Paclobutrazol Application Research Articles

Flower and pod development, grain-setting characteristics and grain yield in Chinese milk vetch (Astragalus sinicus L.) in response to pre-anthesis foliar application of paclobutrazol.

The number of grains per unit land area is the most important grain yield component in Chinese milk vetch. Flower and pod survival seem to be critical determinants of grain number, which is related to the number of fertile flowers and pods during the anthesis period. Flower and pod growth are frequently considered the key determinants to establish grain number. The objective of this study was to explore the influences of paclobutrazol on flower and pod development, grain-setting characteristics and grain yield in Chinese milk vetch under different concentrations of foliar spray and try to explore the physiological regulatory mechanisms. Field experiments were carried out during the 2017-2018 and 2018-2019 growing seasons at the Dayuzhuang experimental field. The experiment involved the Chinese milk vetch cultivar "Xinzi No. 1" and six levels of foliar application of paclobutrazol, 0, 200, 300, 400, 500, and 600 mg L-1, in treatments CK, T1, T2, T3, T4, and T5, respectively. Foliar spray was applied once, at the squaring stage. In comparison with the CK treatment, all of the paclobutrazol treatments yielded, to various degrees, increased values of the number of inflorescences per unit area, number of pods per unit area, grain-setting rate of pods, and number of grains per pod in all six inflorescence layers, with the largest increases observed in the T3 treatment. In the T3 treatment compared with the CK treatment, from the first to sixth inflorescence layers, the number of inflorescences per unit area was increased by 34.07-58.97%, the number of pods per unit area was increased by 39.69-68.35%, the grain number per pod was increased by 44.31-53.69%, and the grain-setting rate of pods was increased by 1.84-4.89%. An analysis of yield composition revealed that the paclobutrazol spray treatment had little impact on the grain weight of Chinese milk vetch. The correlations between the concentration of paclobutrazol spray and the grain yield of Chinese milk vetch reached a significant level. Grain yield was highest at the paclobutrazol concentration of 373.10 mg/L. The inflorescence contents of gibberellic acid 3 (GA3), indole-3-acetic acid (IAA), and abscisic acid (ABA) were reduced, whereas that of cytokinin (CTK) was increased, by foliar application of paclobutrazol (400 mg L-1, T3 treatment) relative to CK treatment during the stages of flowers and pods developing into grains.

Paclobutrazol Applications in Agriculture, Plant Tissue Cultures and Its Potential as Stress Ameliorant: A mini Review

Paclobutrazol Applications in Agriculture, Plant Tissue Cultures and Its Potential as Stress Ameliorant: A mini Review

Vegetative anatomy of three potted Chrysanthemum varieties under various paclobutrazol concentrations

Abstract. Lailaty IQ, Nugroho LH. 2021. Vegetative anatomy of three potted Chrysanthemum varieties under various paclobutrazol concentrations. Biodiversitas 22: 563-570. Chrysanthemum is one ornamental plant with high potential to be developed commercially. It has many varieties such as colors, types, and shapes of flowers. Paclobutrazol (PBZ) is one of plant growth regulators used to suppress plant growth. The PBZ action mechanism is to inhibit gibberellin synthesis. The application of PBZ with a certain concentration on Chrysanthemum plants has the potential to form potted Chrysanthemum. The aim of this study was to analyze the anatomical variation of potted mums varieties, i.e. Jaguar Red, Snow White and Fiji White, and also the effect of PBZ with various concentrations on the anatomy of the stems and leaves of three Chrysanthemum varieties. The research was conducted by applying PBZ concentrations of 0, 50, 100, 150 ppm to the three Chrysanthemum varieties and grown for 8 weeks to form potted Mums. Then, the anatomy of stems and leaves was studied using the paraffin and freehand section methods. Data analysis was performed using ANOVA and DMRT (Duncan Multiple Range Test) for anatomical characters in stems and leaves of three Chrysanthemum varieties. The results showed that the length of the epidermal cells of Fiji white variety was longer than those of Snow White and Jaguar Red. Meanwhile, Jaguar Red produced greater stem thickness, stomata, and leaf thickness than those of the other two varieties. PBZ could increase the size of the anatomical parameters of Chrysanthemum stems and leaves for all varieties. The PBZ concentration of 150 ppm increased leaf thickness and stem diameter, as well as tracheal diameter. The PBZ concentration of 100 ppm increased the size of the guard cells, palisade and spongy tissue, also peripheral tissues. Meanwhile, the PBZ concentration of 50 ppm had an effect on the increase in the number of stomata and pith diameter. The optimum PBZ concentration to form potted Chrysanthemum was 150 ppm.

