Corn Seedling Emergence Research Articles

Examining the Corn Seedling Emergence-Temperature Relationship for Recent Hybrids: Insights from Experimental Studies.

Corn seedling emergence is a critical factor affecting crop yields. Accurately predicting emergence is crucial for precise crop growth and development simulation in process-based crop models. While various experimental studies have investigated the relationship between corn seedling emergence and temperature, there remains a scarcity of studies focused on newer corn hybrids. In the present study, statistical models (linear and quadratic functional relationships) are developed based on the seedling emergence of ten current corn hybrids, considering soil and air temperatures as influencing factors. The data used for model development are obtained from controlled soil plant atmospheric research chamber experiments focused on corn seedling emergence at five different temperatures. Upon evaluating the developed models, the quadratic model relating the air temperature with time to emergence was found more accurate for all corn hybrids (coefficient of determination (R2): 0.97, root mean square error (RMSE): 0.42 day) followed by the quadratic model based on soil temperature (R2: 0.96, RMSE: 1.42 days), linear model based on air (R2: 0.94, RMSE: 0.53 day) and soil temperature (R2: 0.94, RMSE: 0.70 day). A growing degree day (GDD)-based model was also developed for the newer hybrids. When comparing the developed GDD-based model with the existing GDD models (based on old hybrids), it was observed that the GDD required for emergence was 16% higher than the GDD used in the current models. This showed that the existing GDD-based models need to be revisited when adopted for newer hybrids and adapted to corn crop simulation models. The developed seedling emergence model, integrated into a process-based corn crop simulation model, can benefit farmers and researchers in corn crop management. It can aid in optimizing planting schedules, supporting management decisions, and predicting corn crop growth, development, and it yields more accurately.

Factors Underlying the Prevalence of Pythium Infection of Corn Seeds Following Seed Treatment Application of Tebuconazole

Microbial communities are essential for soil health, but fungicide application may have significant effects on their structure. It is difficult to predict whether nontarget pathogens of applied fungicides in the soil will cause crop damage. Tebuconazole is a triazole fungicide that can be used as a seed treatment and, thereby, introduced to the soil. However, seed-applied tebuconazole has a potential risk of causing poor emergence of corn (Zea mays) seedlings. Using soil with a history of poor corn seedling emergence, we demonstrate through TA cloning and isolation that the poor emergence of corn seedlings from tebuconazole-coated corn seeds was primarily because of infection by surviving soil pathogens, specifically Pythium species that are not targeted by tebuconazole, rather than the phytotoxic effects of tebuconazole. Bioassay tests on tebuconazole-amended media showed that tebuconazole can suppress soil fungi while allowing Pythium to grow. Pythium species primarily contributing to the corn seed rot were more pathogenic at cooler temperatures. Furthermore, the nontarget biocontrol agent of Trichoderma spp. was strongly inhibited by tebuconazole. Taken together, the nontarget effects of tebuconazole are likely not significant under favorable plant growing conditions but are considerable because of low-temperature stress.

Seed Size, Planting Depth, and a Perennial Groundcover System Effect on Corn Emergence and Grain Yield

The intensive corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) production practices currently used in the Midwestern U.S. concern producers and stakeholders. The negative impact of these two-crop rotations on the environment affects water quality and soil erosion and increases flooding risks. Due to these concerns, cover crops and, specifically, perennial groundcover (PGC) cropping systems have gained greater interest. These perennial species have growing patterns compatible with corn and soybean, and can help rebuild the ecosystem while maintaining good cash crop yields. In addition, producers also are interested in the possible effect of seed size and planting depth on uneven emergence in corn. The successful adoption of PGC systems ultimately depends on the successful corn seedling emergence and consistent yield. The objective of the study was to understand the effects of seed characteristics and placement on emergence, grain yield, and grain quality in corn planted using a Kentucky bluegrass (Poa pratensis L.) (KBG)-PGC and a bare-soil cropping system and to determine grain quality attributes and grain moisture dry-down in a PGC field when compared to a conventional cropping system. Commercially-sized seed and seed sized in the laboratory to represent a narrower seed size distribution were planted in KBG-PGC and bare soil systems at two planting depths (3.18 and 6.35 cm). The two-year experiments were planted in a split-plot RCB design with four replications. Individual plants were flagged at emergence, and ears from each plant were harvested individually. Separating the seed lot into different size distributions did not affect seed germination under ideal (standard germination and speed of germination tests) or stressful (cold test) conditions. Seed size distribution also did not influence emergence rate and yield in a conventional tillage (bare soils) or KBG-PGC system. These results indicate that seed sizing specifications and seed size cutoffs currently used by seed companies are suitable for uniform emergence and maximum grain yield in both cropping systems. Seed placement was crucial to uniform emergence in both cropping systems, while seed size distribution did not play a role in emergence for either system. The PGC cropping system delayed seed corn emergence and reduced grain yields as much as 50%. This information is important for those producers considering adopting a PGC system because it demonstrates that uniform planting depth is more important than seed size distribution.

