Search

Sesame (Sesamum indicum L.) is an important oilseed crop with significant economic importance in many developing countries. This study rigorously investigated the impact of various applications and doses of two specific plant growth regulators, paclobutrazol (PAC) and mepiquat chloride (MC), on the development, yield components, oil content, and fatty acid composition of sesame plants across two consecutive growing seasons. The research revealed that while paclobutrazol application increased the plant height it also resulted in a slight decrease in oil content. The paclobutrazol treatment resulted in the highest seed yield (21.3 g/plant), which was significantly different from both the MC (13.1 g/plant) and PAC + MC (14.6 g/plant) treatments. In contrast, the mepiquat chloride treatment resulted in the lowest oil content. The combined application of both regulators showed intermediate effects. In addition, variations in fatty acid content were observed between applications and doses, with significant differences in saturated and unsaturated fatty acid levels. The findings provide valuable insights into the potential benefits and implications of using growth regulators in sesame cultivation, especially in the context of mechanized harvesting and oil quality optimization. [ABSTRACT FROM AUTHOR]

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Finland, and co‐rapporteur Member State, Estonia, for the pesticide active substance mepiquat (evaluated variant mepiquat chloride) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of mepiquat chloride as a plant growth regulator on cereals and grass (field uses). The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. [ABSTRACT FROM AUTHOR]

Abstract Background Drought can result in yield losses, the application of plant growth regulators is an effective measure to improve drought resistance and yield. The objective of the study was to explore the application potential of mepiquat chloride (MC) in regulating soybean yield and drought resistance. Methods In this study, a three-year field experiment was designed and combined with drought experiments to measure the yield of popularized varieties during 2021–2022 and drought-resistant and drought-sensitive varieties were selected, and planted in the field in 2023. Results MC increased the yield of HN84 and HN87 for two consecutive years from 2021 to 2022 and improved their physiological characteristics under field conditions. Under M200 treatment, the yield of HN84 increased by 6.93% and 9.46%, and HN87 increased by 11.11% and 15.72%. Different concentrations of MC have different effects on soybeans. The maximum increase of SOD, POD and proline in HN84 under M400 treatment reached 71.92%, 63.26% and 71.54%, respectively; the maximum increase of SOD, POD and proline in HN87 under M200 treatment reached 21.96%, 93.49% and 40.45%, respectively. In 2023, the foliar application of MC improved the physiological characteristics of HN44 and HN65 under drought-stress conditions. On the eighth day of drought treatment, compared to the drought treatment, the leaf and root dry weight of HN44 under M100 treatment increased by 17.91% and 32.76%, respectively; the dry weight of leaves and roots of HN65 increased by 20.74% and 29.29% under M200 treatment, respectively. MC also reduced malondialdehyde (MDA) content, decreased antioxidant enzyme activity and proline content. In addition, different concentrations of MC increased the chlorophyll fluorescence parameters (Fs, Fv/Fm, YII, and SPAD). In the field, the plant height of the two varieties decreased significantly, the yield increased, the number of two-grain and three-grain pods increased, and the stem length at the bottom and middle decreased with MC induction. Conclusions The application of 100–200 mg/L MC effectively improved drought resistance and increased yield. This study provided support for the rational application of MC in soybean production.

Abstract Background Natural and synthetic plant growth regulators are essential for plant health, likewise these regulators also play a role in increasing organic production productivity and improving quality and yield stability. In the present study, we have evaluated the effects of foliar applied plant growth regulators, i.e., moringa leaf extract (MLE) and mepiquat chloride (MC) alone and in combination MC and MLE on the conventional cotton cultivar (CIM 573) and transgenic one (CIM 598). The growth regulators were applied at the start of bloom, 45 and 90 days after blooming. Results The application of MC and MLE at 90 days after blooming significantly improved the relative growth rate, net assimilation rate, the number of bolls per plant, and seed cotton yield. Likewise, the combined application of MLE and MC at 90 days after blooming significantly boosted the nitrogen uptake in locules, as well as the phosphorus and potassium uptake in the leaves of both cotton cultivars. The application of MLE alone has considerably improved the nitrogen uptake in leaves, and phosphorus and potassium contents in locules of Bt and conventional cotton cultivars. Similarly, Bt cotton treated with MLE at 90 days after blooming produced significantly higher ginning out turn and oil contents. Treatment in combination (MLE + MC) at 90 days after blooming produced considerably higher micronaire value, fiber strength, and staple length in conventional cultivar. Conclusion The natural growth enhancer, MLE is a rich source of minerals and zeatin, improving the nutrient absorption and quality of cotton fiber in both conventional and Bt cotton cultivars.

Copyright of Mustafa Kemal University Journal of Agricultural Sciences / Mustafa Kemal Üniversitesi Tarım Bilimleri Dergisi is the property of Mustafa Kemal University, Faculty of Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Drought can result in yield losses, the application of plant growth regulators is an effective measure to improve drought resistance and yield. The objective of the study was to explore the application potential of mepiquat chloride (MC) in regulating soybean yield and drought resistance. Methods: In this study, a three-year field experiment was designed and combined with drought experiments to measure the yield of popularized varieties during 2021–2022 and drought-resistant and drought-sensitive varieties were selected, and planted in the field in 2023. Results: MC increased the yield of HN84 and HN87 for two consecutive years from 2021 to 2022 and improved their physiological characteristics under field conditions. Under M200 treatment, the yield of HN84 increased by 6.93% and 9.46%, and HN87 increased by 11.11% and 15.72%. Different concentrations of MC have different effects on soybeans. The maximum increase of SOD, POD and proline in HN84 under M400 treatment reached 71.92%, 63.26% and 71.54%, respectively; the maximum increase of SOD, POD and proline in HN87 under M200 treatment reached 21.96%, 93.49% and 40.45%, respectively. In 2023, the foliar application of MC improved the physiological characteristics of HN44 and HN65 under drought-stress conditions. On the eighth day of drought treatment, compared to the drought treatment, the leaf and root dry weight of HN44 under M100 treatment increased by 17.91% and 32.76%, respectively; the dry weight of leaves and roots of HN65 increased by 20.74% and 29.29% under M200 treatment, respectively. MC also reduced malondialdehyde (MDA) content, decreased antioxidant enzyme activity and proline content. In addition, different concentrations of MC increased the chlorophyll fluorescence parameters (Fs, Fv/Fm, YII, and SPAD). In the field, the plant height of the two varieties decreased significantly, the yield increased, the number of two-grain and three-grain pods increased, and the stem length at the bottom and middle decreased with MC induction. Conclusions: The application of 100–200 mg/L MC effectively improved drought resistance and increased yield. This study provided support for the rational application of MC in soybean production. [ABSTRACT FROM AUTHOR]