Ameliorating effects of exogenous paclobutrazol and putrescine on mung bean [Vigna radiata (L.) Wilczek] under water deficit stress

Plant growth regulators play crucial roles in modulating plant response to environmental stresses. In this experiment, the effect of different doses of paclobutrazol (PBZ) and putrescine (Put), i.e., 0, 50, 100 and 150 mg/L on mung bean in two conditions of water deficit (WD) and well-watered (WW) was investigated. The seed yield decreased due to water deficit stress, while the PBZ and Put application alleviated the damage of drought stress through increasing proline and leaf chlorophyll content and improving membrane stability, and thus increased plant yield compared to untreated control plants. According to regression equations, the high PBZ levels (150 mg/L or more) and moderate levels of Put (about 90 mg/L) were determined as the optimal concentrations to maximise mung bean yield in WD conditions. In WW conditions, the mung bean responses to PBZ were inconsistent, whereas Put application positively affected some physiological traits and seed yield. In conclusion, the physiological attributes and, subsequently, the seed yield of drought-stressed mung bean plants could be improved by foliar application of PBZ and Put.

Growth and yield of sweet potato in response to the application of nitrogen rates and paclobutrazol

The excess of nitrogen (N) causes the overgrowth of sweet potato foliage, increasing the self-shading and reducing the root yield. Therefore, a combined N and paclobutrazol (PBZ) application can reduce the vegetative overgrowth and benefit the sweet potato yield. The purpose of this study was to evaluate the plant growth, yield, uptake and removal of N by sweet potato plants fertilized with N and treated with PBZ during two planting seasons. The treatments consisted of four N rates (0, 50, 100 and 200 kg·ha–1), three forms of PBZ application (PBZ-10: PBZ applied at 10 days after side-dressing N fertilization [DASNF]; PBZ-25: PBZ applied at 25 DASNF, and PBZ-10 + 25: PBZ applied at 10 plus 25 DASNF), and a control (without PBZ application). Paclobutrazol application temporarily reduced the length of the main branches of sweet potato planted in the rainy season, but it did not reduce the shoot biomass of plants in both planting seasons. A single application of PBZ at 10 DASNF increased the yield of fresh storage roots in the two planting seasons, but, during the rainy season, the increases were greater when two applications were carried out. The application of 50 kg·ha–1 N in the rainy season was sufficient to reach the maximum yield of fresh storage roots, but, in the dry season, the N fertilization increased the N uptake without benefiting the root yield.

Modified Off–Season Technology to the Flowering Time and Fruit Yield of Arumanis Mango (Mangifera indica L.)

The purpose of this study was to observe the technology of mango fruit production at off-season used growth regulators. The research was conducted with three treatments namely: i) Paclobutrazol dosage (control, 5 mL L–1 per tree, 10 mL L–1 per tree and 15 L–1 per tree). ii) Ethephon dosages (0 mL L-1 per tree, 400 mL L–1 per tree, 600 mL L–1 per tree and 800 mL L–1 per tree) that applied 1 mo after paclobutrazol addition. iii) Paclobutrazol (P) and organic fertilizer (F) application in combination as follows: (control, 5 mL + 10 kg, 10 mL + 15 kg, 15 mL + 20 kg) Randomized Completely Block Designed (RCBD) with five replications was used. The results indicated that i) Paclobutrazol application accelerated the flowering age, shortens the panicle length, and increased fruit yield of the tree. ii) Giving Ethephon accelerated the flowering period, enhanced both the panicles number and yields. The treatment of ethephones 600 mL L–1 produced the highest fruit weight, 182.60 kg, respectively iii) The Paclobutrazol and organic fertilizer application indicated significantly (p < 0.05) to the panicles number and the fruit weight yield is higher than the control.

