Effects Of Ethephon Research Articles

The Effect of Ethephon on the Berry Colour of Flame Seedless and Bonheur Table Grapes

Flame Seedless grafted onto Richter 99 situated in the Lower Orange River region and Bonheur grafted onto Ramsey in the Berg River Valley region of South Africa were used to test ethephon treatments for berry colour improvement. The trial was repeated over three seasons. Four ethephon dosages (100, 200, 300 and 400 mg/L) in combination with five application times (weekly intervals starting from acid maximum) were compared to an untreated control. As soon as general minimum maturity for export was reached, pack-out percentage was determined and representative bunch samples harvested and packed as for export. After storage for four weeks at -0.5°C and one week at l0°C, bunch quality was evaluated according to standard industry norms. As a preliminary determination anthocyanin and phenol absorbance levels were determined during one season to possibly complement visual evaluation of berry colour. The best overall result with regard to the timing of application for both Flame Seedless and Bonheur was obtained with an ethephon application two weeks after acid maximum (30 to 40% colour). Significant seasonal differences were observed regarding various quality variables of Bonheur. This timing was not very critical for improved export pack-out or meeting the berry colour quality norm. Treatments closer to harvest increase the risk of quality defects during cold storage, such as berry crack, S02 burn, as well as soft and loose berries. An ethephon dosage of 300 mg/L for Flame Seedless and 200 mg/L for Bonheur gave satisfactory results regarding export pack-out, export-quality berry colour at harvest and post-cold-storage quality. The preliminary evaluation of anthocyanin and total phenol absorbance levels did not correlate well with visual evaluation of berry colour, showing the difficulty of sensory determinations for quality evaluation.

Ethylene-induced transcriptional and hormonal responses at the onset of sugarcane ripening

The effects of ethephon as a sugarcane ripener are attributed to ethylene. However, the role of this phytohormone at the molecular level is unknown. We performed a transcriptome analysis combined with the evaluation of sucrose metabolism and hormone profiling of sugarcane plants sprayed with ethephon or aminoethoxyvinylglycine (AVG), an ethylene inhibitor, at the onset of ripening. The differential response between ethephon and AVG on sucrose level and sucrose synthase activity in internodes indicates ethylene as a potential regulator of sink strength. The correlation between hormone levels and transcriptional changes suggests ethylene as a trigger of multiple hormone signal cascades, with approximately 18% of differentially expressed genes involved in hormone biosynthesis, metabolism, signalling, and response. A defence response elicited in leaves favoured salicylic acid over the ethylene/jasmonic acid pathway, while the upper internode was prone to respond to ethylene with strong stimuli on ethylene biosynthesis and signalling genes. Besides, ethylene acted synergistically with abscisic acid, another ripening factor, and antagonistically with gibberellin and auxin. We identified potential ethylene target genes and characterized the hormonal status during ripening, providing insights into the action of ethylene at the site of sucrose accumulation. A molecular model of ethylene interplay with other hormones is proposed.

On the mechanism of genotoxicity of ethephon on embryonic fibroblast cells

Ethephon is one of the most widely used plant growth regulator in agriculture that its application has been increased in recent years. Many reports have raised concern over the safety of this organophosphorus compound. The aim of the current study was to assess the potential genotoxic effect of ethephon on murine embryonic fibroblast (MEF) cell line, using two genotoxicity endpoints: γH2AX expression and comet assay. γH2AX served as an early and sensitive biomarker of genotoxic damage. Oxidative stress biomarkers, including reactive oxygen species (ROS), lipid peroxidation (LPO) and total antioxidant capacity were also examined. The results showed a significant increase in cell proliferation, 24 h post-treatment with 10, 40,160 μg/ml ethephon, while at the higher concentrations cytotoxic effect was observed. The γH2AX expression and γH2AX foci count per cell were significantly increased at non-cytotoxic concentrations of ethephon, accompanied with increased DNA damage as illustrated by comet assay. LPO and ROS levels were elevated only at 160 μg/ml and higher doses. The results interestingly showed that low non-cytotoxic doses of ethephon promoted DNA damage inducing cell proliferation, raising the possibility of ethephon mutagenicity. The genotoxic effect of ethephon at low doses might not relate to oxidative damage and that increased in the level of ROS and LPO generation at higher doses could account for the cytotoxic effect of ethephon. Taken together, our study provides strong in vitro evidence on potential genotoxicity of ethephon at low doses. More precise studies are needed to clarify the mutagenic effect of chronic exposure to ethephon.

