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The present investigation was undertaken to test the influence of a wide range of growth retardants (Paclobutrazol, Flurprimidol, Triapenthenol, Chlorphonium chloride, Uniconazol, Ancymidol, Tetcyclacis, Mepiquat chloride, Chlormequat chloride, Daminozide, BTS 44584) on wilting of plantlets of Dendranthema grandiflora Pennine Reel.

The bioregulator, mepiquat chloride (1,1-dimethylpiperidium chloride), consistently rank growth of cotton (Gossypium hirsutum L.), but yield responses are erratic. The objective of this study was to determine cotton plant response to mepiquat chloride (MC) at different temperatures, so that appropriate functions can be provided to the cotton crop simulation model

A simple, fast and precise High Performance Liquid Chromatographic method with diode array detector was developed and single laboratory validated for the determination of mepiquat chloride in soluble concentrate pesticide formulations. From the results obtained, the repeatability of the method expressed as relative standard deviation (%RSD) was found to be 0.3%, and the limit of detection was 0.02 microg/mL. The accuracy of the whole procedure estimated by the comparison of the results obtained with the reference values, and was found to be acceptable as t(cal) < t(crit). The precision of the method also considered acceptable as the experimental repeatability relative standard deviation (RSD(r)) was lower than the interlaboratory relative standard deviation (RSD(R)), calculated by the Horwitz equation.

Made available in DSpace on 2021-07-14T10:51:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-09. Added 1 bitstream(s) on 2021-07-14T11:39:37Z : No. of bitstreams: 1 S1807-86212008000300011.pdf: 124296 bytes, checksum: f02734a266633760a5f5e8ce659cb282 (MD5) Atualmente, o cultivo do algodoeiro está alicerçado em um modelo de produção em escala, caracterizado por altas produtividades e intenso uso de insumos e mecanização. Objetivou-se, com este trabalho, avaliar a influência de diferentes espaçamentos de cultivo, submetidos ou não à aplicação de regulador de crescimento, no desenvolvimento e na produtividade do algodoeiro. O delineamento experimental foi de blocos casualizados, em esquema fatorial 3x3, com nove tratamentos e quatro repetições, constituído por três espaçamentos: 0,45, 0,70 e 0,90 m entre linhas; regulador de crescimento: a) aplicação parcelada em quatro etapas; b) aplicação única aos 70 d.a.e.; e c) sem a aplicação do regulador. O projeto foi instalado no município de Selvíria, estado do Mato Grosso do Sul, em novembro de 2005. De posse dos resultados, verificou-se que a aplicação de regulador vegetal é eficiente em termos de limitação do crescimento em altura. A maior produtividade aliada a maior massa de capulhos foram encontradas em aplicação do regulador de forma parcelada em comparação à não-utilização do produto, para a cv. Deltaopal. O número de capulhos e de ramos reprodutivos, por planta, foi maior nos maiores espaçamentos. Currently, the cultivation of the cotton plant is based on a scale production model, characterized by high yields and intensive use of fertilizers, agrochemicals and mechanization. The objective of this study was to evaluate the influence of different row spacings on cotton crops, with or without growth regulator, and their effects in crop development and yield. The experimental design was in completely randomized blocks, in a 3x3 factorial scheme with 4 replications, using three row spacings: 0.45, 0.70 and 0.90 m. Three growth regulator conditions were tested: a) application split into four stages, b) single application at 70 d.a.e, and c) no regulator application. The project was conducted in the city of Selvíria, Mato Grosso do Sul state, in November 2005. It was verified that the application of growth regulator is efficient in the limitation of plant height. The highest yield and boll mass was found in the split application of the regulator. The number of bolls and reproductive branches per plant was higher in the wider row spacings. Universidade Estadual Paulista, Departamento de Fitotecnia, Tecnologia de Alimentos e Socioeconomia Universidade Estadual Paulista, Departamento de Fitotecnia, Tecnologia de Alimentos e Socioeconomia

