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This study aims to determine the best interaction of potassium (K) fertilizer dose and retardant concentration on the growth, yield, and seed quality of G0 potato grown in the medium land of Jantinangor. The experiment was conducted at Screen House Station Ciparanje, Jatinangor, Faculty of Agriculture Universitas Padjadjaran from November 2022 until January 2023 at an elevation of ± 685 meters above sea level. The experimental design used was the Factorial Randomized Block Design (RBD). The first factor was the K fertilizer dose including 50%, 100%, and 150%. The second was the retardant concentration including without retardant, 100 ppm paclobutrazol, 100 ppm prohexadione-Ca, and 150 ppm prohexadione-Ca. The experimental results showed that there was an interaction effect between the K dose and retardant concentration. The interaction effect of 150% K and 100 ppm prohexadione-Ca showed the highest percentage of L class seed tuber and the lowest tuber weight loss. Independently, 150% K improved growth rate, number of tubers (6.67 knol/plant), and weight of tubers (73.33 g/plant). Independently, 100 ppm paclobutrazol concentration increased the chlorophyll content index. 150 ppm prohexadione-Ca concentration suppressed leaf area and plant height but increased stomatal conductance, fast emergence shoot time, and shoot length. 100 ppm prohexadione-Ca concentration produced the highest number of tubers and the weight of tubers, i.e., 6.78 knol/plant and 74.33 g/plant, respectively. [ABSTRACT FROM AUTHOR]

Increasing shoot branch numbers of Chrysanthemum morifolium Ramat cv. Hangbaiju (Hangbaiju) is crucial for producing high flower yields. Pot experiments were designed to evaluate the effects of foliar application of 6-benzylaminopurine (6-BA) combined with prohexadione-Ca (Pro-Ca) on the yield and quality of Hangbaiju flowers. Foliar application of 6-BA combined with Pro-Ca typically increased leaf chlorophyll content and decreased leaf soluble sugar and soluble protein contents throughout the floral organ growth phase. At the bud formation phenophase stage (August), the contents of gibberellin (GA), indole-3-acetic acid (IAA), and zeatin (ZA) decreased (except for GA content in the 10 mg L−1 6-BA combined with 100 mg L−1 Pro-Ca treatment), but abscisic acid (ABA) content increased. The yield of Hangbaiju flowers was found higher in plants treated with foliar application of 6-BA combined with Pro-Ca. Higher yields were found in the 6-BA5 + Ca100 and 6-BA10 + Ca100 treatments than in the 6-BA5 + Ca50 and 6-BA10 + Ca50 treatments, and the highest yield was observed in the 6-Ba5 + Ca100 treatment both in 2019 and 2020. Nutritional indices such as soluble sugar, soluble protein, total amino acid, and water extract increased, and medicinal indices such as flavonoid, total phenolics, chlorogenic acid, cynaroside, and 3,5-dicaffeoyl quinic acid slightly decreased after foliar application of 6-BA combined with Pro-Ca; however, they were all higher than the standards recorded in the Chinese Pharmacopeia. Overall, foliar application of 6-BA combined with Pro-Ca could increase the yield and nutritional quality of Hangbaiju flowers, enhancing its tea quality. [ABSTRACT FROM AUTHOR]

BACKGROUND The gibberellins (GAs) GA5 (inhibitor of GA3‐oxidase), GA4 (biologically active), GA4/7 (commercially available mixture of Ga4 and GA7) prohexadione‐calcium (ProCa, inhibitor of dioxygenases that render GAs bioactive, negative control), and GA3 (positive control) were applied to bunches of Vitis vinifera cv. Malbec. Different techniques, doses, and timings were used in a 3‐year field experiment. In year 1, GA5, ProCa, and GA3 were applied at 35, 20, and 0 days before veraison (DBV) by dipping bunches three times. In year 2, single applications of GA5 and GA3, also by immersion, were tested at 60, 45, and 30 DBV. In year 3, applications at 60 and 30 DBV of GA5, GA4, and a mixture of GA4/7 were evaluated by dipping or spraying the bunches. RESULTS: Vegetative growth, berry weight, and sugar content were unaffected by treatments. ProCa did not affect the yield with respect to water control, although it reduced the levels of phenolics in berry skins, an undesirable effect for winemaking. GA5, in the dose range 5–50 mg L−1, raised berry numbers, thereby augmenting bunch weight and skin phenolics at harvest, so increasing berry quality for winemaking. GA4 and GA4/7 produced similar benefits to GA5, with similar doses. CONCLUSION: The applications of GA5, GA4, and GA4/7 to developing grape berry bunches, in a range of concentrations and by dipping or spraying, increased berry numbers per bunch at harvest. The method can be used as a viticultural practice to improve the production and quality of wine grapes. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The key to high productivity of plants, especially cereals, is to control lodging of cereals. Among the derivatives of acylcyclohexadiones (ACHD), highly effective retardants have been invented, which are widely used in modern crop production to control the lodging of cereals, mainly winter wheat, spring and winter wheat, winter, spring and hybrids of barley. The mechanisms of influence of ACHD derivatives – trinexapac-ethyl and prohexadione-Ca on plants and features of their application in technologies of cultivation of cultivated plants are considered. By using a composition of ACHD derivatives with a number of agrochemicals, enhancement of retardant activity is achieved. Given the identified varietal variability of the effectiveness of the use of ACHD derivatives in cereals, it is advisable to conduct registration and post-registration studies primarily on varieties that occupy the largest sown areas in the country. The peculiarities of ACHD derivatives’ influence on stem components as the main one, along with the flag leaf, carbon pool for grain filling in the ear and possible reasons for the lack of productivity increase of grain crops due to ACHD derivatives are also considered. This class of substances continues to be widely studied in the world and remains among the most promising for the development of new agrochemicals and drugs.