Background: Natural and synthetic plant growth regulators are essential for plant health, likewise these regulators also play a role in increasing organic production productivity and improving quality and yield stability. In the present study, we have evaluated the effects of foliar applied plant growth regulators, i.e., moringa leaf extract (MLE) and mepiquat chloride (MC) alone and in combination MC and MLE on the conventional cotton cultivar (CIM 573) and transgenic one (CIM 598). The growth regulators were applied at the start of bloom, 45 and 90 days after blooming. Results: The application of MC and MLE at 90 days after blooming significantly improved the relative growth rate, net assimilation rate, the number of bolls per plant, and seed cotton yield. Likewise, the combined application of MLE and MC at 90 days after blooming significantly boosted the nitrogen uptake in locules, as well as the phosphorus and potassium uptake in the leaves of both cotton cultivars. The application of MLE alone has considerably improved the nitrogen uptake in leaves, and phosphorus and potassium contents in locules of Bt and conventional cotton cultivars. Similarly, Bt cotton treated with MLE at 90 days after blooming produced significantly higher ginning out turn and oil contents. Treatment in combination (MLE + MC) at 90 days after blooming produced considerably higher micronaire value, fiber strength, and staple length in conventional cultivar. Conclusion: The natural growth enhancer, MLE is a rich source of minerals and zeatin, improving the nutrient absorption and quality of cotton fiber in both conventional and Bt cotton cultivars. [ABSTRACT FROM AUTHOR]

Background: Drought is an important factor restricting the development of agriculture. In recent years, plant growth regulators have achieved more results in improving crop stress resistance. The physiological mechanism of exogenous application of mepiquat chloride on soybean seedlings has undergone significant changes under drought stress. Methods: In order to study the effect of exogenous chlorine on the physiology of soybean under drought stress., 'Heinong 65' was used as the experimental material, 15% PEG-6000 was used to simulate drought stress and different concentrations of mepiquat chloride solution (100, 300, 500, 700 mg/L) were sprayed at the three-leaf stage of soybean growth by pot method. The dry matter accumulation, auxin (IAA), zeatin (ZA), gibberellin (GA3), abscisic acid (ABA) content and superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) activity of soybean were determined. Result: The results showed that the activities of antioxidant enzymes SOD, POD, CAT and APX in soybean leaves under drought stress were significantly increased by the treatment of appropriate concentration of mepiquat chloride solution. IAA, GA3 and ZA endogenous hormone levels increased, dry matter accumulation increased, root-shoot ratio and ABA endogenous hormone levels decreased significantly. It can be seen that mepiquat chloride treatment can improve the antioxidant capacity, promote the growth of soybean seedlings under drought stress and effectively alleviate the inhibition of drought stress on soybean growth and development. [ABSTRACT FROM AUTHOR]

Copyright of Progress in Plant Protection is the property of Institute of Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Finland, and co‐rapporteur Member State, Estonia, for the pesticide active substance mepiquat (evaluated variant mepiquat chloride) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of mepiquat chloride as a plant growth regulator on cereals and grass (field uses). The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant BASF SE submitted a request to the competent national authority in Finland to modify the temporary maximum residue level (MRL) to a permanent MRL for the active substance mepiquat in cultivated fungi (with a specific MRL for oyster mushrooms). The data submitted in support of the request (monitoring data from food business operators) are not sufficient to derive permanent MRL proposals. The assessment of these data, complemented by an analysis of the most recent monitoring data available from EU monitoring programmes, supports the conclusion that the existing t‐MRL for cultivated fungi is still sufficient to account for the residue uptake in cultivated mushrooms other than oyster mushrooms. It was also noted that lower t‐MRLs could be derived based on the assessment of the most recent monitoring data. A risk management decision is still needed on whether to maintain the existing t‐MRL value. Regarding oyster mushrooms, EFSA derived different options for risk managers to eventually update the values of the temporary MRLs based on the most recent monitoring data from food business operators. Adequate analytical methods for enforcement are available to control the residues of mepiquat (expressed as mepiquat chloride) in the commodities under consideration at the validated limit of quantification (LOQ) of 0.01 mg/kg. Based on the risk assessment results, EFSA concluded that the short‐term and long‐term intake of residues resulting from the cross‐contamination of untreated cultivated fungi (including oyster mushrooms) from cereal straw lawfully treated with mepiquat according to the current agricultural practices is unlikely to present a risk to consumer health. [ABSTRACT FROM AUTHOR]

Copyright of Avances en Ciencias e Ingenierías (ACI) is the property of USFQ Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Background Ensuring that seeds germinate and emerge normally is a prerequisite for cotton production, esp. in areas with salinized soil. Priming with mepiquat chloride (MC) can promote seed germination and root growth under salt stress, but its mechanism has not been fully elucidated. In this study, physiological and biochemical experiments revealed that MC-priming promotes the tolerance of cotton seeds to salt stress by increasing the ability of antioxidant enzymes related to the ascorbate–glutathione (AsA-GSH) cycle to scavenge reactive oxygen species (ROS). Results Results revealed that treatment with inhibitors of abscisic acid (ABA) and γ-aminobutyric acid (GABA) biosynthesis reduced the positive effects of MC-priming. Similarly, MC-priming increased the contents of ABA and GABA under salt stress by stimulating the expression levels of GhNCED2 and GhGAD4 and the activity of calmodulin-binding (CML) glutamate decarboxylase (GAD). Further analysis showed that an inhibitor of ABA synthesis reduced the positive impacts of MC-priming on the content of GABA under salt stress, but the content of ABA was not affected by the GABA synthesis inhibitor. Furthermore, a multi-omics analysis revealed that MC-priming increased the abundance and phosphorylation levels of the proteins related to ABA signaling, CML, and Ca2+ channels/transporters in the MC-primed treatments, which resulted in increased oscillations in Ca2+ in the MC-primed cotton seeds under salt stress. Conclusion In summary, these results demonstrate that MC-mediated ABA signaling operates upstream of the GABA synthesis generated by GAD by activating the oscillations of Ca2+ and then enhancing activity of the AsA-GSH cycle, which ensures that cotton seeds are tolerant to salt stress.

