Mepiquat Chloride Application Research Articles

Estado nutricional e produtividade de algodoeiro em função de diferentes espaçamentos e aplicação de regulador de crescimento

Strategies of cotton growth as row spacing and use of growth regulator are efficient when the knowledge of crop production potential as well as the amounts of nutrients content. The objective of this study was to evaluate the nutritional status of cotton DeltaOpal cultivar through leaf analysis of macronutrient, chlorophyll index and yield in relation to plant arrangement and managements of the growth regulator. The treatments consisted of plant arrangement: arrangement 1: 88,900 plant ha-1 and row spacing at 0.9m, arrangement 2: 114,300 plant ha-1 and row spacing at 0.7m, arrangement 3: 178,000 plant ha-1 and row spacing at 0.45m; management of growth regulator (mepiquat chloride) at 1.0 L ha-1 dose, concentration was50g L-1: a- no regulator application; b- single application at 70 days after emergency (d.a.e.); c- split application into four stages (35, 45, 55, and 65 d.a.e.). The reading reviews SPAD chlorophyll, leaf analysis of macronutrients and cotton yield were conducted in three agricultural years 2006/07, 2007/08 and 2008/09, under the experimental design of completely randomized blocks, in a 3x3 factorial scheme totaling up nine treatments with four replications. The reduction of row spacing and increasing plant density gives less absorption of potassium and sulfur by cotton crop. A single application of mepiquat chloride increase calcium leaf content. The split application of mepiquat chloride provides increased SPAD reading index, higher foliar magnesium concentration and highest seed cotton yield.

The effect of mepiquat chloride on elongation of cotton (Gossypium hirsutum L.) internode is associated with low concentration of gibberellic acid

The growth regulator mepiquat chloride (MC) is globally used in cotton (Gossypium hirsutum L.) canopy manipulation to avoid excess growth and yield loss. However, little information is available as to whether the modification of plant architecture by MC is related to alterations in gibberellic acid (GA) metabolism and signaling. Here, the role of GA metabolism and signaling was investigated in cotton seedlings treated with MC. The MC significantly decreased endogenous GA3 and GA4 levels in the elongating internode, which inhibited cell elongation by downregulating GhEXP and GhXTH2, and then reducing plant height. Biosynthetic and metabolic genes of GA were markedly suppressed within 2–10d of MC treatment, which also downregulated the expression of DELLA-like genes. A remarkable feedback regulation was observed at the early stage of MC treatment when GA biosynthetic and metabolic genes expression was evidently upregulated. Mepiquat chloride action was controlled by temporal translocation and spatial accumulation which regulated GA biosynthesis and signal expression for maintaining GA homeostasis. The results suggested that MC application could reduce endogenous GA levels in cotton through controlled GA biosynthetic and metabolic genes expression, which might inhibit cell elongation, thereby shortening the internode and reducing plant height.

SUNFLOWER MORPHOLOGY AND YIELD AS AFFECTED BY FOLIAR APPLICATIONS OF PLANT GROWTH REGULATORS

Plant height of sunflower is a major agronomic trait affecting crop performance in the field and its adaptation to mechanical harvest. Field experiments were conducted to study the effect of foliar application of paclobutrazol (PBZ) at 12.5 g ai/ha, mepiquat chloride (MPC) at 25.0 g ai/ha and chlormequat chloride (CCC) at 1,500 g ai/ha in single or double applications on sunflower plant morphology, growth and achene yield and oil content. Single applications of PBZ or MPC reduced sunflower plant height at maturity by 11.1% and 11.7%, respectively. Single applications of PBZ, MPC or CCC did not reduce the above ground dry weight of the plants, provided similar achene yield per plant and 100-achenes weight compared with those of the non-treated control, whereas increased the total number of achenes as well as the number of filled achenes per capitulum. Double applications of PBZ, MPC or CCC reduced plant height by 13.9%, 15.6% and 13.4%, respectively, but proved in certain cases to have a phytotoxic effect on achene and oil production. Double application of PBZ resulted in lower achene and oil yield than the non-treated control, whereas double application of MPC resulted in lower above ground dry weight at maturity, achene yield and 100-achenes weight. Double application of CCC resulted in reduced 100-achenes weight. Overall, PBZ and MPC under the single dose scheme applied can reduce plant height in sunflower without adverse effects on achene and oil yields, thus providing a basis for reducing the risk of plant lodging.

