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Determining the effect of prohexadione calcium growth regulator on growth and yield of peanut [Arachis hypogaea (L.)] in MississippiTreadway, Zachary Ray 01 May 2020 (has links)
Studies were conducted in small-plot and onarm environments in Mississippi in 2018 and 2019 to determine the effect of prohexadione calcium growth regulator on the growth and yield of peanut [Arachis hypogaea (L.)]. Onarm trials conducted in 2018 and 2019 concluded that in situations where the application of prohexadione calcium increased yield, variation in application rate had no effect on yield. Yields of peanut where any rate of prohexadione calcium was applied were 415 kg ha-1 greater than yields of peanut where prohexadione calcium were not applied. The addition of other agrichemicals had no effect on the efficacy of prohexadione calcium. Small-plot research in 2019 concluded that no rate variation had any effect on the growth or yield of peanut, and also concluded that alternative application timing methods had no effect on yield or growth of peanut.
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Novel applications in Mississippi cotton and peanutGaudin, Anna Beth 09 August 2022 (has links) (PDF)
Studies were conducted in the field from 2020-2021 in peanut and cotton to optimize peanut growth and yield through prohexadione calcium application methods as well as weed control through increasing herbicide sites of action. These studies were established on multiple on-farm and small-plot locations in Mississippi. Prohexadione calcium studies concluded that following application of prohexadione calcium effects on yield and peanut growth were inconsistent. Neither varying application timing nor rate resulted in peanut yield that was different than when adhering to the label recommendations. Increasing sites of action studies concluded that broadleaf signalgrass and Amaranthus species control was optimized at four SOAs and two SOAs, respectively. Based on this study, the current recommendation of additional SOAs will not result in increased weed control.
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Environmental and endogenous influences on carbohydrate assimilation and allocation of apple trees (Malus domestica Borkh)Pretorius, Jeremia Jesaja Bierman 04 1900 (has links)
Stellenbosch University. Faculty of AgriSciences. Dept. of Horticulture. / Thesis (PhD (Agric))--Stellenbosch University, 2006. / ENGLISH ABSTRACT: Market preferences for larger fruit have forced producers to adopt cultural practices that will
ensure bigger fruit even if this comes at the expense of reduced total yields. In order to obtain
acceptable fruit size there must be an adequate supply of photosynthetic carbon products
especially during the cell division stage of fruit growth. Competition between fruits and
between fruit and vegetative growth, as well as adverse climatic conditions, may limit the
carbon supply to the fruits at this critical period and thus limit the final fruit size. Growers are
showing renewed interest in the use of girdling or scoring in combination with the usual fruit
thinning program to achieve growth control and increase fruit size. A new and milder
chemical growth retardant, prohexadione-calcium (ProCa), is now also available for
vegetative growth control of apple trees. [n this study, the effects of, and potential interaction
between scoring, ProCa and fruit thinning were investigated, with respect to shoot and fruit
growth, yield and photosynthetic capacity, in 'Royal Gala" 'Fuji' and 'Cripps' Pink' apple
trees.
ProCa decreased final extension shoot length in all three cultivars. Extension shoots
were generally more sensitive than bourse shoots to scoring and ProCa. ProCa seems to be a
more effective way of controlling shoot growth than scoring, with 'Fuji' and 'Cripps' Pink'
being more sensitive than 'Royal Gala' to the application of ProCa. Scoring led to increased
fruit growth rates during the first 40 days after full bloom (DAFB), and culminated in better
fruit size at harvest. Scoring improved the total soluble solids concentration (TSS) of 'Fuji'
and 'Cripps' Pink' compared to control and ProCa treatments. ProCa inhibited shoot growth
effectively, but no evidence was found for improved carbon allocation to fruits and
reproductive buds.
Yield efficiencies of scored trees were significantly improved in all cultivars during
the second season, due to better reproductive bud development after the first year of scoring.