Abstract Background Mepiquat chloride (MC) application and plant population density (PPD) increasing are required for modern cotton production. However, their interactive effects on leaf physiology and carbohydrate metabolism remain obscure. This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics, and thus final cotton yield. PPD of three levels (D1: 2.25 plants·m−2, D2: 4.5 plants·m−2, and D3: 6.75 plants·m−2) and MC dosage of two levels (MC0: 0 g·ha−2, MC1: 82.5 g·ha−2) were combined to create six treatments. The dynamics of nonstructual carbohydrate concentration, carbon metabolism-related enzyme activity, and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020. Results Among six treatments, the high PPD of 6.75 plants·m−2 combined with MC application (MC1D3) exhibited the greatest seed cotton yield and biological yield. The sucrose, hexose, starch, and total nonstructural carbohydrate (TNC) concentrations peaked at the first flowering (FF) stage and then declined to a minimum at the first boll opening (FBO) stage. Compared with other treatments, MC1D3 improved starch and TNC concentration by 5.4% ~ 88.4%, 7.8% ~ 52.0% in 2019, and by 14.6% ~ 55.9%, 13.5% ~ 39.7% in 2020 at the FF stage, respectively. Additionally, MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages, indicating greater carbon production and utilization efficiency. MC1D3 displayed the maximal specific leaf weight (SLW) at the FBO stage, and the highest chlorophyll a (Chl a), Chl b, and Chl a + b concentration at the mid-late growth phase in both years. The Rubisco activity with MC1D3 was 2.6% ~ 53.2% higher at the flowering and boll setting stages in both years, and 2.4% ~ 52.7% higher at the FBO stage in 2020 than those in other treatments. These results provided a explanation of higher leaf senescence-resistant ability in MC1D3. Conclusion Increasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence.

Abstract In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant BASF SE submitted a request to the competent national authority in Finland to modify the temporary maximum residue level (MRL) to a permanent MRL for the active substance mepiquat in cultivated fungi (with a specific MRL for oyster mushrooms). The data submitted in support of the request (monitoring data from food business operators) are not sufficient to derive permanent MRL proposals. The assessment of these data, complemented by an analysis of the most recent monitoring data available from EU monitoring programmes, supports the conclusion that the existing t‐MRL for cultivated fungi is still sufficient to account for the residue uptake in cultivated mushrooms other than oyster mushrooms. It was also noted that lower t‐MRLs could be derived based on the assessment of the most recent monitoring data. A risk management decision is still needed on whether to maintain the existing t‐MRL value. Regarding oyster mushrooms, EFSA derived different options for risk managers to eventually update the values of the temporary MRLs based on the most recent monitoring data from food business operators. Adequate analytical methods for enforcement are available to control the residues of mepiquat (expressed as mepiquat chloride) in the commodities under consideration at the validated limit of quantification (LOQ) of 0.01 mg/kg. Based on the risk assessment results, EFSA concluded that the short‐term and long‐term intake of residues resulting from the cross‐contamination of untreated cultivated fungi (including oyster mushrooms) from cereal straw lawfully treated with mepiquat according to the current agricultural practices is unlikely to present a risk to consumer health.

Background: Ensuring that seeds germinate and emerge normally is a prerequisite for cotton production, esp. in areas with salinized soil. Priming with mepiquat chloride (MC) can promote seed germination and root growth under salt stress, but its mechanism has not been fully elucidated. In this study, physiological and biochemical experiments revealed that MC-priming promotes the tolerance of cotton seeds to salt stress by increasing the ability of antioxidant enzymes related to the ascorbate–glutathione (AsA-GSH) cycle to scavenge reactive oxygen species (ROS). Results: Results revealed that treatment with inhibitors of abscisic acid (ABA) and γ-aminobutyric acid (GABA) biosynthesis reduced the positive effects of MC-priming. Similarly, MC-priming increased the contents of ABA and GABA under salt stress by stimulating the expression levels of GhNCED2 and GhGAD4 and the activity of calmodulin-binding (CML) glutamate decarboxylase (GAD). Further analysis showed that an inhibitor of ABA synthesis reduced the positive impacts of MC-priming on the content of GABA under salt stress, but the content of ABA was not affected by the GABA synthesis inhibitor. Furthermore, a multi-omics analysis revealed that MC-priming increased the abundance and phosphorylation levels of the proteins related to ABA signaling, CML, and Ca2+ channels/transporters in the MC-primed treatments, which resulted in increased oscillations in Ca2+ in the MC-primed cotton seeds under salt stress. Conclusion: In summary, these results demonstrate that MC-mediated ABA signaling operates upstream of the GABA synthesis generated by GAD by activating the oscillations of Ca2+ and then enhancing activity of the AsA-GSH cycle, which ensures that cotton seeds are tolerant to salt stress. [ABSTRACT FROM AUTHOR]

Introduction: Cotton (Gossypium hirsutum L.) is the most widely used natural fiber and the most important dual-purpose industrial plant in the world. Delayed transplanting of cotton using early cultivars is one of the effective methods to increase the cultivated area and increase the production of this strategic crop. Plant growth regulators can be effective in the source-sink balance in different plants and are progressively used to increase yield in many plants. Cytokinins are one of the most important plant growth regulators, which increase cell division and differentiation, reduce the effect of terminal dominance, increase leaf surface development, increase the number of lateral branches, increase mobility of nutrients, prevent chlorophyll decomposition, and prevent aging. Growth regulators containing mepiquat chloride, such as pix, reduce vegetative growth in cotton by preventing the synthesis of gibberellic acid. Controlling the growth of cotton as a result of the use of pix, allocates the photosynthetic assimilates to the fruit organs and growing bolls, which increases the weight of the bolls. Materials and Methods: To investigate the effect of foliar application of 6-benzylaminopurine and pix on the growth and yield of cotton (cv. May 344) in delayed transplanting, a factorial experiment was conducted in a randomized complete block design with three replications in Sabzevar during 2020. The factors studied were foliar application of pix at two levels of no foliar application and foliar application at the rate of 1.5 liters per hectare and 6-benzylaminopurine (BAP) foliar application at five concentrations of 0, 5, 25, 50 and 100 mg l-1. May 344 cotton cultivar was used in this experiment. Results and Discussion: The results showed that foliar application of pix significantly increased the content of chlorophyll a compared to the no foliar application conditions. Foliar application with concentrations of 50 and 100 mg l-1 BAP also caused a significant increase in the content of chlorophyll a compared to the no foliar application conditions. The highest content of chlorophyll a was observed in the concentration of 50 mg l-1 BAP, which had an increase of 17.7% compared to the control treatment. The highest height of the plant (67.9 cm) was obtained by foliar application of 25 mg l-1 BAP alone, which showed an increase of 15.1% compared to the control. The lowest plant height (51.6 cm) was also observed in the treatment of foliar application of pix along with 100 mg l-1 BAP. Foliar application of pix along with 25 mg l-1 BAP produced the highest number of bolls per plant, which was 29.8% higher than the control. The highest average boll weight (5.4 g) and the highest percentage of open bolls (83.8%) were obtained in the foliar application treatment of pix with 100 mg l-1 BAP, which was not significantly different from the control treatment. Foliar application of 1.5 liters per hectare of pix alone produced the highest seed cotton yield (2754.3 kg ha-1), which had a 40.2% increase compared to the control. The highest biological yield was produced in the foliar application treatment of PIX along with 5 mg l-1 of BAP, which had an increase of 26.5% compared to the control treatment. The lowest biological yield was obtained in the treatment of foliar application with 100 mg l-1 of BAP, which was not significantly different from the control treatment. The highest percentage of lint (52.2%) was observed in the pix foliar application treatment along with 50 mg l-1 BAP, which showed an increase of 20.3% compared to the control. Conclusion: According to the results, foliar application of 1.5 liters per hectare of pix is recommended to produce high seed cotton yield and increase the percentage of lint in delayed transplanting cotton. [ABSTRACT FROM AUTHOR]

