Comparison of the forage and grain composition from insect-protected and glyphosate-tolerant MON 88017 corn to conventional corn (Zea mays L.)

The next generation of biotechnology-derived products with the combined benefit of herbicide tolerance and insect protection (MON 88017) was developed to withstand feeding damage caused by the coleopteran pest corn rootworm and over-the-top applications of glyphosate, the active ingredient in Roundup herbicides. As a part of a larger safety and characterization assessment, MON 88017 was grown under field conditions at geographically diverse locations within the United States and Argentina during the 2002 and 2003-2004 field seasons, respectively, along with a near-isogenic control and other conventional corn hybrids for compositional assessment. Field trials were conducted using a randomized complete block design with three replication blocks at each site. Corn forage samples were harvested at the late dough/early dent stage, ground, and analyzed for the concentration of proximate constituents, fibers, and minerals. Samples of mature grain were harvested, ground, and analyzed for the concentration of proximate constituents, fiber, minerals, amino acids, fatty acids, vitamins, antinutrients, and secondary metabolites. The results showed that the forage and grain from MON 88017 are compositionally equivalent to forage and grain from control and conventional corn hybrids.     

Glyphosate-tolerant corn: the composition and feeding value of grain from glyphosate-tolerant corn is equivalent to that of conventional corn (Zea mays L.)

Glyphosate-tolerant (Roundup Ready) corn line GA21 has been developed by genetic modification to tolerate glyphosate, the active ingredient in Roundup herbicide. The purpose of this study was to evaluate the compositional and nutritional safety of corn line GA21 compared to that of conventional corn. Compositional analyses were conducted to measure proximate, fiber, amino acid, fatty acid, and mineral contents of grain and proximate, fiber, and mineral contents of forage collected from 16 field sites over two growing seasons. The nutritional safety of corn line GA21 was evaluated in a poultry feeding study conducted with 2-day old, rapidly growing broiler chickens, at a dietary concentration of 50-60% w/w. Compositional analysis results showed that, except for a few minor differences that are unlikely to be of biological significance, the grain and forage of GA21 corn were comparable in their composition to that of the control corn line and to conventional corn. Results from the poultry feeding study showed that there were no differences in growth, feed efficiency, adjusted feed efficiency, and fat pad weights between chickens fed with GA21 grain or with parental control grain. These data taken together demonstrate that Roundup Ready corn is as safe and nutritious as conventional corn for food and feed use.     

Compositional equivalency of Cry1F corn event TC6275 and conventional corn (Zea mays L.)

Maize (Zea mays L.) plants have been transformed to express a Cry1F insecticidal crystal protein originally isolated from Bacillus thuringiensis Berliner. This protein controls lepidopteran pests of maize, including the European corn borer, Ostrinia nubilalis (Hübner). As part of the safety assessment for crops containing transgenes, a compositional analysis of the food and feed is conducted. This analysis is designed to detect unintended changes in the nutrient and antinutrient content of the raw commodities produced by the crop due to the insertion of the genes into the genomic DNA of the plant (pleotropic effects). Samples of transgenic and nontransgenic maize forage and grain were collected from six field sites located in the U.S. and Canada. Forage samples were analyzed for proximates and minerals, and grain was further analyzed for fatty acids, amino acids, vitamins, secondary metabolites, and antinutrients. Results demonstrated that maize expressing the Cry1F protein was equivalent to nontransgenic maize with respect to these important components. Comparison of the variability within the nontransgenic and transgenic hybrid, as compared to composition values reported in the literature, suggest that factors other than transgenes may contribute more substantially to the composition of crops.     

Composition of grain and forage from corn rootworm-protected corn event MON 863 is equivalent to that of conventional corn (Zea mays l.)

