017, 2020, and 2021. Correlations among the percentage of damage and the time series of satellite images were explored. Based on our results, Sentinel-2 satellite imagery is suggested for damage surveillance, as 82% of all the extremes of the correlation coefficients were stronger, and this satellite provided 20–64% more cloud-free images. We identified that the maturity groups of maize are an essential factor in cotton bollworm surveillance. No correlations were found before canopy closure (BBCH 18). Visible bands were the most suitable for damage surveillance in mid–late grain maize (|rmedian| = 0.49–0.51), while the SWIR bands, NDWI, NDVI, and PSRI were suitable in mid–late grain maize fields (|rmedian| = 0.25–0.49) and sweet maize fields (|rmedian| = 0.24–0.41). Our findings aim to support prediction tools for cotton bollworm damage, providing information for the pest management decisions of advisors and farmers.

Optimal Plant Density Improves Sweet Maize Fresh Ear Yield without Compromising Grain Carbohydrate Concentration

It is crucial to synergistically improve the yield and quality of sweet maize by implementing precise and strategic planting methods. However, a comprehensive understanding of how increasing plant density affects the sweet maize fresh ear yield, grain-filling rate, and grain carbohydrate concentration is not fully understood. Thus, a field experiment was performed using a split-plot design in Southeast China in 2021 and 2022, involving four sweet maize varieties (MT6855 and WT2015 were compact-type varieties, XMT10 and YZ7 were flat-type varieties) and three plant densities (D1: 4.5 plants m−2; D2: 6.0 plants m−2; and D3: 7.5 plants m−2). The results showed that an increasing plant density markedly increased the fresh ear yield of sweet maize varieties (MT6855 and WT2015) over the two years. However, it did not influence the fresh ear yield of XMT10 and YZ7. Across all four varieties in 2021 and 2022, the increasing plant density decreased the sweet maize filled ear length, while it did not affect the grain soluble solid concentration and grain residue ratio. The sweet maize grain weight, the maximum grain-filling rate, and the mean grain-filling rate decreased significantly with the increase in planting density across all four varieties. However, plant density did not significantly affect the grain soluble sugar, sucrose, fructose, and starch concentrations across different varieties at most stages during the grain filling. The current study also found that the sweet maize fresh ear yield was dramatically positively correlated with ears ha−1, grains per ear, grain-filling rate, and grain starch concentration but negatively correlated with the bare plant rate. Notably, a parabolic relationship existed between the fresh ear yield and 100-grain weight. These findings suggest that optimizing the plant density, particularly with compact-type varieties, can improve the sweet maize fresh ear yield without decreasing its quality.

An Evaluation of the Crop Preference and Phenotypic Characteristics of Ceracris kiangsu Tsai (Orthoptera: Arcypteridae) under Different Temperatures.

The yellow-spined bamboo locust (YSBL), Ceracris kiangsu Tsai, has historically had a significant impact on different bamboo varieties in East Asia and Southeast Asia. Since 2014, there have been many outbreaks of YSBL populations in Laos, and YSBLs subsequently invaded Southwest China in 2020 and 2023. However, there was limited information about the damage to staple crops. Life table parameters and fitness parameters were assessed using wheat, rice, waxy maize, and sweet maize under three different temperatures (25 °C, 30 °C, and 35 °C) in the laboratory. The results indicated that the YSBLs feeding on wheat seedlings displayed a significantly higher survival rate, a shorter developmental time, and a higher adult emergence rate compared to YSBLs feeding on the other host species at 30 °C. The developmental durations of 1st and 3rd instar YSBLs on wheat (1st: 8.21 ± 0.35 d; 3rd: 6.32 ± 0.34 d) and rice (1st: 7.19 ± 0.23 d; 3rd: 9.00 ± 0.66 d) were significantly shorter than those of 1st and 3rd instar YSBLs on waxy maize (1st: 13.62 ± 1.22 d; 3rd: 13.67 ± 6.33 d) and sweet maize (1st: 16.00 ± 1.79 d; 3rd: 18.00 ± 3.49 d) at 30 °C. The body lengths of male and female YSBLs on wheat (male: 29.52 ± 0.40 mm, female: 34.97 ± 0.45 mm) and rice (male: 28.85 ± 0.68 mm, female: 34.66 ± 0.35 mm) were significantly longer than those observed when they were fed on sweet maize (male: 25.64 ± 1.60 mm, female: 21.93 ± 6.89 mm). There were only male adults obtained on waxy maize. The phenotypic characteristics of the YSBLs feeding on rice seedlings were very close to those of the YSBLs feeding on wheat seedlings. A relatively slower decline was observed in the survival rates of YSBL nymphs on wheat and rice compared to those on waxy maize and sweet maize at 25 °C, 30 °C, and 35 °C. In short, this study implied that YSBLs prefer wheat and rice. This study is the first report of direct damage caused by the YSBL to wheat in the laboratory, and its results could be useful in improving our understanding of the host preference of the YSBL and providing strategies for the management of this pest in field crops.