Background: Mepiquat chloride (MC) application and plant population density (PPD) increasing are required for modern cotton production. However, their interactive effects on leaf physiology and carbohydrate metabolism remain obscure. This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics, and thus final cotton yield. PPD of three levels (D1: 2.25 plants·m−2, D2: 4.5 plants·m−2, and D3: 6.75 plants·m−2) and MC dosage of two levels (MC0: 0 g·ha−2, MC1: 82.5 g·ha−2) were combined to create six treatments. The dynamics of nonstructual carbohydrate concentration, carbon metabolism-related enzyme activity, and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020. Results: Among six treatments, the high PPD of 6.75 plants·m−2 combined with MC application (MC1D3) exhibited the greatest seed cotton yield and biological yield. The sucrose, hexose, starch, and total nonstructural carbohydrate (TNC) concentrations peaked at the first flowering (FF) stage and then declined to a minimum at the first boll opening (FBO) stage. Compared with other treatments, MC1D3 improved starch and TNC concentration by 5.4% ~ 88.4%, 7.8% ~ 52.0% in 2019, and by 14.6% ~ 55.9%, 13.5% ~ 39.7% in 2020 at the FF stage, respectively. Additionally, MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages, indicating greater carbon production and utilization efficiency. MC1D3 displayed the maximal specific leaf weight (SLW) at the FBO stage, and the highest chlorophyll a (Chl a), Chl b, and Chl a + b concentration at the mid-late growth phase in both years. The Rubisco activity with MC1D3 was 2.6% ~ 53.2% higher at the flowering and boll setting stages in both years, and 2.4% ~ 52.7% higher at the FBO stage in 2020 than those in other treatments. These results provided a explanation of higher leaf senescence-resistant ability in MC1D3. Conclusion: Increasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence. [ABSTRACT FROM AUTHOR]

Abstract Purpose In recent years, considerable research has been conducted on the use of plant growth regulators (PGRs) to improve crop yields. Large amounts of PGRs are applied to regulate crop growth. However, few studies have assessed the impact of PGRs, which leave soil residues, on soil microorganisms, especially rhizobia. Methods In this study, the influence of inoculation of soybean roots with Sinorhizobium fredii and Bradyrhizobium japonicum exposed to gibberellin A3 (GA3) and mepiquat chloride (MC) on nodule number, nitrogenase activity, and a symbiotic nitrogen fixation gene (fixA) expression was studied. The nitrate content, free amino acids, and nitrate reductase activity of the roots, and seed yield and quality of soybean were measured. Result Nodulation was promoted to some extent, whereas nitrogenase activity and fixA expression were inhibited to some extent by treatment with GA3; however, these effects were reversed by treatment with MC. In a pot experiment to study phenotypic characteristics, rhizobia treatment in combination with GA3 or MC significantly improved soybean yield and seed nitrogen content, and increased the root nitrate content, free amino acid content, and nitrate reductase activity. Conclusion The results indicated that PGRs, which leave soil residues, have significant positive effects on the growth and activity of soybean and rhizobia.

Cowpea, Vigna unguiculata, is an important food and forage legume worldwide. The cowpea weevil is a major cowpea pest that causes damage both in the field and during storage. This study investigated the effects of some foliar treatments, including three foliar fertilizers (Ca, K, B) and two growth regulators (mepiquat chloride (MC) and forchlorfenuron (CPPU) on the cowpea yield and its components. Furthermore, evaluating the susceptibility and resistance of cowpea seeds resulting from the previous treatments against the C. maculatus insect. The results showed that all foliar sprays had significant effects on yield and its components in both seasons compared with the control. The highest yield was achieved by CPPU treatment, followed by K treatment, and the lowest yield was achieved by MC treatment. The results of the free-choice and no-choice tests revealed that cowpea seeds treated with MC treatment were the most susceptible to C. maculatus attack. At the same time, cowpea seeds treated with K and CPPU treatments showed their resistance to infestation by the same insect. Foliar application of K and CPPU treatments could be used in integrated pest management programs to reduce the risk of pesticides to human health and increase crop production. [ABSTRACT FROM AUTHOR]

Seed treatment against soil pests and soil-borne pathogenic fungi, foliar application of microelement and mepiquat chloride at flowering and after flowering periods promise to increase peanut (Arachis hypogaea L.) yield. A two-year field study was conducted to test this hypothesis by seed fungicide and insecticide treatment, foliar micronutrient and mepiquat chloride (Pix) applications at different combinations and different growth stages of peanut in the eastern Mediterranean region. The treatments were different combinations of Vitavax (200 g/L Carboxin + 200 g/L Thiram) 400 g/L 100 kg seed, Gaucho (600 g/L Imidacloprid) 800 g/L 100 kg seed, Fertilon Combi (Fe, Zn, B, Mn, Cu, Mn and Mo) 1000 g /ha and Pix (150 cc /ha mepiquat chloride). Peanut seeds were treated with fungicide and insecticide before planting. Microelement fertilizer and Pix combinations were applied at the beginning of flowering, after flowering and at the beginning of flowering + after flowering. The best results for seed kernel ratio, 100 seed weight and pod yield were obtained from Pix + Fertilon Combin treatment after flowering. This treatment was followed by Goucho + Vitavax seed treatment before planting + Pix application after flowering. In this study, it was observed that Goucho + Vitavax seed treatment and Pix, Fertilon Combi and Pix + Fertilon Combi applications at flowering, after flowering and at flowering + after flowering applications generally contributed pod yield increases. [ABSTRACT FROM AUTHOR]

