Dent Stage Research Articles

Abnormal ear development in corn: Does hybrid, environment, and planting date matter?

AbstractCorn (Zea mays L.) yields have increased historically, but production concerns still exist. For decades, abnormal corn ear development symptoms have been reported. Most of these reports have not been addressed through research, perhaps due to low occurrence and challenges in replicating them. In 2016, widespread abnormal ear development (multiple ears per node, barbell‐ears, and short‐husk ears) issues were reported in several cornfields in the Texas Panhandle, Eastern Colorado, Nebraska, and other US Midwest states. Fields with a high frequency of abnormalities resulted in lower yields. To investigate causal factors, a field trial was established to study the effect of hybrids, environments, and planting dates on abnormal ears. The project was conducted at two Nebraska sites during the 2018, 2019, and 2020 growing seasons. Six hybrids, six environments, and four planting dates were studied. Approximately 59,200 plants were individually assessed at the dent stage (R5). Abnormal ear percentages ranged from 0% to 45% per plot, with a mean of 6.66% across all conditions. Interactions among hybrids, environments, and planting dates were documented despite the overall low incidence of abnormal ears. Grain yields ranged from 5.2 to 22.5 Mg ha−1; hybrids with higher abnormal ear percentages were associated with lower yields. The main documented symptom was short‐husk ears. Abnormal ears were often placed at lower heights in the plant relative to normal ears. The results presented here demonstrate the importance of studying abnormal ears and understanding the impact of planting dates and hybrid selection as potential strategies to mitigate abnormal ears.

Physiological Response and Aflatoxin Contamination in Maize (Zea Mays L.) Grown Under Varying Water-Deficit Levels in a Semi-Arid Region

The present study explored the effects of water deficit levels at different growth stages of maize (Zea mays L.) cultivated in semi-arid conditions with regard to physiological responses and aflatoxin contamination. The physiological growth changes of maize hybrids were gauged for parameters viz. relative water content (RWC, %), root-shoot ratio (R/S), and specific leaf area (SLA). At the same time, the study used HELICA total Aflatoxin Assay for estimating aflatoxin contamination in the produced maize kernel. Results revealed the third level of water-deficit, which extended to the dent stage, led to lower RWC%, and higher (R/S), alongside lower (SLA). Although the aflatoxin level was estimated to be 18.5 ppb in the maize kernels (FDA limit = 20 ppb), it was apparent that cultivation in a semi-arid condition runs the risk of aflatoxin contamination, likely due to water shortage and high growing temperatures.

Evaluation of Silage Quality of Forage Maize (Zea mays L.) and Sweet Sorghum (Sorghum bicolor L. Moench) Varieties at Different Phenophases

Aim: To evaluate the green fodder production potential of forage maize and sweet sorghum varieties at different phenophases.
 Experiment Design: Factorial Randomized Block Design (FRBD).
 Place and Duration of Study: AICRP on Forage Crops and Utilization, Agricultural Research Institute. Duration from July 2022 to Nov 2022.
 Methodology: Field experiment was conducted at AICRP on Forage Crops and Utilization, Agricultural Research Institute (ARI), Rajendranagar, Hyderabad during kharif 2022. The treatments consisted of four maize varieties (African tall, J –1006, TSFM 15-5 and DHM-117) and two sweet sorghum varieties (CSH-22SS and CSV-49SS) and three harvest stages (S1: Milky stage, S2: Soft dough stage and S3: Dent stage) laid out in randomized block design with factorial concept with two factors. Factor (A) as six varieties and factor (B) as three harvest stages (phenophases) with three replications. Texture of the soil was sandy loam with the pH of 7.0, low in available nitrogen (199.3 kg ha-1), medium in available phosphorous (39.12 kg ha-1) and potassium (195.30 kg ha-1).
 Results: Fodder maize variety African tall recorded significantly higher plant height (265.8 cm) at dent stage, leaf-stem ratio (0.36) at milky stage, green fodder yield (438 q ha-1) at soft dough stage and dry fodder yield (122.7 q ha-1) at dent stage of harvest. while J-1006 recorded significantly highest dry matter content (29.8%) at the dent stage of harvest. CSH 22SS recorded significantly higher crude protein content (10%) in the milky stage.
 Conclusion: African tall variety has recorded significantly higher green fodder yield (438 q ha-1) at soft dough stage and dry fodder yield at the dent stage (122.7 q ha-1).