Modelling the structural response of cotton plants to mepiquat chloride and population density.

Cotton (Gossypium hirsutum) has indeterminate growth. The growth regulator mepiquat chloride (MC) is used worldwide to restrict vegetative growth and promote boll formation and yield. The effects of MC are modulated by complex interactions with growing conditions (nutrients, weather) and plant population density, and as a result the effects on plant form are not fully understood and are difficult to predict. The use of MC is thus hard to optimize. To explore crop responses to plant density and MC, a functional-structural plant model (FSPM) for cotton (named CottonXL) was designed. The model was calibrated using 1 year's field data, and validated by using two additional years of detailed experimental data on the effects of MC and plant density in stands of pure cotton and in intercrops of cotton with wheat. CottonXL simulates development of leaf and fruits (square, flower and boll), plant height and branching. Crop development is driven by thermal time, population density, MC application, and topping of the main stem and branches. Validation of the model showed good correspondence between simulated and observed values for leaf area index with an overall root-mean-square error of 0·50 m(2) m(-2), and with an overall prediction error of less than 10% for number of bolls, plant height, number of fruit branches and number of phytomers. Canopy structure became more compact with the decrease of leaf area index and internode length due to the application of MC. Moreover, MC did not have a substantial effect on boll density but increased lint yield at higher densities. The model satisfactorily represents the effects of agronomic measures on cotton plant structure. It can be used to identify optimal agronomic management of cotton to achieve optimal plant structure for maximum yield under varying environmental conditions.

Crop growth, light utilization and yield of relay intercropped cotton as affected by plant density and a plant growth regulator

Modern cotton cultivation requires high plant densities and compact plants. Here we study planting density and growth regulator effects on plant structure and production of cotton when the cotton is grown in a relay intercrop with wheat, a cultivation system that is widespread in China. Field experiments were carried out in 2010, 2011 and 2012 in Anyang, Henan province, China. Plant densities (PD) were 3.0, 4.5, 6.0 and 7.5plantsm−2, and growth regulator mepiquat chloride (MC) was applied in four different schedules. Plant density significantly affected cotton biomass, but MC did not. Aboveground biomass was linearly associated with plant density. Increasing plant density significantly increased crop light use efficiency, especially during the reproductive phase. This effect was attributed to a better light distribution in the canopy, resulting in higher crop photosynthesis. MC increased the partitioning to leaves, expressed as leaf/shoot ratio. Plant height and length of fruit branches were significantly reduced by MC, resulting in a more compact canopy. Maximum leaf area index was slightly lowered at higher MC dose, but MC did not significantly affect light interception. Plant density and MC showed a significant interaction effect on crop height, but not on leaf growth, biomass or lint yield. At high plant densities, 3–4 consecutive applications of MC improved plant architecture, resulting in a higher LUE and yield. Lint yields were about 10% higher with MC applied at a high cumulative dose with high plant densities compared to MC free control.

Managing mepiquat chloride and plant density for optimal yield and quality of cotton

The growth regulator mepiquat chloride (MC) is used in cotton production across the globe to control plant growth and maximize yield and quality of cotton. With the conversion from hand picking to mechanical harvesting in China, plant densities are increased, and more compact plants are required, leading to the need to reconsider MC application schedules. Experiments were carried out in 2009 and 2010 to identify optimal use schedules of MC at four plant densities: 3.0, 4.5, 6.0 and 7.5plantsm−2. Eleven MC schedules were compared with respect to their effect on cotton yield and quality. Application of MC at squaring stage or at both squaring and flowering stages significantly improved cotton quality parameters: fiber length (by 1.7%) and fiber strength (by 2.8%) at all tested plant densities without significant loss of yields. However, average lint yield of all MC treatments over all densities and years was decreased by 4.6% due to a decrease in boll density and lint percentage which was only partly offset by an increase in boll weight. No effects on yield were also observed if MC applications were started at flowering stage, but such later starting application schedules only slightly improved fiber quality. The results suggest that use of MC at squaring or at both squaring and flowering stages is a viable strategy to improve cotton architecture, productivity and quality at high plant density in mechanized cotton production in the Yellow River cotton growing region in China.