Currently, the cultivation of the cotton plant is based on a scale production model, characterized by high yields and intensive use of fertilizers, agrochemicals and mechanization. The objective of this study was to evaluate the influence of different row spacings on cotton crops, with or without growth regulator, and their effects in crop development and yield. The experimental design was in completely randomized blocks, in a 3x3 factorial scheme with 4 replications, using three row spacings: 0.45, 0.70 and 0.90 m. Three growth regulator conditions were tested: a) application split into four stages, b) single application at 70 d.a.e, and c) no regulator application. The project was conducted in the city of Selvíria, Mato Grosso do Sul state, in November 2005. It was verified that the application of growth regulator is efficient in the limitation of plant height. The highest yield and boll mass was found in the split application of the regulator. The number of bolls and reproductive branches per plant was higher in the wider row spacings. Atualmente, o cultivo do algodoeiro está alicerçado em um modelo de produção em escala, caracterizado por altas produtividades e intenso uso de insumos e mecanização. Objetivou-se, com este trabalho, avaliar a influência de diferentes espaçamentos de cultivo, submetidos ou não à aplicação de regulador de crescimento, no desenvolvimento e na produtividade do algodoeiro. O delineamento experimental foi de blocos casualizados, em esquema fatorial 3x3, com nove tratamentos e quatro repetições, constituído por três espaçamentos: 0,45, 0,70 e 0,90 m entre linhas; regulador de crescimento: a) aplicação parcelada em quatro etapas; b) aplicação única aos 70 d.a.e.; e c) sem a aplicação do regulador. O projeto foi instalado no município de Selvíria (MS), em novembro de 2005. De posse dos resultados, verificou-se que a aplicação de regulador vegetal é eficiente em termos de limitação do crescimento em altura. A maior produtividade aliada a maior massa de capulhos foram encontradas em aplicação do regulador de forma parcelada em comparação à não-utilização do produto, para a cv Deltaopal. O número de capulhos e de ramos reprodutivos, por planta, foi maior nos maiores espaçamentos.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:51:43Z No. of bitstreams: 1 S0006-87052008000300001.pdf: 126957 bytes, checksum: 0166c10d5dee2601145d4719d1cac66f (MD5) Made available in DSpace on 2013-08-22T18:51:43Z (GMT). No. of bitstreams: 1 S0006-87052008000300001.pdf: 126957 bytes, checksum: 0166c10d5dee2601145d4719d1cac66f (MD5) Previous issue date: 2008-01-01 Made available in DSpace on 2013-09-30T17:44:09Z (GMT). No. of bitstreams: 2 S0006-87052008000300001.pdf: 126957 bytes, checksum: 0166c10d5dee2601145d4719d1cac66f (MD5) S0006-87052008000300001.pdf.txt: 34274 bytes, checksum: 4a5436a6a8453812b76c5d468718e230 (MD5) Previous issue date: 2008-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:19:41Z No. of bitstreams: 2 S0006-87052008000300001.pdf: 126957 bytes, checksum: 0166c10d5dee2601145d4719d1cac66f (MD5) S0006-87052008000300001.pdf.txt: 34274 bytes, checksum: 4a5436a6a8453812b76c5d468718e230 (MD5) Made available in DSpace on 2014-05-20T13:19:41Z (GMT). No. of bitstreams: 2 S0006-87052008000300001.pdf: 126957 bytes, checksum: 0166c10d5dee2601145d4719d1cac66f (MD5) S0006-87052008000300001.pdf.txt: 34274 bytes, checksum: 4a5436a6a8453812b76c5d468718e230 (MD5) Previous issue date: 2008-01-01 Em clima tropical semi-árido, o uso de reguladores vegetais em fruteiras permite o manejo do crescimento vegetativo, tão necessário ao escalonamento da produção e ao aumento da fertilidade das gemas. Estas substâncias influenciam vários fenômenos fisiológicos relacionados com a absorção mineral, como a condutância de membrana e utilização metabólica de íons. O objetivo deste trabalho foi avaliar o crescimento vegetativo, produção de matéria seca dos ramos, concentração e quantidade acumulada de N, P, K, Ca e Mg nos ramos e nos pecíolos e produção de panículas florais em resposta ao uso de reguladores vegetais, em plantas de videira da cultivar Itália. No experimento foram avaliados três ciclos vegetativos e cinco tratamentos (controle, chlormequat - 1500 mg L-1; daminozide - 3000 mg L-1; uniconazole - 30 mg L-1 e cloreto de mepiquat - 300 mg L-1), aplicados nas plantas em pulverizações aos 35 e 70 dias após a poda. Com o chlormequat e o uniconazole ocorreu efeito cumulativo nas plantas, quando aplicados em ciclos sucessivos da cultura, favorecendo o acúmulo de nutrientes e a diferenciação de gemas férteis em comparação com as plantas controle das videiras 'Itália'. Embora o daminozide tenha inibido significativamente o crescimento das plantas, não resultou em maior acúmulo de nutrientes e emissão de panículas florais nas plantas tratadas. In semi-arid tropical climate, the use of plant growth regulators in fruit trees allows the vegetative growth control, so necessary to the assignment of the production and the increase of the fertility of the buds. These substances influence several physiological processes related to the mineral absorption, for example: membrane condutance and metabolic use of ions. The objective of this work was to evaluate vegetative growth, stem dry mater, N, P, K, Ca and Mg content in the stem and petiole and panicle production in response to plant growth regulators in grape Itália. Three vegetative cycles were evaluated and five treatments (control, chlormequat - 1500 mg L-1; daminozide - 3000 mg L-1; uniconazole - 30 mg L-1 and mepiquat chloride - 300 mg L-1). The plants were sprayed at 35 and 70 days after pruning. It was observed an effect of Chlormequat and Uniconazole on nutrient content and fertile buds formation when applied in successive cycles. The Daminozide inhibited plant growth, but it did not alter nutrient content and panicles production. UNESP FCA Departamento de Produção Vegetal/Horticultura Universidade Federal de Pelotas UNESP FCA Departamento de Produção Vegetal/Horticultura

TEZ6759 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2008. Kaynakça (s.41-44) var. viii, 45 s. ; 29 cm. This study was conducted to evaluate the effects on yield and lint quality of cotton of plant growth regulator Pix (mepiquat chloride) which applied different doses and different times at the experimental area D.Ü. Faculty of Agriculture in 2007. Split plot design with three replications was applied as experimental design. Treatments times had constituted the main plots and treatments doses had constituted the sub plots. In the study, line lengthiness of the plots was designed 12 m, and row spacing x intra-row spacing of plants was designed as 70x20cm. The plots, on planting time were designed 4 lines, on harvest time were designed in the middle 2 lines after eliminating of edge effects. Plant growth regulator Pix was applied on early bloom and on top bloom as 50-100-150 cc/da. Bu çalışma farklı zamanlarda ve farklı dozlarda uygulanan PixTM (mepiquat chloride) bitki büyüme düzenleyicisinin pamuğun verimi ve lif kalitesi üzerine etkilerini araştırmak amacıyla D. Ü. Ziraat Fakültesi Deneme Alanında 2007 yılında yürütülmüştür. Deneme, bölünmüş parseller deneme deseninde, 3 tekrarlamalı olarak kurulmuş; uygulama zamanları ana parselleri, uygulama dozları ise alt parselleri oluşturmuştur. Çalışmada, parsellerin sıra uzunluğu 12 m, bitkilerin sıra arası x sıra üzeri uzaklığı 70 x 20 cm olarak düzenlenmiştir. Parseller, ekimde, 4 sıradan, hasatta ise kenar tesirleri atıldıktan sonra ortadaki 2 sıradan yapılmıştır. Bitki büyüme düzenleyicisi PixTM uygulaması, çiçeklenme başlangıcında 50-100-150 cc/da, çiçeklenme doruğunda 50-100-150 cc/da olacak şekilde uygulanmıştır. Çalışmada, koza kütlü pamuk ağırlığı, 100 tohum ağırlığı, çırçır randımanı özellikleri yönünden uygulama zamanlarının; bitki boyu, meyve dalı sayısı yönünden uygulama dozlarının; bitki boyu, 100 tohum ağırlığı, koza sayısı, lif inceliği ve lif kopma dayanıklılığı yönünden ise uygulama zamanı x uygulama dozları interaksiyonunun istatistiki anlamda önemli olduğu saptanmıştır. Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi Tarafından Desteklenmiştir. Proje No

(...) An experiment was conducted to determine the crop responses to temperature in naturally lighted, temperature- and CO 2 -controlled plant growth chambers. The experiment was conducted at five temperatures and measurements were made of several plant parameters. A preliminary experiment showed that mepiquat chloride (MC) caused a dramatic reduction in plant height and number of main-stem nodes. (...)