Growth, Productivity, Competitive Ratio, Maize Equivalent Yield, Land Equivalent Ratio, and Profitability of Hybrid Maize as Influenced by Relay Cropping with Mukhikachu (Colocasia esculenta Schott.) during Rabi Season

Relay cropping is a method that increases total productivity through maximum utilization of resources. In this study, we planned a field experiment, which was conducted at the Regional Agricultural Research Station, Ishwardi, Pabna during 2016-2017 and 2017-2018 to find out the most suitable way of relaying mukhikachu (MU) with hybrid maize to get the maximum benefit. Seven treatments: T1= Relay at silking stage (100 DAS), T2 = Relay at the blister stage (110 DAS), T3 = Relay at the milk stage (120 DAS), T4 = Relay at the dough stage (130 DAS), T5 = Relay at the dent stage (140 DAS), T6 = Sole hybrid maize, T7 = Sole mukhikachu, were compared in the study. It was found that among the treatments (relay cropping and sole stand), there was no significant difference in terms of yield and attributes of both base (maize) and relay crop (mukhikachu). In the entire treatment, maize yielded 10.54-11.30 t ha-1 with results of 3.28-3.66 MJ m-2day-1 light energy interception (120 DAS), 2.68-2.84 LAI (120 DAS) and 1534.63-1592.69 g m-2 TDM (140DAS). The mukhikachu yielded 26.88-27.28 t ha-1 among the relay cropping system. Maize equivalent yield (MEY) and BCR ranged from 28.48-29.18 t ha-1 and 2.33-2.39, respectively, amongst the relay cropping treatments. The land equivalent ratio (LER) of the relay cropping treatment produced almost double (1.934-1.996) that of the sole crops. Farmers can benefit by adopting this relay cropping technology when they grow long-duration crops, and this technology can lead to improved system productivity.

Abnormal ear development in corn: Does hybrid, environment, and seeding rate matter?

AbstractCorn (Zea mays L.) yields have increased in the United States since the 1930s and in other parts of the world since the 1950s and 1960s because of improvements in agricultural management and genotypes. Despite these increases, production concerns still exist. In July 2016, abnormal ear development (multi‐ears per node, barbell‐ears, and short‐husks) was reported in cornfields that extended from the Texas Panhandle to eastern Colorado and east through Kansas, Nebraska, Iowa, and Illinois. Surveys in Nebraska farmer fields revealed significant productivity losses due to the issues, but little was known about the underlying causes. A research study was conducted in four Nebraska fields during the 2018 and 2019 growing seasons. The research investigated the effects of hybrids, environments, seeding rates, and their interactions on abnormal ears. Eight hybrids, eight environments, and five seeding rates were studied. About 63,500 plants were individually assessed at or after the dent stage (R5). Grain yield ranged from 4.3 to 20.1 Mg ha−1. In 2018, about 5% of ears were abnormal; in 2019, about 11%, if combined, about 8%. Higher‐yielding hybrids were associated with lower percentages of abnormalities. Hybrids, environments, and seeding rates influenced the occurrence of abnormal ears. In most cases, abnormal ears had lower heights in the canopy, suggesting that primary ear loss may be a factor. The results reinforced the overriding hypothesis that ear abnormalities result from environmental, genetic, and management interactions. Depending on the environment, selecting certain hybrids with optimum seeding rates could help mitigate the occurrence of abnormal ears.