Growth regulation of apple trees is an important measurement to guarantee a constant yield and good fruit quality. In two different trials at Laimburg Research Centre, few methods of growth regulation were evaluated. With the commercial product Paclot New, the active agent paclobutrazol - well known in the past as the commercial product Cultar - was also evaluated. Despite positive results in the past with paclobutrazol, in these two trials no effect of growth inhibition was observed. Only the treatments with prohexadione-Ca could reduce the shoot growth significantly in comparison with the untreated control. Moreover, the root pruning and treatments with paclobutrazol reduced the fruit size significantly in some years. No residues of paclobutrazol were detected during the trials; only in the leaf and shoots and one single year in the soil residues were found.

Increasing shoot branch numbers of Chrysanthemum morifolium Ramat cv. Hangbaiju (Hangbaiju) is crucial for producing high flower yields. Pot experiments were designed to evaluate the effects of foliar application of 6-benzylaminopurine (6-BA) combined with prohexadione-Ca (Pro-Ca) on the yield and quality of Hangbaiju flowers. Foliar application of 6-BA combined with Pro-Ca typically increased leaf chlorophyll content and decreased leaf soluble sugar and soluble protein contents throughout the floral organ growth phase. At the bud formation phenophase stage (August), the contents of gibberellin (GA), indole-3-acetic acid (IAA), and zeatin (ZA) decreased (except for GA content in the 10 mg L−1 6-BA combined with 100 mg L−1 Pro-Ca treatment), but abscisic acid (ABA) content increased. The yield of Hangbaiju flowers was found higher in plants treated with foliar application of 6-BA combined with Pro-Ca. Higher yields were found in the 6-BA5 + Ca100 and 6-BA10 + Ca100 treatments than in the 6-BA5 + Ca50 and 6-BA10 + Ca50 treatments, and the highest yield was observed in the 6-Ba5 + Ca100 treatment both in 2019 and 2020. Nutritional indices such as soluble sugar, soluble protein, total amino acid, and water extract increased, and medicinal indices such as flavonoid, total phenolics, chlorogenic acid, cynaroside, and 3,5-dicaffeoyl quinic acid slightly decreased after foliar application of 6-BA combined with Pro-Ca; however, they were all higher than the standards recorded in the Chinese Pharmacopeia. Overall, foliar application of 6-BA combined with Pro-Ca could increase the yield and nutritional quality of Hangbaiju flowers, enhancing its tea quality.

Fire blight of apples (Erwinia amylovora) can be a serious disease depending on production area and year. Bloom is the most frequent starting point for infection and the primary focus for sprays which can prevent infection, or of growth regulators such as prohexadione-Ca (ProCa) to limit spread. Because of the sporadic cases, many growers opt to forego bloom sprays when disease pressure is low. When symptoms do appear, quickly pruning out affected branches is currently the most effective control measure. Our goal was to determine if ProCa applied when symptoms appear, instead of during bloom when infection risks are predicted, could be used to limit disease spread, and if this would interact with summer symptom removal. The study was carried out in 2018 and 2019 at the IRDA orchard in Saint-Bruno-de-Montarville, Québec. Plots inoculated during bloom were allocated to treatments in which diseased branches were either pruned during summer or only in winter, and trees sprayed with ProCa starting at bloom, when symptoms appeared, or not. Potential for disease progression was assessed by inoculating shoots and rating them for disease severity and ooze production. Significantly less wood was removed from trees pruned during the summer as opposed to winter, but total yield was reduced. ProCa had no effect on the amount of dead wood pruned, but still reduced disease severity. We found that ProCa reduced ooze on inoculated shoots and that post symptom timing was as effective as the bloom spray. Delaying sprays until symptoms appear could become an alternative strategy to reduce summer spread of fire blight. [ABSTRACT FROM AUTHOR]

A study was conducted on effect of various bio-regulators and girdling on winter flushing, flowering intensity, fruit yield and quality of litchi cv. China. The experimental results revealed that winter flushing was inhibited by girdling (removal of bark at 3mm width in 75 % branches] and application of paclobutrazol (PBZ). The number of floral panicles per tree was highest due to spray of KNO3 and prohexadione-Ca (207.50 and 206.17 respectively), while least in control trees (109.16). The fruit retention, average fruit weight was insignificant amongst the treatments. Spray of KNO3 during September end, led to highest yield in terms of number of fruits per tree (2,427) and in weight (55.42 kg per tree). The control trees had only 35 fruit per tree (i.e., 0.80 kg per tree). KNO3 also led to highest pulp percent (65.35 %) of the fruits. Spray of salicylic acid caused highest fruit ascorbic acid (29.26mg/100g pulp) and highest total sugar (22.4 %) of the fruit. Besides lowest yield, the least pulp content (50.61 %), total anthocyanin content (6.15 mg per 100 g pulp), total sugar (11.80 %) and reducing sugar (9.03 %) were observed in control trees. The highest TSS (22.60° Brix) and TSS/acidity ratio (66.97) of the fruits were recorded in paclobutrazol applied trees while least titratable acidity was found after spray of prohexadione-calcium. Thus, spray of KNO3 (2.0 %) was able to record highest yield and pulp content in litchi cv. China while salicylic acid @ 2000 ppm application was found very effective for improving fruit quality attributing characters. Girdling and spray of prohexadione- Ca in litchi tree can also be an effective intervention for yield enhancement. [ABSTRACT FROM AUTHOR]