Excessive vegetative growth of cotton occurs under favourable growing conditions and this contributes to yield losses. Low concentrations of mepiquat chloride (1, 1-dimethylpiperidinium chloride) were applied to vigorous, growing cotton by means of two or more sprays at different time intervals. Application of 6, 3–12, 5 g a.i. ha−1 at 14-day intervals limited the growth rate of the main stem in cotton to 8–9 cm per 100 degree days (DD) and reduced plant height by 13–18%. Continuous, but controlled growth is essential to maintain high yield. In four trials, seed cotton yields averaged 3 900 kg ha−1 and were not affected by the various mepiquat chloride treatments. Under conditions of luxurious growth (>10 cm per 100 DD), the yield at first picking increased by between 20 and 26%, and total yield by 5%. It is necessary that intervals between supplementary applications of mepiquat chloride be adjusted according to the expected growth rate.

Cotton (Gossypium hirsutum L.) growth and development, lint yield, and fiber quality are influenced by many management decisions. Three field experiments examining the interaction of plant population and planting date, and cultivar or herbicide and plant growth regulator application on these parameters were conducted in Virginia during 2005 and 2006 and in North Carolina, South Carolina, and Louisiana during specific years. Experiment I: Plant Population and Planting Date Lint yields were highest with populations of 8.9 and 12.8 plants m¯² compared to 5.3 plants m¯² in Virginia and North Carolina, while in Louisiana the highest yields resulted from populations of 5.8 and 9.5 plants m¯² compared to 17.1 plants m¯². Earlier planted (1 May) cotton produced higher yields relative to later planted (21 May) cotton in Louisiana, while yield was not influenced by planting date in Virginia and North Carolina. The impact of plant population and planting date on cotton appeared to be influenced significantly by heat unit accumulation. Experiment II: Cultivar and Mepiquat Pentaborate Application Mepiquat pentaborate (MPB) application consistently decreased plant height, HNR, and enhanced maturity for all cultivars, compared to untreated cotton. A trend of decreasing yield with increasing MPB application in Virginia was observed. These data suggests that cotton response to MPB application is influenced by cultivar maturity or fruiting interval. Experiment III: Trifloxysulfuron-sodium and Mepiquat Chloride Application Trifloxysulfuron-sodium (TFS) did not influence vegetative growth, maturity, or yield in comparison to untreated cotton. Mepiquat chloride (MC) application reduced vegetative growth and enhanced maturity in most years. The results of this experiment demonstrate that TFS application does not have the same effects on plant growth as MC application. Master of Science

The present work aims to identify the vegetal regulators and optimum dose to reduce plant height and layering and their influence on production and productivity components in sprinkler-irrigated highland rice grains. Treatments consisted of three vegetal regulators and four doses. Mepiquat chloride (Pix) and ethyl-trinexapac (Moddus) were applied at doses of 0, 2000, 4000 and 8000 mg L-1 , while paclobutrazol (Paclobutrazol) was applied at 0, 1000, 2000 and 4000 mg L-1 , commercial product. The vegetal regulators were applied during the profiling state, utilizing Primavera cultivar. Results showed that ethyl-trinexapac reduced the plant height and influenced negatively grain production and productivity components. No optimum dose was identified to reduce plant height and increase grain productivity.

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.El objetivo de los experimentos de campo fue investigar el efecto del nitrogeno, potasio y retardantes del crecimiento de plantas sobre el contenido en proteínas y aceite de una semilla de algodón cultivada en Egipto (Gossypium barbadense Giza 86). Los tratamientos consistieron en la aplicación en suelo de N (95 and 143 kg N ha-1 en forma de nitrato amónico), aplicación foliar de K (0, 319, 638 or 957 g K ha-1 como sulfato potásico) y aplicación foliar de cloruro de m mepiquat (MC) (0 and 48 + 24 g de ingrediente activo ha-1) sobre un cultivar de algodón «Giza 86» (Gossypium barbadense). La aplicación de la cantidad más elevada de N, unida a la aplicación de potasio y del retardador MC, aumentó significativamente el rendimiento en semilla, así como el contenido en proteinas y en aceite. Respecto al aceite, aumentó el índice de refracción, la fracción insaponificable y el contenido total en ácidos insaturados (oleico y linoleico). Por el contrario, la acidez del aceite y su índice de saponificación disminuyó con la aplicación foliar de K y MC. El contenido en aceite de la semilla disminuyó cuando sólo se aplicó N.

TEZ6145 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2007. Kaynakça (s.115-126) var. xii, 127 s. ; 29 cm. This study was conducted to evaluate the effect of plant density and mepiquat chloride applications on cotton growth, yield and fiber quality. Pix applications (at rates of 25 cc and 75 cc da-1 at early square and first bloom, respectively) were evaluated for cotton grown at densities of 12500, 8300 ve 6250 plants da-1. . Vegetative and reproductive growth characteristics including dry weights of vegetative, reproductive, total, stem, leaf, and fruit, leaf area index (LAI) in addition to plant height, number of monopodial branches, number of sympodial branches, number of main stem nodes, number of bolls per plant were evaluated at 70 and 100 DAP (days after planting). The interaction term was found to be not significant for all traits studied. Plant density applications affected plant height, number of monopodial branches, number of sympodial branches, number of main stem nodes, number of node for first fruiting branch, fiber uniformity and fiber strength; while Pix applications had significant effect on plant height, number of monopodial branch, number of sympodial branch, seed cotton yield, boll weight and lint yield. Main effects of plant density and Pix applications on number of bolls per plant, weight of seed cotton per boll, lint percentage, fiber length, short fiber index, fiber elongation, fiber fineness (micronaire) and fiber color (reflectance and yellowness). Bu çalışma bitki sıklığı ve Pix bitki büyüme düzenleyicisi uygulamalarının, pamuk bitkisinin büyümesi, verimi ve lif kalitesi üzerine etkilerini araştırmak amacıyla yürütülmüştür. Çalışmada m2'ye 12.5, 8.30 ve 6.25 bitki sıklıklarında ekilen pamuğa, taraklanma başlangıcında 25 cc/da ve çiçeklenme başlangıcında 75 cc/da Pix uygulaması yapılmıştır. Ekimden 70 ve 100 gün sonra vejetatif kuru madde ağırlığı, generatif kuru madde ağırlığı, sap kuru madde ağırlığı, yaprak kuru madde ağırlığı, koza kuru madde ağırlığı, toplam kuru madde ağırlığı, yaprak alan indeksi (LAI), bitki boyu, odun dalı sayısı, meyve dalı sayısı, boğum sayısı, koza sayısı gibi vejetatif ve generatif büyüme özellikleri saptanmıştır. İncelenen tüm özellikler yönünden bitki sıklığı x Pix uygulamaları interaksiyonu önemsiz bulunmuştur. Bitki sıklığı uygulamalarının bitki boyu, odun dalı sayısı, meyve dalı sayısı, boğum sayısı, ilk meyve dalı boğum sayısı, lif yeknesaklığı ve lif kopma dayanıklılığı; Pix uygulamalarının ise bitki boyu, odun dalı sayısı, meyve dalı sayısı, kütlü pamuk verimi, koza ağırlığı ve lif verimi özelliklerinde farklılık oluşturduğu; bitki sıklığı ve Pix uygulamalarının koza sayısı, koza kütlü pamuk ağırlığı, çırçır randımanı, lif uzunluğu, kısa lif indeksi, lif esneme oranı, lif inceliği ve lif rengi özelliklerinde etkisinin önemli olmadığı belirlenmiştir. Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi Tarafından Desteklenmiştir. Proje No:ZF2005YL29