Water Use Efficiency of Maize (Zea mays L.) Crop under Selected Soil and Water Conservation Practices along the Slope Gradient in Ruzizi Watershed, Eastern D.R. Congo

Maize (Zea mays L.) productivity is constrained by water shortages in the predominantly rainfed agriculture of the tropical semi-arid Ruzizi Plain, in the eastern Democratic Republic of Congo (DRC). The region is characterized by a high seasonal and inter-annual rainfall variability and a frequent occurrence of consecutive dry days within growing seasons. Consequently, planning water utilization in rainfed agriculture has become complex, as appropriate soil water conservation (SWC) practices are lacking among most smallholder farmers. Identifying practices that increase water use efficiency (WUE) along the slope gradient is crucial for supporting maize production in the region. In this study, we assessed, for three growing seasons, the effectiveness of two SWC practices (tied ridges and Zai pits) in improving the WUE of two maize varieties along three slope gradients (0–2, 2–8, and 8–15%) in the tropical semi-arid Ruzizi Plain. In this area, rainfall amounts (142–289 mm) were consistently below the evapotranspiration demands (356–533 mm) across the three growing seasons. Tied ridges recorded the highest grain yield (2.16 t ha−1) and WUE (15.23 kg mm−1), especially at low slopes, when compared to Zai pits and conventional tillage. For all SWC practices, WUE decreased with the slope gradient (p < 0.01). Furthermore, a decrease in stored soil water (SWS) at silking and maturity stages (milk, dough, and dent stages) negatively affected the WUE. The variety had no significant effect on grain yield and WUE. Root biomass (RBM), shoot biomass (SBM), and leaf area index (LAI) at the flowering stage were the most associated with the WUE (R2 = 58.5%). In conclusion, tied ridges showed potential for improving maize WUE and yield in the water-deficient conditions that characterize the Ruzizi Plain, and could be promoted to improve the maize productivity among smallholder farmers.

Characteristics and candidate genes associated with excellent stalk strength in maize (Zea mays L.).

Lodging is a major problem in maize production, which seriously affects yield and hinders mechanized harvesting. Improving stalk strength is an effective way to improve lodging. The maize inbred line Jing2416 (J2416) was an elite germplasm in maize breeding which had strong stalk mechanical strength. To explore the characteristics its stalk strength, we conducted physiological, metabolic and transcriptomic analyses of J2416 and its parents Jing24 (J24) and 5237. At the kernel dent stage, the stalk rind penetrometer strength of J2416 was significantly higher than those of its two parents in multiple environments. The rind thickness, sclerenchyma tissue thickness, and cellulose, hemicellulose, and lignin contents of J2416 were significantly higher than those of its parents. Based on the significant differences between J2416 and 5237, we detected metabolites and gene transcripts showing differences in abundance between these two materials. A total of 212 (68.60%) metabolites and 2287 (43.34%) genes were up-regulated in J2416 compared with 5237. The phenylpropanoid and glycan synthesis/metabolism pathways were enriched in metabolites and genes that were up-regulated in J2416. Twenty-eight of the up-regulated genes in J2416 were involved in lignin, cellulose, and hemicellulose synthesis pathways. These analyses have revealed important physiological characteristics and candidate genes that will be useful for research and breeding of inbred lines with excellent stalk strength.

Genetic Perturbation of the Starch Biosynthesis in Maize Endosperm Reveals Sugar-Responsive Gene Networks.

In maize, starch mutants have facilitated characterization of key genes involved in endosperm starch biosynthesis such as large subunit of AGPase Shrunken2 (Sh2) and isoamylase type DBE Sugary1 (Su1). While many starch biosynthesis enzymes have been characterized, the mechanisms of certain genes (including Sugary enhancer1) are yet undefined, and very little is understood about the regulation of starch biosynthesis. As a model, we utilize commercially important sweet corn mutations, sh2 and su1, to genetically perturb starch production in the endosperm. To characterize the transcriptomic response to starch mutations and identify potential regulators of this pathway, differential expression and coexpression network analysis was performed on near-isogenic lines (NILs) (wildtype, sh2, and su1) in six genetic backgrounds. Lines were grown in field conditions and kernels were sampled in consecutive developmental stages (blister stage at 14 days after pollination (DAP), milk stage at 21 DAP, and dent stage at 28 DAP). Kernels were dissected to separate embryo and pericarp from the endosperm tissue and 3′ RNA-seq libraries were prepared. Mutation of the Su1 gene led to minimal changes in the endosperm transcriptome. Responses to loss of sh2 function include increased expression of sugar (SWEET) transporters and of genes for ABA signaling. Key regulators of starch biosynthesis and grain filling were identified. Notably, this includes Class II trehalose 6-phosphate synthases, Hexokinase1, and Apetala2 transcription factor-like (AP2/ERF) transcription factors. Additionally, our results provide insight into the mechanism of Sugary enhancer1, suggesting a potential role in regulating GA signaling via GRAS transcription factor Scarecrow-like1.

