Plant growth regulators in crop management.

Author(s):  
Mary Taylor

Abstract Overbeek et al. (1954) defined plant hormones as 'regulators produced by plants, which in low concentrations regulate plant physiological processes. Hormones usually move within the plant from a site of production to a site of action'. Plant hormones can exert their influence on tissues in the site of origin/production - mainly meristems and growing fruits - or they can be translocated to sites far removed from their origin/production (Rademacher, 2015). Plant hormones enable plants to react to internal and external stimuli and include auxins, gibberellins, cytokinins, abscisic acid, and ethylene. Brassinosteroids, jasmonates, salicylic acid, polyamines and florigen are currently considered hormones.

2019 ◽  
Vol 10 (3) ◽  
pp. 331-336
Author(s):  
Т. P. Mamenko ◽  
R. A. Yakymchuk

An important way of regulating the key units of metabolism in the plant organism under the action of stressors is the use of biologically active substances with regulating properties – plant growth regulators. They affect endogenous regulatory systems, altering key metabolic pathways and thus increasing the plant's sustainability and productive potential in adverse environmental conditions. The aim of the research was to establish the possibility of regulation of physiological processes in winter wheat varieties by exogenous treatment of plants with growth regulators of synthetic (salicylic acid) and natural (Emistim C and Biolan) origin to increase their resistance to the phytopathogen Erysiphe graminis DC f. sp. tritici Em. Marchal , the causative agent of powdery mildew. The intensity of the physiological processes in plants was evaluated by the dynamics of the activity of antioxidant enzymes – ascorbate peroxidase and catalase, the release of ethylene and the integrity of the cell membranes. The objects were selected varieties of soft winter wheat, which were grown in controlled growing conditions against the background of infection by powdery mildew. The treatment of plants was carried out using aqueous salicylic acid solutions in the concentration of 10–5 M (experimentally established by us), Emistim C and Biolan (manufacturer Agrobiotech) in the concentration specified by the manufacturer at the rate of 20 mL/ha, when the development of the disease reached 5% of the total natural background of the infection in the plants during the stages of heading-beginning of flowering. Infection of winter wheat with powdery mildew leads to disruption of cell membrane integrity, increased activity of catalase and ascorbate peroxidase in leaves of the susceptible winter wheat variety. The intensification of ethylene release by leaves of the resistant variety was observed, which was caused by the hypersensitive reaction of the hormone to the effect of stress. The use of plant treatment by growth regulators contributes to maintaining the integrity of membrane structures, adaptive changes in the activity of antioxidant enzymes and regulation of the synthesis of the stress hormone ethylene in both winter wheat varieties under stress. Such changes in the physiological processes induced by plant growth regulators are accompanied by the preservation of the grain productivity of winter wheat and the increase of their resistance to the development of the disease.


Author(s):  
Bizuayehu Desta ◽  
Getachew Amare

AbstractPlant growth regulators are chemical substances which govern all the factors of development and growth within plants. The application of plant growth regulators to crops modifies hormonal balance and growth leading to increased yield, enhanced crop tolerance against abiotic stress and improved physiological trait of crops. Paclobutrazol (PBZ) [(2RS, 3RS)-1-(4-chlorophenyl)- 4, 4-dimethyl-2-(1H-1, 2, 4-trizol-1-yl)-pentan-3-ol], is one of the members of triazole family having growth regulating property. The growth regulating properties of PBZ are mediated by changes in the levels of important plant hormones including the gibberellins (GAs), abscisic acid (ABA) and cytokinins (CK). PBZ affects the isoprenoid pathway, and alters the levels of plant hormones by inhibiting gibberellin synthesis and increasing cytokinins level and consequent reduction in stem elongation. When gibberellins synthesis is inhibited, more precursors in the terpenoid pathway accumulate and that resulted in the production of abscisic acid. PBZ is more effective when applied to the growing media and application on the growing medium would give longer absorption time and more absorption of active ingredient than foliar spray. The application of PBZ to crops is important in reducing plant height to prevent lodging and in increasing number and weight of fruits per tree, in improving the fruit quality in terms of increases in carbohydrates, TSS, TSS/TA and decreases acidity. It further reduces evapo-transpiration and decreases plant moisture stress by enhancing the relative water content of leaf area and develops resistance in the plants against biotic and abiotic stresses. In addition, it acts as highly active systemic fungicide and used against several economically important fungal diseases. In this review, the current knowledge and possible applications of PBZ, which can be used to improve the growth, yield and quality of crops, have been reviewed and discussed. The role of PBZ to mitigate the harmful effects of environmental stresses in crops is also examined. Moreover, various biochemical and physiological processes leading to improved crop production under the effect of PBZ are discoursed in detail.


2021 ◽  
Author(s):  
Jiajia Li ◽  
Dongmei Li ◽  
Boyang Liu ◽  
Ruiqi Wang ◽  
Yixuan Yan ◽  
...  