On 'Royal Gala' and 'Cripps' Pink', the efficiency of scoring to stimulate reproductive bud
development on old and new spurs declined after 4 weeks after full bloom (WAFB). In 'Fuji',
scoring later than I WAFB led to a decreasing positive response on old and new spurs. In
contrast, reproductive bud development on long shoots increased with later scoring (6 and 8
W AFB) on all cultivars. It seems that the most beneficial time of scoring is 2-4 W AFB, as early as possible during the cell division stage offruit growth, but not before natural drop has
occurred. The combination of early-season scoring and application of ProCa seems to hold
potential for increasing carbon allocation to the fruit and improving fruit size and quality
attributes.
Scoring early in the season reduced photosynthetic capacity, and this reduction in
carbon availability led to earlier cessation of shoot growth as well as shorter shoots. Later in
the season, reduced fruit numbers led to a decrease in photosynthesis. The optimum
temperature range for photosynthesis was found to adjust according to seasonal temperature
variations. The harvest-induced reduction in sink strength changed stomatal sensitivity to
higher temperature. Due to a reduced demand for carbohydrates by the plant, the maximum
rate of photosynthesis (Amax) was reduced post-harvest. Following this reduction in sink
strength and Am .. , stomata became more sensitive to high leaf temperatures, thus restricting
water loss. Pre-harvest there was a strong demand for carbohydrates, therefore stomata were
kept open at higher temperatures to ensure a high rate of C02 incorporation, but at a cost with
regard to water use efficiency. The sharp increase in dark respiration (Rd) in leaves and fruit
with an increase in temperature would mean that significant carbohydrate shortages could
occur in trees during source limited periods early in the season, especially under warm
weather conditions commonly experienced in the Western Cape region. / AFRIKAANSE OPSOMMING: Die effek van omgewings- en interne faktore op koolstofproduksie en -allokasie in
appelbome (Malus domestlca Borkh.).
Mark voorkeur vir groter vrugte forseer produsente om tegnieke te gebruik wat groter vrugte
sal verseker selfs al beteken dit verlaagde totale opbrengste. Om aanvaarbare vruggrootte te
bereik moet daar voldoende voorsiening van fotosinteties geproduseerde koolstofprodukte
aan die vrug wees, veral gedurende die selverdelingstadium van vruggroei. Kompetisie tussen
vrugte, en tussen vrugte en vegetatiewe groei sal die voorsiening van koolstof gedurende die
kritieke stadium aan die vrug beperk en so vruggroote benadeel. Daar is dus hernude
belangstelling in die gebruik van ringelering in kombinasie met die gewone vrug
uitdunprogramme om groei te beheer en vruggrootte te verbeter. 'n Nuwe, sagter chemiese
groeireguleerder, proheksadioon-kalsium (ProCa) is ook nou beskikbaar vir groeibeheer op
appelbome. In hierdie studie is die effekte van, en moontlike interaksie tussen ringelering,
ProCa en vruguitdunning ondersoek ten opsigte van loot- en vruggroei en opbrengs, sowel as
die effekte op gaswisseling op 'Royal Gala', 'Fuji' en 'Cripps' Pink' appelbome.
ProCa veroorsaak korter lote in aJ drie kultivars. Verlengingslote is meer sensitief as
beurslote vir ringelering en ProCa. ProCa is effektiewer as ringelering om lootgroei te beheer,
en 'Fuji' en 'Cripps' Pink' is sensitiewer as 'Royal Gala'. Ringelering lei tot verbeterde
vruggroeitempos gedurende die eerste 40 dae na volblom en verbeterde vruggrootte by oes.
Ringelering verbeter die totale oplosbare vastestotkonsentrasie (TOVS) van 'Fuji' en
'Cripps' Pink' in vergelyking met kontrole- en ProCa-behandelings, onderskeideHk. ProCa
inhibeer lootgroei effektief, maar geen bewyse van verbeterde koolstomllokasie na vrugte en
reproduktiewe knoppe is gevind nie.
Opbrengseffektiwiteit van geringeleerde borne verhoog gedurende die tweede seisoen
van ringelering weens beter reproduktiewe knopontwikkeling. Ringelering later as 4 weke na
volblom (WNVB) is minder effektief om reproduktiewe knopontwikkeling op ou en nuwe
spore in 'Royal Gala' en 'Cripps' Pink' te stimuleer. Die positiewe effek van ringelering op
reproduktiewe knoppe op 'Fuji' verminder sodra dit later as I WNVB gedoen word. Op
langlote het 'n laat ringelering (6 en 8 WNVB) die beste effek op reproduktiewe
knopontwikkeling. Die mees voordelige tyd om te ringeIeer was 2-4 WNVB, so vroeg as
moontlik gedurende die selverdelingstadium van vruggroei, maar nie voor natuurlike vrugval voltooi is nie. Die kombinasie van vroei! ringelering en die toediening van ProCa het
potensiaal om koolstofallokasie na die vrug te verbeter, met die gepaardgaande verbetering in
vruggrootte en -kwaliteit.