Mısır bitkisinde sulamayı sonlandırma zamanının tane verimi, hasatta tane nemi ve bazı tarımsal özellikler üzerine etkileri

This study was conducted to investigate the effects of different irrigation termination dates on maize grain yield, kernel moisture at harvest and some other agronomic traits. The relationships between irrigation termination dates and investigated traits were visually assessed through biplot analysis. Experiments were conducted for two years (2016 and 2017) with three replications. Irrigations were terminated at eight different dates (S1: R2 blister stage; S2: R3 early milk stage; S3: R3 milk stage; S4: R3 late milk stage; S5: R4 dough stage; S6: R5 early dent stage; S7: R5 dented stage; S8: R5 late dent stage). Despite low kernel harvest moisture levels, early irrigation termination dates had low yield levels (S1:10460 kg ha-1 grain yield; 11.7% moisture). However, despite high yield levels, late irrigation termination dates had high kernel harvest moisture levels (S7:16100 kg ha-1 grain yield; and 18.8% moisture; S8:16240 kg ha-1 grain yield and 19.6% moisture). In terms of grain yield and harvest moisture, S4 (14050 kg ha-1 grain yield and 14.2% harvest moisture), S5 (14170 kg/ha grain yield and 15.0% moisture) and S6 (14880 kg ha-1 grain yield and 16.1% moisture) treatments had similar values and were considered to be as the most appropriate irrigation termination dates. Kernel weight per ear varied between 150.6 (S1) and 238.7 g (S7); number of kernels per ear varied between 677 (S1) and 741 kernels (S5), ear lengths varied between 16.7 (S1) - 24.1 cm (S4), thousand-kernel weights varied between 271 g (S1) and 381 g (S8), hectoliter weights varied between 74.3 (S1) and 78.1 kg (S4) and number of days to physiological maturity varied between 112.5 (S1) and 124.5 days (S8).

Nondestructive measurement of husk-covered corn kernel layer dynamic moisture content in the field

Corn kernel moisture content is the most frequently used indicator for kernel maturity prediction and determination of the appropriate mechanized harvesting time. Corn varieties with lower moisture contents and thus faster dehydration of the corn kernels after physiological maturity are suitable for high plant density and mechanized harvesting. However, nondestructive measurement of the dynamic moisture content of the husk-covered corn kernel layer before physiological maturity in the field remains challenging at present. Therefore, in this study, a nondestructive measurement method based on the vector reflection coefficient measurement technique is proposed and developed for in situ monitoring of the husk-covered corn kernel layer moisture in the field. Based on the one-port calibration procedure used for the handheld moisture detection device, quadratic regression models were established for the corn kernel layer moisture using impedance parameters from 51 husk-covered corn samples. Results showed that this method enabled nondestructive estimation of the husk-covered corn kernel layer moisture (R2=0.62) with a 3.53% root mean square error (RMSE) using a serial capacitor Cs and the husk moisture (R2=0.85) with a RMSE of 7.12%. Additionally, intact corn ears were measured in the field from the dent stage to the maturity stage using this device to investigate the dynamic moisture contents of the kernels and husks. Results showed that the measured moisture content of kernels before physiological maturity followed exponential decay functions with increasing numbers of days, and the mean difference between the measured kernel moisture contents of the intact corn ears and the oven-drying moisture contents of these kernels is 3.72%. In conclusion, the handheld moisture detection device allows us to measure the moisture of husk-covered corn kernel layers nondestructively before maturity in the field. This study thus provides a new way to obtain corn kernel dehydration curves in situ before maturity and estimate the corn maturity time.