Effect of drought stress on in situ ruminal starch degradation kinetics of corn for silage

The objective of this study was to determine the effect of drought stress on the in situ ruminal starch degradation kinetic parameters of corn for silage. Five commercial corn hybrids for silage were utilized. The experiment was designed as a split-plot within a randomized complete block design with 4 blocks. Eight plots were blocked and randomly subjected to a watered (W) or non-watered (NW) treatment. Within each block, plots were split into 5 sub-plots, to which 1 of the 5 corn hybrids were randomly assigned. Before planting, all plots were irrigated with 150 mm of water to ensure a consistent emergence of corn seedlings. After this pre-planting irrigation, NW plots were not irrigated ever again. After planting, W plots were irrigated with 75 mm of water when the crop showed 2 visible leaves, 6 visible leaves, and pre-tasseling and with 45 mm every week, thereafter, for a total of 8 weeks (360 mm post-tasseling). Three ears from each subplot were collected when corn crops were between the 1/4 and 3/4 milk-line stage of maturity. Kernels were shelled by hand and dried. The in situ ruminal starch degradability was determined on ground (4-mm) grain samples placed in Dacron porous bags. All bags were immersed within the rumen of 3 rumen-cannulated cows fed a totally mixed ration containing 32 % corn silage, 3 % alfalfa hay, and 65 % concentrate mix (DM basis). Bags were incubated for 0, 4, 8, 12, 24, and 48 h. Water stress did not affect the fraction of instantly degraded starch (203 mg/g), the fraction of potentially degraded starch (759 mg/g), the fraction of undegraded starch (38 mg/g), or the differential starch degradation rate (0.0669/h). Corn hybrids did not affect any of these degradation kinetic parameters and no interactions existed between irrigation treatment and corn hybrid. In conclusion, drought stress had no effect on the in situ ruminal starch degradability of corn for silage.

Stover harvest and tillage effects on corn seedling emergence

AbstractCorn (Zea mays L.) stover is an increasingly important feedstock for biofuel and bioproduct production; however, excessive harvest of corn stover from agricultural fields may affect corn seedling emergence and subsequent plant population which may reduce corn growth and yield. Field experiments were conducted over four consecutive growing seasons in southwestern Ontario to determine under continuous corn cropping system the effects of no‐tillage (NT), conventional tillage (CT), and five rates of stover harvest (0, 25, 50, 75, and 100 wt. %) on corn seedling emergence in a Harrow sandy loam and in a Brookston clay loam. Time to achieve 50% seedling emergence (t0.5), emergence rate constant (kG), and final seedling population (MG) were adequately simulated using the Gompertz function. Irrespective of stover removal rate and soil type, t0.5 was 2 d longer, and kG was 32% lower, under NT compared to CT. In Harrow sandy loam, stover removal from NT reduced t0.5 in 1 out of 4 yr. The 100% removal reduced t0.5 relative to 0, 25, 50, and 75% removal by 1.1–2.2 d in 2015. Averaged across both tillages and all removal rates, kG was greater in Harrow sandy loam than in Brookston clay loam. Stover removal rates had no effect on MG but averaged over all removal rates and soil types, MG was 9% lower for NT compared to CT in 2016. No‐tillage practice under corn production can impede seedlings emergence early in the growing season and stover removal from the field can help mitigate against this effect.