RingeJering vroeg in die seisoen inhibeer fotosintese en hierdie verlaging in koolstof
beskikbaarheid het tot gevolg dat lootgroei vroei!r gestaak word. Later in die seisoen
veroorsaak verlaagde vruggetalle 'n afname in fotosintese. Die optimum temperatuur vir
fotosintese verander na gelang van heersende lugtemperature. Die oes-geinduseerde verlaging
in sinksterkte verander stomatale sensitiwiteit vir hoo temperature. Weens 'n verJaagde
aanvraag vir koolhidrate deur die plant word fotosintese verlaag na-oes. Weens die verlaging
is stomata sensitiewer vir hoer temperature en beperk dus waterverlies. V oor oes is daar 'n
hoo aanvraag na koolhidrate dus word stomata oop gehou selfs by hoe temperature ten koste
van watergebruiksdoeltreffendheid. Die skerp styging in donker respirasie in blare en vrugte
met 'n verhoging in temperature sal beteken dat koolhidraat-tekorte kan ontstaan in bome
gedurende die bron-beperkte periodes vroeg in die seisoen, veral onder warm toestande 500S
wat algemeen ervaar word in die Wes Kaap.
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Plant Bioregulator Strategies to Alleviate Biennial Bearing, Enhance Precocity, and Control Vegetative Growth of ‘Northern Spy’ Apple TreesDuyvelshoff, Christopher 11 May 2011 (has links)
Biennial bearing, low precocity, and vigorous vegetative growth are major production constraints of ‘Northern Spy’ apple trees. Experiments were conducted in bearing and non-bearing ‘Northern Spy’/M.9 orchards to determine whether plant bioregulator applications of ethephon (ETH), napthaleneacetic acid (NAA), prohexadione-calcium (P-Ca), and/or benzyladenine (BA) could be used to overcome these production constraints of ‘Northern Spy’. Ethephon application at 150, 300, or 450 mg∙L-1 in the ‘on’ year increased return bloom, fruit yield, and alleviated biennial bearing in the ‘off’ year in a positive linear relationship to concentration when trees were moderately biennial in cropping. Applications applied 22 June were more effective than 27 July or 31 Aug. applications. However, single or multiple (2, 3, or 4) application(s) of 150 mg∙L-1 ETH or 5 mg∙L-1 NAA were ineffective when trees were not biennial. Two ETH applications at 1500 mg∙L-1 to non-bearing trees significantly increased flowering and fruit yield the year following treatment. The combination of P-Ca with ETH had an additive effect on shoot growth and improved growth control compared to P-Ca alone. Two BA applications at 500 mg∙L-1 had no effect on lateral branching of young trees. / Chudleigh's Limited, MITACS Accelerate
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Effect of Prohexadione-Calcium on Spearmint (Mentha spicata L.)Meagy, Md J. 01 January 2009 (has links) (PDF)
Prohexadione-calcium (Pro-Ca), a plant growth regulator used primarily in fruit trees to suppress excessive vegetative growth and to inhibit disease incidence, is known to inhibit dioxygenase enzymes and to inhibit GA biosynthesis. It induces genes for polyphenols synthesis. The objective of this project was to determine if the bioregulator Pro-Ca would alter the yield of essential oil, secondary metabolites, and growth in spearmint. Spearmint shoot cuttings from the same mother plant were used in this study. The plants were treated with 0, 125, 250, 375, and 500 mg/L a.i. of Pro-Ca over four weeks, and growth responses were measured every week and at harvest. Compared with the untreated control plants, plant height, branch length, number of nodes, and fresh weight were decreased with increased concentration of Pro-Ca treatment, and total phenolics accumulation increased. Rosmarinic acid and total chlorophyll content were reduced relative to control after treatment. Treatment with increased concentration of Pro-Ca altered the accumulation of flavonoids compounds. Increased concentration of catechin and eriodictyol-7-glucoside, and decreased concentrations of procyanidin and luteolin occurred compared with the untreated plant. Modification of newly formed flavonoid synthesis could be used as a new potential strategy in plant protection.