大气CO2浓度升高对春玉米土壤呼吸的影响

为探讨春玉米不同生育期土壤呼吸速率对大气CO₂浓度升高的响应，以黄土高原旱作春玉米为研究对象，通过改进的开顶式气室（OTC）模拟大气CO₂浓度升高的环境，在田间条件下设置自然大气CO₂浓度（CK）、OTC对照（OTC，CO₂浓度同CK）与CO₂浓度升高（OTC+CO₂，OTC系统自动控制CO₂浓度700 μmol/mol）3种处理。研究了旱区覆膜高产栽培春玉米播前（V0）、六叶期（V6）、九叶期（V9）、吐丝期（R1）、乳熟期（R3）、蜡熟期（R5）及完熟期（R6）土壤呼吸速率对大气CO₂浓度升高的响应特征，以及大气CO₂浓度升高对土壤呼吸速率的温度与水分效应的影响。研究发现，OTC+CO₂处理土壤呼吸速率，与CK相比，在R3和R5期分别增加43%、104%（P<0.05），与OTC相比，R3和R5期分别提升了63%、109%（P<0.05）；OTC处理与CK相比，在整个生育期对土壤呼吸影响不显著；3种处理条件下，土壤温度和水分随生育期变化趋势基本一致，土壤呼吸速率与土壤温度和水分分别呈指数相关和抛物线型相关；结果表明：大气CO₂浓度升高对土壤呼吸的影响因生育期而异，土壤温度和土壤水分是影响旱地农田土壤呼吸的重要因素，CO₂浓度升高会使土壤呼吸温度效应值（Q₁₀）降低，土壤呼吸对土壤水分响应的阈值提高。;Understanding the effects of elevated atmospheric CO₂ on soil respiration is crucial for predicting the greenhouse gas emission in the future. A field experiment was conducted to study the effects of elevated CO₂ on soil respiration of spring maize under three atmospheric conditions (treatments):natural atmospheric conditions with the current CO₂ concentration (marked as CK), open-top chamber (OTC) system with the current atmospheric CO₂ concentration (as the contrast, marked as OTC), and OTC system with elevated CO₂ concentration of 700 μmol/mol (marked as OTC+CO₂). Soil respiration, soil temperature and moisture were measured at the main growth stages of spring maize including pre-sowing (V0), jointing stage (V6), ninth-leaf stage (V9), silking stage (R1), milk stage (R3), dent stage (R5), and physiological maturity stage (R6). The results showed that, compared with CK, OTC+CO₂ enhanced soil respiration rates by 43% and 104% (P<0.05), respectively, at the R3 and R5 stage. Compared with OTC, OTC+CO₂ increased soil respiration rates by 63% and 109% (P<0.05) at the R3 and R5 stage, respectively. There was no significant difference in soil respiration between OTC and CK during the whole growth period of spring maize. The changing dynamics of soil temperature with growth period for the three treatments were consistent, also soil moisture changing dynamics with growth period under the three atmospheric conditions were similar. Soil respiration showed an exponential and parabolic correlation with the soil temperature and soil moisture, respectively. In conclusion, the effects of elevated CO₂ on soil respiration varied with growth stage. Soil temperature and soil moisture were the main factors affecting soil respiration, the elevated CO₂ decreased the temperature effect value (Q₁₀), and increased the threshold value of soil respiration to soil moisture.

Effect of northern corn leaf blight severity on Fusarium ear rot incidence of maize