Insect-protected corn hybrids containing event MON 863 protect corn plants against feeding damage from corn rootworm (Diabrotica), a major North American insect pest. Corn event MON 863 contains a gene that expresses an amino acid sequence variant of the wild-type Cry3Bb1 insecticidal protein from Bacillus thuringiensis. The purpose of this study was to compare the composition of corn containing event MON 863 with that of conventional nontransgenic corn. Compositional analyses were conducted to measure proximates, fiber, amino acids, fatty acids, minerals, folic acid, thiamin, riboflavin, vitamin E, antinutrients, and certain secondary metabolites in grain and proximates and fiber content in forage collected from a total of eight field sites in the U.S. and Argentina. Compositional analyses demonstrated that the grain and forage of event MON 863 are comparable in their nutritional content to the control corn hybrid and conventional corn. These comparisons, together with the history of the safe use of corn as a common component of animal feed and human food, support the conclusion that corn event MON 863 is compositionally equivalent to, and as safe and nutritious as, conventional corn hybrids grown commercially today.     

Foliar nutrition of baby corn (Zea mays L.)

Abstract

Field experiments were conducted during late Rabi (January to March) and Kharif (June to September) seasons of 2002, to study the influence of foliar spraying of nutrients on growth and yield of baby corn (Zea mays L.). The experiment was laid out in randomized complete block design with three nutrients (phosphorous [P], potassium [K] and boron [B]) each at three concentrations along with control (water spray) and absolute control (no spray). Di-ammonium phosphate, Muriate of Potash and Borax are the sources of P, K and B nutrients respectively. Results showed that spraying of P favorably influenced the growth parameters, yield attributes and green cob and fodder yields of baby corn. Application of P at 0.75% concentration at 25 and 45 days after sowing (DAS) gave significantly higher growth parameters with thicker cobs and corns, increasing the individual cob weight, which in turn increased the green cob yield of baby corn. Increased growth parameters resulted in increased green fodder yield. Application of B and K with different concentrations and P (0.25 and 0.50%) failed to influence the growth and yield of baby corn.     

Composition of forage and grain from second-generation insect-protected corn MON 89034 is equivalent to that of conventional corn (Zea mays L.)

Insect-protected corn hybrids containing Cry insecticidal proteins derived from Bacillus thuringiensis have protection from target pests and provide effective management of insect resistance. MON 89034 hybrids have been developed that produce both the Cry1A.105 and Cry2Ab2 proteins, which provide two independent modes of insecticidal action against the European corn borer ( Ostrinia nubilalis ) and other lepidopteran insect pests of corn. The composition of MON 89034 corn was compared to conventional corn by measuring proximates, fiber, and minerals in forage and by measuring proximates, fiber, amino acids, fatty acids, vitamins, minerals, antinutrients, and secondary metabolites in grain collected from 10 replicated field sites across the United States and Argentina during the 2004-2005 growing seasons. Analyses established that the forage and grain from MON 89034 are compositionally comparable to the control corn hybrid and conventional corn reference hybrids. These findings support the conclusion that MON 89034 is compositionally equivalent to conventional corn hybrids.     

Comparison of two ground-based active-optical sensors for in-season estimation of corn (Zea mays,L.) yield

Thirty field experiments were conducted in North Dakota during 2011 and 2012 to compare two ground-based active-optical sensors for their relationship between sensor readings and INSEY (in-season estimate of yield). The experimental design at each site was a randomized complete block with four replications and six nitrogen (N) rate treatments: control, 45, 90, 134, 179, and 224 kg ha^?1 applied pre-plant as ammonium nitrate within five days of planting. The two sensors, GreenSeeker® (Trimble, Sunnydale, CA, USA) (GS) and Crop Circle ACS 470® sensor (Holland Scientific, Lincoln, NE, USA) (CC) were used to scan over the top of the corn at V6 and V12 growth stages. The GS INSEY and the CC INSEY were similarly related to corn yield at V6. The CC using the red-edge lens option improved the INSEY relationship to corn yield compared to the GS or the CC using the red lens option at V12.     