Effects of Ethephon and Abscisic Acid Application on Ripening-Related Genes in ‘Kohi’ Kiwifruit (Actinidia chinensis) on the Vine

The effects of ethephon and abscisic acid (ABA) application on ripening-related genes of pre-harvest ‘Kohi’ kiwifruit (Actinidia chinensis) were studied to clarify the possibility of the fruit ripening on the vine. The fruits were treated on the vine at mature stage with 250 µL⋅L−1 ethephon or 100 µmol⋅L−1 ABA, and the expression levels of chlorophyll synthase (AcCLS), chlorophyllase1 (AcCLH1), polygalacturonase (AcPG), expansin (AcEXP), β-amylase (Acβ-AM), sucrose synthase (AcSUSY), MADS-box SEPALLATA4/RIPENING INHIBITOR-like (AcSEP4/RIN) and FRUITFUL-like (AcTDR4/FUL) genes were analyzed. The expression levels of AcPG, AcEXP, Acβ-AM, and AcSUSY increased in the ethephon-treated fruit, but those of AcCLH1 at 6 and 9 days after treatment and AcCLS decreased. Moreover, the expression levels of AcSEP4/RIN and AcTDR4/FUL, the latter of which is associated with ethylene biosynthesis, were higher in the ethephon-treated fruit. The expression level of each gene in ABA-treated fruit was not significantly different from that of the untreated control. The results suggest that ethephon application increases the expression levels of AcPG, AcEXP, Acβ-AM, AcSUSY, AcSEP4/RIN, and AcTDR4/FUL in ‘Kohi’ kiwifruit on the vine.

Ethephon advances the release time of limit dextrinase from gibberellic acid-treated aleurone layer

Abstract The aleurone layer plays a key role in germination by responding to hormone signals from embryo and producing hydrolases. The barley aleurone layer can be separated from the other seed tissues and maintained in culture, allowing the study of the effect of added signaling molecules in an isolated system. In this work, the effect of ethephon on the protein release from gibberellic acid (GA)-treated aleurone layer was presented for two important enzymes in starch degradation: α-amylase and limit dextrinase (LD). The results showed that the release of proteins from aleurone layer to culture supernatant was remarkably increased when GA- treated aleurone layer was exposed to 1000–10000 ppm ethephon. Ethephon enhanced the release of α-amylase and advanced the release time of LD from GA-treated aleurone layer to culture supernatant. The results supports that the release of LD is dependent to cell wall degradation which can be induced by the effect of ethephon.

The Effect of Application of Ethephon to Processing Tomato Plants on the Chemical Composition of Fruits

Ethephon is used to accelerate fruit ripening on plantations with well-developed plants which have formed a large quantity of fruits. The aim of the study was to determine the effect of ethephon on the chemical composition of the fruits of seven cultivars of processing tomato (‘Rumba’, ‘Hubal’, ‘Sokal’ F1, ‘Mieszko’ F1, ‘Polset’ F1, ‘Hysioux’ F1 and ‘AF1120’ F1), applied to the plants when most of the fruits had reached the mature-green stage. The study was conducted during three consecutiveyears, characterized by different weather conditions. Meteorological elements, i.e. air temperature and precipitation totals, were monitored in the experimental station in Mydlniki, near Krakow, Poland. Ethephon was found to have a beneficial effect on the content of extract and soluble sugars of the harvested tomatoes and on their acidity. Dry matter and lycopene levels were not dependent on the use of this compound, while the ascorbic acid content was reduced by the procedure. The chemicalcomposition of the tomato fruits differed significantly in consecutive years of the study, which confirmed the weather impact on fruit quality and on the varied responses of different cultivars to use of ethephon. The tested cultivars were also compared in terms of their suitability for processing. The ‘Hubal’ cultivar had the highest content of dry matter, extract, soluble sugars of all the cultivars tested. The highest level of lycopene was noted for the tomatoes of the ‘Rumba’ and ‘Sokal’ F1 cultivar, ascorbic acid of the ‘Rumba’ and the highest acidity for ‘AF 1120’ F1.

The effect of ethephon on immune system in male offspring of mice.

Ethephon can liberate ethylene which could interfere the plant growth process. The aim of the present study was to determine the effect of ethephon on developing immune system of male offspring. Ethephon could enhance NK cell activity in male mice. For 4-week-old male mice, lymphocytes of peripheral blood increased while the hemolytic plaque number decreased. Delayed type hypersensitivity(DTH) was inhibited in all groups. The expression of protein Bcl11b and p-p38 in thymus of treatment groups were lower than control group. Our results indicated that cellular immunity of male offspring is more sensitive to ethephon when exposed in pregnancy and lactation period. It should be emphasized that exposure to ethephon during the in utero stage and lactation stage still could damage the immune function of animal in the period before fully mature even in the dosage that could not influence the immune function of adult animal.