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Uso de fitorreguladores em pomar de abacateiro (Persea americana Mill.) \'Hass\' cultivado em condições de sequeiro / Use of plant growth regulators in \'Hass\' avocado (Persea Americana Mill.) orchards under rainfed conditionsBrogio, Bruna do Amaral 19 May 2017 (has links)
Embora o Brasil apresente grande potencial para a expansão da cultura do abacateiro, sobretudo devido as condições edafoclimáticas favoráveis, sua produção ainda é restrita no país, principalmente devido a fatores limitantes, como a não adoção do adensamento nos pomares comerciais e de manejos agronômicos que favoreçam a produção e qualidade de frutos; a presença de Phytophthora cinnamomi, principal patógeno que afeta a cultura em todo o mundo; o fato da grande maioria dos pomares comerciais serem cultivados sob condições de sequeiro; e devido a fatores inerentes a ecofisiologia da planta, como vigor excessivo, baixa fixação de frutos e a dificuldade em controlar a alternância de produção. A aplicação de fitorreguladores é um manejo importante e com bons resultados, nos pomares comerciais dos principais países produtores, sendo esta uma técnica que visa melhorar a produtividade, incrementar o tamanho dos frutos, diminuir a alternância produtiva e reduzir o vigor vegetativo. O objetivo desta pesquisa foi avaliar o efeito de distintos fitorreguladores no desenvolvimento vegetativo, produção, eficiência e alternância produtiva, tamanho e formato de frutos e na qualidade pós-colheita de abacateiros \'Hass\' não irrigados. Entre 2013 e 2016, foram avaliados sete tratamentos via pulverização foliar: T1: água (testemunha); T2: 250 mg.L-1 Viviful® (68,75 mg.L-1 prohexadione-cálcio); T3: 0,7% Cultar® 250 SC (0,175% paclobutrazol); T4: 0,7% Sunny® (0,035% uniconazole); T5: 1% Moddus® (0,25% etil-trinexapac); T6: 1250 mg.L-1 MaxCel® (25 mg.L-1 6- benziladenina) aplicados no florescimento; e T7: 125 mg.L-1 ProGibb® 400 (50 mg.L-1 ácido giberélico) aplicado no início do mês de dezembro antes da segunda queda natural de frutos. O delineamento experimental foi conduzido em blocos ao acaso, com 7 tratamentos, 4 repetições e 2 plantas por parcela. Nos distintos tratamentos foram avaliados: tamanho da planta; crescimento dos brotos de primavera; produção, tamanho e formato de frutos e a qualidade pós-colheita. Os fitorreguladores utilizados não afetaram significativamente o desenvolvimento vegetativo, a eficiência produtiva e a produção de frutos, bem como não influenciaram na qualidade pós-colheita dos mesmos. O inibidor de giberelina uniconazole (T4) foi o responsável por reduzir significativamente o crescimento dos brotos de primavera durante os três anos de avaliações. A citocinina 6-benziladenina (T6) reduziu de forma significativa a alternância produtiva de abacateiros \'Hass\' enquanto o uniconazole (T4), prohexadione-cálcio (T2) e 6-benziladenina (T6) aumentaram significativamente o tamanho dos frutos. A maioria dos fitorreguladores utilizados modificaram o formato dos frutos, tornando-os mais arredondados, com destaque para o efeito do etil-trinexapac (T5). A aplicação dos distintos fitorreguladores se apresentam inconstantes ao longo dos anos de pesquisa e não afetam número, produção de frutos (Kg.planta-1) e eficiência produtiva de abacateiros \'Hass\' não irrigados. / Although Brazil presents great potential for the expansion of the avocado crop, especially due to the favorable edaphoclimatic conditions, its production is still restricted in the country, mainly due to limiting factors, such as the non-adoption of high-density plantings in commercial orchards and agronomic managements to support high fruit yield and quality; the presence of Phytophthora cinnamomi, the main pathogen affecting avocados around the world; the fact that most of the commercial orchards are grown under rainfed conditions; and also due to factors that are inherent to the tree\'s ecophysiology, such as the excessive vigor, low fruit set and difficulty in controlling the alternate bearing. Plant growth regulators (PGRs) have become important management tools in the commercial orchards of the main producer countries for improving yields, increasing fruit size, reducing alternate bearing and reducing vegetative vigor. The aim