Northern corn leaf blight (NCLB) caused by Exserohilum turcicum and Fusarium ear rot caused by Fusarium verticillioides, are economically important maize diseases in South Africa. The effect of induced plant stress by NCLB on F. verticillioides ear rot and fumonisin production is unknown. Four field trials were conducted during 2016/2017 and 2017/2018 (November and December planting dates) at the Agricultural Research Council – Grain Crops in Potchefstroom (South Africa). Three maize cultivars with varying resistance levels to NCLB were selected (IMP50-10B – susceptible, BG3292 – moderately susceptible, DKC 61-94BR – resistant). NCLB severities were created through eight treatments: TMT1 – maximum control (three fungicide applications); TMT2 – standard control (two fungicide applications) and TMT3 – natural control (not inoculated or sprayed). The remaining treatments were inoculated with a cocktail of five NCLB races (Race 3, 3N, 23, 23N and 13N): TMT4 (five weeks after planting / WAP); TMT5 (five and six WAP); TMT6 (five, six and seven WAP); TMT7 (six and seven WAP); and TMT8 (seven WAP). Maize ears were naturally infected with F. verticillioides. Fifteen random plants were labelled at dent stage and NCLB severity (%), area under the disease progress curve, ear rot diseased area, ear rot severity (%), ear rot incidence (%) and total fumonisins (FB1+FB2+FB3; ug/kg) were established. Low levels of cob rot severity and fumonisins were obtained in all four trials. NCLB severity did not affect ear rot related parameters measured. Mean fumonisin levels were below the South African tolerance levels. Fumonisin concentrations differed significantly between cultivars but was not affected by NCLB severity or the cultivar x treatment interaction.&#x0D; Significance:&#x0D; &#x0D; This is the first study to investigate the effect of NCLB severity as a predisposing factor of ear rot incidence and severity of maize.&#x0D; The study confirmed that ear rot incidence and severity are not impacted by secondary stressors induced by NCLB, and that the cultivation of NCLB-resistant varieties would not bring about lower ear rot incidences.&#x0D;

Optimized Nitrogen Application Increases Soil Water Extraction by Changing in-Season Maize Root Morphology and Distribution in Rainfed Farmland

The proper promotion of a deep root system is important for maize cultivation to improve water use efficiency in the arid and semi-arid Loess Plateau. Here, a field experiment was conducted to assess the effect of combined controlled release urea and normal urea on root growth and water extraction of maize in dryland fields. Maize in the combined controlled release urea and normal urea treatment had greater root systems compared to those in the normal urea treatment and no N application treatment. Compared to the urea treatment, combined controlled release urea and normal urea advanced the root length density and root weight density in the 0–10 cm soil layer at R1 stage by 30.99% and 45.03% in 2016 and by 20.54% and 19.13% in 2017. The root length density also increased at the dent stage (R5) by 52.05% and 47.75% in 2016 and 2017, and root weight density increased by 19.58% in 2016. Combined controlled release urea and normal urea promoted production of fine roots and root distribution, as well as decreased soil water storage (SWS) in the deep soil layer at the R5 stage. The grain yield was positively correlated with root length density and root weight density in the topsoil layer at the silking stage (R1) and in the whole soil profile at the R5 stage, suggesting that better root system management is helpful for increasing crop grain yield. Therefore, this work demonstrates that combined use of controlled release urea and normal urea to higher crop yields might attribute to increasing water extraction by optimizing in-season maize root morphology and distribution in the rainfed farmland of the Loess Plateau.

The Effect of Simulated Lepidopteran Ear Feeding Injury on Mycotoxin Accumulation in Grain Corn (Poales: Poaceae).

Fusarium graminearum Schwabe (Hypocreales: Nectriaceae) and Fusarium verticillioides (Saccardo) (Hypocreales: Nectriaceae) Nirenberg infection results in accumulation of deoxynivalenol (DON), zearalenone (ZON), and fumonisin (FBs) mycotoxins in infected corn, Zea mays L. Lepidopteran insect feeding may exacerbate fungal infection by providing entry points on the ear resulting in increased mycotoxin contamination of grain. The objective of the current study was to simulate different types and severity levels (extent of injury) of lepidopteran injury to corn ears at different stages of ear development and its effect on mycotoxin accumulation in grain corn. Field experiments were conducted under conditions favorable for F. graminearum development where insect injury was simulated to corn ears and inoculated with F. graminearum. All simulated injury treatments resulted in elevated mycotoxin concentration compared with ears without simulated injury; however, the severity of injury within a treatment had little effect. Injury to kernels on the side of the ear resulted in greater DON and ZON concentration than injury to tip kernels, grazing injury applied at physiological maturity, or when no injury was simulated. Greater FBs was measured when tip kernel injury was simulated at the blister stage or when side kernel injury was simulated at milk and dent stages compared with noninjured ears, silk clipping, tip injury at milk and dent stages, or grazing injury at physiological maturity. The current study confirms that the risk of mycotoxin accumulation in the Great Lakes region is greater in the presence of ear-feeding insect pests and may differ depending on the feeding behavior of pest species.