Effect of ethephon and 1-MCP treatments on the vase life of cut ‘Sansai Blue’Vanda

Effect of ethephon and 1-MCP treatments on the vase life of cut ‘Sansai Blue’<i>Vanda</i>

Concentration and Timing of Ethephon Drench Applications Interact to Affect Growth and Flowering of Containerized Angelonia and Geranium

Ethephon drenches have been reported to effectively control growth of containerized bedding plants. However, previous researchers have indicated that the effects of ethephon drenches on growth and flowering may differ depending on the timing of applications. Our objectives were to quantify the effects of ethephon concentration, timing of substrate drench application, and their interaction on the growth, size, and flowering of two annual bedding plants. Angelonia (Angelonia angustifolia) and geranium (Pelargonium ×hortorum), seedlings were planted in 10.2-cm-diameter containers filled with a commercial, soilless growing substrate composed of (by vol.) 75% sphagnum peatmoss, and 25% perlite. Five, 10, 15, or 20 days after transplanting seedlings, 70-mL aliquots containing 0, 50, 100, or 200 mg·L−1 ethephon were applied as substrate drenches. Species varied in their growth and flowering responses to ethephon concentration, drench application timing, and their interaction. For angelonia, flowering was delayed most with early applications and high concentrations, and delay was diminished with later applications. Angelonia height was unaffected by late applications, though lateral growth was suppressed 20 days after transplant with 200 mg·L−1 ethephon. Flowering of geranium was only delayed when ethephon was applied 5 days after transplanting, whereas flowering, vegetative height, and shoot dry weight were affected more by earlier applications and higher concentrations. Width and root weight were only affected by ethephon concentration, with growth suppression increasing as concentrations increased. Ethephon is an effective growth regulator when applied as a substrate drench. However, the degree of activity and resulting impact on flowering, size, and growth is influenced by the interaction between ethephon concentrations and the timing of drench applications after transplanting.

Roles of ethylene and cytokinins in development of defense responses in Triticum aestivum plants infected with Septoria nodorum

Effects of ethephon (2-chloroethylphosphonic acid, ET), which is a producer of ethylene, and 1-methylcyclopropene (1-MCP), which inhibits ethylene binding with the corresponding receptors, on defense responses caused by the causal agent of leaf blotch (Septoria nodorum Berk.) in leaves of soft spring wheat (Triticum aestivum L.) of cultivars contrast in the resistance to the pathogen were studied. After treatment with 1-MCP, an induction of wheat resistance to the disease, more prominent in the susceptible cv. Kazakhstanskaya 10 than in the resistant cv. Omskaya 35, was found. The rise in the resistance was accompanied by rise in zeatin content in leaves, enhanced generation of hydrogen peroxide (most likely, due to the decreased catalase activity and increased peroxidase activity), and accumulation of transcripts of marker genes of the salicylate signaling pathway (PR-1 and PR-2). On the contrary, in ET-treated plants, all the studied defense responses were inhibited, and the pathogen developed more intensively. The effect of ethylene on zeatin distribution in infected wheat leaves of the susceptible cv. Kazakhstanskaya 10 was also found. In the 1-MCP-treated wheat leaves, cytokinins were localized in mesophyll cells and cell walls. In the ET-treated leaves, cell walls were free of zeatin, and the hormone concentrated in developing hyphae of the pathogen. The results allow for the hypothesis that wheat plant resistance is controlled by antagonistic interaction of signaling pathways of salicylic acid and ethylene with participation of cytokinins.