Stevia (Stevia rebaudiana Bertoni) is a source of steviol glycoside, a natural sweetener which has almost zero calorie and glycemic index. Steviol glycoside shares the same precursor with gibberellin (GA), ent-kaurenoic acid. Therefore, to manipulate the biosynthesis pathway of steviol glycoside, a gradient of late-stage GA biosynthesis inhibitors, Daminozide and Prohexadione-Ca, was applied to the thin-layer liquid culture of stevia, which was 10 mL of liquid medium in the 100-mL Erlenmeyer flask. The culture was incubated for 3 weeks, followed by the observation of growth parameters and steviol glycoside content. Results showed that both Daminozide and Prohexadione-Ca significantly increased the steviol glycoside content, indicating that the disruption of GA biosynthesis could divert the metabolic pathway toward steviol glycoside production. However, the inhibition effect of Prohexadione-Ca was stronger than Daminozide, and caused poor growth of stevia plantlets. Therefore, Daminozide at the concentrations of 10 ppm and 20 ppm was potential to modulate steviol glycoside production from the stevia culture. [ABSTRACT FROM AUTHOR]

The influence of different concentrations of some bioregulators by foliar application {methyl jasmonate (MJ) and Prohexadione- Ca (Pro-Ca)} on growth, pigment content and volatile oil composition and radical scavenging activity of onion plant were accomplished during two consecutive seasons. The obtained results indicated that foliar application of MJ (at 150mg/l) or Pro-Ca at (30 ppm), significantly promoted onion growth and quality as height, branches number and leaves weights for new and dry onion leaves, crisp and dry loads of branches and yield (g/plant). On the other hand, MJ application led to noteworthy decrease in the plant height at all the used treatments. A significant increase in mineral ions content of the produced onion seeds by foliar application of MJ and Pro-Ca at all the used levels. All the usages of bioregulators produced positive modifications in the photosynthetic pigments as well as yield and oil content of onion plants. Based on the finding, it is recommended the use of MJ and Pro-Ca twice, at the rate of 100 and 20 ppm, respectively for higher onion yield /acre (AC). Moreover, GC/MS analysis shown that the chief identified constituents of volatile oil of onion treated with MJ and Pro-Ca were 4-Mercaptononan-2-ol, 3-Mercaptononyl acetate, Diallyl thiosulfinate, 4-Mercaptononan-2-one, Diallyl trisulphide, 2- Heptyl thiophene, Methyl propyl trisulphide, 1,3-Propanedithiol, 3,5-Diethyl-1,2,4 trithiolane and 3,5-Methyl ethyl- 1,2,4,trithiolane. MJ and Pro-Ca usages caused qualitative alterations in these components of onion volatile oil. In addition, the bioregulators used caused significant variation in the free radical scavenging effect measured by DPPH and B- carotene assays of onion volatile oil compared to TBHQ. [ABSTRACT FROM AUTHOR]

Effect in reducing maize plant height using growth regulators ethephon, chlormequat chloride (CCC), CCC + ethephon, and mepiquat chloride + prohexadione-Ca was studied in field experiments during 2010 and 2011. It was found that maize plant height could be reduced by as much as 125 cm (49% of control) using a double application of ethephon (576 g a.i./ha) at growth stages BBCH 18-19 and BBCH 34-36. The other growth regulators displayed weak or no influence. An optimum level of shortening was achieved using ethephon (576 g a.i./ha) at BBCH 34-36 (reducing plant height by 40-90 cm), but it is necessary to count upon yield loss of 0.5-0.6 t/ha.

Malus 3domestica Borkh. cv. Honeycrisp has been widely planted in North America during the past two decades. However, it is susceptible to many disorders that result in high postharvest losses. Excessive vegetative vigor in apple trees can reduce fruit calcium (Ca) concentrations and increase bitter pit incidence in apple fruit. Plant growth regulators are used routinely in tree fruit orchards to control vegetative growth to increase light penetration into the canopy. The objective of this study was to determine whether shoot growth inhibition using the application of prohexadione-calcium (P-Ca; Apogee®) or stimulation via application of gibberellic acid (GA3; ProGibb®) affected bitter pit incidence in 'Honeycrisp' apple. In 2016 and 2017, the experiment was conducted in a commercial 'Honeycrisp' orchard with five treatments [untreated control, 62.5 mg·L-1 P-Ca (low P-Ca); 125 mg·L-1 P-Ca (high P-Ca); 16 mg·L-1 GA3 (low GA3); and 32 mg·L-1 GA3 (high GA3)]. Treatments were applied twice during the growing season. Shoot length and the number of internodes for new growth were measured 4 weeks apart after treatment. Overall yield and fruit quality were assessed at harvest, and bitter pit incidence was assessed after 4 months of storage. Low and high PCa rates limited shoot growth extension; high GA3 increased shoot extension compared with the untreated control. However, the number of internodes did not change substantially for each shoot. The number of internodes is one of the primary factors affecting leaf area and, consequently, the transpiration balance between fruit and leaves. In both years, treatments with either GA3 or P-Ca did not affect fruit elemental concentration or bitter pit incidence. These results indicate that growth-inhibiting plant growth regulators that reduce shoot extension may not be useful for managing bitter pit incidence in 'Honeycrisp' apple. [ABSTRACT FROM AUTHOR]