Cotton root and shoot growth as affected by application of mepiquat chloride to cotton seeds

The effects of mepiquat chloride (MC) application to cotton seeds on the initial growth of the plant roots and shoots were studied in a greenhouse experiment. Glass-front containers with 27 L of soil were used in the experiment. Cotton seeds of the cultivar FM 993 were sprayed with MC at five different doses of active ingredient (a.i.): 0, 3, 6, 9 and 12 g kg -1 seed. The shoot and root dry matter, leaf area, shoot:root ratio, leaf area: root growth ratio, and shoot length were evaluated 21 days after sowing. The root growth was evaluated every three days up to 18 days. The application of MC to cotton seeds decreased the shoot length but had no significant effect on the dry matter production, root length, shoot:root ratio or leaf area: root length ratio. Thus, the application of MC to cotton seeds is not expected to have a deleterious effect on plant water acquisition.

Alteration of cotton source–sink relations with plant population density and mepiquat chloride

Improvements in carbohydrate source–sink relations are needed to improve efficiency of yield formation in cotton ( Gossypium hirsutum L.). Most source–sink research has focused on leaf–boll relationships, with little study of vegetative storage reserves. Possible ways of altering the source–sink balance include increasing the plant population density (PPD) and using a plant growth regulator, mepiquat chloride (MC). We evaluated effects of PPD and MC on plant growth and development, stem starch reserves and lint yield in a 3-year field experiment at Milan, Tennessee. Row spacings of 25, 51, and 102 cm averaged 17.6, 13.2, and 8.3 plants m −2, respectively. Mepiquat chloride rates were 0 and 86 g ha −1. Higher PPD in narrower rows tended to reduce boll number more than leaf area per plant, reducing the number of bolls per unit leaf area. However, boll distribution was more concentrated, implying more synchronous demand for photosynthate in 25-cm rows than in wider rows. Stem starch concentrations during boll filling were similar to, or slightly lower, in 25-cm rows than in wider rows. Findings are consistent with the hypothesis that availability of photosynthate may limit boll load at higher PPD, despite more leaf area per boll. Application of MC tended to reduce leaf area per plant more than boll load, and to increase the number of bolls per unit leaf area. The MC treatment also concentrated the boll set on lower sympodia, increasing the synchrony of boll maturation and demand for photosynthate. Application of MC increased boll set percentage and decreased stem starch reserves slightly. Lint yields were increased by MC application in finger-stripped 25- and 51-cm rows in 2 of 3 years, by an average of 11%, but not in spindle-picked 51- and 102-cm rows. Findings support the hypothesis that MC benefits boll set and yield formation in narrow-row systems by reducing LAI. Source–sink alteration with PPD and MC may be useful in future research to improve carbohydrate use and yield formation in cotton.

Direct and residual effects of nitrogen fertilization, foliar application of potassium and plant growth retardant on Egyptian cotton growth, seed yield, seed viability and seedling vigor

In order to obtain high productivity for a cotton crop, one of the major requirements is to establish an adequate plant population. The use of good-quality seed may ultimately be the best approach to attain this goal problem. The objective of this research was to study the effect of N-fertilization (at rates of 95.2 and 142.8 kg of N ha −1), foliar application of K (at rates of 0, 0.38, 0.77, 1.15 kg of K 2O ha −1, applied twice during square initiation and boll development stages) and the plant growth retardant (PGR), mepiquat chloride (applied twice, 75 days after planting at 0.0 [control] and 0.048 kg a.i. ha −1, and 90 days after planting at 0.0 [control] and 0.024 kg a.i. ha −1), on seed yield, viability, and seedling vigor of Egyptian cotton ( Gossypium barbadense cv. Giza 86). A field experiment was conducted at the Agricultural Research Center, Giza, Egypt in two growing seasons. Growth, mineral uptake, seed yield per plant and per ha, seed weight, seed viability, seedling vigor and cool germination test performance were all found to increase significantly due to the addition of the high N-rate, the foliar application of three potassium concentrations, and the PGR mepiquat chloride. The N and K rates as well as application of mepiquat chloride had no significant effect on the germination rate index in both seasons. Under the conditions of this study, applying N at a rate of 142.8 kg ha −1 combined with spraying cotton plants with K 2O at 1.15 kg ha −1 and with mepiquat chloride at 0.048 + 0.024 kg ha −1 were found to improve seed yield as well as seed viability and seedling vigor in the next season.