An adapted Weibull function for agricultural applications

The Weibull function is applied extensively in the life sciences and engineering but underused in agriculture. The function was consequently adapted to include parameters and metrics that increase its utility for characterizing agricultural processes. The parameters included initial and final dependent variables (Y0 and YF, respectively), initial independent variable (x0), a scale constant (k), and a shape constant (c). The primary metrics included mode, integral average, domain, skewness, and kurtosis. Nested within the Weibull function are the Mitscherlich and Rayleigh functions where c is fixed at 1 and 2, respectively. At least one of the three models provided an excellent fit to six example agricultural datasets, as evidenced by large adjusted coefficient of determination (RA2 ≥ 0.9266), small normalized mean bias error (MBEN ≤ 1.49%), and small normalized standard error of regression (SERN ≤ 8.08%). The Mitscherlich function provided the most probable (PX) representation of corn (Zea mays L.) yield (PM = 87.2%); Rayleigh was most probable for soil organic carbon depth profile (PR = 96.4%); and Weibull was most probable for corn seedling emergence (PW = 100%), nitrous oxide emissions (PW = 100%), nitrogen mineralization (PW = 58.4%), and soil water desorption (PW = 100%). The Weibull fit to the desorption data was also equivalent to those of the well-established van Genuchten and Groenevelt–Grant desorption models. It was concluded that the adapted Weibull function has good potential for widespread and informative application to agricultural data and processes.

Effect of drought stress on in vitro neutral detergent fiber digestibility of corn for silage

The objective of this study was to determine the effect of drought stress on neutral detergent fiber (NDF) and lignin (LIG) concentrations and on in vitro dry matter digestibility (IVDMD) and in vitro neutral detergent fiber digestibility (IVNDFD) of leaf blades and stem internodes of corn for silage. Eight plots were blocked (i.e., 4 blocks) and randomly subjected to a watered (W) or non-watered (NW) treatment. Within each block, plots were split into 7 sub-plots, to which 1 of 7 corn hybrids were randomly assigned. Before planting, all plots were irrigated with 150 mm of water to ensure a consistent emergence of corn seedlings. After this pre-planting irrigation, NW plots were not irrigated ever again. After planting, W plots were irrigated with 225 and 360 mm of water pre-tasseling and post-tasseling, respectively. Stem internodes and leaf blades from the second phytomer below (LOWER) and the second phytomer above (UPPER) the ear insertion were collected to determine tissue composition and digestibility. Drought stress increased the concentration of NDF in both leaf blades (628 vs. 613 mg NDF/g DM) and stem internodes (625 vs. 572 mg NDF/g DM). Drought stress decreased IVDMD in stem internodes (0.575 vs. 0.525 IVDMD) but had no effect on IVDMD of leaf blades (0.561 IVDMD). Similarly, drought stress decreased IVNDFD in stem internodes (0.422 vs. 0.391 IVNDFD) but had no effect on IVNDFD of leaf blades (0.536 IVNDFD). Drought stress increased the concentration of lignin in the cell wall of leaf blades (161 vs. 141 mg/g CW) but had no effect on stem internodes (266 mg/g CW). Under the conditions of this study, water supply had a minimal effect on lignin concentration in the cell wall and did not increase the in vitro digestibility of fiber in corn for silage. The latter observation is contrary to the general industry belief that water stress increases fiber digestibility in forages.