The bacterial antagonists (Bacillus subtilis GB03, B. subtilis QST713, B. subtilis Y1336 and Pantoea agglomerans P10c) and plant defense activators (acibenzolar-S-methyl (ASM), fosetyl aluminium (F-Al), potassium phosphites (PH) and prohexadione-Ca (ProCa)) were evaluated individually and in combination for efficacy in controlling fire blight in Morocco. Under laboratory conditions, on detached blossoms of apple and pear, only biocontrol treatments based on P. agglomerans P10c and their mixture with B. subtilis QST713 showed a significant reduction in the incidence of the disease when compared to other treatments. Under field conditions, both the above mixture of biocontrol agents as well as all other strains were tested alone or combined with plant defense activators using a split-split-plot design. The treatments were applied on the trees at timings based on their modes of action. Results showed that, when used alone, P. agglomerans P10c, B. subtilis QST713, their mixture (1:1), B. subtilis GB03 and B. subtilis Y1336 reduced blossom infection under field conditions by 66, 63.8, 61.7, 64.2, and 53% respectively. For plant defense activators this reduction was 61.5, 56.6, 50 and 49% for ASM, ProCa, F-Al and PH, respectively. On shoots, it ranged from 40 to 80% for biocontrol agents, but for plant defense activators it varied from 46 to 96.5%. Two individual applications of ProCa were the most effective treatment for reducing shoot blight incidence. The combination of plant defense activators and biocontrol agents allowed the highest protection rate against blossom and shoot blight ranging from 76 to 98.2%. The greatest protection was insured by B. subtilis QST713, P. agglomerans P10c or their mixture combined with ASM or ProCa. [ABSTRACT FROM AUTHOR]

O paclobutrazol é utilizado para o manejo da produção de manga na maioria dos pomares, com aplicação no solo, o que contribui para a maior persistência no ambiente. Assim, este trabalho teve como objetivo avaliar o efeito de reguladores de crescimento vegetal aplicado via foliar, prohexadione-Ca, etil-trinexapac e cloreto de chlormequat, e via solo, paclobutrazol, no controle da brotação vegetativa e na floração de mangueiras 'Kent'. O experimento foi conduzido na região do Vale do São Francisco, em Petrolina-PE, no período de dezembro de 2007 a julho de 2008, em mangueiras cultivadas no espaçamento de 8 m nas entrelinhas e 5 m entre plantas. Foram avaliados os efeitos dos tratamentos com reguladores vegetais aplicados via foliar e via solo, com relação ao vigor (número, comprimento e número de folhas dos novos fluxos vegetativos) e à floração (percentagem e comprimento das panículas). Verificou-se que o tratamento com paclobutrazol, combinado com o prohexadione-Ca, foi mais eficiente no controle do crescimento vegetativo dos ramos da mangueira 'Kent', mas não com relação à floração, em que não foram observadas diferenças siginificativas entre os tratamentos.

A mangicultura no semiárido brasileiro destaca-se pelos altos rendimentos, pela qualidade do fruto produzido e pela possibilidade de produção durante todo o ano, devido a condições climáticas e tecnologias para o manejo do crescimento vegetativo e da floração, com uso da irrigação, podas e retardantes vegetais. O paclobutrazol aplicado ao solo é utilizado no manejo da produção da mangueira na maioria dos pomares. Entretanto, há a necessidade de identificar retardantes vegetais que possam ser aplicados via foliar, de forma a minimizar os resíduos no solo e evitar o uso de quantidades inadequadas ao longo dos anos. Assim, este trabalho teve como objetivo avaliar retardantes vegetais aplicados via foliar na inibição do crescimento vegetativo de mudas de mangueira 'Tommy Atkins'. Prohexadione-Ca, etil-trinexapac e cloreto de chlormequat, aplicados via foliar, na dose de 1g i.a. planta-1, regulam o crescimento de ramos vegetativos, mas apresentam tempo diferenciado de atividade nas mudas, sendo 20 dias para prohexadione-Ca, 30 dias para cloreto de chlormequat e 45 dias para etil-trinexapac, nas condições em que o experimento foi conduzido.The mango in the Brazilian semi-arid region stands out in the national scenario due to high yields and fruit quality, as well as to the possibility of all-year production due to climatic conditions and technologies which allow the management of plant growth and flowering through irrigation, pruning and use of plant growth regulators. Paclobutrazol applied to the soil is used for the production management of mangoes in most of the orchards. However, it is necessary to identify plant growth regulators which might be applied to the leaves, so as to minimize the risk of residues in the soil and to avoid inadequate application levels over several years. The present paper aimed at evaluating the effect of plant growth regulators applied to the leaves, regarding their efficiency for flowering management of mango 'Tommy Atkins'. Prohexadione-Ca, trinexapac-ethyl and chlormequat chloride at the dosage of 1.0 g a.i. plant-1 acts on the regulation of vegetative growth; the period of efficiency of the products applied to the leaves lasted 20 days for prohexadione-Ca, 30 days for chlormequat cloride, and 45 days for trinexapac-ethyl.