of this research was to evaluate the effect of different PGRs on vegetative growth, fruit yield, yield efficiency and alternate bearing, fruit size and shape, and post-harvest quality of \'Hass\' avocados non-irrigated. Between 2013 and 2016, seven treatments were evaluated by foliar sprays : T1: water (control); T2: 250 mg.L-1 Viviful® (68,75 mg.L-1 prohexadione-calcium); T3: 0,7% Cultar® 250 SC (0,175% paclobutrazol); T4: 0,7% Sunny® (0,035% uniconazole); T5: 1% Moddus® (0,25% trinexapac-ethyl); T6: 1250 mg.L-1 MaxCel® (25 mg.L-1 6-benzyladenine) all applied in full bloom; and T7: 125 mg.L-1 ProGibb® 400 (50 mg.L-1 gibberelic acid) applied at the beginning of December, before the second natural fruit drop. The experiment was conducted in a randomized block design with seven treatments, four replications and two plants per plot. The following variables were evaluated: tree size, spring shoot growth, fruit yield, size and shape and post-harvest fruit quality. The applied PGRs did not significantly affect tree size, yield efficiency and fruit yield, nor did they influence the post-harvest fruit quality. Uniconazole (T4) was responsible of a significant shortening of spring shoots during the three years of evaluations. The cytokinin 6-benzyladenine (T6) significantly reduced alternate bearing of \'Hass\' avocado trees. Spring sprays of uniconazole (T4), prohexadione-calcium (T2) and 6-benzyladenine (T6) significantly increased fruit size. Most of the PGRs modified -fruit shape of \'Hass\' avocados to a more rounded format, with trinexapac-ethyl (T5) showing a stronger effect. The application of the different PGRs are inconsistent throughout the years of research and do not affect fruit number and yield (kg.tree-1) and yield efficiency of non-irrigated \'Hass\' avocados.
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Crescimento vegetativo, potencial produtivo e qualidade dos frutos de macieiras tratadas com reguladores de crescimento / Vegetative growth, yield potential and fruit quality of apple trees sprayed with plant growth regulatorsSilveira, João Paulo Generoso 22 July 2011 (has links)
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Previous issue date: 2011-07-22 / The aim of this study was to evaluate effects of spraying apple trees with prohexadione-calcium (ProCa) (na inhibitor of gibberellins synthesis) and gibberellin (GA₃) on vegetative growth, yield potential, fruit quality, and occurrence of bitter pit in the fruit. The experimente was conducted in na orchard located in São Joaquim, Santa catarina State (Southern Brazil), in 2009/2010. catarina and Fuji apple trees were sprayed with water (control), ProCa and gibberellin (both products at the dose of 319 mg L¯¹), at the petal fall stage (October 15, 2009), when shoots were 5-10 cm long, with treatments repeated after 20 days. Leaves were assessed (in termsmof chlorophyll contente, área, dry mater and specific área) in January/2010, and length of current season shoots and weight of shoots removed by winter pruning were assessed in May/2010. The number of flower buds ando f fruit per flower bud were assessed in October/2009 and November/2010, respectively. Fruit were harvest at comercial maturity and then assessed for percentage of red skin área, skin color, density, weight, skin and pulp textures, flesh firmness, titratable acidity (TA), solids soluble contente (SSC) and starch index. Fruit were cold stored (0±0.5°C/90-95% RH) for four months, followed seven days for simulate marketing (20±4°C/60-70% RH) for four months, same evaluation carried out at harvest, as well as for incidence (%) and index of bitter pit. Trees treated with ProCa had higher leaf chlorophyll contente and lower specific leaf área in Fuji , lower leaf área in Catarina , lower shoot growth in both cultivars, and lower weight of shoots removed by winter pruning in Catarina , in the year following the treatment of the trees, both cultivars sprayed with ProCa had lower fruit set. the ProCa incresead the red color in Catarina apples. At harvest, the force for pulp penetratoon in the red side of the fruit was incresead in apple trees of both cultivars sprayed with ProCa. After cold stored, Fuji apples of trees sprayed with GA₃ had lower flesh firmness, while Catarina apples