Comparison of nutritional traits variability in selected eighty-seven inbreds from Chinese maize (Zea mays L.) germplasm

Among cereals, only maize has not only a high amount of carotenoids, tocopherols, and oil content but also is rich in starch and protein content compared with other major food crops, such as rice and wheat. The present investigation was made primarily to assess the genetic variability for nutritionally important traits in 87 elite maize inbreds representing major heterotic groups in China. Carotenoid and tocopherol fractions were measured by high-performance liquid chromatography (HPLC), whereas oil, starch, and protein contents were detected by a VECTER22/N near-infrared analyzer. Significant interactions between genotypes and years were observed for all the traits. The pooled mean values of beta-carotene, beta-cryptoxanthin, alpha-carotene, lutein, zeaxanthin, and total carotenoids were 0.449, 0.876, 0.121, 5.803, 3.048, and 10.298 microg g (-1), respectively, whereas the combined mean performance of alpha-tocopherol, gamma-tocopherol, delta-tocopherol, and total tocopherols were 23.98, 32.90, 2.189, and 59.55 microg g (-1), respectively. The average protein, starch, and oil contents were observed to be 12.28, 64.51, and 3.55%, respectively. High level of heritability estimates were observed for all the traits and ranged from 65.6% (protein content) to 92.5% (alpha/gamma-tocopherol ratio). Most of the traits studied in this experiment were either significantly positive correlated or independent. The present finding exhibits substantial opportunities to the breeders for improvement of these traits in maize cultivars and also suggests further exploration of a new source of elite breeding stocks containing a high level of these nutritionally important compounds. Finally, these findings may also help in biofortification of maize.     

转基因玉米NK603基体标准物质研制

由于转基因标准物质的缺乏,无法保证检测结果的准确、可靠和可比。本研究将筛选后的转基因玉米(Zea mays)NK603 阳性材料及受体进行研磨筛分,粒径测定结果表明,研磨后的粒径大小为 100 μm左右。采用重量法配置了 3 个不同水平的转基因玉米基体物质,应用实时荧光定量 PCR 方法对研制的标准物质进行均匀性和稳定性检测,统计结果表明,所研制的基体标准物质均匀性良好;在 4 ℃保存条件下,一年内未发现不稳定现象。重量法确定的标准值和扩展不确定度(k=2)分别为(0.50±0.10)%、(1.00±0.35)%和(5.00±0.35)%。同时选择 7 家实验室进行协同验证,结果表明,研制的转基因玉米 NK603 基体标准物质量值准确可靠,与国外标准物质相比,不确定度水平相当。本实验研制的转基因玉米 NK603 基体标准物质适用于转基因玉米 NK603 的定量检测。     

Composition and thermal stability of anthocyanins from chinese purple corn ( Zea mays L.)

Chinese purple corn extracts ( Zea mays L., Zhuozhou, Hebei, China) (EZPC) were selected among five Chinese purple corn hybrids due to their higher anthocyanin content, and their thermal stability was evaluated. The total anthocyanin content and total phenolic content of EZPC were 304.5 +/- 16.32 mg of cyanidin-3-glucoside equiv/100 g of dry seeds and 489.8 +/- 24.90 mg of gallic acid equiv/100 g of dry seeds, respectively. Moreover, the individual anthocyanins of EZPC were determined by HPLC-DAD/ESI-MS analysis. Seven main compounds were determined, including cyanidin-3-(malonylglucoside), cyanidin-3-O-glucoside-2-malonylglucoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, peonidin-3-(malonylglucoside), pelargonidin-3-(6'-malonylglucoside), and peonidin-3-(dimalonylglucoside). The thermal stability of EZPC was studied by differential scanning calorimetry. Thermodynamic analysis showed that the conversion of EZPC followed an Arrhenius relationship, where the delta enthalpy (H) and activation energy (E(a)) were 97.0 J/g and 204 +/- 2.72 kJ/mol, respectively. Furthermore, the relationships between the degree of conversion of EZPC and time or temperature were reported. This study demonstrated that the evaluated Chinese purple corn hybrids are a natural source of anthocyanins and are stable over a wide range of temperatures and times.     