Coupling Effects of Optimized Planting Density and Variety Selection in Improving the Yield, Nutrient Accumulation, and Remobilization of Sweet Maize in Southeast China

Low planting density and lack of density-tolerant varieties are the critical factors limiting the yield of sweet maize in Southeast China. However, there is relatively limited information about the interaction effects of plant density and variety on sweet maize in Southeast China. A two-year (2021–2022) field experiment was conducted with two sweet maize varieties (MT6855 and XMT10) and three plant densities (D1: 45,000 plants ha−1, D2: 60,000 plants ha−1, and D3: 75,000 plants ha−1). The results showed that plant density and variety had significant interaction effects on sweet maize yield and most traits. Increasing plant density significantly increased the fresh ear yield of MT6855, while it did not affect the XMT10 variety. The increase in fresh ear yield for MT6855 under D2 treatment was 14.9% and 14.0% higher than that under D1 treatment in 2021 and 2022, respectively. Meanwhile, increasing plant density significantly increased the bare plant rate and decreased the number of grains per ear of XMT10, while no sustainable changes were observed in MT6855. Moreover, we observed significantly increased pre-silking dry matter, N, P, and K accumulation across different densities in both varieties. In contrast, during the post-silking stage, the increasing plant density significantly improved the accumulation of dry matter, N, P, and K, only in MT6855 but not in XMT10. Meanwhile, harvest index, dry matter remobilization, and leaf N, P, and K remobilization of MT6855 were significantly higher than those of XMT10. Increasing plant density significantly increased N, P, and K partial factor productivity of MT6855 but did not remarkably affect those of XMT10. In addition, fresh ear yield of sweet maize was significantly and positively correlated with pre-silking, post-silking, and total N and P accumulation but had no significant relationship with leaf K remobilization across the two varieties. These results suggest that MT6855 is a density-tolerant variety of sweet maize, and optimizing planting density with a density-tolerant variety can improve the accumulation and remobilization of dry matter and nutrients, thereby improving the fresh ear yield and nutrient use efficiency of sweet maize.

Silage Quality, Nutrient Content and Relative Feed Value of Urea and Molasses Added Sweet Maize [Zea mays (L.) saccharata Sturt.] Silage

Background: This study was carried out to determine silage quality, nutrient content, relative feed value (RFV), fermentation parameters and Fleig scores of sweet maize [Zea mays (L.) saccharata Sturt.] without the cob ensiled with urea or molasses. Methods: Plant parts remaining from the sweet maize whose cobs were harvested were ensiled with the addition of 1% urea and 5-10% molasses. In the liquid samples collected from the silages, pH values, ammonia nitrogen (NH3-N) and volatile fatty acid (VFA) concentrations were measured and the silage samples were subjected to crude nutrient analyses, RFV and Fleig score determination. Result: Significant differences were found among the groups in terms of their dry matter (DM), organic matter (OM), crude ash (CA), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) values. The difference between silage groups was significant in terms of NH3 and VFA values. In the analyses of Fleig scores, physical parameters and RFV results, the groups were found significantly different except for Fleig scores. In parallel with the increase in the concentration of urea used in the silage groups, there were reductions in Fleig scores, physical parameters and RFV values, while their CP levels increased. The molasses that was added to the silages led to a reduction in their silage pH, NH3-N and butyric acid (BA) values and an increase in their lactic acid (LA) values. It was concluded that the additives used in this study contributed positively to the quality of the silages, all silages with additives were quality silages and they could be used as an alternative quality roughage resource in feeding ruminants.