of trees sprayed with ProCa had higher firmness. Fruit Ca contente was not diferente between ProCa and GA₃ and between ProCa e the control in both cultivars. Fuji apples from trees treated with ProCa had lower N/Ca ratio in the skin tissue. Teh treatment with ProCa incresead the flesh firmness in the reddish fruit side and reduced the index of bitter pit during cold storage in both cultuivars. The use of ProCa in apples orchards might represent a new technology to reduce trees vegetative growth and the occurrence of bitter pit in the fruit. The GA₃ sprayed after full bloom increases trees vegetative growth and might cause changes in fruit quality atributes, leading to advanced maturiry, as well as increases the development of bitter pit / Este trabalho foi desenvolvido com o objetivo avaliar os efeitos da pulverização de macieira com um inibidor da síntese de giberelinas, o prohexadiona-cálcio (ProCa), e com giberelina (GA₃), no crescimento vegetativo e potencial produtivo das plantas, e na qualidade e ocorrência de bitter pit nos frutos. O experimento foi conduzido em um pomar localizado no município de São Joaquim, SC, na safra 2009/2010. Macieiras Catarina e Fuji foram pulverizadas com água (tratamento controle), ProCa e GA₃ (ambos os produtos na dose de 319 mg L¯¹), na queda das pétalas (15/10/2009), quando as brotações do ano estavam com 5-10 cm de comprimento, sendo repetidas após 20 dias. Foram feitas avaliações foliares (teor de clorofila, área, matéria seca e área específica), em janeiro/2010, e de comprimento dos ramos do ano e de peso dos ramos podados, em maio/2010. A contagem dos cachos florais e do números de frutos por cacho floral ocorreram em outubro/2009 e novembro/2010, respectivamente. A colheita foi realizada na maturação comercial, ocasião em que foram feitas análises nos frutos do índice de cor vermelha, cor da epiderme, densidade, peso, atributos de textura (força para a penetração da casca e força para a penetração da polpa), firmeza de polpa, acidez titulável, sólidos solúveis totais (SS) e índice de iodo-amido. Os frutos foram armazenados em câmara fria convencional (0±0,5°C/90-95% UR), durante quatro meses, seguido de sete dias de comercialização simulada (20±4°C/60-70 UR), e após submetido as mesmas avaliações feitas na colheita, bem como de incidência (%) e índice de bitter pit . O tratamento com ProCa aumentou o teor de clorofila e reduziu a área foliar específica em macieira Fuji , reduziu a área foliar em Catarina , reduziu o comprimento dos ramos do ano nas duas cultivares e o peso dos ramos podados em Catarina . No ano subsequente ao da aplicação dos tratamentos, macieiras pulverizadas com o ProCa, de ambas as cultivares, apresentaram menor frutificação. O tratamento com ProCa proporcionou maior coloração vermelha em maçãs Catarina . No momento da colheita, maçãs Fuji e Catarina provenientes de plantas pulverizadas com ProCa apresentaram maior força para a penetração da polpa no lado mais vermelho dos frutos. Após o armazenamento, maçãs Fuji de plantas pulverizadas com GA₃ apresentaram menor firmeza de polpa e maçãs Catarina de plantas pulverizadas com ProCa apresentaram maior firmeza de polpa. O teor de Ca nos frutos não diferiu entre os tratamentos ProCa e GA₃ e entre ProCa e controle, em ambas as cultivares. Maçãs Fuji apresentaram menor relação N/Ca no tecido da casca quando pulverizadas com ProCa. O tratamento com ProCa proporcionou aumento na firmeza no lado mais vermelho do fruto e reduziu o índice de bitter pit durante o armazenamento refrigerado em ambas as cultivares. A utilização do ProCa na cultura da macieira pode ser uma nova alternativa para o controle do crescimento vegetativo de da manifestação do bitter pit nos frutos. O GA₃, pulverizado em pós-floração, em macieiras aumenta o crescimento vegetativo e pode ocasionar algumas modificações nos atributos de qualidade nos frutos, indicando um avanço na maturação, e na manifestação do bitter pit
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Uso de fitorreguladores para controle do desenvolvimento vegetativo e aumento da frutificação em macieira e pereira. / Use of growth regulators to control vegetative growth and frutification increase in apple and pear treesHawerroth, Fernando José 23 November 2010 (has links)