Potted platycodon production in response to paclobutrazol

ABSTRACT Platycodon grandiflorus is an ornamental species that can be marketed as a potted flower; however, it has fragile and bending floral stems. Plant growth regulators, such as paclobutrazol, are compounds that reduce stem elongation, enabling the production of plants with a more compact formation. This study aimed to evaluate the effects of paclobutrazol on platycodon growth, in a greenhouse. A completely randomized blocks experimental design was used in a 4 × 5 factorial scheme, with four replicates. The treatments consisted of four varieties of ‘Astra Semi-Double’ platycodon (Blue, Lavender, Pink and White) and five paclobutrazol doses (0, 1.25, 2.5, 3.75 and 5.0 mg pot-1). The paclobutrazol application did not affect the stem diameter, number of leaves, days until anthesis, number of flowers or flower buds, and flower diameter. The shoot length, leaf area and shoot dry mass decreased with higher doses of the growth regulator. Lavender showed the highest values for shoot length, number of leaves, leaf area and shoot dry mass. Pink had the earliest anthesis, followed by Blue and White, whereas Lavender had the latest anthesis. The dose of 3.75 mg pot-1 of paclobutrazol efficiently controlled the growth and improved the visual quality of all the platycodon varieties.

Flowering induction in mango tree: updates, perspectives and options for organic agriculture

ABSTRACT The artificial flowering induction in mango tree is the most important crop management in mango orchards and requires greater attention from growers. The management involves three steps: stoppage of plant growth, branch maturation and flowering induction with nitrates. The first stage starts with the application of paclobutrazol to the soil. However, problems with the use of excessive concentrations are common and lead to the accumulation of residues in the soil. In addition, the use of paclobutrazol is not allowed in organic agriculture. Therefore, this review article aimed to compile information about the updates and efforts to solve these problems in conventional mango crops, as well as identify alternatives for its organic management. In conventional orchards, the application of fulvic acids in association with paclobutrazol, as an alternative to the single use of paclobutrazol, was identified as a way to improve the absorption of the product by plants and, consequently, reduce the concentrations and residues in the soil. Researches involving pruning, girdling, fertilization and irrigation should be developed as an alternative to the use of paclobutrazol for the organic crop system of mango cultivars in tropical and subtropical regions.

Efecto de densidades de población y aplicaciones de paclobutrazol en calidad de plántula y rendimiento en jitomate

he development of an alternative greenhouse tomato (Solanum lycopersicum L.) production system to obtain four annual growing cycles requires delaying transplantation from 50 to 60 days after sowing (das). The study objectives were to evaluate the effects of paclobutrazol applications and population densities in the seedbed on the quality of seedlings to be transplanted at 60 das, and on the number of flowers and yield of plants pruned to three clusters. A randomized complete block experimental design was used with a split-plot arrangement with four replicates and 16 treatments that resulted from combining two population densities (150 and 300 seedlings∙m-2) and seven paclobutrazol treatments (one, two and three applications with 25 and 50mg∙L-1 of active ingredient), plus two controls (without application). The lower density in the seedbed resulted in lower height, larger stem diameter and higher seedling dry weight at 60 das; however, at the end of the growing cycle the number of flowers and the yield per plant were lower. Triple applications of paclobutrazol, with 25 and 50 mg∙L-1, significantly decreased height and leaf area, but dry weight and stem thickness were similar to the control. Triple application of paclobutrazol resulted in two flowers and two more fruits per plant compared to the control, possibly because the temporary arrest of vegetative growth, caused by paclobutrazol, left more photoassimilates available for the inflorescences in formation.