Timing sulfur applications for corn (Zea mays L.) production on irrigated sandy soil

Abstract

The importance of sulfur (S) for corn (Zea mays L.) production on sandy soils has been noted for a number of years. Yet, there has been no extensive evaluation of the timing of S applications on corn production in these specific situations. This study was conducted for the purpose of measuring the effect of split applications of fertilizer S on com grown on irrigated sandy soils. The study was conducted in 1985 and 1986. Fourrâtes of fertilizer S (0, 6.5, 13, and 26 kg/ha) were combined with six times of application schemes in a randomized complete block design with four replications. Granular gypsum was used as the source of S. Corn responded to the use of fertilizer S in 1986 only. Time of application had no significant effect on yield in either year. There were no advantages to the use of split applications. The S concentration in the ear leaf tissue at silking was affected by both rate and time of S application at each experimental site. The current recommendation is to apply fertilizer S, when needed, in a starter fertilizer at planting. The results of this study indicate that there is no need to change this recommendation.     

Antimutagenic and antioxidant properties of phenolic fractions from Andean purple corn (Zea mays L.)

The antimutagenic and antioxidant properties of various phenolic fractions obtained from Andean purple corn were examined by the Ames test and the DPPH antiradical assay. An anthocyanin-rich water fraction (WF) and an ethyl acetate fraction (EAF) showed a dose-dependent antimutagenic behavior against the food mutagen Trp-P-1 with IC50 values of 321.7 +/- 21.36 and 95.2 +/- 10.95 microg of chlorogenic acid equiv/plate, respectively, indicating that EAF was a more potent antimutagen. The antioxidant activities for WF and EAF were 1.019 +/- 0.05 and 0.838 +/- 0.11 microg of Trolox equiv/mug of phenolics, respectively. Further fractionation of WF and EAF revealed an ethyl acetate subfraction, EA-IV, with high antimutagen potency that contained a quercetin derivative. The mechanism of antimutagenic action of the WF is predominantly a blocking effect on the S-9 Mix activation system of the mutagen, whereas for the EAF, it is a dual mechanism involving blocking of the S-9 Mix and a scavenging action on Trp-P-1 electrophiles.     

Soluble and bound phenolic compounds in different Bolivian purple corn ( Zea mays L.) cultivars

In nine Bolivian purple corn ( Zea mays L.) varieties the content of phenolic compounds as well as the anthocyanin composition has been determined. The phenotypes under investigation included four red and five blue varieties (Kulli, Ayzuma, Paru, Tuimuru, Oke, Huaca Songo, Colorado, Huillcaparu, and Checchi). In purple corn, phenolic compounds were highly concentrated in cell walls. Thus, simultaneous determination of soluble and bound-form phenolics is essential for analysis, extraction, and quantification. The present study reports the determination of soluble and insoluble-bound fraction of phenolic compounds by HPLC-DAD and HPLC-ESI-MS(n) in Bolivian purple corn varieties. Enzymatic, thermal, and alkaline hydrolyses were used to obtain the cell wall-linked phenolic compounds. Ferulic acid values ranged from 132.9 to 298.4 mg/100 g, and p-coumaric acid contents varied between 251.8 and 607.5 mg/100 g dry weight (DW), respectively, and were identified as the main nonanthocyanin phenolics. The total content of phenolic compounds ranged from 311.0 to 817.6 mg gallic acid equivalents (GAE)/100 g DW, and the percentage contribution of bound to total phenolics varied from 62.1 to 86.6%. The total monomeric anthocyanin content ranged from 1.9 to 71.7 mg cyanidin-3-glucoside equivalents/100 g DW. Anthocyanin profiles are almost the same among the different samples. Differences are observed only in the relative percentage of each anthocyanin. Cyanidin-3-glucoside and its malonated derivative were detected as major anthocyanins. Several dimalonylated monoglucosides of cyanidin, peonidin, and pelargonidin were present as minor constituents.     