ПРИМЕНЕНИЕ ГЕРБИЦИДОВ НОВОГО ПОКОЛЕНИЯ ПРИ ВОЗДЕЛЫВАНИИ КУКУРУЗЫ В ПРЕДГОРНОЙ ЗОНЕ РСО – АЛАНИЯ

The article discusses the results of studying the effectiveness of using new generation herbicides: both applied before the emergence of corn seedlings ("Merlin" (150 g/ha); "Cassius" (50 g/ha)), and by seedlings ("Elumis" (1.0–2.0 l/ha)) – on crops of three maize hybrids. The studies were carried out in 2017–2019. The objects of research were maize hybrids of various early ripening (originator Kabardino-Balkaria Research Institute of Agriculture) – Kabardinskaya 3812 (late ripening), Camilla SV (mid-late), and white grain food corn Bella 451 (cultivated not only for obtaining varietal seeds, fodder, but also to meet the food needs of the indigenous population). Flour and cereals from white grain corn are used in most ethnic cuisines of the North Caucasus. In this regard, it is very important to put into production, along with the yellow grain forms used for fodder, highly productive varieties and hybrids of white grain corn for food purposes. The variety is medium late and food grade. The purpose of the research was to establish the level of harmfulness of weeds and their death rate at different periods of their introduction, as well as to determine their effect on the growth, development and yield of corn grain. The scientific novelty lies in the fact that in the conditions of the foothill zone of the Republic of North OssetiaAlania, studies have been carried out to establish the optimal terms and methods of applying herbicides in the fight against weeds when cultivating new highly productive corn hybrids. As a result of the studies, it was found that the treatment of the soil with the herbicide "Elumis" was more effective in comparison with the control option. At the same time, the grain yield was: for the Kabardinskaya 3812 hybrid 8.7 t/ha – on an unfertilized background, 12 t/ha – on a fertilized one; for the hybrid Camilla SV – 8.5 t/ha on an unfertilized background, 11.7 t/ha – on a fertilized one; the Bella 451 hybrid has 7.0 t/ha – on an unfertilized background, – 9.9 t/ha – on a fertilized one. The responsiveness of the Kabardinskaya 3812 hybrid to the application of herbicides was more effective than that of other studied hybrids.

Effects of soil moisture content and tractor wheeling intensity on traffic-induced soil compaction

Soil compaction causes deleterious effects on physical and mechanical proprieties of agricultural soils. In order to investigate the effect of soil moisture content and tractor wheeling intensity on traffic-induced soil compaction, this study was carried out on a field with clay loam soil. Soil dry bulk density and hydraulic conductivity as well as emergence percentage of corn seedlings and dry mass of the sampled mature plants were considered the dependent variables of the experiment. Independent variables consisted of soil moisture content with five levels (12, 15, 17, 19, and 21%), traffic intensity with three levels (four, two, and zero passes of tractor wheel (tractor model: John Deere 3350) from the entire area of the plot), and soil sampling depth with three levels (0-10, 10-20, and 20-30 cm). According to the results of this study, gradual increase in soil water content generally resulted in an increase in soil bulk density; moreover, increasing the tractor wheeling intensity from 0 to 4 passes increased bulk density by 13%. Furthermore, the driest soil water content had the highest and the wettest soil water content had the lowest emergence percentage of corn seedlings among the treatments; moreover, traffic intensity treatment inversely affected the emergence percentage of corn seedlings and the dry mass of mature plants. To sum up, these results indicate that, for improving water permeability and reducing dry bulk density of the examined clay loam soil, as well as better emergence of corn seedlings and ultimately increasing crop yield, it is recommended to avoid wheeling when soil moisture content is high, reduce the number of machinery wheel passes from the farm as low as possible, and restrict the wheel passes to fixed strips along the field, whenever possible.

Seed Vigor and the Uniformity of Emergence of Corn Seedlings

ABSTRACTSeed vigor is defined as those “seed properties that determine the potential for rapid, uniform emergence and development of seedlings under a wide range of field conditions.” Seedlings from high‐vigor seed lots are expected to emerge more uniformly than those from low‐vigor lots. We tested this hypothesis in a series of greenhouse and growth chamber experiments with several high‐ and low‐vigor corn (Zea mays L.) samples that had high standard germination. Seed‐vigor levels were estimated with the saturated cold test where the seeds were stressed with low temperature (10°C) and field soil for 7 d and then germination was measured after 5 d at 25°C. The uniformity index (UI) (time from 10 to 90% of final emergence) was estimated by planting seeds 3.8 cm deep in soil and counting emergence every 6 h in greenhouse and growth chamber experiments. Lowering the soil temperature from roughly 23 to 15°C increased the time to 10% of final emergence (T10) from about 100 to more than 300 h and increased the UI. Low‐vigor seed always had a larger UI than high‐ vigor seed, but the difference was less when the seedlings emerged rapidly (UIs were 20 to 30 h) than when they emerged slowly (maximum of ~80 h for high‐vigor seed and 140 h for low‐vigor seed). High‐vigor seed had more uniform emergence, but soil temperature and the time to emergence also influenced uniformity.