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:07Z No. of bitstreams: 1 S0103-90162007000200004.pdf: 220911 bytes, checksum: e994ea72b3047d1cb2ad390a52354dcf (MD5) Made available in DSpace on 2013-08-22T19:01:07Z (GMT). No. of bitstreams: 1 S0103-90162007000200004.pdf: 220911 bytes, checksum: e994ea72b3047d1cb2ad390a52354dcf (MD5) Previous issue date: 2007-01-01 Made available in DSpace on 2013-09-30T20:00:45Z (GMT). No. of bitstreams: 2 S0103-90162007000200004.pdf: 220911 bytes, checksum: e994ea72b3047d1cb2ad390a52354dcf (MD5) S0103-90162007000200004.pdf.txt: 24081 bytes, checksum: 40a2a9e1da6fd0a908e4733190430f9a (MD5) Previous issue date: 2007-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:34Z No. of bitstreams: 2 S0103-90162007000200004.pdf: 220911 bytes, checksum: e994ea72b3047d1cb2ad390a52354dcf (MD5) S0103-90162007000200004.pdf.txt: 24081 bytes, checksum: 40a2a9e1da6fd0a908e4733190430f9a (MD5) Made available in DSpace on 2014-05-20T15:15:34Z (GMT). No. of bitstreams: 2 S0103-90162007000200004.pdf: 220911 bytes, checksum: e994ea72b3047d1cb2ad390a52354dcf (MD5) S0103-90162007000200004.pdf.txt: 24081 bytes, checksum: 40a2a9e1da6fd0a908e4733190430f9a (MD5) Previous issue date: 2007-01-01 Em parte das regiões onde se encontram as maiores áreas de algodão no Brasil atualmente, o índice pluviométrico está ao redor de 2.000 mm anuais, existindo risco de ocorrer lavagem do Cloreto de Mepiquat (CM) das folhas do algodoeiro antes de ser absorvido pelas plantas. O objetivo deste trabalho foi avaliar a lavagem do CM aplicado no algodoeiro por diferentes laminas de chuva simulada. Os tratamentos constaram de três doses do regulador à base de cloreto de mepiquat: 0, 15.0 e 30.0 g ha-1 e quatro lâminas de chuva simulada: 5, 10, 20 e 40 mm, mais um tratamento sem chuva. Foram utilizados vasos de 12 litros de capacidade e a cultivar Delta Opal. Os parâmetros avaliados foram: altura de plantas, número de ramos reprodutivos, massa de matéria seca, retenção de estruturas reprodutivas e área foliar. Quanto maior a intensidade de chuva ocorrida após a aplicação do regulador maior foi o comprometimento da ação do produto, que repercutiu em interferência no crescimento das plantas. Chuvas de 5.0 mm, ocorridas 90 minutos após a aplicação do cloreto de mepiquat, já causaram prejuízo na ação do produto no crescimento do algodoeiro, sendo o efeito maior com o aumento da quantidade de chuva simulada. In some regions where cotton is grown in Brazil rainfall amounts to about 2,000 mm per year, which imposes a great risk for Mepiquat Chloride (MP) to be washed from cotton leaves before being absorbed. The objective of this research was to evaluate the MC persistence when applied on cotton plants submitted to different rain intensities after spraying. The treatments were three MC rates: 0, 15.0 and 30.0 g a.i. ha-1 and four simulated rainfalls, applied 90 minutes after MC spraying: 5, 10, 20 and 40 mm, plus a treatment without rain. Cotton plants of the cv. Delta Opal were grown in 12 L pots filled with an Haplortox. The experimental design was consisted of complete randomized blocks, in a factorial scheme, with four replicates. The evaluated parameters were: plant height, number of reproductive branches, dry matter weight, reproductive structures, retention and leaf area. The higher the rainfall the lower the effectiveness of the plant growth regulator in controlling plant height. A simulated rainfall as low as 5 mm occurring 90 minutes after MC application was enough to wash some of the plant growth regulator from cotton leaves. UNESP FCA Programa de Pós-Graduação em Agronomia UNESP FCA Depto. de Produção Vegetal UNESP FCA Programa de Pós-Graduação em Agronomia UNESP FCA Depto. de Produção Vegetal