Introduction: Soybean is the world's most important cultivated crop, and drought can affect their growth and, eventually, yields. Foliar application of mepiquat chloride (MC) can potentially alleviate the damage caused by drought stress in plants; however, the mechanism of MC regulation of soybean drought response has not been studied. Methods: This study investigated the mechanism of soybean drought response regulation by mepiquat chloride in two varieties of soybean, sensitive Heinong 65 (HN65) and drought-tolerant Heinong44 (HN44), under three treatment scenarios, normal, drought stress, and drought stress + MC conditions. Results and discussion: MC promoted dry matter accumulation under drought stress, reduced plant height, decreased antioxidant enzyme activity, and significantly decreased malondialdehyde content. The light capture processes, photosystems I and II, were inhibited; however, accumulation and upregulation of several amino acids and flavonoids by MC was observed. Multi-omics joint analysis indicated 2-oxocarboxylic acid metabolism and isoflavone biosynthetic pathways to be the core pathways by which MC regulated soybean drought response. Candidate genes such as LOC100816177, SOMT-2, LOC100784120, LOC100797504, LOC100794610, and LOC100819853 were identified to be crucial for the drought resistance of soybeans. Finally, a model was constructed to systematically describe the regulatory mechanism of MC application in soybean under drought stress. This study fills the research gap of MC in the field of soybean resistance. [ABSTRACT FROM AUTHOR]

Purpose: In recent years, considerable research has been conducted on the use of plant growth regulators (PGRs) to improve crop yields. Large amounts of PGRs are applied to regulate crop growth. However, few studies have assessed the impact of PGRs, which leave soil residues, on soil microorganisms, especially rhizobia. Methods: In this study, the influence of inoculation of soybean roots with Sinorhizobium fredii and Bradyrhizobium japonicum exposed to gibberellin A3 (GA3) and mepiquat chloride (MC) on nodule number, nitrogenase activity, and a symbiotic nitrogen fixation gene (fixA) expression was studied. The nitrate content, free amino acids, and nitrate reductase activity of the roots, and seed yield and quality of soybean were measured. Result: Nodulation was promoted to some extent, whereas nitrogenase activity and fixA expression were inhibited to some extent by treatment with GA3; however, these effects were reversed by treatment with MC. In a pot experiment to study phenotypic characteristics, rhizobia treatment in combination with GA3 or MC significantly improved soybean yield and seed nitrogen content, and increased the root nitrate content, free amino acid content, and nitrate reductase activity. Conclusion: The results indicated that PGRs, which leave soil residues, have significant positive effects on the growth and activity of soybean and rhizobia. [ABSTRACT FROM AUTHOR]

Soybeans are the main sources of oil and protein for most of the global population. As the population grows, so does the demand for soybeans. However, drought is a major factor that limits soybean production. Regulating soybean response to drought stress using mepiquat chloride (MC) is a feasible method; however, its mechanism is still unclear. This study used PEG-6000 to simulate drought stress and quantitative proteomic techniques to reveal changes in Heinong44 (HN44) and Heinong65 (HN65) subjected to drought following the application of 100 mg/L of MC. The results showed that SOD in HN44 did not change significantly but decreased by 22.61% in HN65 after MC pretreatment, and MDA content decreased by 22.75% and 21.54% in HN44 and HN65, respectively. Furthermore, MC improved the GSH–ASA cycle and simultaneously promoted the Calvin cycle process to enable the plant to maintain a certain carbon assimilation rate under osmotic stress. In addition, MC upregulated some proteins during gluconeogenesis and starch metabolism and increased soluble sugar content by 8.41% in HN44. MC also reduced ribosomal protein abundance, affecting translation and amino acid metabolism. In summary, MC improved GSH–ASA cycle and Calvin cycle under stress to alleviate oxidative damage and maintain crop growth. Our study is the first to report the mechanism of MC regulation in soybean under osmotic stress, providing new insights for the rational application of MC in soybean. [ABSTRACT FROM AUTHOR]

The balance between vegetative and reproductive growth is the central objective in the cotton production system, which is associated with cotton maturity and yield. In China, manual topping (MT) has been performed many years prior to or during the flowering period to inhibit vegetative growth and enhance reproductive growth. MT is gradually being replaced by chemical topping (CT) with mepiquat chloride (MC, 180 g ha−1, 98% soluble powder) due to labor shortages and increasing labor cost. To determine whether CT influences cotton maturity and yield relative to MT, we carried out field experiments at four locations in the Yellow River Valley of China during 2018–2020. The results showed that CT did not alter the boll age, and although it produced taller and slender spatial boll distribution under several environments, it had little effect on the accumulation of boll fraction (the number of bolls in a given period divided by total boll number) over time at the end of blooming across locations. As a result, there were no significant differences between MT and CT in boll opening percentage in the late season. CT did not influence yield or yield components, except under severe drought. Therefore, CT with MC (180 g/ha, 98% soluble powder) during the flowering period will not compromise the maturity or yield of cotton in the Yellow River Valley of China. Similar outcomes would be achieved in other areas with similar ecological conditions and social conditions that require an alternative to extensive manual labor. [ABSTRACT FROM AUTHOR]

Bioethanol production from algal biomass is a promising alternative for sustainable biofuel production. Algae possess a high photosynthetic capacity and an adaptive ability to thrive under harsh environmental conditions. The potential properties of Scenedesmus acuminatus CCALA 436 were assessed in this research for its bioethanol efficiency, and the effects of growing the algae in wastewater and at different concentrations of mepiquat chloride were studied. Also, pre-treatment efficiencies of different concentrations of calcium oxide were carried out on microalgae biomass. Superoxide dismutase, catalase activity, glutathione, and malondialdehyde contents of microalgae were examined, and the changes in chlorophyll, photoprotective carotenoid contents, and protein concentrations were determined. The results revealed that the maximum sugar and ethanol contents of Scenedesmus acuminatus CCALA 436 were 44.7 ± 1.5% and 20.32 g/L, respectively, for 50% wastewater and mepiquat chloride (2.5 mg/L) after pre-treatment with calcium oxide (0.08%). Additionally, the levels of oxidative enzymes varied depending on the wastewater concentrations. These findings indicate Scenedesmus acuminatus CCALA 436 grown in wastewater and mepiquat chloride can be used for the treatment of wastewater and the production of ethanol and high-value products such as carotenoid. [ABSTRACT FROM AUTHOR]