Emergence of corn according to the sowing depth of the seed and loads on press wheels

The seeding process was the operation that suffered the most changes in no-tillage system due the cover crop soil and new particle soil arrangement. The objective of this study was to verify the effects of loads applied to the wheels and adjustments of sowing depth on seedling emergence of corn in no-tillage system. The experimental design was completely randomized with a factorial arrangement 5x4, with five loads applied to the wheels and four theoretical sowing depth adjustments. The real sowing depth increased in the lower theoretical depth and decreased in the higher theoretical depth, due to the compaction loads. Regarding the time of emergence, loads applied had not influence at the greater depths. Emergence time decreased with the load increase in the lower depths. Thus, the adjustment of the compactor wheels can influence in the corn seeding process.

Influence of brick air scrubber by-product on growth and development of corn and hybrid poplar

Studies were conducted to determine the effects of spent reagent from air pollution control scrubbers used at a brick manufacturing facility on emergence, growth, and physiological responses of corn and hybrid poplar plants. Scrubber by-product was obtained from General Shale Brick, Louisville, KY. Potting substrate was weighed and quantities of scrubber by-product were added to the substrate to obtain treatments of 0%, 6.25%, 12.5%, 25%, 50%, 75%, and 100% scrubber by-product (w:w) for the corn study. Each treatment mix was potted into nine replicate polyethylene pots and four corn seeds were sown per pot. The pots were randomized in a greenhouse at Clemson University and the number of seedlings emerging from each treatment, dark-adapted leaf chlorophyll a fluorescence, and shoot heights were measured at the end of a 21-day growth period. Then, dry shoot biomass was determined for plants from each treatment and plant tissues were analyzed for selected constituents. For the poplar study, nine-inch cuttings of hybrid poplar clone 15–29 ( Populus trichocarpa × P. deltoides) and clone OP367 ( P. deltoides × P. nigra) were planted in treatments of scrubber by-product-potting soil mixes of 0% , 5% , 10% , and 25% w:w. Leaf chlorophyll a fluorescence was measured over six weeks and cumulative leaf area, dry biomass, and nutrient content of tissues were determined upon harvest. Results of these studies indicate that percent seedling emergence for corn plants decreased with increasing scrubber by-product application rates. Application rates up to 12.5% scrubber by-product w:w had no adverse effect on corn seedling emergence. Shoot elongation, biomass production, and the status of the photosynthetic apparatus of the seedlings were also not severely impaired at applications below this level. A critical value of 58.2% w:w scrubber by-product was estimated to cause 25% inhibition of seedling emergence. Biomass production, cumulative leaf area, and chlorophyll a fluorescence of hybrid poplar plants were not affected by scrubber by-product applications of up to 5% w:w.

Tillage Effects on Corn Production in a Coarse‐Textured Soil in Southern Ontario

Minimum tillage has been shown to slow early corn (Zea mays L.) growth and reduce grain yields in some soil types and under some climatic conditions. To overcome these limitations, the no‐till (NT) system can be modified by incorporating residues and loosening the soil in a zone over the center of the row while leaving the interrow area untilled. This study compares soil temperatures and corn growth and productivity under zone till (ZT), NT, and conventional tillage (CT) systems in a coarse‐textured soil (Psammentic Hapludalf) located in southwestern Ontario, Canada. Soil temperature at the 4‐cm depth decreased with decreasing tillage intensity from CT to NT during warmer years but was similar in CT and ZT during a cooler year. This resulted in reduced growing degree days in the seed zone with decreasing tillage. Lower soil temperatures in NT did not delay the initiation of corn seedling emergence but did reduce the rate of emergence compared with CT plots. Corn growth rates were found to be similar among tillage systems in the early part of the growing system but were higher for both the ZT and NT systems during late vegetative and early reproductive growth. Grain yields increased as tillage intensity decreased in a year with drier conditions at tasseling but were similar across tillage systems in the other 2 yr. These results suggest that converting a NT system to a ZT system would neither result in significantly higher yields, nor cause a serious grain yield reduction relative to CT.