Iris germanicaL. is a popular perennial flower worldwide, but its use is limited in China due to an inadequate availability of propagules. To accelerate rhizome growth and lateral bud production using plant growth retardants (PGRs), chlorocholine chloride (CCC; at 1,500 or 3,000 mg l−1) or prohexadione-Ca (at 700 or 1,500 mg l−1) were applied to uniform plants ofI. germanica. Time-course measurements of changes in morphogenesis, carbohydrate metabolism, total soluble protein (TSP) concentrations, and endogenous phytohormone concentrations in rhizomes were conducted to test the efficacy of CCC or prohexadione-Ca for increasing rhizome growth and lateral bud production. The results showed that both PGRs increased the fresh weights of rhizomes at 2, 4, and 6 weeks after treatment (WAT). Overall, 700 mg l−1prohexadione-Ca was most effective at promoting the formation of lateral buds which increased by 183.5% at 12 WAT relative to untreated control plants. Concentrations of sucrose and starch in PGR-treated rhizomes increased at 2, 4, and 6 WAT, while a decline was observed by 12 WAT. TSP concentrations increased during rhizome enlargement, then decreased during lateral bud germination after prohexadione-Ca treatment. In general, concentrations of endogenous phytohormones, such as gibberellins, indole-3-acetic acid, jasmonic acid, and zeatin riboside, decreased significantly in rhizomes at 4 WAT, then increased at 12 WAT. Our study indicated that prohexadione-Ca promoted rhizome growth and the accumulation of sucrose and starch before summer dormancy, then significantly accelerated the production of lateral buds. [ABSTRACT FROM PUBLISHER]

The effect of retardant Prohexadione-Ca (BAS 125 10W, BASF Corp., Germany) and heavy metal copper on growth and endogenous concentrations of free and conjugated putrescine, spermidine and spermine in roots and leaves of pea plants were investigated. It was found that the polyamine concentrations increased seven days after the treatments. Most considerable increase of polyamines was detected in plants treated with copper and Prohexadione-Ca. The variations in polyamine concentrations in leaves and roots of pea plants suggest that Prohexadione-Ca had a protective effect against Cu stress of pea plants, which was expressed by additional accumulation of polyamines. [ABSTRACT FROM AUTHOR]

Effect in reducing maize plant height using growth regulators ethephon, chlormequat chloride (CCC), CCC + ethephon, and mepiquat chloride + prohexadione-Ca was studied in field experiments during 2010 and 2011. It was found that maize plant height could be reduced by as much as 125 cm (49% of control) using a double application of ethephon (576 g a.i./ha) at growth stages BBCH 18-19 and BBCH 34-36. The other growth regulators displayed weak or no influence. An optimum level of shortening was achieved using ethephon (576 g a.i./ha) at BBCH 34-36 (reducing plant height by 40-90 cm), but it is necessary to count upon yield loss of 0.5-0.6 t/ha. [ABSTRACT FROM AUTHOR]

Although melatonin biosynthetic genes from plants have been cloned, the melatonin catabolism mechanisms remain unclear. To clone the genes responsible for melatonin metabolism, we ectopically expressed 35 full-length cDNAs of rice 2-oxoglutarate-dependent dioxygenase (2- ODD) in Escherichia coli and purified the corresponding recombinant proteins. In vitro 2- ODD assays showed four independent 2- ODD proteins that were able to catalyze melatonin into 2-hydroxymelatonin, exhibiting melatonin 2-hydroxylase (M2H). These M2H proteins had peak activities at pH 8.0 and 30°C. The Km ranged from 121 μ m to 371 μ m with the Vmax ranging from 1.7 to 18.5 pkat/mg protein, respectively. The M2H enzyme activities were dependent on cofactors such as α-ketoglutarate, ascorbate, and Fe2+, similar to the 2- ODD enzymes. M2H activity was inhibited by prohexadione-Ca, an inhibitor of 2- ODD, in a dose-dependent manner. M2H activity was high in the roots of rice seedlings, concurrent with high transcription levels of 2- ODD 21, suggesting that 2- ODD 21 was a major gene for M2H activity. Analogous to the high M2H activity in the roots, 2-hydroxymelatonin was found in large quantities in roots treated with melatonin. These results suggest that melatonin was metabolized into 2-hydroxymelatonin by the M2H genes in plants, but the physiological significance of 2-hydroxymelatonin remains to be examined in the future. [ABSTRACT FROM AUTHOR]

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

Bacterial canker of tomato caused by Clavibacter michiganensis subsp. michiganensis produces considerable economic losses in many countries because effective control measures are lacking. In this study, the effectiveness of some chemicals, a plant growth regulator (Prohexadione-Ca (PC)), two plant activators (hydrogen peroxide (HP)) and harpin protein (Hrp), fungicides, maneb+copper (MC), copper compounds (copper sulfate pentahydrate (CSP) copper hydroxide (CH) and copper oxychloride (CO)) and an antibiotic, streptomycin sulphate on the pathogen were assessed in vitro and in vivo on two tomato cultivars, Newton and Orient. In Hrp and HP treated plants, reduction in disease severity (about 45%) was correlated with suppression of bacterial growth during the time course of infection. The activities of POX, GPX and PAL enzymes were determined at 5th day as markers of resistance and applications of Hrp, PC and HP induced a progressive and significant increase of both enzymes in locally treated tissues. Only PC treatments have decreased plant heights and the effectiveness of PC in reduction of plant heigths was up to 40%. Among copper compounds, CSP and CO combination with Maneb were the most effective on the disease severity (about 50%). In addition, CSP combination with Hrp, HP and PC significantly limited the pathogen population in vitro and they showed considerable effects on the disease symptoms compared with CSP alone. We conclude that Hrp, HP and PC may be useful in controlling external symptoms of this disease in greenhouses, and is environmentally friendly, reducing the amount of copper applied to crops. [ABSTRACT FROM AUTHOR]