Effects of cytokinin and paclobutrazol application time on growth and yield of G2 potato (Solanum tuberosum L.) Medians cultivar at medium altitude in Indonesia

Effects of cytokinin and paclobutrazol application time on growth and yield of G2 potato (Solanum tuberosum L.) Medians cultivar at medium altitude in Indonesia

Effect of Different Levels and Time of Application of Paclobutrazol on Morphology, Yield and Yield Attributing Characters and Economics of Groundnut (Arachis hypogaea L.)

Background: Groundnut is one of the most important oilseed crops of Odisha and grown in both in kharif and rabi-summer seasons. Because of excessive vegetative growth in kharif season, the yield potential is lower than rabi-summer resulting in low yield. Keeping this in view, an experiment was set up to investigate the effect of different concentration and time of paclobutrazol application on growth and yield of groundnut.Methods: A field experiment was conducted during kharif 2016 to 2018 at AICRP on Groundnut Research Farm, OUAT, Bhubaneswar, Odisha. The experiment was laid out in split plot design with different concentration of paclobutrazol in main plot and time of application in sub plot and replicated thrice. Recommended dose of 20:40:40 kg of N, P2O5 and K2O entirely applied as basal. Yield and yield attributing characters were taken at the time of harvest.Conclusion: Application of paclobutrazol at different concentration significantly reduced groundnut plant height and significant reduction was observed with application at 30 DAE. Among various yield attributing characters; pod/plant and pod yield increased significantly (24.6% and 27.4%, respectively) with application of paclobutrazol @ 100 ppm with higher benefit cost ratio of 1.97 and upto (8.4% and 17.5%) with application at 30 DAE.

Gibberellins are required for dimorphic flower development in Viola philippica

Photoperiod is a major determinant of chasmogamous (CH)–cleistogamous (CL) dimorphic flower development in Viola philippica, and only long-day (LD) conditions induce CL flowers. In this study, it was found that the active gibberellin (GA) content in CL floral buds was higher than in CH floral buds formed under short-day (SD) conditions, suggesting that the biosynthesis of active GAs is enhanced by a longer photoperiod and may be associated with dimorphic flower development. Thus, the next step was to molecularly characterize the key V. philippica GA synthesis genes GA 20-oxidase (VpGA20ox) and GA 3-oxidase (VpGA3ox). In terms of the expression of VpGA20ox and VpGA3ox, it was found that the active GAs could be upregulated in developing pistils under both LD and SD conditions to develop functional pistils, and GAs could also accumulate in the stamens under SD conditions. The anthers and the adjacent petals were well developed under SD conditions. In contrast, the above-mentioned floral organs displayed low GA contents under LD conditions and were poorly developed. Although the application of paclobutrazol, an inhibitor of GA synthesis, did not reverse CL development under LD conditions, exogenous GAs could partially trigger the transition from CH to CL flowers under relative SD conditions (≤12 h daylight). This was coupled with the downregulation of B-class MADS-box genes, thereby restraining stamen and petal development. Both VpGA20ox and VpGA3ox exhibited similar expression profiles with B-class MADS-box genes in the development of the stamens and petals. Therefore, in response to photoperiod, GA signaling could affect the expression of B-class homeotic genes and regulate dimorphic flower development in Viola. As a compensation for poorly-developed nectaries, anthers, and petals, filament elongation, style shortness, and inward bending could ensure self-pollination in CL flowers. This work provides new insights into the regulation of CH–CL floral development and the evolutionary significance of the formation of dimorphic flowers.