Delayed maize leaf senescence increases the land equivalent ratio of maize soybean relay intercropping system

Abstract Different planting pattern affects the leaf senescence of maize under intercropping systems, which regulate the grain yield of maize plants. In this study, we observed that a narrow-wide-row planting pattern in maize soybean relay intercropping system (MS) improved the leaf greenness and green leaf area, delayed the leaf senescence process in maize and increased the photosynthetic rate of maize leaves during the reproductive stages of maize in MS. In a three-year field experiment, soybean was relay-intercropped with maize under different planting patterns (1M1S, “50 cm + 50 cm” 1-row of maize and 1-row of soybean with an equal row distance of 50 cm; and 2M2S, “40 cm + 160 cm” narrow-wide-row planting pattern, where 2-rows of maize were planted in narrow rows, and 2-rows of soybean were planted in wide rows, and 60 cm distance was maintained between the rows of maize and soybean) of MS, and both planting patterns of MS were compared with sole cropping systems of maize and soybean. Compared with 1M1S, planting pattern 2M2S significantly increased the number of green leaves (by 36%), leaf greenness (by 17%), and leaf nitrogen content (by 13%) at the dent stage (R5). The improved leaf nitrogen content in 2M2S at R5 significantly increased the green leaf area (by 16%, from 4170 cm2 plant−1 in 1M1S to 4960 cm2 plant−1 in 2M2S) of maize, indicating that leaf senescence of maize plants was delayed, which in turn significantly enhanced the photosynthetic rate of maize leaves at R5 by 57% in 2017, 75% in 2018 and 49% in 2019 than 1M1S. Overall, in 1M1S and 2M2S, relay-cropped maize produced 100%, and 89% of sole maize yield and relay-cropped soybean produced 27% and 66% of sole soybean yield, respectively. Importantly, compared to 1M1S, the decline of maize yield by 11% in 2M2S was compensated by a substantial increase in soybean yield by 147%, and 2M2S achieved the highest land equivalent ratio value of 1.54 compared to the land equivalent ratio value of 1.27 in 1M1S. Our results suggest that by selecting the appropriate planting pattern or stay-green maize hybrids, we can improve the land equivalent ratio of maize soybean relay intercropping system.

Corn hybrid silage quality according to harvesting time

The present study aimed to evaluate the dry matter production of different corn hybrids, the plant chemical composition at the time of ensiling and the participation of the structural components of the plant at the different phenological stages. Corn hybrids P2530, P30B39H and P30R50H were harvested successively at the kernel blister (R2); kernel milk (R3); kernel dough (R4); and kernel dent (R5) stages. We determined the dry matter contents, the percentage participation of each physical structure of the plant at the time of each evaluation, as well as the first ear height, plant height, number of dry leaves, production of dry ensilable phytomass, grain and chemical composition at the time of ensiling (kernel dent stage, R5). There was no difference (p > 0.05) in dry phytomass production between the evaluated hybrids. In general, the hybrid P30R50H, considering dry biomass production and fiber composition of the plant and relative value of the food was balanced for silage. The advance of the stages provided an increase in the grain participation and consequent reduction of the other components in the physical composition of the plant, and the R4 stage was the moment of best association between productivity and physical composition of the plant for silage production.