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

Abstract: The effect of foliar application of prohexadione-calcium (ProCa) on the expression of color and the content of secondary metabolites was observed in two rose cultivars: an orange-red cultivar ‘KORcrisett’ and a dark red cultivar ‘KORikis’. The study aims to describe the induced accumulation of specific flavanones in rose by ProCa sprayings and the effects on the content levels of major flavonoids and anthocyanins in rose petals important for their ornamental value. Plants were sprayed once with 300ppm Regalis® solution in bi-distilled water and the control plants with bi-distilled water only. Color parameters were colorimetrically evaluated, and individual phenolic compounds were identified with the use of HPLC–MS. A significant visual change in red petal coloration was observed and recorded as a decline of the color parameter a* after the application of Regalis® on day 9 and particularly on day 15. Similarly, lightness (L*) increased and chroma (C) decreased in both analyzed cultivars as expected in paler petals. The content of major anthocyanins in rose petals, cyanidin-3,5-di-glucoside, pelargonidin-3,5-di-glucoside, cyanidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside, was drastically reduced after Regalis® application in both analyzed roses. Also, the content of quercetin and kaempferol compounds generally decreased to the point of detection; however, newly formed eriodictyol was identified in the petals of the treated ‘KORikis’ flowers 15 days after application and in the petals of ‘KORcrisett’ flowers 9 and 15 days after application. Foliar application of ProCa thus altered visual properties of red rose flowers, which has been directly correlated to the content of anthocyanins, and also induced the formation of 3-deoxyflavonoids, normally not present in roses under natural conditions. Different shades of red and light pink flowers were present on a single rose plant which can potentially present an interesting marketable product for the consumers. [Copyright &y& Elsevier]

The goal of this study was to determine whether bacterial antagonists could be used to control Xanthomonas arboricola pv. juglandis (Xaj), the causal agent of bacterial blight of walnut. A total of 35 potentially bacterial antagonists, 29 of which were isolated as epiphytes from the phylloplane of healthy walnut trees, were screened for their in vitro biological control activity against Xaj. Pantoea vegans strain C9/1 was also tested as reference biological control agent. Eighteen strains, that inhibited the growth of Xaj between 3.0 mm to 13.0 mm on TSA medium, were selected and further tested for their ability to control bacterial blight on immature nuts. Approximately 60% of the antagonistic strains, significantly reduced bacterial blight by 41% to 77% as compared to the positive control. Bacterial antagonistic strains, which effectively inhibited the development of Xaj on immature nuts were selected for further testing on walnut seedlings. Antagonistic strains were sprayed in a suspension of 109 CFU ml-1 on the leaves which were subsequently inoculated with suspension of Xaj strain W7/1 (108 CFU ml-1), 24 h after the antagonist treatments. According to the in vivo biocontrol tests on walnut seedlings (cv. Chandler), 4 putative antagonists significantly reduced the symptoms on walnut leaves (41% to 82%) compared with the positive conttol. Strains WH77/1, WH68 and WH48/1A were the most effective in the seedling test, yielding 55%, 42%, and 82% disease reduction, respectively, in two consecutive years. These strains were tentatively identified as Pseudomonas fluorescens on the basis of biochemical and physiological tests. P. vagans strain C9/1 agent, reduced the severity of bacterial blight on the leaves by 71%. The results obtained both nut and seedling tests agreed, except for P. fluorescens strain WH55/4 which was less effective in inhibiting symptom development in walnut leaves than in the fruits. Prohexadione-Ca (Pro- Ca) treatments of walnut leaves reduced by 66% blight symptoms. [ABSTRACT FROM AUTHOR]

The mango in the Brazilian semi-arid region stands out in the national scenario due to high yields and fruit quality, as well as to the possibility of all-year production due to climatic conditions and technologies which allow the management of plant growth and flowering through irrigation, pruning and use of plant growth regulators. Paclobutrazol applied to the soil is used for the production management of mangoes in most of the orchards. However, it is necessary to identify plant growth regulators which might be applied to the leaves, so as to minimize the risk of residues in the soil and to avoid inadequate application levels over several years. The present paper aimed at evaluating the effect of plant growth regulators applied to the leaves, regarding their efficiency for flowering management of mango 'Tommy Atkins'. Prohexadione-Ca, trinexapac-ethyl and chlormequat chloride at the dosage of 1.0 g a.i. plant-1 acts on the regulation of vegetative growth; the period of efficiency of the products applied to the leaves lasted 20 days for prohexadione-Ca, 30 days for chlormequat cloride, and 45 days for trinexapacethyl. [ABSTRACT FROM AUTHOR]