An investigation was carried out at Department of Floriculture and Landscape Architecture, College of Agriculture Vellanikkara to evaluate the effects of growth regulators and pruning on induction of off-season flowering in jasmine (Jasminum sambac L.). The experiment was laid out in randomized block design (with two factors) viz. time of pruning (factor 1) - last week of September, last week of October and last week of November, and application of growth regulators (factor 2) such as cycocel (1000 ppm, 1500 ppm), paclobutrazol (200 ppm, 300 ppm), mepiquat chloride (150 ppm, 300 ppm) GA3 (100 ppm, 150 ppm), with two replications. In the present study, P x G interaction had a significant effect on the days to bud initiation, number of cymes per plant and number of buds per plant. The treatment combination P1 x G1 (pruning during last week of September along with application of cycocel 1000 ppm) was found to give better flower yield during offseason. [ABSTRACT FROM AUTHOR]

Carbon reserves in cotton roots can be remobilized to support reproductive growth, thus potentially affecting cotton yield. However, the regulation of carbon remobilization in cotton roots and its relationship with cotton yield are still poorly understood. Plant population density (PPD) and mepiquat chloride (MC) have been hypothesized to affect the dynamics of nonstructural carbohydrate content and the resulting carbon remobilization in cotton roots through the regulation of carbohydrate metabolism enzyme activities. A mid-maturation cotton line 4003–6 was field-grown in 2019 and 2020. Three different levels of PPD (D1: 2.25 plants m−2, D2: 4.5 plants m−2, and D3: 6.75 plants m−2) and two levels of MC dosage (M0: 0 g hm−2, M1: 82.5 g hm−2) were combined to create six populations differing in terms of the source–sink relationship. The changes in the hexose, sucrose, and starch contents and the key carbon metabolic enzyme activities in cotton roots were examined during peak squaring (PS) to late boll opening (LB). The combination of the PPD of 6.75 plants m−2 and MC application (M1D3) exhibited the greatest cotton yield and reproductive biomass–to–leaf area ratio from peak flowering (PF) onwards. M1D3 presented the greatest total nonstructural carbohydrate (TNC) remobilization amount of 2.96 and 3.80 g m−2, the highest efficiency of 39.11% and 48.39%, and the largest gross contribution to seed cotton yield of 0.66% and 0.79% in 2019 and 2020, respectively. The three parameters were positively correlated with the seed cotton yield except for the remobilization rate in 2019. Unlike the other treatments, the greater carbohydrate content per unit ground area in M1D3 prior to the PF stage was attributed to the higher sucrose phosphate synthase (SPS) and ADP-glucose pyrophosphorylase (AGPase) activities during the PS to first flowering (FF) stages. Conversely, the greater α-amylase and β-amylase activities in M1D3 at the PF stage accounted for the lower starch content at the EB stage, and the smaller vacuolar invertase (VIN) and cell wall invertase (CWIN) activities at the EB stage could be responsible for the lower hexose concentration at that time. The TNC remobilization amount had a positive association with the AGPase and SPS activities at the FF stage and with β-amylase activity at the PF stage in cotton tap roots in 2019 and 2020. This study provides a cotton yield-improving alternative through the promotion of carbon remobilization in roots using certain agronomic practices. • Carbon remobilization in cotton roots was affected by certain agronomic practices. • Carbon remobilization was positively correlated with seed cotton yield. • Carbon remobilization was regulated by carbon metabolism enzyme activities in roots. • Carbohydrate content of cotton roots was positively correlated with seed cotton yield. [ABSTRACT FROM AUTHOR]

Early maturity, complete defoliation and boll opening are essential for the efficient machine harvesting of cotton. Chemical topping, involving one extra application of mepiquat chloride (MC) in addition to its traditional multiple-application strategy, may be able to replace manual topping. However, it is not known whether this chemical topping technique will influence maturity or cotton responses to harvest aids. In this 2-yr field study, we determined the effects of the timing of chemical topping using various rates of MC on boll opening percentage (BOP) before application of harvest aids (50% thidiazuron·ethephon suspension concentrate, referred to as TE), and the defoliation percentage (DP) and BOP 14 days after TE application. The results indicated that late chemical topping (near the physiological cutout, when the nodes above white flower is equal to 5.0) significantly decreased BOP before TE by 5.9–11.2% compared with early (at peak bloom) or middle (seven days after peak bloom) treatments in 2019, which was a relatively normal year based on crop condition. Also, a high MC rate (270 g ha−1) showed a significantly lower (22.0%) BOP before TE than low (90 g ha−1) or medium (180 g ha−1) rates. In 2020, which was characterized by stronger vegetative growth in the late season, the late chemical topping reduced the number of leaves before TE application relative to early or middle treatments, but had lower DP (23.2–27.2%) 14 days after TE application. The high MC rate showed a leaf count before TE application that was similar to the low and medium rates, but it showed the most leaves after TE and much lower (15.0–21.7%) DP in 2020. These results suggest that late timing of chemical topping and a high MC rate decreased the sensitivity of leaves to harvest aids. Further analysis indicated that the late chemical topping mainly affected the leaf drop from the mainstem and fruiting branches where the late regrowth occurred, and the high MC rate reduced leaf shedding from these parts and also from the vegetative branches. In conclusion, chemical topping with MC during the bloom period affected cotton maturity and responses to harvest aids in different ways according to the crop condition. To avoid the risks of delayed maturity and poor defoliation after the application of harvest aids, chemical topping should not be performed too late (i.e., near the physiological cutout) by using MC at more than 180 g ha−1. The optimum timing of chemical topping probably varies from peak bloom to around seven days later, and the safest MC rates for chemical topping should be less than 180 g ha−1.

Soybeans are an important economic crop. As the most widely used growth regulator globally, the molecular mechanism of mepiquat chloride (DPC) in soybean remains unknown. In this study, RNA sequencing technology combined with ultra-performance liquid chromatography and tandem mass spectrometry were used to analyze the changes in the leaf transcriptome and metabolomics of soybean leaves at the seedling stage under DPC stress. The results showed that differentially expressed genes related to photosynthesis and cell wall synthesis were significantly downregulated at the transcriptional level. In addition, the syntheses of gibberellin, zeatin, brassinolide, and other plant hormones were inhibited in the signal transduction pathway of plant hormones, thereby inhibiting plant growth. In contrast, at the metabolic level, the expression levels of flavonoid differential metabolites were significantly increased, and the proportions of flavonoids in the two varieties were 61.5 and 66%, respectively. The combined analysis of transcriptome and metabolomics showed that the differential expressed genes and metabolites were mainly enriched in the isoflavonoid biosynthesis and flavonoid biosynthesis pathways. Principally, DPC inhibited plant growth but improved drought resistance. Our study is the first to report the molecular mechanism of DPC regulation in soybean, providing useful insights into the rational application of DPC in soybean. [ABSTRACT FROM AUTHOR]