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Previous issue date: 2010-11-23 / The proper balance between vegetative growth and frutification in pome fruit species
such as apple and pear, it is essential to increase production efficiency and
improving fruit quality. In this sense, control of vegetative growth and frutification
increase are needed in the management of these species, which may be obtained by
use of growth regulators. The objective of this study was to evaluate the control of
vegetative growth and frutification increase of apple and pear orchards in the
Southern Brazil climatic conditions in response to the use of growth regulators. For
this, three experiments were carried out in this research. In the first experiment,
different concentrations of prohexadione calcium were evaluated in 'Imperial Gala'
and 'Fuji Suprema' apple trees, grafted on Marubakaido rootstock with M9 interstock,
in an orchard located in Fraiburgo/SC. The treatments (0, 165, 330, 495, 660, and
990 g ha-1 prohexadione calcium) were applied during the vegetative growth in
2008/2009 and 2009/2010 growing seasons. The concentrations corresponding to
each treatment were applied split into three parts. The first application was done
when the shoots of the control treatment showed growth of 10 cm. The second and
third applications were made at 30 and 60 days after the first application,
respectively. The prohexadione calcium was effective in controlling vegetative growth
of apple trees 'Imperial Gala' and 'Fuji Suprema', reducing the total weight and
average weight of pruned shoots, as well as the average shoot length, in the
Southern Brazil climatic conditions. The use of prohexadione calcium at
concentrations ranging from 165 to 330 g ha-1 increased the fruit production of
'Imperial Gala' apples, but high concentrations of this growth regulator tends to
reduce the fruit production, especially in 'Fuji Suprema' apples. The reduction of
vegetative growth by the use of prohexadione calcium contributed to increase
calcium content in fruits of 'Fuji Suprema'. The second experiment was carried out in
Pelotas/RS, using 'Hosui' pears grafted on Pyrus calleryana rootstock. Different
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concentrations of prohexadione calcium were evaluated (0, 275, 550, and 825 g ha-
1), being half the concentration corresponding to each treatment applied when the
shoots had between 5 to 10 cm in length, and the remainder applied 30 days after
the first application. The use of prohexadione calcium was effective in controlling the
vegetative growth of 'Hosui' pears, decreasing the need for winter pruning by
reducing the total weight and the number of shoots pruned. The control of vegetative
growth by use of prohexadione calcium determined increase the productive capacity
of 'Hosui pears, especially at concentrations ranging from 450 to 750 g ha-1. The aim
of the third experiment was to evaluate the effectiveness of thidiazuron, gibberellic
acid, prohexadione calcium and combination of these substances on frutification
increase of 'Shinseiki' asian pears. The following treatments were applied at full
bloom: 1. control (no application); 2. thidiazuron (TDZ) 20 mg L-1; 3. gibberellic acid
(GA) 20 mg L-1; 4. prohexadione calcium (PCa) 600 mg L-1; 5. PCa 600 mg L-1 + TDZ
20 mg L-1; 6. PCa 600 mg L-1 + AG 20 mg L-1; e 7. AG 20 mg L-1 + TDZ 20 mg L-1.
The application thidiazuron at 20 mg L-1, gibberellic acid at 20 mg L-1 and the
combination of these substances during the full bloom increased significantly the
frutification and the fruit production of 'Shinseiki' pears. The prohexadione calcium,
when sprayed at flowering alone or in combination to thidiazuron and gibberellic acid,
was not effective to increase the fruit set and fruit production. The use of growth
regulators on flowering decreased the number of seeds per fruit. / O adequado balanço entre o desenvolvimento vegetativo e a frutificação em
espécies pomáceas, como a macieira e a pereira, é fundamental ao aumento da
eficiência produtiva e a melhoria da qualidade dos frutos. Neste sentido, o controle
do desenvolvimento vegetativo e o aumento da frutificação são necessários no
manejo de tais espécies, podendo ser obtidos pelo uso de fitorreguladores.