Análise de crescimento em plantas de soja tratadas com substâncias reguladoras

Growth analysis of soybean plants treated with plant growth regulators. This work aimed to verify the effect of plant growth regulators on soybean plant growth and chlorophyll content. In an experiment carriedout in a greenhouse, soybean plants were cultivated (Glycine max (L.) Merrill cv. BRS-184) in 10-liter pots containing soil from the arable layer, corrected and fertilized according to the soil analysis. The treatments used were: control; GA3 100mg.L-1; BAP 100mg.L-1; IBA 100mg.L-1; Stimulate® (IBA, GA3 and kinetin) 20mL.L-1; mepiquat chloride 100mg.L-1 and mepiquat chloride 100mg.L-1 + BAP 100mg.L-1 + IBA 100mg.L-1. Treatments were applied three times at 30-day intervals. Six samplings were taken at 13-day intervals. The results indicated that the highest total dry weight value resulted from the application of IBA and Stimulate®, and that the applicationof mepiquat chloride in association with IBA and BAP reduced total dry matter production. The leaf area was smaller than the control in most treatments. The chlorophyll content and growth rate were slightly infl uenced by the treatments. The cytokinin treatment alone or in association with other plant growth regulators retained the chlorophyll content. RGR and NAR decreased from 99 days after sowing with the application of mepiquat chloride.

Nitrogen, potassium and plant growth retardant effects on oil content and quality of cotton seed

The aim of this field experiment was to investigate the effect of nitrogen, potassium and a plant growth retardant (PGR) on seed yield and protein and oil content of an Egyptian cotton cultivar ( Gossypium barbadense Giza 86). Treatments consisted of: soil application of N (95 and 143 kg N ha -1 in the form ammonium nitrate), foliar application of potassium (0, 319, 638 or 957 g K ha -1 as potassium sulfate) and foliar application of mepiquat chloride (MC) (0 and 48 + 24 g active ingredient ha -1 ) on seed, protein and oil yields and oil properties of Egyptian cotton cultivar “Giza 86” ( Gossypium barbadense ). After applying the higher N-rate, foliar application of potassium and plant growth retardant MC significantly increased seed yield and the content of seed protein and oil, seed oil refractive index, unsaponifiable matter and total unsaturated fatty acids (oleic and linoleic). In contrast, oil acid and saponification value as well as total saturated fatty acids were decreased by foliar application of potassium and MC. The seed oil content was decreased with soil application of N.

Elaboration and test of a decision rule for the application of mepiquat chloride on cotton in Mali

Farmers often make complex management decisions during a cropping cycle. To design new cropping systems that go beyond standard setups and are better adapted to local constraints, agronomists must formalize these farmer's decisions into decision rules that can be tested and disseminated. In Mali, there has been a marked decrease in cotton productivity over the last 10 years, whereas the area planted with cotton has doubled. However, cropping recommendations remain almost the same throughout the country. Cotton researchers have been asked to put forward new technical proposals suited to a wider range of socio-economic and biophysical cropping conditions. The aim of this study was to develop a methodology to build a decision rule (DR) to help Malian farmers in making decisions on the use of growth regulators in cotton fields. In the first phase, a 2-year experiment was conducted in two experimental stations, under a wide range of cotton vegetative growth conditions, along with different stand densities and fertilization rates. Mepiquat chloride (MC) was applied to half of the plots, and its effects were then computed against selected vegetative growth indicators measured before the date of MC application. A DR was proposed on this basis. In the second phase, the DR was tested in a six-village experiment. MC was applied in plots on 15 farms in each village and its effects on yield were recorded. The results showed that is possible to build a DR for MC application based on LAI or aerial biomass indicators. The usual indicators, such as the five-node length technique, were not found to be useful. The response of cotton plots to MC for a given level of vegetative growth remained scattered, as other factors probably interfered, such as the length of the rainy season. Testing the DR in farmers’ fields showed that it was useful in determining appropriate MC applications. The usefulness of the DR is discussed on the basis of its accuracy and on the complexity of the selected indicator.