Com o intuito de aumentar os índices de produtividade, reduzir os custos de produção e melhorar a eficiência na colheita mecanizada, novas tecnologias vêm sendo incorporadas como o uso regulador de crescimento e aplicação de subdose de glyphosate com promissor efeito hormético nas plantas de algodão. Para tal, objetivou-se com o trabalho avaliar o efeito do sistema de aplicação de subdose de glyphosate e de regulador de crescimento nas características agronômicas do algodoeiro. O delineamento experimental foi de blocos ao acaso em um esquema fatorial 6 x 2 + 1, com 4 repetições, sendo o primeiro fator frequência de aplicação do glyphosate, utilizando-se a mesma dose (78 g e.a. ha-1) em 1 única vez aos 40 dias após emergência (DAE), parcelada em 2 vezes (aos 40 e 50 DAE), em 3 vezes (40, 50 e 60 DAE), em 4 vezes (40, 50, 60 e 70 DAE) e 5 vezes (40, 50, 60, 70 e 80 DAE) , e o segundo fator foi com e sem aplicação de cloreto de mepiquat na dose 1 L ha-1, com pulverização parcelada em 5 vezes, aos 45, 55, 65, 75, 85 DAE, além da testemunha sem aplicação dos produtos. Verificou-se que o uso do cloreto de mepiquat diminuiu a altura da planta e número de nós do caule. A aplicação parcelada da subdose do herbicida em 3 vezes propiciou aumento da produtividade do algodão em relação aos tratamentos que não receberam aplicação.

The cotton crop management for plant population, cultivars and growth regulator application system to adequate the plant architecture are technical aspects of relevant importance. The present work was developed at the experimental station of the Sao Paulo State University/Ilha Solteira Campus, State of Sao Paulo, Brazil, in a Dark red latosol. The experimental design was the randomized completely blocks with twelve treatments and four replications, arranged in a factorial scheme 2x3x2, aiming to study: cotton cultivars (IAC 23 and CNPA ITA 90), plant density (6, 10 and 14 plants m -1 ); application systems of growth regulator (mepiquat chloride) with single application at 72 days after emergence (DAE) (1,0L ha -1 ) and in four times (0,1; 0,2; 0,3 and 0,4L ha -1 ), at 28, 43, 57 e 72 DAE. It was concluded that the application systems of the growth regulator do not affect the yield. The cotton plants with parceled application of growth regulator showed lower values of stem diameter and height when compared with single application. The IAC 23 presents stem diameter higher than the CNPA ITA 90. The CNPA ITA 90 presents fiber percentage higher than the IAC 23. The effect of growth regulator application system under the plant height depends of the plant population and the cultivar. The CNPA ITA 90 presents higher averages of fiber length, uniformity and tenacity. The parceled system of growth regulator application presets the higher values of uniformity and fiber length

Made available in DSpace on 2014-06-11T19:29:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-02-21Bitstream added on 2014-06-13T20:39:24Z : No. of bitstreams: 1 zanqueta_r_me_ilha.pdf: 210504 bytes, checksum: 6f3de164204adb7eca66ea26dbbb66f7 (MD5) Um manejo diferenciado da cultura do algodoeiro mediante a adequação da população de plantas, cultivar e o uso de regulador de crescimento para limitar o excessivo crescimento vegetativo, consistem em aspectos técnicos de relevante importância. O presente trabalho foi desenvolvido na área experimental da Fazenda de Ensino e Pesquisa da Unesp/Câmpus de Ilha Solteira-SP, com solo classificado como Latossolo vermelho escuro. O delineamento experimental empregado foi em blocos ao acaso com doze tratamentos e quatro repetições, arranjados em um esquema fatorial 2x3x2, visando estudar: cultivares de algodoeiro (IAC23 e CNPA ITA 90), densidade de plantas (6, 10 e 14 plantas m-1); e modos de aplicação de regulador de crescimento (cloreto de mepiquat) com aplicação em dose única aos 72 dias após a emergência (DAE) (1,0 L ha-1) e parcelada em 4 vezes (0,1; 0,2; 0,3 e 0,4 L ha-1), respectivamente, aos 28,43, 57 e 72 DAE. Pode-se concluir que o modo de aplicação única ou parcelada do regulador de crescimento na densidade populacional de 6 a 14 plantas m-1 não interfere na produção de algodão em caroço das cultivares utilizadas. A aplicação parcelada do regulador propicia a obtenção de plantas com altura final e diâmetro médio do caule da planta inferior aos obtidos quando se aplica o regulador em dose única. A densidade populacional de 10 e 14 plantas m-1 ocasionam uma diminuição do número de capulhos por planta. A cultivar IAC 23 apresenta diâmetro do caule e número de ramos frutíferos superiores a CNPA ITA 90, que apresenta porcentagem de fibra e número médio de capulhos superiores àqueles verificados para a IAC 23. Dependendo da cultivar e da densidade de planta utilizada, o modo de aplicação de regulador (única ou parcelada) pode interferir na altura de final das plantas. As cultivares estudadas, independente da aplicação de regulador de crescimento... , at 28, 43, 57 e 72 DAE. It was concluded that the application systems of the growth regulator do not affect the yield. The cotton plants with parceled application of growth regulator showed lower values of stem diameter and height when compared with single application. The plant densities of 10 and 14 plants m-1 reduce the square numbers plants-1. The IAC 23 presents stem diameter and number of productive branches higher than the CNPA ITA 90, that presents lint percentage and square number higher than the IAC 23. The application system of growth regulator and its effect for plant height can be depent of the Cultivar and Plant densities. The response of Cotton cultivars for the number of productive branches depends of the plant densities. The CNPA ITA 90 presents higher values of fiber length, uniformity and tenacity. The parceled application of growth regulator increase the fiber length and tenacity. The CNPA ITA 90 presents the higher values of financial return when compared with the IAC 23.

The influence of plant growth regulators ethrel (50, 100, 200 ppm), cycocel (25, 50, 75 ppm), and mepiquat chloride (50, 100, 200 ppm) on flower induction and sex forms of gherkin was investigated. Aqueous spray of each treatment was given on four leaf stage. Ethrel treatment brought down the number of days for the appearance of the female flowers and delayed the appearance of male flowers followed by cycocel and mepiquat chloride. Ethrel at 200 ppm had marked effect on the early appearance of pistillate flowers. Maximum number of female flowers and higher fruit set percent were recorded with 100 ppm ethrel.