Effects of pre-harvest application of ethephon or abscisic acid on ‘Kohi’ kiwifruit (Actinidia chinensis) ripening on the vine

The effects of ethephon, abscisic acid (ABA), and nordihydroguaiaretic acid (NDGA) application on the ripening of pre-harvest ‘Kohi’ kiwifruit (Actinidia chinensis) were studied. The fruits were treated on-vine at 155days after full bloom (DAFB) (mature stage) with 250μL/L ethephon, 100μmol ABA, or 100μmol NDGA. The fruits were sampled at 0, 3, 6, 9, and 12days after treatment (DAT), and the following were analyzed at each time point: ethylene production, 1-aminocyclopropane-1-carboxylate (ACC) and ABA concentrations, ACC synthase (ACS) and ACC oxidase (ACO) activities, volatile compounds (n-hexanal and (E)-2-hexexnal), and the expressions of AcACS1, AcACO1, and 9-cis-epoxycarotenoid dioxygenase 1 (AcNCED1) genes. ABA concentrations and AcNCED1 gene expression increased in ABA-treated fruit. Malic acid concentrations and fruit firmness decreased in ethephon-treated fruit, but soluble solids concentrations (SSC), ethylene biosynthesis, and both AcACS1 and AcACO1 gene expressions increased. The accumulated fruit drop rate in ethephon-treated fruit was 4% at the edible stage at 9 DAT. Moreover, the production of n-hexanal and (E)-2-hexexnal decreased in ethephon-treated fruit. These results suggest that ‘Kohi’ kiwifruit may be ripened by on-vine ethephon application at 9 DAT, thus obviating ripening treatment after harvest.

Effects of Trunk-shaker Harvester and Ethephon on Plant Water Status, Leaf Gas Exchange, and Yield of Citrus Cultivated under Mediterranean Conditions

This work was aimed to study whether the application of ethephon as an abscission agent and mechanical harvest using a trunk shaker have any effect on plant water status, leaf gas exchange, and yield of mandarin and orange trees cultivated under Mediterranean conditions. The experiment was performed from 2008 to 2011 in five commercial orchards where parameters related to the plant water status and leaf gas exchange were measured before the application of ethephon, at harvest time and at different occasions after harvest. In addition, the effects of ethephon dose on yield in the current and subsequent seasons were also evaluated. Results showed that ethephon applications and mechanical harvest did not detrimentally affect plant water status in any of the cultivars studied. Furthermore, either had no effect or had a short temporal decrease effect on leaf gas exchange depending on the cultivar studied although with no consequences for the fruit yield obtained during the current season. Increasing ethephon doses led to fruit yield reductions in the mandarin ‘Orogrande’ trees in subsequent seasons. When trunk-shaker and ethephon applications were combined, however, yields from the late-maturing orange significantly decline in subsequent seasons. Overall, results show that using a trunk shaker is a viable technique to mechanically harvest citrus trees destined to both fresh and industry market and can be considered as an alternative to the traditional manual harvest usually performed under Mediterranean conditions. However, its use cannot be recommended for late-maturing oranges, such as the ‘Navel Lane Late’ in which mature fruit and fruitlets coexist in the tree at the time of harvest.

Effects of Ethephon on Fresh In‐Husk Walnut Preservation and its Possible Relationship with Phenol Metabolism

Fresh walnuts (Juglans regia L.) are in demand due to their high nutrition value and unique flavor of the kernel. In this study the effects of ethephon on decay control and kernel quality of fresh walnuts and its possible relationship with phenolic metabolism were investigated. Fresh in-husk walnuts treated with 0, 10, 500, and 800 mg/L ethephon were stored at 0 ± 0.5°C for 42 d. Decay incidence, total phenolic (TP) compounds, phenylalanine ammonialyase (PAL), polyphenol-oxidase (PPO), and peroxidase (POD) activities of green husks, and acid values (AV) and peroxide values (PV) of kernels were assessed at 6-d intervals. The respiration rate of the whole walnut was assessed at 3-d intervals. Treatment with 500 mg/L ethephon enhanced respiration, reduced the decay index, and inhibited PPO and POD activity and browning of green husks, and also promoted PAL activity and TP content of green husks. This treatment also reduced the PV and AV of kernels. A concentration of 10 mg/L ethephonhad similar, but weaker, effects on walnuts. Treatment with 8000 mg/L ethephon, however, had opposite effects. These data indicate ethephon treatment at a proper concentration can extend storage life and maintain kernel quality of fresh in-husk walnuts through the manipulation of phenolic metabolism.

Effect of Ethephon as an Ethylene-Releasing Compound on the Metabolic Profile of Chlorella vulgaris

In this study, Chlorella vulgaris (C. vulgaris) was treated with ethephon at low (50 μM) and high (200 μM) concentrations in medium and harvested at 0, 7, and 14 days, respectively. The presence of ethephon led to significant metabolic changes in C. vulgaris, with significantly higher levels of α-tocopherol, γ-aminobutyric acid (GABA), asparagine, and proline, but lower levels of glycine, citrate, and galactose relative to control. Ethephon induced increases in saturated fatty acids but decreases in unsaturated fatty acids. The levels of highly saturated sulfoquinovosyldiacylglycerol species and palmitic acid bound phospholipids were increased on day 7 of ethephon treatment. Among the metabolites, the productivities of α-tocopherol (0.70 μg/L/day) and GABA (1.90 μg/L/day) were highest for 50 and 200 μM ethephon on day 7, respectively. We propose that ethephon treatment involves various metabolic processes in C. vulgaris and can be an efficient way to enrich the contents of α-tocopherol and GABA.