Kinetics of zinc uptake by mycorrhizal (VAM) and non-mycorrhizal corn (Zea mays L.) roots

Summary The kinetics of Zn absorption were studied in mycorrhizal (Glomus macrocarpum) and non-mycorrhizal roots of corn (Zea mays L.) at pH 6.0 at Zn concentrations of 75 mol to 1.07 mol m^-3. Five concentration-dependent phases of Zn absorption were recognized; phase 0 (1.5–4.0 mmol m^-3) was linear but the other four phases (4.0 mmol to 1.07 mol m^-3) obeyed Michaelis-Menten kinetics. At low concentrations (less than 4 mmol m^-3), sigmoidal kinetics of Zn absorption were observed. The absorption of Zn by mycorrhizal maize was greater at low concentrations but decreased at higher levels. This appeared to be a result of a higher maximal uptake rate in phase 1 and lower K _m values in the subsequent phases. Kinetic models yielding continuous isotherms could not account for the observed multiphasic pattern.Research paper no. 6820 through the Director, Experiment Station, G.B. Pant University of Agriculture and Technology, Pantnagar 263 145, UP, India     

Improving iron bioavailability and nutritional value of maize (Zea mays L.) in sulfur-treated calcareous soil

Soil factors such as pH, calcium, carbonate, and bicarbonate precipitation products in calcareous soils reduce iron (Fe) availability to crops and limit grain Fe concentrations. In the present greenhouse study, we evaluated the potential of Fe fertilizer amendments combined with organic amendments, like biochar (BC) and poultry manure, in sulfur (S)-treated low pH calcareous soils (pH_S1) to assess Fe biofortification of maize. Elemental sulfur (S) was used both for lowering soil pH and Fe solubilization. Soil pH was successfully lowered down from 7.8 to 6.5 by S application at the rate of 2.5 g kg^?1 soil. Pot experiment results revealed that Fe fertilizer combined with BC and S (pH_S1) significantly increased root and shoot dry weight, grain weight, photosynthetic rate, transpiration rate, and stomatal conductance by 69%, 86%, 28%, 74%, 57%, and 33%, respectively, relative to the control. Similarly, combined application of Fe + BC in S-amended (pH_S1) soil increased starch (34%), protein (64%), and fat (1 fold) while antinutrient phytate and polyphenols were decreased up to 29% and 40%, respectively, over control. Regarding the maize nutrients profiles, application of Fe with BC gave the maximum increase of Fe and ferritin was increased 1.7 fold at pH_S1. The results of this study showed that Fe fertilization with BC at pH_S1 soil is beneficial for crop growth and Fe bioavailability.     

Long-term winter cover cropping effects on corn (Zea mays L.) production and soil nitrogen availability

 This study was conducted to determine effects of long-term winter cover cropping with hairy vetch, cereal rye and annual ryegrass on soil N availability and corn productivity. From 1987 to 1995, with the exception of the first year of the study, the cover crops were seeded each year in late September or early October after the corn harvest and incorporated into the soil in late April or early May. Corn was seeded 10 days to 2 weeks after the cover crop residues had been incorporated, and N fertilizer was applied as a side-dressing at rates of 0, 67, 134, or 201 kg N ha^–1 each year. While the average annual total N input from the above-ground biomass of the cover crops was highest for hairy vetch (72.4 kg N ha^–1), the average annual total C input was highest for cereal rye (1043 kg C ha^–1) compared with the other cover crops. Hairy vetch was the only cover crop that significantly increased pre-side-dressed NO₃ ^–-N (N_i) corn biomass and N uptake at 0 N. At an N fertilizer rate of 134 kg N ha^–1 or higher, the cover crops had a minimal effect on corn biomass. This indicated that even after 9 years of winter cover cropping, the effect of the cover crops on corn growth resulted primarily from their influence on soil N availability. The amount of available N estimated from the cover crops (N_ac) was significantly correlated with relative corn biomass production (r ²=0.707, P<0.001). The total amount of available N, comprising N_ac and N added from fertilizer (N_f), was strongly correlated (r ²=0.820, P<0.001)) with relative corn biomass production. The correlation was also high for the available N comprising N_i and N_f (r ²=0.775, P<0.001). Although cereal rye and annual ryegrass did not improve corn biomass production in the short term, they benefited soil organic N accumulation and gradually improved corn biomass production compared with the control over the long term. Received: 10 August 1999     