Influence of Plant Density on Cotton Response to Mepiquat Chloride Application

Increased yield potential associated with full‐season cotton (Gossypium hirsutum L.) varieties can be offset by excessive vegetative growth that leads to undesirable fruit shed and boll rot. Producers often make multiple mepiquat chloride (1,1‐dimethyl‐piperidinium chloride) applications with excessive seasonal use rates to combat this problem, often with inconsistent results. Field studies were conducted in 2004 and 2005 to evaluate reduced plant populations as a potential management tool to be used in conjunction with mepiquat chloride application strategies for managing plant height. Plant populations of 152883, 101929, and 50958 plants ha−1 received a single application at 12 nodes (15.2 g a.i. ha−1) or early bloom (45.8 g a.i. ha−1), sequential applications at 12 nodes (15.2 g a.i. ha−1) and early bloom (30.6 g a.i. ha−1), or the modified early bloom schedule (a plant growth regulator application decision aid that recommends rates and timing based on plant growth parameters). Mepiquat chloride application reduced final plant height at least 15 cm compared with the nontreated in both years but also reduced the number of main stem nodes in 2005. In 2005, lint yield was inversely related to plant population, and a significant yield response occurred with the modified early bloom mepiquat chloride application strategy. Mepiquat chloride application increased lint yield in 1 of 2 yr but was useful for reducing plant height regardless of population. Reducing plant population had no adverse effects on lint yield or fiber properties and may be valuable in achieving a desired plant stature with less intensive plant growth regulator management.

Effect of Prohexidione-Ca and Mepiquat Chloride on Stolon Production and Yield of Florida Grown Strawberry (Fragaria × ananassaDuch)

Abstract Removal of stolons from strawberry plants in Florida's annual winter production system incurs significant costs to growers. Mepiquat chloride (Ponnax®) and prohexidione-calcium (Apogee®) were evaluated for the ability to reduce stolon production of strawberries grown under annual production techniques. Two rates of mepiquat chloride (170.6 and 273.5 g ai/ha) and two rates of prohexidione-calcium (113.8 and 227.6 g ai/ha) were applied three times at two week intervals beginning 4 weeks after establishment. Significant control of stolon production was achieved with both rates of prohexidione-calcium compared to mepiquat chloride and untreated controls. However, significant reductions in yields were associated with prohexidione-calcium. Application of mepiquat chloride at 273.5 g ai/ha increased fruit yield during the month of January above all other treatments.

Performance of hybrid rice cultures under different levels of nitrogen in combination with growth regulators

Field experiments were carried out during the North East Monsoon season of 1995-96 and 1996-97 with the objectives of studying the performance of newly developed rice hybrid in response to nutrient management practices and growth regulators. Rice hybrid TNRH-17 showed a good response to 175 kg N ha-1 applied in four splits along with K2O2 in both the years and gave significantly higher grain yield of 8.17 t ha-1 with foliar application of mepiquat chloride @ 1500 ml ha-1 at flowering stage. The highest returns and benefit cost ratio were recorded in the same treatment combination, compared to the other treatments.

Drymatter production and nutrient uptake as influenced by mepiquatchloride in potato

Field experiments were conducted during 1997-98 at wood house farm, Udhagamandalam to study the effect of mepiquatchloride (MC) at different concentration from 50 to 250 gai ha compared along with pesticides, water spray and control. Plant samples were collected at 60 and 90 DAS and at harvest and analyzed for N, P and K contents. The results indicated that, foliar application of MC at 45 DAS recorded increased Total dry matter production (TDMP), nutrient content and uptake in the treatment of MC at 62.5 g ai ha-1 alone or in combination with endosulfan and mancozeb.