Accelerating rhizome growth is crucial to enhancing propagule production in rhubarb ( Rheum rhabarbarum L.) because the crop is propagated through rhizome divisions. This can be achieved through manipulating source-sink activity. This study tested the hypothesis that synthetic plant growth retardants Prohexadione-Ca and CCC enhance rhizome growth in rhubarb. Two different concentrations of these plant growth retardants and GA3 (positive control) were foliarly applied on the cultivar German Wine at three stages of shoot growth under greenhouse conditions. Both Prohexadione-Ca and CCC favorably enhanced rhizome growth through suppressing shoot growth. CCC at 3000 mg L−1 produced the best results and the effect was apparent when applied at 12 weeks after shoot emergence. The rhizome diameter, fresh weight, and the number of viable buds were enhanced significantly in plants sprayed with CCC 3000 mg L−1. Both Prohexadione-Ca and CCC were equally effective in enhancing dry mass and starch allocation preferentially toward the rhizome. Prohexadione-Ca- and CCC-induced rhizome growth enhancement could possibly be due to their known role as GA biosynthesis inhibitors or through increasing photosynthetic efficiency and preferentially reallocating carbohydrates to the rhizome. [ABSTRACT FROM AUTHOR]

Due to the lack of effective and non-phytotoxic materials for control of the blossom and shoot blight phase of fire blight in pome fruit trees, two novel control strategies have emerged: shoot growth retardation by bioregulators and applying resistance inducer compounds. Prohexadione calcium (ProCa) is the active ingredient of the bioregulator Regalis® registered in several European countries. The reduction of shoot growth elongation is the most obvious effect of ProCa. Furthermore, it causes significant changes in the spectrum of flavonoids and their phenolic precursors, leading to the considerable reduction of susceptibility to fire blight. In Poland, potted one-year-old apple trees of cvs. Gala Must grafted on M.26 and Sampion on M.9 (in 2001) as well as Gala Must on P.60 (in 2002) were treated with Regalis® at a range of concentration of 250, 150 or 150 + 100 ppm, respectively. The inoculation of shoots was made with the strain No.691 of E. amylovora (107 cfu/ml), on the 7th and 21st'day after treatments with Regalis. In Hungary, during the years of 2002 and 2003 one-year-old container grown apple trees of the cvs. Idared/M.9 and Freedom/M.9 were treated with the prohexadione-Ca, the active ingredient of Regalis® 100, 150 or 200 ppm, two weeks before inoculation with the Ea 1 strain of E. amylovora (107 cfu/m1). In Poland, the suppression of fire blight in shoots reached up to 80%, depending on concentration and application time of Regalis®. In Hungary, the effect of prohexadione-Ca treatments, determined by the length of necrotic lesion developed, proved to be better than that of streptomycin used for comparison.

Recently, novel strategies and chemical agents for prophylactic protection against the bacterial (Erwinia amylovora) disease fire blight are being sought. Resistance-inducing compounds, such as prohexadione-Ca represent promising alternatives. Prohexadione-Ca is the active ingredient of the bioregulator Regalis, currently being introduced in several European countries and overseas. Another product used in this study was Biomit Plussz, a leaf fertiliser providing harmonic supply of nutrient elements, the complete supply is assumed to improve the tolerance against diseases. Treatments' effects of both of these products were compared to the effectiveness of treatments with antibiotics repeated twice, three or four times a season. In the years of 2001 and 2002, the effectiveness of both Regalis and Biomit Plussz in reduction of incidence of shoot blight was similar, or proved to be superior to the check treatments consisting of repeated sprayings of antibiotics. Last year (2003) treatments of streptomycin resulted — although within the same magnitude — in a somewhat better control of shoot blight than sprayings with the other compounds. As regards severity of blossom blight, inconsistent results were recorded concerning both Regalis and Biomit Plussz. In general, prohexadione-Ca is less efficient for controlling flower infection by E. amylovora as compared to shoot infections, since successful prophylactic treatments are difficult to carry out early in the season. The highest effectiveness in fire blight management can, therefore, be achieved by using prohexadione-Ca (as preventive protection) in combination with streptomycin or other suitable antibiotics (as curative protection).

Abstract: 2-Oxoglutarate-dependent dioxygenases (2-ODDs) catalyze numerous steps in biosynthetic pathways of plants. Prohexadione-Ca is a known inhibitor of such reactions, due to its structural similarity to 2-oxoglutarate. In apple (Malus domestica) and pear (Pyrus communis) leaves, the transient inhibition of 2-ODDs flavanone 3β-hydroxylase (FHT) and flavonol synthase (FLS) by prohexadione-Ca results in distinct changes in the flavonoid spectrum, which are responsible for an enhanced resistance against two major pome fruit diseases, fire blight (caused by Erwinia amylovora) and apple scab (caused by Venturia inaequalis). We used recombinant apple and pear FHT and apple FLS for screening 23 structural analogues of 2-oxoglutarate, mostly cyclohexanediones, pyridine dicarboxylic acids and N-heterocycles with carbonyl functions for other dioxygenase inhibitors. Activations, which were also observed for some compounds, are interpreted as in vitro effects due to Fe2+-chelating ability. Apart from structural similarity to 2-oxoglutarate, close structural similarity of cyclohexanediones and some pyridine dicarboxylic acids to flavonoid substrates was identified. Beyond the competitive inhibition for the co-substrate 2-oxoglutarate, flavonoid converting 2-ODDs may also be inhibited at the substrate binding site by these inhibitors. All compounds found to be active as inhibitors may prove useful for studying the reaction mechanisms and substrate specificities of various 2-ODDs. [Copyright &y& Elsevier]