Cotton is the most important global cash crop which controls economy of many nations. Global sustainability of cotton yield is one of the major challenges for meeting impending threats under climate change. Though India is one among the leading countries in cotton production, the supply is not enough considering the increasing demand. Scientists across the Globe are indulged in developing new lines and cultures with capacity to produce more yields. In this context, here, we have made an attempt to study the growth, physiology, and yield traits of cotton culture - TCH 1819 before its release (now released in the name of CO 17) by different chemical treatments. Observation on the leaf gas exchange traits, leaf parenchymal cells distinguished the source sink relationship of the culture. Chemical manipulation by growth retardants reduced the gibberellins content and modified the foliage structure. By characterizing the physiological potential through manipulation by growth retardant (Mepiquat chloride (0.015 %)) increased the yield by 30%. The traits identified in this study are potential indicators in breeding programme before releasing the variety. [ABSTRACT FROM AUTHOR]

Soybeans are the main sources of oil and protein for most of the global population. As the population grows, so does the demand for soybeans. However, drought is a major factor that limits soybean production. Regulating soybean response to drought stress using mepiquat chloride (MC) is a feasible method; however, its mechanism is still unclear. This study used PEG-6000 to simulate drought stress and quantitative proteomic techniques to reveal changes in Heinong44 (HN44) and Heinong65 (HN65) subjected to drought following the application of 100 mg/L of MC. The results showed that SOD in HN44 did not change significantly but decreased by 22.61% in HN65 after MC pretreatment, and MDA content decreased by 22.75% and 21.54% in HN44 and HN65, respectively. Furthermore, MC improved the GSH–ASA cycle and simultaneously promoted the Calvin cycle process to enable the plant to maintain a certain carbon assimilation rate under osmotic stress. In addition, MC upregulated some proteins during gluconeogenesis and starch metabolism and increased soluble sugar content by 8.41% in HN44. MC also reduced ribosomal protein abundance, affecting translation and amino acid metabolism. In summary, MC improved GSH–ASA cycle and Calvin cycle under stress to alleviate oxidative damage and maintain crop growth. Our study is the first to report the mechanism of MC regulation in soybean under osmotic stress, providing new insights for the rational application of MC in soybean.

Abstract Background Mepiquat chloride (DPC) is a chemical that is extensively used to control internode growth and create compact canopies in cultured plants. Previous studies have suggested that DPC could also inhibit gibberellin biosynthesis in sugarcane. Unfortunately, the molecular mechanism underlying the suppressive effects of DPC on plant growth is still largely unknown. Results In the present study, we first obtained high-quality long transcripts from the internodes of sugarcane using the PacBio Sequel System. A total of 72,671 isoforms, with N50 at 3073, were generated. These long isoforms were used as a reference for the subsequent RNA-seq. Afterwards, short reads generated from the Illumina HiSeq 4000 platform were used to compare the differentially expressed genes in both the DPC and the control groups. Transcriptome profiling showed that most significant gene changes occurred after six days post DPC treatment. These genes were related to plant hormone signal transduction and biosynthesis of several metabolites, indicating that DPC affected multiple pathways, in addition to suppressing gibberellin biosynthesis. The network of DPC on the key stage was illustrated by weighted gene co-expression network analysis (WGCNA). Among the 36 constructed modules, the top positive correlated module, at the stage of six days post spraying DPC, was sienna3. Notably, Stf0 sulfotransferase, cyclin-like F-box, and HOX12 were the hub genes in sienna3 that had high correlation with other genes in this module. Furthermore, the qPCR validated the high accuracy of the RNA-seq results. Conclusion Taken together, we have demonstrated the key role of these genes in DPC-induced growth inhibition in sugarcane.

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mepiquat chloride (PIX) is an important management tool to reduce stress damage in cotton plants during germination. In this study, the effects of different drought levels and the amount of mepiquat chloride (PIX) were investigated on growth indices and antioxidant enzymes as well as the malondialdehyde and hydrogen peroxide contents of seedlings in two cotton cultivars under laboratory conditions. The study was laid in a completely randomized design using 0, 5, and 10 g/l Pix and also under different drought levels using 0, -4, and -8 bar polyethylene glycol 6000 in petri dishes on two cultivars of cotton plant, namely Sahel (drought sensitive) and Shayan (drought resistant). Germination indices as well as physiological parameters of seedlings were measured under drought and Pix treatment after 4 days. Results showed that the use of Pix increased the germination percentage, root length, dry and fresh weights of seedlings, and the activity of peroxidase and catalase enzymes of cotton cultivars under drought stress while drought stress alone reduced these parameters. Drought also increased oxidative indices such as malondialdehyde and hydrogen peroxide in seedlings of Sahel and Shayan cultivars while Pix application reduced these indices. In general, the results of this study showed that the use of Pix improved growth responses and antioxidant system of the two cotton cultivars and the response of cultivar Shayan was better than Sahel.

The cotton direct seeding after wheat (rape) harvested is under trial and would be the future direction at the Yangtze River Valley region of China. The objective of this study was to quantify the effects of branch and stem architecture on cotton yield and identify the optimal cotton architecture to compensate the yield loss due to the reduction of individual production capacity under high planting density in the direst seeding after wheat harvested cropping system. The characteristics of the stem and branch architecture and the relationships between architecture of the stem and branch with yield formation were studied on eight short season cotton cultivars during 2015 and 2016 cotton growth seasons. Based on the two years results, three cultivars with different architectures of stem and branch were selected to investigate the effect of mepiquat chloride (MC) application on the architecture of the stem and branch, boll retention, and the yield in 2017. Significant differences were observed on plant height, all fruiting nodes to branches ratio (NBR) in the cotton plant, and the curvature of the fruiting branch (CFB) among the studied cultivars. There were three types of stem and fruiting branch structures: Zhong425 with stable and suitable plant height and NBR (about 90 cm and 2.5, respectively), high CFB (more than 10.0), and high boll retention speed and seed cotton yield; Siyang 822 with excessive plant height and NBR, low CFB, and low boll retention speed and seed cotton yield; and other studied cultivars with unstable structure of stem and branch, boll retention speed, and seed cotton yield across years. And MC application could promote the appropriate plant height and NBR and high CFB and thus resulted in high boll retention speed and the yield. The results suggested that the suitable plant height and NBR (about 90 cm and 2.5 respectively), and high CFB (more than 10.0), which was related to both genotype and cultural practice, could promote the higher boll retention speed and seed cotton yield.