Factors Governing Organic Amendments and NPK Fertilizers Effects on Sweet Maize in Old and Intensively Cultivated Experimental Farm

Applying organic amendment (OA) containing humic compounds (HC) and phytohormones is a promising solution to intensify sustainable food production under increasing global food needs, declining environmental carrying capacity and changing climate. However, most positive claims on OA efficacy often came from controlled, greenhouse experiments. The field trial was conducted on an intensively cultivated experimental farm station, Department of Soil Science and Land Resources, Faculty of Agriculture, IPB University. The OA testing was done on sweet maize (Zea mays L. saccharata) using a fractional factorial randomized block design by comparing five rates of the organic amendment (0, ½, 1, 1½, and 2 standards OA) with three rates of NPK fertilizer (0, 1, and ¾ standards NPK). The results revealed that a single OA application did not significantly boost the growth and biomass of sweet maize, especially when applied to an old and intensively cultivate and organically manured farm. OA had significant interaction with NPK at most of the yields and biomass parameters. Amending soils more than 12 L OA ha-1 could improve the sweet maize’s growth and development while saving 25% NPK fertilizers. Linear mixed effect model and multivariate analysis uncovered higher heterogeneity in trial plots controlled maize growth, biomass, and agronomic effectivity, regardless of the given treatments. This study highlighted three important marks for future research: (1) soil plowing, harrowing and mixing must be intensively done across plots, (2) adequate HC contents must be increased from the OA current rate, and (3) the greater role of phytohormone in stimulating maize growth and production at the OA current rate.

Investigation of the Detectability of Corn Smut Fungus (Ustilago maydis DC. Corda) Infection Based on UAV Multispectral Technology

Corn smut fungus (Ustilago maydis [DC.] Corda) is a globally widespread pathogen affecting both forage and sweet maize hybrids, with higher significance in sweet maize. Remote sensing technologies demonstrated favorable results for disease monitoring on the field scale. The study focused on the changes in vegetation index (VI) values influenced by the pathogen. In this study, four hybrids, two forage maize and two sweet maize hybrids were examined. Artificial infection was carried out at three different doses: a low (2500 sporidium number/mL), medium (5000 sporidium number/mL) and high dose (10,000 sporidium number/mL) with a non-infected control plot for each hybrid. The experimental plots were monitored using a multispectral UAV sensor of five monochrome channels on three different dates, i.e., 7, 14 and 21 days after infection. Five different indices (NDVI, GNDVI, ENDVI, LCI, and NDRE) were determined in Quantum GIS 3.20. The obtained results demonstrated that the infection had a significant effect on the VI values in sweet maize hybrids. A high-dose infection in the Dessert R 73 hybrid resulted in significantly lower values compared to the non-infected hybrids in three indices (NDVI, LCI and GNDVI). In the case of the NOA hybrids, GNDVI and ENDVI were able to show significant differences between the values of the infection levels.

Genetic basis of the oil biosynthesis in ultra-high-oil maize grains with an oil content exceeding 20.