Flowering and Yield Response of Cotton to Application of Mepiquat Chloride and PGR‐IV

Few studies have documented the effects of mepiquat chloride (MC) (1,1‐dimethyl piperidinium chloride) and PGR‐IV [0.001% (w/v) indolebutyric acid (IBA), 0.001% gibberellic acid (GA)] on flowering. This study was conducted in an effort to better understand the effects of these two plant growth regulators (PGRs) on cotton (Gossypium hirsutum L.) flowering when applied alone or used in sequential applications. Field experiments conducted in 1996 and 1997 at the Texas A&M University Agricultural Experiment Station near College Station, TX, contained the following treatments: an untreated control, MC, PGR‐IV, and a combination of both MC and PGR‐IV applied sequentially (PGR‐IV + MC). The MC and PGR‐IV + MC treatments caused plants to have a season‐long average of 0.55 and 0.48 more flowers m−1 of row d−1, respectively, than the untreated plants. All PGR treatments resulted in a higher rate of flowering than untreated plants between the 16th and 20th d of flowering. The MC treated plants also had 19.1 more total flowers per meter than PGR‐IV treated plants by the 40th d of flowering. Treatment effect on flower survival was different only for flowers that bloomed between the 36th and 40th d of flowering. At this time, the PGR‐IV + MC treated plants had a greater flower survival than plants treated with only PGR‐IV. All PGR treatments resulted in increased yields and boll numbers. These studies indicate that the application of MC and PGR‐IV, either in sequential applications or alone, increases both the rate of flowering and the number of flowers per meter of row, but does not impact the ability of flowers to survive to maturity.

I Effect of Mepiquat chloride and boron on irrigated cotton (Gossypium hirsutum) in Turkey

A field study was conducted from 2003 to 2004 to evaluate effects of foliar application of Mepiquat chloride and boron on growth and yield of upland cotton (Gossypium hirsutum L.). Mepiquat chloride @ 0.15 litrelha sig- nificantly reduced plant height, number of main stem nodes and nodes to first fruiting branch compared to the control. Plants treated with Mepiquat chloride at first flowering and 2 weeks after first flower stage and boron 8 0.15 litrelha at first flowering and and 4 weeks after first flowering resulted in significantly highest number of open bolls and seed-cotton yield. All foliar B applications applied either at 2 weeks and 4 weeks after first flower resulted in similar but higher yields than the control. Neither Mepiquat chloride nor B affected gin turnout. I Key words : Boll weight, Boron, Cotton, Plant height, Main stem nodes, Yield

Response of cotton (Gossypium hirsutum) to mepiquat chloride and topping under varying levels of nitrogen

A field experiment was conducted during the rainy (kharit) seasons of 1999 and 2000 at New Delhi to examine the response of cotton (Gossypium hirsutum L.) to nitrogen, mepiquat chloride and topping. Application of N significantly increased plant height, bollslplant, boll weight, seed cotton yieldlplant and seed cotton and lint yieldlha. Mean increase in seed cotton yield with the appli cation of N at 45 and 90 kglha was 19 and 31 % over the control respectively. Higher levels of N application delayed the maturity of cotton. Application of mepiquat chloride significantly reduced the plant height by 26%, but increased the yield and yield attributes. Topping had no significa t influence on yield and yield attributes.

Pix Plus and Mepiquat Chloride Effects on Physiology, Growth, and Yield of Field-Grown Cotton

An important objective for using plant growth regulators in cotton (Gossypium hirsutum L.) is to balance vegetative and reproductive growth as well as to improve lint yield and fiber quality. Field studies were conducted at two locations (Clarkedale and Fayetteville) in Arkansas in 1997 and 1998 to determine physiologic and yield responses of cotton to foliar applications of mepiquat chloride [N,N-dimethyl-piperidinium chloride and inert ingredients] (MC) and Pix Plus [MC + Bacillus cereus]. Compared with the untreated control, application of Pix Plus and MC efficiently reduced plant height, improved leaf CO 2 -exchange rate, and increased leaf starch content. Neither Pix Plus nor MC affected photoassimilate translocation from leaves to 10- to 15-day-old bolls. Pix Plus and MC had very similar effects on plant growth and most physiologic parameters investigated in our studies. There was no difference in lint yield between Pix Plus and mepiquat chloride. However, Pix Plus increased the fraction of fruit dry matter in total dry matter.