Abstract Plant growth regulators and improved planting density are the innovative techniques in the establishment of more productive cotton crop. A field study was planned to assess the role of growth regulators in the resource utilization efficiency of cotton cultivars under different row spacing at Agronomic Research Area, Bahauddin Zakariya University Multan and Usmania Agricultural Farm, Shujaabad during Kharif 2012. The study was comprised of cotton cultivars viz. CIM-573 and CIM-598, cultivated under conventional (75 cm), medium (50 cm) and improved ultra-narrow row spacing (25 cm) and foliar spray of growth regulators viz. moringa leaf extract (MLE) and mepiquat chloride (MC), either alone or in combination, distilled water as a control. The application of MLE alone and in combination (MLE + MC) showed the promoting effect on crop growth rate, net assimilation rate, leaf area index, leaf area duration, sympodial branches and number of bolls leading to higher seed cotton yield of both cotton cultivars grown under conventional row spacing. While application of MC averts the plant growth without considerably improving the productivity. MLE being rich source of growth promoting hormone and nutrients showed its potential to a far greater extent under conventional row spacing in efficient utilization of available resources compared to MC and distilled water.

The balance between vegetative and reproductive growth is the central objective in the cotton production system, which is associated with cotton maturity and yield. In China, manual topping (MT) has been performed many years prior to or during the flowering period to inhibit vegetative growth and enhance reproductive growth. MT is gradually being replaced by chemical topping (CT) with mepiquat chloride (MC, 180 g ha−1, 98% soluble powder) due to labor shortages and increasing labor cost. To determine whether CT influences cotton maturity and yield relative to MT, we carried out field experiments at four locations in the Yellow River Valley of China during 2018–2020. The results showed that CT did not alter the boll age, and although it produced taller and slender spatial boll distribution under several environments, it had little effect on the accumulation of boll fraction (the number of bolls in a given period divided by total boll number) over time at the end of blooming across locations. As a result, there were no significant differences between MT and CT in boll opening percentage in the late season. CT did not influence yield or yield components, except under severe drought. Therefore, CT with MC (180 g/ha, 98% soluble powder) during the flowering period will not compromise the maturity or yield of cotton in the Yellow River Valley of China. Similar outcomes would be achieved in other areas with similar ecological conditions and social conditions that require an alternative to extensive manual labor.

Abstract A field study was carried out to determine the influence of foliage applied plant growth promoter and retardant in improving soil applied sulphur fertilizer use efficiency in cotton during two consecutive summers 2014 and 2015. Experimental trial comprised of three different sources of sulphur (ammonium sulphate, potassium sulphate and elemental sulphur) and foliar spray of plant growth promoter and growth retardant including tap water was taken as control. Among treatments soil applied ammonium sulphate with foliage applied amino acid produced maximum plant height, sympodial branches, pods per plant, seed cotton yield, fiber yield, biological yield, protein contents, oil contents and leaf nitrogen uptake as compared to the other treatments. Whereas, soil applied potassium sulphate with foliar spray of mepiquat chloride on cotton significantly improved the boll weight and leaf potassium uptake. We conclude that soil applied ammonium sulphate and foliage spray of amino acid was more effective in improving the productivity and quality attributes of cotton.

Potassium deficiency causes severe losses in yield and quality in crops. Mepiquat chloride, a plant growth regulator, can increase K+ uptake in cotton (Gossypium hirsutum), but the underlying physiological mechanisms remain unclear. In this study, we used a non-invasive micro-test technique to measure K+ and H+ fluxes in the root apex with or without inhibitors of K+ channels, K+ transporters, non-selective cation channels, and plasma membrane H+-ATPases. We found that soaking seeds in mepiquat chloride solution increased the K+ influx mediated by K+ channels and reduced the K+ efflux mediated by non-selective cation channels in cotton seedlings. Mepiquat chloride also increased negative membrane potential (E m) and the activity of plasma membrane H+-ATPases in roots, due to higher levels of gene expression and protein accumulation of plasma membrane H+-ATPases as well as phosphorylation of H+-ATPase 11 (GhAHA11). Thus, plasma membrane hyperpolarization mediated by H+-ATPases was able to stimulate the activity of K+ channels in roots treated with mepiquat chloride. In addition, reduced K+ efflux under mepiquat chloride treatment was associated with reduced accumulation of H2O2 in roots. Our results provide important insights into the mechanisms of mepiquat chloride-induced K+ uptake in cotton and hence have the potential to help in improving K nutrition for enhancing cotton production. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Background Cottonseed oil and protein content as well as germination traits are major indicators of seed quality. However, the responses of these indicators to plant density and mepiquat chloride (MC) are still uncertain. To investigate plant density and MC effects on cottonseed yield and main quality parameters, we conducted a two-year field experiment including four plant densities (1.35, 2.55, 3.75 and 4.95 plants·m− 2) and two doses of MC (0 and 135 g·hm− 2) in Dafeng, Jiangsu Province, in 2013 and 2014. Results The application of MC reduced plant height, fruit branch length and fruiting branch number under different plant densities, resulting in a lower and more compact plant canopy. Cottonseed yield showed a nonlinear increase as plant density increasing and achieved the highest value at 3.75 plants·m− 2, regardless of MC application. No significant interactions were found between plant density and MC for cottonseed yield and quality parameters. The 100-seed weight, cottonseed oil content and vigor index significantly decreased as plant density increased, while these parameters significantly increased with MC applying under different plant densities. Seed vigor index was positively correlated with 100-seed weight and seed oil content across different plant densities and MC treatments. Conclusions Thus, application of MC could realize a win-win situation between cottonseed yield and main quality parameters under various densities; and plant density of 3.75 plants·m− 2 combined with 135 g·hm− 2 of MC applying is optimal for high cottonseed yield and quality in this cotton production area.

In this study, Two field experiments were conducted in Ourabi operation Farm, Cairo-Ismaellia desert road at Kalubia Governorate. The experiment was carried out during the two seasons of 2013/2014 and 2015/2016, to investigate the effect of plant growth regulator (Mepiquat chloride) with three different potassium fertilizers sources [chemical potassium (KC), foliar potassium (KF) and rock potassium (KR)] on growth development and total yield in potato plants (Solanum tuberosum L. cv. Spunta) . Chemical potassium (control) with / without Mepiquat chloride achieved better plant height, no. of stem and leaf area/plant. Rock potassium with mepiquat chloride obtained the highest productivity of fresh and dry weights, total tuber yield and yield components (weight of tubers, size of tubers, diameter of tubers and number of tubers) following by foliar potassium with mepiquat chloride compared with control treatment.