拔节期淹水玉米的生理性状和产量形成

为了探明夏玉米拔节期对淹水历时的响应规律,采用大田环境下无底测坑试验,在玉米拔节期设置不同的淹水天数(1、2、3、5、7 d),分析了淹水历时对夏玉米生长发育、灌浆过程、物质分配及产量性状的影响。结果表明,玉米拔节期淹水抑制玉米的营养期发育,淹水1、2、3、5、7d的平均株高分别比非涝渍环境下玉米(CK)降低2.26%、2.26%、2.45%、11.36%和10.17%;平均叶面积指数LAI分别降低23.79%、18.93%、13.04%、32.74%和34.27%;玉米拔节期淹水5 d以上,植株矮而黄。在植株生理反应方面,淹水3 d后测定结果表明,淹水1、2、3 d的叶绿素质量分数比CK高,根系活力增强,而淹水5d和7d叶绿素质量分数和根系活力下降。玉米灌浆至乳熟期叶绿素测定结果表明,淹水5 d以上处理的叶绿素质量分数仍较CK降低10.87%,表明受淹5 d以上,叶绿素质量分数降低并无法恢复。玉米拔节期受淹影响其后期灌浆过程中的籽粒质量,同一时间的淹水1、2和3 d与对照籽粒质量比较接近,淹水5 d较低,淹水7 d为最低。玉米穗长和穗粗随淹水历时呈减小的趋势,但各处理间无显著差异(P0.05)。淹水使玉米出现较长的秃尖,淹水1、2、3、5 d的秃尖长度为CK的2倍左右,淹水7 d的秃尖长度为CK的5倍;淹水历时越长,玉米穗长、穗粒质量、穗质量和百粒质量的减幅就越大,淹水1、2、3、5、7的玉米产量分别降低16.58%、16.65%、26.11%、34.32%和39.01%。玉米拔节期淹水5 d以上,严重影响玉米正常生长,造成产量显著降低。研究结果为涝渍灾害监测和灾损快速评估以及涝渍排水标准确定提供参考。     

Nutrient concentration and yield of maize (Zea mays L.) after vetch (Vicia sativa L.) in conventional and reduced tillage systems

The effects of tillage on plant availability nutrients are critical to develop nutrient management strategies to optimize yield. The objective of this study was to evaluate differences in the concentration of 19-nutrient and yield after 4-year of conventional [moldboard plough (MT)] and two reduced [rototiller (ST) and chisel (CT)] tillage systems in maize (Zea mays L.) after winter vetch (Vicia sativa L.) in double crop one year. Three tillage systems were compared from 2005 to 2008 in area located in the western region of Turkey under semi-arid Mediterranean clay-loam soils. Nutrients were determined in maize leaves, stems, roots and soils. Results show that the concentration of macronutrients were found to be higher in leaves and stems of maize than roots in three tillage systems of all years, while the opposite was true for micronutrients. Among the macro and micro-nutrients, there was no effect of tillage on nutrient concentration in all maize tissues for sulfur, magnesium, sodium and copper (S, Mg, Na and Cu). However, the nitrogen, potassium, calcium, boron, zinc, manganese, iron, aluminum, barium, cadmium, cobalt, chromium, nickel, lead and selenium (N, K, Ca, B, Zn, Mn, Fe, Al, Ba, Cd, Co, Cr, Ni, Pb and Se) were affected by tillage. ST increased N in stems of 2006 compared with other systems. K in roots of 2006 was 52 and 30% greater in CT than in ST and MT, respectively, while ST and MT of 2007 resulted in 38 and 41% greater than CT. In two of four years, ST contributed to higher grain yield compared with other systems. In general, ST can effectively contribute to increase maize yield following winter vetch compared with MT under this region. Results suggested the need for different management systems associated with reduced tillage including rotation, particularly for basic nutrients. Further, results showed similarities and differences with other studies under tillage with maize following winter vetch.     