Influence of plant growth regulators ethrel (50, 100, 200 ppm), cycocel (25, 50, 75 ppm) and mepiquat chloride (50, 100, 200 ppm) on the yield and fruit quality of gherkin was evaluated. Seeds were sown on the sides of the raised beds under open conditions and aqueous spray of each treatment was given at four true-leaf stage. The highest total yield was recorded with ethrel treatments followed by mepiquat chloride and cycocel. Maximum number of marketable fruits were obtained with ethrel 100 ppm. Mepiquat chloride yielded more unmarketable fruits. Ethrel at 200 ppm had profound effect on increasing the grade wise fruit number and fruit yield.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:46:34Z No. of bitstreams: 1 S0100-204X2000000300005.pdf: 68703 bytes, checksum: 972f1026481725830bb762e865464d06 (MD5) Made available in DSpace on 2013-08-22T18:46:34Z (GMT). No. of bitstreams: 1 S0100-204X2000000300005.pdf: 68703 bytes, checksum: 972f1026481725830bb762e865464d06 (MD5) Previous issue date: 2000-03-01 Made available in DSpace on 2013-09-30T19:35:53Z (GMT). No. of bitstreams: 2 S0100-204X2000000300005.pdf: 68703 bytes, checksum: 972f1026481725830bb762e865464d06 (MD5) S0100-204X2000000300005.pdf.txt: 31587 bytes, checksum: 321d31afdd69ebb0f974618014034b98 (MD5) Previous issue date: 2000-03-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:16:23Z No. of bitstreams: 2 S0100-204X2000000300005.pdf: 68703 bytes, checksum: 972f1026481725830bb762e865464d06 (MD5) S0100-204X2000000300005.pdf.txt: 31587 bytes, checksum: 321d31afdd69ebb0f974618014034b98 (MD5) Made available in DSpace on 2014-05-20T13:16:23Z (GMT). No. of bitstreams: 2 S0100-204X2000000300005.pdf: 68703 bytes, checksum: 972f1026481725830bb762e865464d06 (MD5) S0100-204X2000000300005.pdf.txt: 31587 bytes, checksum: 321d31afdd69ebb0f974618014034b98 (MD5) Previous issue date: 2000-03-01 Com o objetivo de avaliar os efeitos de diferentes doses de cloreto de mepiquat aplicadas parceladamente no algodoeiro (Gossypium hirsutum L.) cv. CNPA-ITA 90, dois experimentos foram conduzidos durante os anos agrícolas de 1993/94 e 1994/95, na Fazenda Itamarati, Ponta Porã, MS. As doses estudadas foram: 1) 0,0; 2) 12,5+12,5+25,0 (50,0); 3) 25,0+25,0+25,0 (75,0); 4) 0,0+ 50,0+50,0 (100,0) e 5) 12,5+62,5+50,0 (125,0) g ha-1 de cloreto de mepiquat. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. As aplicações foram efetuadas aos 34, 47 e 62 dias após a emergência (DAE), em 1993/94, e aos 42, 60 e 73 DAE no ano de 1994/95, quando as plantas apresentavam altura média de 51, 84 e 93 cm e 61, 79 e 97 cm, respectivamente. Com o aumento da dose de cloreto de mepiquat, verificou-se redução da altura de plantas, da matéria seca foliar, do caule e do total da parte vegetativa, do número de nós, de ramos, do comprimento de ramos, do número de frutos danificados e do número de maçãs, e aumento do número de capulhos totalmente abertos. The effects of different doses of mepiquat chloride on cotton (Gossypium hirsutum L.) plants, cultivar CNPA-ITA 90, during the 1993/94 and 1994/95 growing seasons were evaluated at Itamarati farm, Ponta Porã, MS, Brazil. The doses were split in three application dates and the experimental design was in randomized blocks, with five treatments replicated four times. The treatments were as follows: 1) unsprayed control; 2) 12.5+12.5+25.0 (50.0); 3) 25.0+25.0+25.0 (75.0); 4) 0.0+50.0+50.0 (100.0); and 5) 12.5+62.5+50.0 (125.0) g ha-1 of mepiquat chloride. The spraying was done at 34, 47 and 62 days after emergence (DAE) in 1993/94 and at 42, 60 and 73 DAE in 1994/95, when the plants were at the average hight of 51, 84 and 93 cm and 61, 79 and 97 cm, respectively. Increasing dose of mepiquat chloride caused decreasing in plant height; leaf stems and total above ground dry matter; number of nodes and branching; the branches length; the number of damaged fruits; the total number of bolls and the number of fully opened bolls. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Centro de Pesquisa Agropecuária do Oeste UNESP FCAV Dep. de Fitotecnia UNESP Dep. de Ciências Exatas UNESP FCAV Dep. de Fitotecnia UNESP Dep. de Ciências Exatas

Foram aplicados na cultura da batata cv. Monalisa, 45 dias após o plantio, retardadores de crescimento: cloreto de mepiquat, nas concentrações de 25, 50 e 100 mg L-1 e cloreto de (2 - cloroetil) trimetilamônia (chlormequat), 250, 500 e 1000 mg L-1, além do controle. O objetivo foi o aumento de produção. O delineamento adotado foi em blocos casualizados, com 7 tratamentos e 4 blocos por tratamento. Os parâmetros analisados a cada 2 semanas após as aplicações foram: área foliar, teor de clorofila total, massa de matéria seca, produção total e classificação dos tubérculos (tipos I, II, III e IV). O tratamento cloreto de mepiquat 25 mg L-1 apresentou maior taxa de degradação de clorofila. Os aumentos na produção de tubérculos do tipo I e II foram verificados com chlormequat (500 e 250 mg L-1) e cloreto de mepiquat (25 mg L-1). Observou-se um aumento na produção total de 3,32% para o tratamento com cloreto de mepiquat (25 mg L-1) e de 12,33% para o tratamento com chlormequat (500 mg L-1). O aumento de produção deve-se, provavelmente à maior atividade fotossintética e força de dreno dos tubérculos (principalmente dos tipos I e II). Fourty five days after planting, plant regulators were sprayed on potato plants. The treatments were a control, 25, 50 and 100 mg L-1 of mepiquat chloride and 250, 500 and 1000 mg L-1 of (2-chloroetyl) trimetylammonium-chloride (chlormequat), with the objective of increasing the production. The experiment was distributed in 4 randomized blocks for each treatment. The main parameters analized were leaf area, chlorophyll rate, dry matter and total yield. The classification of the tubers was also stablished according to their types (I, II, III and IV). Higher chlorophyll degradation rates were observed when mepiquat chloride was used at 25 mg L-1. There was an increase of types I and II tuber yield when chlormequat was sprayed at rates of 250 and 500 mg L-1 and mepiquat chloride at 25 mg L-1. Chlormequat 500 mg L-1 was the most effective treatment and increased total tuber yield by 12.3% and mepiquat chloride 25 mg L-1 increased 3.32% in relation to the control. This increase was probably due to the photossinthetic activity and sink strength of tubers, wich was higher for tubers of types I and II.