Effects of Ethephon on spermatogenic cells and sex hormone levels of adolescent male rats

Objective To investigate the effects of Ethephon on spermatogenic cells and sex hormones levels of adolescent male rats. Methods The male SD rats of 25-day old were randomly (from the random number table)divided into high dose group (2 000 mg/kg), middle dose group (1 000 mg/kg), low dose group (500 mg/kg) and control group (the same amount of physiological saline). They were given Ethephon through stomach for 14 d. The pathological changes in testis tissues were observed by HE staining.The apoptosis of germ cells were detected by terminal transferase labeling (TUNEL). The automatic chemical luminescence immunoassay analyzer was used to test the serum sex hormone levels. Results After ethephon and saline lavage for 14 days in the dose of 2 000 mg/kg, 1 000 mg/kg, 500 mg/kg concentrations respectively, body weight growth was significantly decreased (F=3.58, P=0.03). Testis mass growth [(0.91±0.17 ) g, (1.13±0.15) g, (1.21±0.11) g, (1.29±0.28) g]was significantly decreased (F=4.31, P=0.02). Experimental group spermatogenic cell apoptosis, the apoptosis index increased (F=156.00, P=0.00), high dose group[(2.40±0.18)%] and middle dose group[(1.72±0.14)%] was significantly increased (P<0.01). The levels of testosterone and estrogen in serum showed a decreasing trend along with the increase of the doses, and there was a statistical significance(F=11.85, 38.93, all P=0.00). Compared with the control group[(0.86±0.10) μg/L], the testosterone levels in high dose group[(0.31±0.08) μg/L], middle dose group[(0.36±0.05) μg/L] decreased significantly (P<0.01). Compared with the control group, low dose group, middle dose group [(36.43±3.57) ng/L, (38.62±2.24) ng/L, (31.87±5.78) ng/L], the estrogen level in high dose group[(27.39±2.11) ng/L]was significantly reduced (P<0.01). Conclusion Ethephon has reproductive toxicity, and can cause the serum level of testosterone and estradiol decreased, resulting in spermatogenic cell apoptosis index increased and the spermatogenic capability decreased. Key words: Ethephon; Spermatogenic cell; Apoptosis; Sex hormone

Effects of Ethephon on Terpenoids in Cannabis sativa L. in Vegetative Stage

In the present study we investigated the effect of ethephon on changes in the amount of many terpenoid compounds including, tetrahydrocannabinol (THC), cannabidiol (CBD), chlorophyll, carotenoids, α-tocopherol and pyruvate as one of substrate in plastidic terpenoids biosynthesis in Cannabis sativa at vegetative stage. Treatment with 1 and 100 µM ethephon increased THC content up to 9 fold in vegetative stage. Plants treated with 10 µM ethephon had more CBD content in comparison with control plants. The amount of CBD decreased in plants subjected to 5 and 100 µM ethephon. Leave area in plant treated with ethephon did not show significant changes in comparison to control plants. Ethephon treatment caused a declined in the amount of α-tocopherol. The levels of chlorophylls and carotenoids raised in treated plants with 1 µM ethephon. With regard to the fact that ethephon had not negative effect on the surface of leaves and chlorophyll content thus its application can be a suitable way for increasing of THC and α-tocopherol in Cannabis sativa L.

Effects of ethephon on anatomical changes in sunflower (Helianthus annuus L.) stems associated with lodging

Stem lodging causes significant losses in crops of cereals and oilseeds. The aim of the present study was to identify the anatomical causes that generate differences in response to stem lodging in sunflower. Two sunflower hybrids (Stay-Green, resistant to stem lodging; Zenit, susceptible to stem lodging) were grown at three crop population densities and artificially lodged at two advanced ontogeny stages (R7 and R8), which were preceded by ethephon application near the flower button stage (R1). Measurements included stem failure moment of force (Bs), thickness of primary and secondary structures in the stem lodging zone (t), diameter of the stem lodging zone (di), sclerenchyma packages area (sp), secondary xylem tissue area (xt) and yield. Stay-Green had significantly higher values for Bs, t, di, sp and xt. At higher crop densities and more advanced ontogeny stages these parameters were reduced, favouring stem lodging, although the effects were ameliorated by ethephon application through anatomical modifications. Zenit exhibited the greatest responses to ethephon application. The present study is the first field study identifying anatomical changes causing stem lodging and intraspecific variability in sunflowers. The information provided can be used by geneticists in selection programs for stem lodging tolerance in the context of increasing crop population densities to improve sunflower yield.