Physiological and biochemical aspects of 'Tommy Atkins' mango subjected to doses and methods of application of paclobutrazol

The paclobutrazol has been widely used to stimulate the flowering of mango trees, regulating vegetative growth and promoting changes in photosynthetic activity and in the production of photoassimilates. In this context, the objective of this study is to evaluate the effects of forms and doses of PBZ on the biochemical and physiological variables of mango, cultivar ‘Tommy Atkins,’ in the Brazilian semiarid region. The experimental design was randomized blocks in a 5 x 2 + 1 factorial design with the first factor was paclobutrazol doses applied by irrigation (0.5, 1.0, 1.5, 2.0 and 2.5 g a.i.-1, linear canopy); the second factor was two phases of collection (vegetative and flowering), and an additional treatment (control) with the application of a dose in the conventional form (2.0 g a.i.-1 linear canopy applied manually by haul), and four replications. The variables analyzed were levels of total soluble sugars, reducing sugars, non-reducing sugars, total amino acids, total soluble proteins, liquid photosynthesis, stomatal conductance, transpiration, and leaf temperature. The application of PBZ by fertigation proved more efficient than the conventional application, allowing a greater assimilation of the product by the plant and the reduction of the dose. Most biochemical characteristics showed the highest values by applying lower doses of paclobutrazol. The increase in paclobutrazol doses applied by irrigation system reduced the gas exchange of the ‘Tommy Atkins’ cultivar.

Water‐use efficiency of maize may be increased by the plant growth regulator paclobutrazol

AbstractContradictory results of the paclobutrazol (PAC) effect on maize plants were obtained under semiarid compared to well‐watered conditions with grain yield improvements versus depressions, respectively. In addition, maize cultivars differed in their reactions to similar PAC dosages. Thus, in the present study PAC was applied in the appropriate dosage at growth stage V5 to six maize cultivars (Zea mays L. cvs. Amanova, Severeen, Hubble, Galactus, Fabregas, Pioneer 3906) grown in a container experiment under well‐watered conditions. PAC caused significant decreases in plant height, increases in culm diameter and reduced transpiration rates in comparison with the untreated control plants. At anthesis, start and duration of pollen production, start of silking and anthesis‐silking interval (ASI) were mostly unaffected by PAC application. Senescence of PAC‐treated plants was delayed by one week. Apart from cultivar Galactus, PAC treatment caused significant grain yield reductions between 9% and 20%, which were solely based on decreases in kernel number because higher single kernel weights were obtained. In all cultivars, reductions in straw yield of 28% to 49% were achieved with PAC application, which were responsible for significant improvements of the harvest index by 8%–36%. PAC‐treated plants showed reduced water consumption (11%–21%), resulting in significantly improved WUEgrain during the critical period of kernel setting of the cultivars Amanova, Severeen, Galactus and Fabregas. The results indicate that PAC treatment of maize plants bears several advantages such as reduced water demand and improved water‐use efficiency (WUE), higher mechanical strength of the stalk and an enhanced harvest index. Possible grain yield decreases per plant under well‐watered conditions could be counteracted by moderate increases in plant density, yet concurrently this might diminish some of the beneficial PAC effects.

Growth and Anatomical Responses of Gogo Rice Plant (Oryza sativa L.) Var. Inpago Unsoed 1 to Paclobutrazol Application

The improvement of gogo rice production in dryland is constrained by its extraordinary height, which leads to falling, and its long lifespan. The shorter gogo rice plant can be obtained through growth inhibition using paclobutrazol. Gogo rice plant var. Inpago Unsoed 1 was used during the study. An experimental study was performed using factorial completely randomized design. The main factor was four paclobutrazol concentrations (0,100, 200, and 300 ppm). The sub-main factor was paclobutrazol application time after planting (three, four, and five weeks). The results showed that the interaction between paclobutrazol concentration and application time was highly significantly affecting plant height. The most appropriate treatment resulting in optimum plant height was the combination of 100 ppm paclobutrazol applied four weeks after planting. Interaction between paclobutrazol concentration and application time also significantly affect stem diameter, leaf width, and stomata number in the lower leaf epidermis. However, there was no significant effect of paclobutrazol observed on stomata size. The significant result of the combination of paclobutrazol concentration and the application time was also supporting tissue thickness. The thickest tissue was obtained by 300 ppm of paclobutrazol applied five weeks after plantation.