Vegetable oil is an important part of the human diet and has multiple industrial uses. The rapid increase in vegetable oil consumption has necessitated the development of viable methods for optimizing the oil content of plants. The key genes regulating the biosynthesis of maize grain oil remain mostly uncharacterized. In this study, by analyzing oil contents and performing bulked segregant RNA sequencing and mapping analyses, we determined that su1 and sh2-R mediate the shrinkage of ultra-high-oil maize grains and contribute to the increase in the grain oil content. Functional kompetitive allele-specific PCR (KASP) markers developed for su1 and sh2-R detected su1su1Sh2Sh2, Su1Su1sh2sh2, and su1su1sh2sh2 mutants among 183 sweet maize inbred lines. An RNA sequencing (RNA-seq) analysis indicated that genes differentially expressed between two conventional sweet maize lines and two ultra-high-oil maize lines were significantly associated with linoleic acid metabolism, cyanoamino acid metabolism, glutathione metabolism, alanine, aspartate, and glutamate metabolism, and nitrogen metabolism. A bulk segregant analysis and sequencing (BSA-seq) analysis identified another 88 genomic intervals related to grain oil content, 16 of which overlapped previously reported maize grain oil-related QTLs. The combined analysis of BSA-seq and RNA-seq data enabled the identification of candidate genes. The KASP markers for GRMZM2G176998 (putative WD40-like beta propeller repeat family protein), GRMZM2G021339 (homeobox-transcription factor 115), and GRMZM2G167438 (3-ketoacyl-CoA synthase) were significantly related to maize grain oil content. Another candidate gene, GRMZM2G099802 (GDSL-like lipase/acylhydrolase), catalyzes the final step of the triacylglycerol synthesis pathway and was expressed at significantly higher levels in the two ultra-high-oil maize lines than in the two conventional sweet maize lines. These novel findings will help clarify the genetic basis of the increased oil production in ultra-high-oil maize lines with grain oil contents exceeding 20%. The KASP markers developed in this study may be useful for breeding new high-oil sweet maize varieties.

Effect of nicosulfuron on dynamic changes in the starch-sugar interconversion in sweet maize (Zea mays L.)

Starch is an important reserve of sugar, and starch-sugar conversion in plants plays an important role in the response of plants to various abiotic stresses. Nicosulfuron is a post-emergence herbicide commonly applied to maize fields. However, it is unclear how sucrose and starch in sweet corn are converted to accommodate nicosulfuron stress. Field and pot experiments were conducted to study the effects of nicosulfuron on the sugar metabolism enzymes, starch metabolism enzymes, non-enzyme substances, and expression of key enzyme genes in leaves and roots of sweet maize seedlings. Accordingly, this research compared the responses of the sister lines HK301 and HK320, which are nicosulfuron tolerant and sensitive, respectively. Under nicosulfuron stress, compared with HK301 seedlings, the accumulation of stem and root dry matter of HK320 seedlings was significantly reduced, resulting in a lower root-to-shoot ratio. Compared with HK320 seedlings, nicosulfuron stress significantly increased the sucrose, soluble sugar, and starch contents in HK301 leaves and roots. This may be related to the enhanced carbohydrate metabolism under nicosulfuron stress, including significant changes in sugar metabolism enzyme activity and the levels of SPS and SuSys expression. Further, under nicosulfuron stress, sucrose transporter genes (SUC 1, SUC 2, SWEET 13a, and SWEET 13b) in the leaves and roots of HK301 seedlings were significantly upregulated. Our results emphasize that changes in sugar distribution, metabolism, and transport can improve the adaptability of sweet maize to nicosulfuron stress.

Public Willingness to Pay For Purple Corn Attributes

Sweet corn (Zea mays L. saccharata), also known as sugar corn or sweet maize, is a popular multi-purpose cereal crop of the family Poaceae (Muhumed et al., 2014). The crop is the second most important crop in Asia after rice. China remains as the largest producer with a production of 260 million MT in 2019. In Malaysia, the crop area is estimated 10 thousand ha with production yield of 73 thousand MT. Purple variety that rich with anthocyanin content is classified as sweet corn that relatively new in local market. The cultivation of purple corn is not encouraging as Malaysian Department of Agriculture (DOA) recorded only eight farmers throughout Malaysia with a total area of 17.7 ha. Considering this variety is new and less accessible, this study evaluates consumers’ Willingness to Pay (WTP) in Malaysia towards purple corn. Data was collected through online platforms using structured questionnaires. The total of 431 responses were received in one month. The discrete choice experiment (DCE) is used to measure consumer WTP and the results showed that anthocyanin content and sweetness of purple corn are positive and significant at the level of 1%. This indicated that the higher the anthocyanin content and corn sweetness, the higher the level of consumer utility would be. Consumers are willing to pay for higher prices than the lowest market price if the purple corn variety satisfies both value-added anthocyanin and sweetness attributes.