A rapid and sensitive method for simultaneous determination of hexanoic acid 2-(diethylamino)ethyl ester (DA-6) and mepiquat chloride (MQ) residues in soil and cotton samples was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). DA-6 and MQ were extracted with water–0.6% formic acid containing 5.0 mL 0.2% NH4Cl (cotton seeds 2% NH4Cl). Then, extracts containing the target compounds were analysed using UPLC-MS/MS with an electrospray ionization source in positive mode. The determination of the target compounds was achieved in less than 2.0 min. The limits of detection (LOD) were below 0.005 mg kg−1, while the limits of quantification (LOQ) did not exceed 0.015 mg kg−1 in all three matrices. Quantification was performed by calibration curves of standards from 0.005–1.0 mg kg−1 with r2 > 0.997. Recovery studies were evaluated at three spiked levels 0.5, 1.0 and 2.0 mg kg−1 for soil and cotton samples, and the overall average recoveries ranged from 76.3% to 100.0% with relative standard deviations 4.7–11.8% (n = 5).

In field trails on lemon grass, the effect of growth regulators, Viz. indole butyric acid (IBA) and mepiquat chloride (MC), and their mode of application was studied to assess their effects on herb, oil yield and hormonal contents. The results suggested that application of growth regulators had no favourable effect on herb and oil yields in lemon grass. However, application of me decreased endogenous GA and IAA while IBA increased them.

Estudaram-se, em dez experimentos de campo, os efeitos dos seguintes fitorreguladores de crescimento e da capação na cultura algodoeira: cloreto de clorocolina, aplicado na dose de 50 g/ha; cloreto de chlormequat, 100 g/ha e cloreto de mepiquat, 100 g/ha. A capação foi realizada manualmente, planta por planta, na mesma época da aplicação dos fitorreguladores, aos 60-70 dias da emergência das plantas. O delineamento estatístico foi de blocos ao acaso, com cinco tratamentos e seis repetições e, a variedade utilizada, a IAC 19. Para a avaliação dos resultados de produção e altura de plantas, efetuaram-se dois agrupamentos de ensaios, sendo um com maior e outro com menor desenvolvimento, ou seja: plantas em parcelas testemunhas com altura superior e inferior a 100 cm respectivamente. As demais características agronômicas e tecnológicas da fibra foram analisadas em um só grupo. Para o grupo de plantas com maior desenvolvimento, foi obtido, em média, um aumento de 16,3 e 8,4%, respectivamente, para o tratamento com capação e aplicação de fitorreguladores. O fitorregulador proporcionou, em média, redução de 12,1% na altura das plantas e a capação, em média, 20,8%. Os fitorreguladores, indistintamente, proporcionaram aumento de peso do tapulho e das sementes, enquanto, com a prática da capação, não se verificou esse efeito. A aplicação de cloreto de clorocolina resultou em menor porcentagem de fibra do que o cloreto de mepiquat. The effects of growth phytoregulators and pruning on the cotton crop were studied in ten field experiments. The phytoregulators used were: chlorocholine chloride, applied on dose of 50 g/ha; chlormequat chloride 100 g/ha, and mepiquat chloride, applied on dose of 100 g/ha. The pruning was done handly and individually by plant, at the same period of the application of the phytoregulators by 60-70 days after the plant emergence. The statistical delineament used was the randomized complete block design, with five treatments and six replications. The variety used was the IAC 19. Two groups of tests were done for the evaluation of yield and plant height results, one with a bigger development and another one with a smaller development, that is: plants of check plots with a height above and below 100 cm, respectively. The others agronomic and technological fiber characteristics were analyzed in an only group. For plants with the biggest development there was, on average, an increase in height of 16.3 and 8.4%, respectively, for the pruning treatment and for application of the phytoregulators. The application of the phytoregulator provided, on average, a reduction of 12.1% in the height of plants. In the other hand on average the practice of the pruning reduced in 20.8% the height of the plants, on average. The use of phytoregulators indistinctly, provided boll and seed weight increases, while with the practice of pruning, this effect was not significant. The application of chlormequat resulted in a lower percentage of fiber than the mepiquat chloride.

Experiments were conducted to determine the relative efficacy of ethephon, alone and in combination with chlormequat chloride (CCC) or mepiquat chloride (DPC), in reducing barley height and lodging in order to protect potential yield. The effects of timing and cultivar of barley were investigated. The results depended on both cultivar and year, indicating that both genetic and environmental factors are important. For Leger barley, application of ethephon between Zadoks Growth Stage (ZGS) 37 and 45 was effective in reducing plant height and lodging; CCC and DPC had no positive or negative effect when added to ethephon. CCC and DPC appeared to enhance the effects of ethephon on lodging control of Micmac barley especially when applied at ZGS 45. Rodeo barley showed the only detrimental effects to grain yield. Ethephon alone applied at ZGS 37 in 1986 caused significant yield loss. CCC or DPC reduced the detrimental effect of the ethephon by acting as apparent antagonists to its effects on this cultivar.Key words: Ethephon, CCC, DPC, lodging, barley

Radiometric canopy and laboratory spectrophotometric single-leaf reflectance measurements were used to compute the reflectance differences, at four sample dates through the 1980 growing season, between untreated and mepiquat chloride (MC)-treated cotton. The single-leaf reflectance measurements for the MC-treated cotton plants were lower at 650 nm and higher at 850 nm than the untreated cotton plants for three of the four sample dates. Early in the growing season the canopy reflectance of MC-treated cotton was lower in the red and higher in the near infrared (NIR) reflectance of untreated cotton canopies. Later in the season the canopy reflectance measurements indicated that the untreated cotton plants senesced faster than the MC-treated cotton plants. These results should provide a basic understanding of temporal canopy reflectance obtained from untreated and MC-treated cotton for use by operational remote sensing.