Tillage Effects on Corn Production in a Coarse-Textured Soil in Southern Ontario

Minimum tillage has been shown to slow early corn (Zea mays L.) growth and reduce grain yields in some soil types and under some climatic conditions. To overcome these limitations, the no-till (NT) system can be modified by incorporating residues and loosening the soil in a zone over the center of the row while leaving the interrow area untilled. This study compares soil temperatures and corn growth and productivity under zone till (ZT), NT, and conventional tillage (CT) systems in a coarse-textured soil (Psammentic Hapludalf) located in southwestern Ontario, Canada. Soil temperature at the 4-cm depth decreased with decreasing tillage intensity from CT to NT during warmer years but was similar in CT and ZT during a cooler year. This resulted in reduced growing degree days in the seed zone with decreasing tillage. Lower soil temperatures in NT did not delay the initiation of corn seedling emergence but did reduce the rate of emergence compared with CT plots. Corn growth rates were found to be similar among tillage systems in the early part of the growing system but were higher for both the ZT and NT systems during late vegetative and early reproductive growth. Grain yields increased as tillage intensity decreased in a year with drier conditions at tasseling but were similar across tillage systems in the other 2 yr. These results suggest that converting a NT system to a ZT system would neither result in significantly higher yields, nor cause a serious grain yield reduction relative to CT.

Soil Management Effects on Planting and Emergence of No-till Corn

Information is lacking on the influence of soil conditions on planting and emergence of row crops. We studied no-till planting and emergence of corn (Zea mays L.) as influenced by nine previous management practices, ranging from 6-yr bromegrass (Bromus inermis Leyss.), B6, to 6-yr conventional-till corn, C6, on a silt loam. Soil structure (air entry value, bulk density, dispersible clay, mass fractal dimension, tension draining the smallest pores, wet-aggregate stability) and water content measurements were made prior to planting. An instrumented 97 kW Case-IH Magnum tractor and a modified John Deere model 7000 planter were used for corn planting. Tractor performance and planter draft were measured with transducers and a data logger. Fuel consumption (r = 0.92), ground speed (r = 0.79), and wheel slip (r = 0.75) were linearly related to draft. Corn seedling emergence was measured 14, 18, and 22 days after planting (DAP). The effect of management was significant for two-thirds of the structure measurements, all of the equipment variables, and corn emergence 14 DAP. Planter draft ranged from 12 kN in C6 to 15 kN in B6. Wet-aggregate stability was the only structure measurement correlated with draft (r = 0.33), fuel consumption (r = 0.34), speed (r = 0.30) or slippage (r = 0.29). These relations were explained by the fact that wet-aggregate stability and draft both increase with increasing root length density. Corn emergence was more rapid in B6 than in C6, but did not correlate with any of the structure measurements. Further research is needed to determine if this result was due to improved soil structure or shallower seed placement following forages.

Effect of Weed Abundance on European Corn Borer (Lepidoptera: Pyralidae) Infestation of Sweet Corn

Two of four sweet corn plantings, each with a broad spectrum of weed abundance in plots 3 rows by 6 m, showed a positive relationship of ear infestation by European corn borer, Ostrinia nubilalis (Hubner), with total weed biomass sampled 5 wk after corn seedling emergence. The relationship was more apparent with wider row spacing (91 versus 76 cm) and without cultivation. With the dominant weeds Digitaria sanguinalis, Panicum dichotomiflorum, Amaranthus retroflexus , and Chenopodium album , linear regression showed an increase from about 20% ear infestation in weedless plots to about 40% infestation in plots with 2,000 kg/ha above-ground dry weight of weeds at week 5 postemergence. The effect may vary with weed species, and the data show a stronger correlation with forb abundance than with grasses. Sweet corn growers would profit economically by avoiding weedy areas of fields when partial harvests are undertaken in infested plantings.