Abstract Endogenous plant hormones play important roles in germination, blossom, senescence, abscission of plants by a series of signal transduction and molecular regulation. The purpose of this research was to investigate the influence of root restriction (RR) cultivation on plant hormones variation tendency at different growth stages in diverse organs or tissues, ‘Muscat Hamburg’ (Vitis ‘Muscat of Alexandria’ × Vitis ‘Trollinger’) grapevine was used as test material. High Performance Liquid Chromatography (HPLC) was used to quantify hormone levels, aiming to investigate the influence of root restriction on the formation and transportation of plant hormones. The results revealed that RR treatment increased abscisic acid, salicylic acid, zeatin riboside, N6-(delta 2-isopentenyl)-adenine nucleoside concentrations, while reduced auxin, 3-indolepropionic acid, 3-indolebutyric acid, gibberellin A3, zeatin, N6-(delta 2-Isopentenyl)-adenine, kinetin, jasmonic acid and methyl jasmonate concentrations. To sum up, our results suggested that RR treatment could initiate stress responses via up-regulating abscisic acid and salicylic acid contents while down-regulating auxin and kinetin contents, resulting in the changes of fruit appearance and improvement of berry quality.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hammad Ishtiaq ◽  
Savita Bhardwaj ◽  
Aaliya Ashraf ◽  
Dhriti Kapoor

Plant growth regulators are significant chemical compounds which are synthesized inside the plant cells and play vital role in plant growth and development. Such compounds are usually active at very low concentrations. These plant growth regulators act as a signalling molecule, which influences the growth of plants. Throughout the previous year’s remarkable investigation have been done for understanding the synthesis of auxin and its effect on various physiological progressions. Auxin is a plant hormone that is involved in various physiological activities, including basic cellular processes such as cell enlargement, regulation of the cell cycle and distinction progress. Plants and several other microorganisms together produce auxin in order to carry out their cell cycle. The chemically synthesized auxins like NAA (naphthalene acetic acid) and IBA (Indole- butyric acid), also take part in various cellular processes. Against various types of biotic and abiotic stress conditions, these plant hormones significantly contribute in promoting acclimatization and adaptation in combination with other phytohormones. The present review highlights some of the important features of auxin role in regulation of plant growth either alone or in crosstalk with other plant hormones.


Author(s):  
Thắng Thanh Trần ◽  
Triều Phương Hoàng ◽  
Hương Thanh Trần

Chrysanthemum indicum cultivar Sakura is one of the daisy cultivars. It is beautiful, but the vase life of cutting flowers is very short. The decrease in flower quality during storage and transportation is a big problem in the flower export. In this study, the morphological, physiological, and biochemical changes during the vase life of cutting flowers were analyzed. The effects of plant growth regulators and sucrose at different concentrations on the vase life of cut flowers were investigated. The vase life of Sakura cutting flowers includes two stages: (1) the growing and blooming of flower, (2) senescence of cutting flowers. During the growing and blooming, the color of disk flowers changed from green to yellow, and the ray flowers continued to expand the dimension leading to an increase in the diameter of the head flower. The senescence of cutting flowers was initiated by the reduction of chlorophyll content in the leaf, which was located at the base. Then, the ray flowers were discolored. In the senescence stage, the respiration rate and the content of the abscisic acid of head flower increased continuously. In contrast, the water absorption, the content of starch, total sugar, salicylic acid, auxin, cytokinin, and gibberellin decreased strongly. The treatment of 10 g/L sucrose, 2 mg/L NAA, 5 mg/L BA, and 20 mg/L salicylic acid in 24 hours extended the vase life of Sakura cutting flowers and the diameter of the head flower.  


2017 ◽  
Vol 52 (11) ◽  
pp. 1118-1122 ◽  
Author(s):  
Alberto Fontanella Brighenti ◽  
Douglas André Würz ◽  
Mateus da Silveira Pasa ◽  
Leo Rufato

Abstract: The objective of this work was to investigate the effect of plant growth regulators for enhancing fruit color of 'Gala Standard' apples (Malus domestica). The experiment was carried out in the 2015 and 2016 crop seasons. The treatments consisted of water, as a control; 300 mg L-1 ethephon, as a positive control; 400 mg L-1 prohydrojasmonate; and 400 mg L-1 abscisic acid. Flesh firmness, soluble solids content, fruit weight, and red color were assessed after harvest. Plant growth regulators enhanced red color of fruit and chlorophyll degradation. Prohydrojasmonate and abscisic acid did not reduce flesh firmness, in the 2016 season.


Biomolecules ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 26 ◽  
Author(s):  
Young Yoon ◽  
Minjae Kim ◽  
Woong Park

Plants absorb melatonin from the environments as well as they synthesize the regulatory molecule. We applied melatonin to the roots of maize (Zea mays) seedlings and examined its accumulation in the leaves. Melatonin accumulation in the leaves was proportional to the exogenously applied concentrations up to 5 mM, without saturation. Time-course analysis of the accumulated melatonin content did not show an adaptable (or desensitizable) uptake system over a 24-h period. Melatonin accumulation in the leaves was reduced significantly by the plant hormones abscisic acid (ABA) and salicylic acid (SA), which commonly cause stomatal closure. The application of ABA and benzo-18-crown-6 (18-CR, a stomata-closing agent) induced stomatal closure and simultaneously decreased melatonin content in the leaves. When plants were shielded from airflow in the growth chamber, melatonin accumulation in the leaves decreased, indicating the influence of reduced transpiration. We conclude that melatonin applied exogenously to the root system is absorbed, mobilized upward according to the transpirational flow, and finally accumulated in the leaves.