Analysis of differential expression of genes induced by ethephon in elongating internodes of maize plants

Plant growth regulators (PGRs) are commonly used in cereal cropping systems to restrict plant height and control lodging. Ethephon has been reported to shorten internodes and increase grain yield of maize. To analyze the transcriptomic profiles of maize internode elongation following ethephon treatment, differentially expressed genes were compared between the treatment and control samples of inbred line Zong 31 using the Affymetrix Maize Genome Array. According to the microarray data, 326 probe sets showed significant change in expression. Further research revealed that the most remarkable effects of ethephon on maize internodes elongation occurred during a 48 h period, when 89 differentially expressed genes were detected. There were dramatic change in transcript levels at 24 h and six Auxin transport genes and four gibberellin biosynthesis pathway genes were differ- entially expressed in Zong 31 in response to ethephon treatment. In summary, we showed that gaseous ethylene release is involved in internode meristem cell elongation through the regulation of plant hormone signaling in maize. This work provides a platform for studies in which candidate genes will be functionally tested for involve- ment in internode elongation.

Effects of pre-harvest chemical application on rice desiccation and seed quality.

Pre-harvest desiccation may increase the efficiency of seed production. Field studies were conducted to determine the effects of diquat, paraquat, and ethephon applications on grain moisture, grain weight, and seed germination of hybrid rice Yanliangyou 88 (Oryza sativa ssp. indica) and conventional rice Wuyunjing 7 (Oryza sativa ssp. japonica). In 2013, we tested 12 treatments applied at four weeks (Yanliangyou 88) and six weeks (Wuyunjing 7) after heading. Results showed that reductions in moisture content were significant two and four days after chemical application. Chemical applications had no adverse effects on 1000-grain weight, germination percentage, or germination index, but there were negative effects on the percentage of normal seedlings. Desiccation effects increased with increase in the period after application, while the effect of ethephon combined with diquat or paraquat on desiccation was limited compared with that of diquat or paraquat alone in a short period after application. In 2013, chemical applications reduced the moisture content by from 0.5% to 6.4%, the germination percentage by from 0% to 3.3%, and the percentage of normal seedlings by from 13.3% to 100.0%. Among the treatments, diquat applied at 120 g/ha resulted in effective desiccation with fewer negative effects on grain weight and seed germination in 2013 and 2014. Therefore, diquat may have potential as a pre-harvest chemical desiccation treatment for rice. These results may provide a basis for developing and implementing protocols for large scale field trials.

Ethephon improved stalk strength associated with summer maize adaptations to environments differing in nitrogen availability in the North China Plain

SUMMARYNitrogen (N) supply is essential for achieving high grain yield in maize production, but excessive N application can lead to lodging risks and potential yield loss. The main objective of the present study was to investigate the effect of ethephon application under different N fertilizer rates in reducing maize lodging. Field experiments were conducted to determine the interactive effects of ethephon (0 and 180 g/ha) and N rate (0, 75, 150 and 225 kg N/ha) on the morphological and chemical characteristics of basal internode and yield across two summer maize-growing seasons (2011/12) in Wuqiao of the North China Plain. Findings showed that ethephon significantly increased the maximum diameter of the 7th to 14th internodes, and decreased the internode lengths, which led to a decrease in plant and ear heights under different N rates. Significant ethephon × N interaction effects were observed on the diameter and length of internode, dry weight per unit internode length and breaking resistance. Ethephon significantly increased N, cellulose and hemicellulose contents of the basal internode, but cellulose and hemicellulose contents decreased as the rate of N application increased. Internode diameter, dry weight per unit internode length, and N content of the basal internode were significantly positively correlated with breaking resistance. Ethephon significantly increased grain yield and harvest index in 2011, but not in 2012. Grain yield and above-ground biomass were increased with increasing N application in both growing seasons, showing linear and quadratic responses. These results suggested that ethephon could increase stalk strength by improving the morphological and chemical characteristics of the basal internode, and maintain high yield and biomass under high N rates.