Objetivou-se com este estudo avaliar o controle do desenvolvimento vegetativo e o
aumento da frutificação de macieiras e de pereiras nas condições climáticas do Sul
do Brasil em resposta ao uso de fitorreguladores. Para tanto, foram realizados três
experimentos. No primeiro experimento, foram avaliadas diferentes concentrações
de proexadione cálcio em macieiras Imperial Gala e Fuji Suprema , enxertadas no
porta-enxerto Marubakaido com interenxerto de M9, em pomar localizado em
Fraiburgo/SC. Os tratamentos (0; 165; 330; 495; 660; e 990 g ha-1 de proexadione
cálcio) foram aplicados durante o período de desenvolvimento vegetativo nos ciclos
2008/2009 e 2009/2010. As concentrações respectivas a cada tratamento foram
aplicadas parceladamente em três momentos. A primeira aplicação foi realizada
quando as brotações do tratamento testemunha apresentavam crescimento de 10
cm. A segunda e a terceira aplicação foram realizadas aos 30 e 60 dias após a
primeira aplicação, respectivamente. O proexadione cálcio foi eficiente no controle
do desenvolvimento vegetativo de macieiras Imperial Gala e Fuji Suprema ,
reduzindo a massa total e a massa média de ramos, assim como o comprimento
médio dos ramos, nas condições climáticas do Sul do Brasil. O uso de proexadione
cálcio em concentrações variando de 165 a 330 g ha-1 aumentou a produção de
maçãs Imperial Gala , porém altas concentrações deste fitorregulador tendem a
reduzir a produção de frutos por planta, sobretudo em macieiras Fuji Suprema . A
redução do desenvolvimento vegetativo pelo uso do proexadione cálcio contribuiu
6
para o aumento dos teores de cálcio em maçãs Fuji Suprema . O segundo
experimento foi realizado no município de Pelotas/RS, utilizando pereiras Hosui
enxertadas no porta-enxerto Pyrus calleryana. Foram avaliadas diferentes
concentrações de proexadione cálcio (0; 275; 550; e 825 g ha-1), sendo metade da
concentração respectiva a cada tratamento aplicada quando as brotações
apresentavam entre 5 a 10 cm de comprimento, e o restante aplicado 30 dias após a
primeira aplicação. O uso de proexadione cálcio foi efetivo no controle do
desenvolvimento vegetativo de pereiras Hosui , minimizando a necessidade de poda
hibernal pela redução da massa total e do número de ramos podados. O controle do
desenvolvimento vegetativo pelo uso de proexadione cálcio determinou aumento da
capacidade produtiva de pereiras Hosui , sobretudo em concentrações de 450 a 750
g ha-1. O objetivo do terceiro experimento foi avaliar a efetividade do thidiazuron,
ácido giberélico, proexadione cálcio e a combinação destas substâncias no aumento
da frutificação de pereiras asiáticas Shinseiki . Os seguintes tratamentos foram
aplicados na plena floração: 1. testemunha (sem aplicação); 2. thidiazuron (TDZ) 20
mg L-1; 3. ácido giberélico (AG) 20 mg L-1; 4. proexadione cálcio (PCa) 600 mg L-1; 5.
PCa 600 mg L-1 + TDZ 20 mg L-1; 6. PCa 600 mg L-1 + AG 20 mg L-1; e 7. AG 20 mg
L-1 + TDZ 20 mg L-1. A aplicação de thidiazuron 20 mg L-1, ácido giberélico 20 mg L-1
e a combinação destas substâncias durante a plena floração aumentaram
significativamente a frutificação e a produção de pereiras Shinseiki . O proexadione
cálcio, quando aplicado na floração isoladamente ou em combinação ao thidiazuron
e ao ácido giberélico, não se mostrou efetivo no aumento da frutificação e na
produção de frutos. A utilização dos fitorreguladores na floração diminuiu o número
médio de sementes por fruto.
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