Paclobutrazol mediated changes in growth and physio-biochemical traits of okra (Abelmoschus esculentus L.) grown under drought stress

A field experiment was done to determine the response of okra to foliar application of Paclobutrazol (PBZ) under drought stress conditions. Two okra cultivars (Nutec and Ganga), four levels of PBZ (0, 20, 40 and 80 ppm) and two water stress levels (irrigation-based) were used. The experiment was laid out in randomized complete block design. Both treatments (PBZ and drought stress) were applied to 14-days old okra seedlings simultaneously. For the statistical analysis and graphical representation of the obtained results, a software COSTAT and Microsoft excel was used. Okra plants were harvested after two weeks of treatment applications. Different morphological parameters; growth, pigments, water relative content, electrolyte leakage, enzymatic and non-enzymatic antioxidant and yield parameters were determined and comparisons were made among the varied treatments of PBZ on okra cultivars under both control and drought stress conditions. It was observed that Paclobutrazol has enhanced the growth attributes except for shoot length. Among cultivars, Nutech showed a better response to stress changes. Paclobutrazol also enhanced the yield per plant with no effect on the 100-seed dry weight. In conclusion, Paclobutrazol had a positive effect on growth and contributed to drought stress tolerance in okra cultivars.

Про роботу Вінницького регіонального відділення Українського товариства фізіологів рослин

The work and the main scientific results of the Vinnytsia branch of the USPP from the moment of its formation to the present time are analyzed. The main direction of research is exogenous regulation of plants source-sink relations in the systems «photosynthesis—growth», «depot of assimilates—growth» in the heterotrophic phase of plant development, and «macrosymbiont—microsymbiont» in symbiotic nitrogen fixation systems. Gibberellin and antigibberellin preparations (retardants) were used to create different tension of source-sink relations. It was found that under the influence of retardants, the decrease in the linear growth rate was accompanied by an increase in the cytokinins content with a decrease in the indoleacetic acid content in stems and leaves tissues of a wide range of plants. The free gibberellins activity was lower compared to control. At the same time, the content of these phytohormones antagonist, abscisic acid, increased. The retardants increased the stem branching, leaves number, weight and leaf surface area, optimized the leaves mesostructural organization, resulting in an increase in the photosynthetic net productivity. These changes lead to increased crop productivity. Under the conditions of artificial combination of external (light/dark) and hormonal factors (gibberellic acid and retardants) during seed germination, changes in the functioning of the source-sink system in the heterotrophic stage of plant development from seeds with different reserve substances types were studied. Gibberellin stimulated the starch breakdown in both light and dark, but under conditions of germination in the dark, the rate of reserve seed starch use was higher. Gibberellin also stimulated the seed reserve proteins hydrolysis, but the process began after intensive starch hydrolysis. Peculiarities of regulation of source-sink relations in the system «macro—microsymbiont» during the processes of symbiotic nitrogen fixation under the action of antigibberellin preparations — retardants are revealed. It was found that the typical reaction of soybean plants to the paclobutrazol application was a decrease in the free form gibberellins activity and an increase in the abscisic acid content, which led to changes in morphogenesis. Under the retardants action, the processes of formation of the symbiotic complex «soybean—Bradyrhizobium japonicum» intensify, nitrogenase activity increased, crop yield rised.

Zinc and Paclobutrazol Mediated Regulation of Growth, Upregulating Antioxidant Aptitude and Plant Productivity of Pea Plants under Salinity.