Relationship between fatty acid profile and vitamin E content in maize hybrids (Zea mays L.)

The balance between the vitamin E (tocochromanols) and polyunsaturated fatty acid (PUFA) contents mainly determines the susceptibility to lipid peroxidation and the storage stability of corn oil. In 1997, field experiments were conducted at two different locations to evaluate a collection of 30 corn hybrids for fatty acid profiles and tocochromanol contents. Hybrids differed significantly (p < 0.01) for major fatty acids, as well as for tocochromanol contents and composition. The major fatty acids were palmitic, oleic, and linoleic acids, whose contents were in the ranges 9.2-12.1%, 19.5-30.5%, and 53.0-65.3%, respectively. The tocopherol contents ranged as follows: alpha-tocopherol, 67-276 mg (kg of oil)(-1); beta-tocopherol, 0-20 mg (kg of oil)(-1); gamma-tocopherol, 583-1048 mg (kg of oil)(-1); delta-tocopherol, 12-71 mg (kg of oil)(-1); total tocopherol, 767-1344 mg (kg of oil)(-1). gamma-Tocopherol was the predominant derivative among all tocopherols. The tocotrienol contents were in the ranges 46-89, 53-164, and 99-230 mg (kg of oil)(-1) for alpha-, gamma-, and total tocotrienol contents, respectively. The tocotrienol profile was not characterized by the predominance of any tocotrienol homologue. alpha-Tocopherol was positively correlated with PUFA (r = 0.41) and with the vitamin E equivalent (vit E equiv) (r = 0.84), and it was not correlated with gamma-tocopherol. gamma-Tocopherol was highly correlated with total tocopherol and tocochromanol contents (r = 0.93 and r = 0.90, respectively), indicating that the contribution of this vitamer to the total tocochromanol content is the most important among all tocochromanols. The high positive correlation found between the vit E/PUFA ratio and the vit E equiv, as well as the absence of correlation between this ratio and PUFA indicates that a higher vit E/PUFA ratio can be easier achieved be increasing the vitamin E content than by modifying fatty acid profile in corn oil.     

Does stable isotope analysis separate transgenic and traditional corn (Zea mays L.) detritus and their consumers?

Transgenic corn crops (including the Bt variety) are expanding rapidly worldwide, and the large amounts of cultural residues remaining after harvest pose questions about the fate of this novel source of plant detritus in soil. To verify whether transgenic and conventional corn litters were different in their isotopic signatures, the ¹³C and ¹⁵N stable isotopes of different portions of Bt and non-Bt Aristis corn plants after harvest were analysed. Laboratory feeding experiments were then conducted to assess the transfer of corn isotopic signals to detritivores using the isopod Trachelipus sp., reared on either Bt or non-Bt corn dead leaves as the only food source. δ¹⁵N differed significantly between Bt and non-Bt corn in kernels and stems, whereas both δ¹⁵N and δ¹³C were different in leaves before and after exposure to isopods. During feeding, the N and C isotopic signatures of isopods shifted towards the diet values. Significant differences existed both between sampling dates and corn treatments. The results suggest that detritus from transgenic and conventional corn crops may have different isotopic signatures and the isotopic differences can persist through the trophic levels, making corn detritus feeders suitable sentinel species for the Bt corn isotopic signal in agroecosystems.