The effects of the growth retardants ancymidol and 2,3-dihydro-5,6-diphenyl-1,4-oxathiin (coded UBI-P293) were compared on early-, mid- and late-season forced tulip bulbs of cultivars ‘Apeldoorn’, ‘Paul Richter’ and ‘Rose Copland’. The chemicals were applied as single soil drenches, 1 day after transferring plants to the glasshouse. These treatments did not affect flower or petal length nor delay flowering, but high concentrations resulted in increased floral bud blasting in early-season ‘Apeldoorn’ (with ancymidol only) and in early- and mid-season ‘Rose Copland’ (with UBI-P293 only). Both ancymidol and UBI-P293 effectively dwarfed plants of all 3 cultivars at each time of forcing, provided sufficiently high concentrations were selected. However, early- and mid-season ‘Apeldoorn’ plants were particularly responsive to these compounds, the highest doses of which resulted in reductions in stem length at flowering of 70–80% (for ancymidol) or 50–60% (for UBI-P293); similar doses achieved less dwarfing in ‘Paul Richter’ and ‘Rose Copland’ and in late-season ‘Apeldoorn’. In ‘Apeldoorn’ and ‘Paul Richter’, ancymidol reduced extension markedly in the first internode, with less effect distally; UBI-P293 was effective in reducing extension of all internodes. Compost drenches of 3 newer growth retardants were also evaluated. Mepiquat chloride had no effect on flowering except that floral bud blasting was increased in ‘Rose Copland’. The stem responses of ‘Paul Richter’ and ‘Rose Copland’ to mepiquat chloride were trivial, but in ‘Apeldoorn’ the highest dose tested (2500 mg a.i./pot) reduced overall stem length via an effect on first internode extension. A quaternary sulphonium carbamate (coded BTS 44 584) had no effects on flowering or stem extension at concentrations up to 2500 mg a.i./pot. An N -carbamoylimidazole (coded BTS 34 723), tested at 1–50 mg a.i./pot, had small effects on internode extension which depended on cultivar, but potentially useful dwarfing was not observed.

SUMMARY Rates of ethephon with mepiquat chloride (as ‘Terpal’) were foliar applied to winter barley during early flag leaf emergence with or without soyal lecithin acidified with proprionic acid included as an adjuvant (‘LI700’). In both the glasshouse and field increasing the rate of ‘Terpal’ decreased the rate of stem extension exponentially, which in turn led to progressively shorter stands. As crop height extended above 0.9 m both the proportion of crop area lodged and the severity of lodging (mean angle of culms to the vertical) increased. As lodging progressed, mean grain weight was depressed and therefore ethephon with mepiquat chloride had the potential to increase yield. However, in the absence of lodging, applications of ‘Terpal’ reduced yield in direct proportion to increasing the dose rate. The influence of ‘Terpal’ on yield becomes a complex interaction between phytotoxicity, probably resulting from exogenous ethylene applications and benefits accruing from the control of lodging. Adding ‘LI700’ as an adjuvant enhanced the performance of ‘Terpal’ in reducing both rate of stem extension and mean grain weight in the absence of lodging.

SummaryEffects of mepiquat chloride on gradients of shoot growth within spring barley plants (cv. Koru) were determined in two small-scale field experiments. Mepiquat chloride was applied at either the lemma primordium stage or the late carpel primordium stage of spike development in the main shoot. The shoot dry weight, stem length, spike length, number and size of florets and floret developmental score were measured for all shoots, over the period from the lemma primordium stage of main shoot spike development to the late milk stage of grain development.Lemma primordium mepiquat chloride increased the size and developmental score of later-formed shorter shoots pre-anthesis while delaying the spike development of the main shoot and other longer shoots by up to 4 days. The overall effect was to produce plants with a reduced range of shoot and spike sizes from the end of floret initiation in the main shoot until maturity. In addition, there was a slight increase in the number of shoots per plant in both experiments. Gradients of carpel development and carpel width along the spike were reduced in all treated spikes by the time of floret abortion in the main shoot but the effects were more noticeable in shorter shoots. The number of florets initiated per plant was increased by 21–22%. All shoots contributed to the larger number of florets but again the major additions came from the shorter shoots. The few extra florets initiated in longer shoots were lost during abortion of distal florets while the 2–5 extra florets on shorter shoots were retained to give extra grains at maturity.Application of mepiquat chloride at the late carpel primordium stage had little effect on gradients of spike size or on number, size and development of florets.

The new growth retardants mepiquat chloride (a quaternary ammonium compound of the piperidinium type, coded BAS 083 00W) and a ternary sulphonium carbamate (coded BTS 44 584) were compared with ancymidol (A-Rest or Reducymol) and chlormequat chloride (Cycocel) for their ability to dwarf virus-free and virus-infected (ordinary) Mid-Century Hybrid lily cultivar ‘Enchantment’. Single compost drenches were given 3 weeks after transferring plants to the glasshouse. Compared with the virus-infected control plants, virus-free controls were 62% taller and 33% greater in leaf spread; floret number was approximately doubled and floret diameter was increased by 12%, but flowering was delayed by 6.5 days. The length of the lower stem bearing dead leaves was 15% of the total in virus-infected controls and 3% of the total in virus-free controls. Ancymidol, chlormequat chloride and mepiquat chloride were all effective growth retardants, and were without adverse side-effects. On a concentration basis, mepiquat chloride was 2–2.5 times as active as chlormequat chloride in reducing stem extension, but ancymidol was several orders of magnitude more active than both those compounds. With BTS 44 584, the maximum reduction in stem length obtained was 16% compared to controls. The decreases in stem extension were more pronounced, in both percentage and absolute terms, in the virus-free bulbs. Nevertheless, for a given retardant treatment, plants of the virus-free stock remained taller than those of the virus-infected stock. As a result, 2–3 times the amount of an active retardant was required by virus-free than by virus-infected plants in order to produce similar stem lengths at flowering. Effects of the retardants on the time of flowering, flower number, floret diameter and leaf spread were small, but increasing concentrations of all chemicals progressively increased the proportion of the stem bearing dead leaves. The effects of ancymidol, chlormequat chloride and mepiquat chloride persisted in the year after treatment.