Histological characterization of rod-cone retinal degeneration in a mouse model of mucopolysaccharidosis type IIIC

Fresh corn stover, which could be separated into fermentable juice and lignocellulosic bagasse, is considered as an alternative raw material for second-generation ethanol production. However, the influence of harvest time of corn stover on ethanol yield has not been evaluated yet. In this work, aiming to improve ethanol yield from fresh corn stover, the harvest time was redefined and optimized. Liquefaction plus simultaneous saccharification and co-fermentation (L + SScF) was carried out to define the realistic ethanol yields. Results showed that compared with the corn stover harvested in the end of physiological stage, the conventional harvest stage, the corn stover harvested in dent stage provided the highest theoretical ethanol yield of 9.92 t/ha (5.64 t/ha for the case that exclude xylan derives). 3.53 t/ha of ethanol was produced from the fresh stover harvested in dent stage, which was 1.64 times higher than using the stover obtained in the conventional harvest time. This study demonstrated that bio-ethanol yield was hugely influenced by harvest time of corn stover, and the stover harvested in dent stage has the highest ethanol yield.

Importance of redefinition of corn stover harvest time to enhancing non-food bio-ethanol production

Fresh corn stover, which could be separated into fermentable juice and lignocellulosic bagasse, is considered as an alternative raw material for second-generation ethanol production. However, the influence of harvest time of corn stover on ethanol yield has not been evaluated yet. In this work, aiming to improve ethanol yield from fresh corn stover, the harvest time was redefined and optimized. Liquefaction plus simultaneous saccharification and co-fermentation (L + SScF) was carried out to define the realistic ethanol yields. Results showed that compared with the corn stover harvested in the end of physiological stage, the conventional harvest stage, the corn stover harvested in dent stage provided the highest theoretical ethanol yield of 9.92 t/ha (5.64 t/ha for the case that exclude xylan derives). 3.53 t/ha of ethanol was produced from the fresh stover harvested in dent stage, which was 1.64 times higher than using the stover obtained in the conventional harvest time. This study demonstrated that bio-ethanol yield was hugely influenced by harvest time of corn stover, and the stover harvested in dent stage has the highest ethanol yield.

Potential of four corn varieties at different harvest stages for silage production in Malaysia.

ObjectiveApart from various climatic differences, corn harvest stage and varieties are two major factors that can influence the yield and quality of corn silage in the tropics. A study was conducted to determine the optimum harvest stage of four corn varieties for silage production in Malaysia.MethodsCorn was harvested at four growth stages; silking, milk, dough, and dent stages from four varieties; Sweet Corn hybrid 926, Suwan, breeding test line (BTL) 1 and BTL 2. Using a split plot design, the treatments were then analysed based on the plant growth performance, yield, nutritive and feeding values followed by a financial feasibility study for potential commercialization.ResultsSignificant differences and interactions were detected across the parameters suggesting varying responses among the varieties towards the harvest stages. Sweet Corn was best harvested early in the dough stage due to high dry matter (DM) yield, digestible nutrient, and energy content with low fibre portion. Suwan was recommended to be harvested at the dent stage when it gave the highest DM yield with optimum digestible nutrient and energy content with low acid detergent fibre. BTL 1 and BTL 2 varieties can either be harvested at dough or dent stages as the crude protein, crude fibre, DM yield, DM content, digestible nutrient and energy were not significantly different at either stage. Further financial analysis showed that only Sweet Corn production was not financially feasible while Suwan had the best financial appraisal values among the grain varieties.ConclusionIn conclusion, only the grain varieties tested had the potential for silage making according to their optimum harvest stage but Suwan is highly recommended for commercialization as it was the most profitable.

The effect of soil fertility and harvesting stage on maize seed quality under rain-fed conditions

Management practices during seed development are crucial for boosting seed quality and establishment. This study determined the interactive effect of soil fertility and maturity stage on maize seed quality. The cultivar SC701 were harvested at milk, dent, and physiological maturity stages and dried to <12% moisture content. Field trials were split plots replicated four times. Seed quality was evaluated using standard germination test, vigor indices and electrical conductivity test. Highly significant interactions (p < .001) occurred for most of the seedling germination and vigor parameters measured. The interactions had strong impact on the germination characteristics and vigor of seeds at dent and physiological maturity. Seeds at dent stage under optimal fertilization gave higher seed quality. Optimal fertilizer application and harvesting at physiological maturity leads to maximum acquisition of seed vigor. However, in the presence of adverse weather conditions seeds from late dent stage under optimally fertilized conditions still give high seed quality.