Novel flavonoids were formed in young leaves of apple (Malus×domestica) after treatment with the dioxygenase inhibitor prohexadione-Ca, which is known to reduce the incidence and severity of fire blight caused by Erwinia amylovora and other plant diseases. The compounds were isolated and identified as luteoliflavan, luteoliflavan 5-glucoside, eriodictyol 7-glucoside and 6″-O-trans-p-coumaroyleriodictyol 3′-glucoside. These flavonoids represent a novel biosynthetic pathway in apple leading to the formation of 3-deoxyflavans. Concomitantly, the content of regularly occurring phenylpropanoids is also influenced by prohexadione-Ca with increasing amounts of hydroxycinnamic acids and decreasing flavan-3-ols and flavonols. The altered flavonoid metabolism may be related to the lowered pathogen incidence though the isolated novel flavonoids do not exhibit antibacterial activity. [Copyright &y& Elsevier]

Background: The gibberellins (GAs) GA 5 (inhibitor of GA 3 -oxidase), GA 4 (biologically active), GA 4/7 (commercially available mixture of Ga 4 and GA 7 ) prohexadione-calcium (ProCa, inhibitor of dioxygenases that render GAs bioactive, negative control), and GA 3 (positive control) were applied to bunches of Vitis vinifera cv. Malbec. Different techniques, doses, and timings were used in a 3-year field experiment. In year 1, GA 5 , ProCa, and GA 3 were applied at 35, 20, and 0 days before veraison (DBV) by dipping bunches three times. In year 2, single applications of GA 5 and GA 3 , also by immersion, were tested at 60, 45, and 30 DBV. In year 3, applications at 60 and 30 DBV of GA 5 , GA 4 , and a mixture of GA 4/7 were evaluated by dipping or spraying the bunches., Results: Vegetative growth, berry weight, and sugar content were unaffected by treatments. ProCa did not affect the yield with respect to water control, although it reduced the levels of phenolics in berry skins, an undesirable effect for winemaking. GA 5 , in the dose range 5-50 mg L -1 , raised berry numbers, thereby augmenting bunch weight and skin phenolics at harvest, so increasing berry quality for winemaking. GA 4 and GA 4/7 produced similar benefits to GA 5 , with similar doses., Conclusion: The applications of GA 5 , GA 4 , and GA 4/7 to developing grape berry bunches, in a range of concentrations and by dipping or spraying, increased berry numbers per bunch at harvest. The method can be used as a viticultural practice to improve the production and quality of wine grapes. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

• Prohexadione-Ca limited angular leaf spot disease symptom development in cucumber. • Prohexadione-Ca had lower impact on plant fitness and leaf growth. • Potential mechanism of prohexadione-Ca action on antioxidative system is discussed. The metabolic response of prohexadione-Ca (Pro-Ca) treated cucumber (Cucumis sativus L.) leaves to Pseudomonas syringae pv. lachrymans (Psl) was analyzed at the local and systemic levels. The activities of antioxidant enzymes such as ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POX) utilizing guaiacol and syringaldazine as well as lipid peroxide level were studied. Observed changes in these parameters were compared to the response induced by benzotiadiazole (BTH) treatment after Psl infection. Cucumber plants pretreatment (priming) with Pro-Ca similarly to BTH priming enhanced the defense response of cucumber leaves to subsequent bacterial infection as shown by the suppression of disease development in comparison to the untreated plants. Pro-Ca priming changed the examined parameters in both pathogen-inoculated leaves and systemic (uninfected) ones depending on Pro-Ca concentration used. However, these changes were pronounced especially in the direct inoculated leaves. In the systemic leaves Pro-Ca pretreatment induced different changes profile in examined parameters than BTH. Obtained results suggested that Pro-Ca as BTH affect the pro-antioxidative metabolism under Psl infection conditions but in a different way. BTH induced mainly APX while Pro-Ca APX and CAT. Strong influence of Pro-Ca on both examined types of POX was also found. The POX utilizing syringaldazine activity indicted that in all examined variants Psl infection affected the lignifications of cell wall. Although the physiological significance of examined pro-antioxidative reactions at the local and systemic levels remains to be elucidated, the presented results support for the first time the protective role of Pro-Ca in defense response of cucumber against P. syringae pv. lachrymans. [ABSTRACT FROM AUTHOR]

Prohexadione-calcium (Regalis) is a shoot growth retardant that inhibits gibberellins biosynthesis The aim of this study was to evaluate the efficacy of applying Regalis by foliar applications in Passé Crassane pear orchards to reduce tree vigor or shoot growth, to improve the structure of the canopy, to accelerate the earliness of fruit bearing and to control the alternate fruit production. Three different dosages were tested: 50ppm, 100ppm 150ppm. Regalis treatments ranging from 50 to 150 ppm were compared with control, without treatments. The first treatment was applied 7days after petal fall and the others every 10 days after the first treatment. The data was collected at the end of the vegetation period on 10 October. The growth vigor of the shoots and the shoot length of node was significantly difference after the treatment of 150 ppm than the application of 100ppm and 50ppm. The mean number of nodes per shoot percentage was not significantly different between different treatment (50ppm, 100ppm and 150ppm). The length of the shoots for non- treated trees was higher than for treated ones. [ABSTRACT FROM AUTHOR]