2014 ◽  
Vol 26 (2) ◽  
pp. 109-115
Author(s):  
Krzysztof Górnik

ABSTRACT The aim of the present study was to improve the chilling tolerance of cucumber seedlings. The conditioned seeds in solutions of salicylic or jasmonic acid in concentrations of 10-2, 10-3 or 10-4 M or brassinolide in concentrations of 10-6, 10-8 or 10-10 M were subjected to temperature shock of 0, 2.5, 5, 35, 40 or 45°C for 1, 2 or 4 hours. Seedlings with 3 mm roots were chilled at 0°C for three days. The chilling susceptibility was evaluated by measurements of roots lengths, electrolyte leakage and total dehydrogenase activity. The obtained results indicated that cucumber tolerance to chilling conditions depended on the plant growth regulators used during seed imbibition and its concentration as well as the temperature initiating thermal shock and its duration. The highest tolerance to chilling, expressed by the subsequent growth of roots, was observed after seed conditioning in salicylic acid solutions in a concentration of 10-4 M for 16 h at 25°C, then exposed for 4 h to a shock temperature of 5°C. The length of seedling roots after such treatment was over 12 times longer than the control (imbibed in distilled water and not subjected to short-term temperature impact). An increased chilling tolerance of cucumber seedlings may result from enhanced membrane integrity and total dehydrogenase activity. Further research is needed to explain the mechanism of the positive effects of salicylic acid, jasmonic acid or brassinolide application to reduce the injurious effects of chilling on cucumber seedlings.


Author(s):  
Zahida Rashid ◽  
Tanveer Ahmad Ahngar ◽  
B. Sabiya ◽  
N. Sabina ◽  
N. S. Khuroo ◽  
...  

A field experiment was conducted at Dry land Agricultural Research Station, Rangreth, Srinagar, SKUAST-K in Kharif 2020 to study the effect of Plant Growth Regulators and micronutrients on growth, yield and quality of sorghum. The objective of the study was to assess the effect of Plant Growth Regulators and micronutrients on herbage yield and quality. The treatments included; T1: Tricontanol 10 ppm at 30 DAS (foliar spray), T2: Salicylic acid 100 ppm at 30 DAS (foliar spray), T3: 5 kg Zn/ha soil application, T4: 2 kg B/ha soil application, T5: 5 kg Zn + 2 kg B/ha soil application, T6: 5 kg Zn/ha (soil application ) + Triacontanol 10 ppm at 30 DAS (foliar spray), T7: 5 kg Zn/ha (soil application) + salicylic acid 100 ppm at 30 DAS (foliar spray), T8: 2 kg B/ha (soil application) + Triacontanol 10 ppm at 30 DAS (foliar spray), T9: 2 kg B/ha (soil application )+ salicylic acid 100 ppm at 30 DAS (foliar spray), T10: 5 kg Zn + 2 kg B/ha (soil application) + Triacontanol 10 ppm at 30 DAS (foliar spray), T11: 5 kg Zn + 2 kg B/ha (soil application) + salicylic acid 100 ppm at 30 DAS (foliar spray) and T12: Water spray at the time of PGR application. Zn and B were applied at the time of sowing in the soil. The crop was raised with recommended package of practices. In treatments, where zinc was not a treatment, an amount of sulphur through gypsum equivalent to sulphate supplied with 5 kg ZnSO4 was applied to compensate. The crop was sown in 30.0 cm apart lines. The trial was laid out in Randomized Block Design with three replications. The results indicated that all the treatments improved the green fodder yield over control. Among different treatments, T10: 5 kg Zn + 2 kg B/ha soil application + Triacontanol 10 ppm at 30 DAS foliar spray and T11: 5 kg Zn + 2 kg B/ha soil application + salicylic acid 100 ppm at 30 DAS foliar spray produced maximum GFY (493.6 and 490.5q/ha) on locational mean basis. It was significantly superior to other treatments. These treatments improved the green fodder yields by 35.0 % and 34.2 %, respectively, over control (spray of water). In terms of dry matter, similar trend was noted and the improvement with T10 and T11 was to the tune of 36.8 % and 41.0 % over control. Tricontanol 10 ppm at 30 DAS (foliar spray) (T1) improved the green fodder yield and dry fodder yield by 13.6% and 14.3 % respectively over T12Water spray at the time of Plant Growth Regulator application. Similarly spray of T2: Salicylic acid 100 ppm at 30 DAS (foliar spray) improved the green fodder yield and dry fodder yield by 14.4% and 15.4% respectively over T12Water spray at the time of Plant Growth Regulator application. Similar trend was observed with respect to quality parameters (crude protein content and crude protein yield) of sorghum.


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