Soil salinity is the main obstacle to worldwide sustainable productivity and food security. Zinc sulfate (Zn) and paclobutrazol (PBZ) as a cost-effective agent, has multiple biochemical functions in plant productivity. Meanwhile, their synergistic effects on inducing salt tolerance are indecisive and not often reported. A pot experiment was done for evaluating the defensive function of Zn (100 mg/L) or PBZ (200 mg/L) on salt (0, 50, 100 mM NaCl) affected pea plant growth, photosynthetic pigment, ions, antioxidant capacity, and yield. Salinity stress significantly reduces all growth and yield attributes of pea plants relative to nonsalinized treatment. This reduction was accompanied by a decline in chlorophyll, nitrogen, phosphorus, and potassium (K+), the ratio between K+ and sodium (Na+), as well as reduced glutathione (GSH) and glutathione reductase (GR). Alternatively, salinity increased Na+, carotenoid (CAR), proline (PRO), ascorbic acid (AsA), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) over nonsalinized treatment. Foliar spraying with Zn and PBZ under normal condition increased plant growth, nitrogen, phosphorus, potassium, K+/Na+ ratio, CAR, PRO, AsA, GSH, APX, GR, and yield and its quality, meanwhile decreased Na+ over nonsprayed plants. Application of Zn and PBZ counteracted the harmful effects of salinity on pea plants, by upregulating the antioxidant system, ion homeostasis, and improving chlorophyll biosynthesis that induced plant growth and yield components. In conclusion, Zn plus PBZ application at 30 and 45 days from sowing offset the injuries of salinity on pea plant growth and yield by upregulating the antioxidant capacity and increasing photosynthetic pigments.

Effect of soil applied paclobutrazol on chemical quality of Litchi (Litchi chinensis Sonn.) cv. rose scented

Paclobutrazol is a plant growth retardant and triazole fungicide has been reported to be very effective for dwarfing a wide range of crops including litchi. It is a cell elongation and internode extension inhibitor that retards plant growth by inhibition of gibberellins biosynthesis. The effect of paclobutrazol at varying time intervals of litchi as soil drench application (1.00-4.00 g a.i. per meter canopy diameter) was investigated during 2016-18 in Pantnagar condition. The Chemical quality of litchi was significantly increased due to higher dose of paclobutrazol (2.0-4.0 g a.i./meter canopy diameter). Application of paclobutrazol at the rate 2.0, 3.0 a.i./tree through soil application method was noted to be more efficient in increasing Ascorbic acid, Total soluble solids, Total sugar, and Anthocyanin. The paclobutrazol applied at the rate 40 ml/tree was the most effective in increasing the Ascorbic acid (27.29 mg/100gm) followed by 60 ml/tree (27.15 mg/100g), while the minimum Ascorbic acid was recorded under control (25.37 mg/100gm). The application of paclobutrazol @ 40 ml/tree, the Titratable acidity of litchi tree was found to be minimum (0.49%) as compared to control (0.54 %). In different time intervals the D2 (October) estimated the minimum titratable acidity (0.51%) followed by D2 (October), while the maximum titratable acidity was noted under D3 (0.53%).The main purpose of this study is to focus upon contemporary information about paclobutrazol in litchi growth.

Foliar Paclobutrazol Application Suppresses Olive Tree Growth While Promoting Fruit Set

In some agricultural practices, application of plant growth regulators is very useful as an efficient means to modulate olive tree vigour to optimize fruit production. However, the physiological mechanisms underlying these effects are still poorly understood. Here, we evaluated the effectiveness of paclobutrazol, chlormequat and prohexadione on the modulation of vegetative growth and fruit set, with a special emphasis on the underlying effects exerted by phytohormones, in one-year-old olive trees (Olea europea cv. Arbosana). Paclobutrazol and chlormequat were tested using both foliar spraying and soil irrigation, while prohexadione was applied by foliar spraying only, and all treatments were compared to a control. Among treatments, paclobutrazol and chlormequat were the most effective in promoting vegetative growth retardation, when applied through foliar spray. Growth retardation by foliar application of paclobutrazol was associated with proline accumulation and reduced gibberellin contents in leaves. Furthermore, hormonal profiling revealed that not only all treatments were effective in reducing the endogenous contents of gibberellins, but also that the entire hormonal profiling was altered upon treatments. It is concluded that (i) various plant growth regulators can be effectively used to control olive tree growth, and (ii) paclobutrazol seems to be more efficient on vegetative growth retardation than the other tested treatments, being foliar application more effective than soil treatment.