Earthworms as a Factor in the Reduction of Soil Crusting

AbstractSurface soil crusting after heavy rainfall is a problem on many cultivated soils. The objective of this study was to investigate the effect of earthworms (Lumbricus rubellus) on the aggregate stability and infiltration rate of a soil and then assess the susceptibility of this soil to surface crusting. The effect of 0, 15 (250 m−2), or 30 (500 m−2) earthworms pot−1 on a Raub silt loam (Aquic Argiudolls) to which no, soybean [Glycine max (L.) Merr.] or corn (Zea mays L.) residue had been added was studied in 16‐L pots over a 54‐d period in the greenhouse. Earthworms increased both mean weight diameters (MWD) and water‐stable aggregates > 2mm when determined on initially moist soil. In the absence of earthworms, steady‐state infiltration rates on the Raub soil were 22 µm s−1 (8 cm h−1). Addition of 15 and 30 earthworms pot−1 to soil containing crop residues, increased infiltration rates to 181 and 328 µm s−1 (65 and 118 cm h−1), respectively. The susceptibility of the undisturbed soil in the 16‐L pots and of sieved, repacked soil to surface crusting under simulated rainfall was evaluated by measuring corn seedling emergence. Ten days after planting and simulated rainfall (6.25 cm h−1), 85 to 100% of corn seedlings had emerged in the undisturbed soil in which earthworms were active, whereas in the absence of earthworms only 50 to 52% of seedlings had emerged. When the sieved soil that had received residues and earthworms was exposed to simulated rainfall, 40 to 73% of seedlings had emerged at 10 d, and by 16 d 80 to 88% had emerged. This compares with only 38% emergence in soil to which neither residue nor earthworms was added. Through their feeding, casting, and burrowing activity, earthworms are an important factor in the reduction of surface crusting.

Effect of drying on soil strength and corn emergence

Laboratory studies were conducted to evaluate the effects of drying on soil strength and corn emergence (Zea mays L.). Corn was germinated in Billings silty clay under a bank of heat lamps which operated 9, 14, 19, or 24 h per day. Soil strength (modules of rupture), soil moisture content and emergence were measured daily. The relationship of soil strength to corn seedling emergence as influenced by the four light and heat durations and bare and mulched soil surfaces was determined. As soil strength increased emergence decreased until it ceased at soil strengths of about 80 kPa. Strength of this soil had a high negative correlation with soil water content and increased with time. Mulching decreased initial rate of drying, decreased crust strength, and improved corn emergence. The 14-hour light and heat treatment resulted in the highest corn emergence.

Influence of soil edaphic factors and their critical limits on seedling emergence of corn (Zea mays L.)

In the present investigation the influence of various soil physical parameters on seeding emergence of corn (Zea mays L.) and their critical limits was studied in order to obtain a proper crop stand. The effect of soil compaction, resulting into various bulk densities on some soil physical properties was also studied. Seedling emergence decreased with increasing bulk density, soil suction, seed placement depth, soil strength and with decreasing oxygen diffusion rates. The critical values for these soil physical parameters were found to be 1.4 g/cm3, 3 atm., 4 cm, 1.0 kg/cm2 and 40×10-8 g O2/cm2/min bulk density, soil suction, seed placement depth, soil strength and oxygen diffusion rates respectively. Increasing bulk density decreased the soil water content, oxygen diffusion rates and increased the soil strength. re]19751117

Morphological Basis for Poor Emergence in Inbred Oh43 Corn

Studies on the seedling emergence of corn (Zea mays L.) inbred Oh43 indicated that poor stand establishment under field conditions was associated with a structural defect of the coleoptile. The ultimate length of Oh43 coleoptiles is comparable to that of other inbreds, but many of the former develop a longitudinal fissure extending abaxially from near the tip to the coleoptile node. In some seedlings this fissure continues as a dual furrow along the abaxial side of the first internode. Although most (ca. 75%) Oh43 seedlings produce such coleoptiles, this feature was not apparent in other inbreds except one derived from Oh43. Hybrids resulting from crosses with Oh43 showed no evidence of this coleoptile anomaly.