Use Of GA3 Research Articles

Waterhemp emergence response to exogenous application of gibberellic and abscisic acids

BackgroundThe exogenous application of phytohormones to manipulate weed seed germination and emergence is a potential avenue for exploring alternative integrated weed management strategies. Greenhouse and field experiments were conducted to investigate the effects of exogenous applications of the phytohormones gibberellic acid (GA3) and abscisic acid (ABA) on waterhemp (Amaranthus tuberculatus [Moq.]) emergence.ResultsIn the greenhouse study, all waterhemp populations in sandy soil and three out of five populations in clay soil demonstrated a positive response to increased GA3; however, the response was small, leading to an increase in waterhemp emergence of up to 10% points, and weak (R2adj < 0.3). Only one population exhibited a small (up to 10 points) and weak (R2adj = 0.1) reduction in emergence in response to increased ABA in clay soil. The field studies demonstrated no differences in waterhemp and soybean emergence in response to application of GA3 and ABA.ConclusionsDespite the low to absent efficacy of the exogenous application of GA3 and ABA in manipulating waterhemp emergence in these experiments, our findings provide foundation information for future research on this concept, particularly supporting further research investing the use of GA3 in lighter textured soils.

Interacting effects of phytohormones and fruit pruning on the morpho-physiological and biochemical attributes of bell pepper

Several factors, such as pruning and phytohormones, have demonstrated an influence on both the quantity and quality in the bell pepper. A factorial experiment using a completely randomized design was conducted on the Lumos yellow bell in a greenhouse. Treatments were the fruit pruning (0, 10, and 30%) and foliar application of phytohormones auxin (AUX) and gibberellic acid (GA3) at concentrations of 10 µM AUX, 10 µM GA3, 10 µM AUX + 10 µM GA3+, and 20 µM AUX + 10 µM GA3 along with controls. The plants were sprayed with phytohormones in four growth stages (1: flowering stage when 50% of the flowers were on the plant, 2: fruiting stage when 50% of the fruits were the size of peas, 3: fruit growth stage when 50% of the fruits had reached 50% of their growth, and 4: ripening stage when 50% of the fruits were at color break). The results of the present investigation showed that pruning rate of 30% yielded the highest flesh thickness and vitamin C content, decreased seed count and hastened fruit ripening. The use of GA3 along with AUX has been observed to augment diverse fruit quality characteristics. According to the results, the application of 10% pruning in combination with 20 µM AUX and 10 µM GA3 demonstrated the most significant levels of carotenoids, chlorophyll, and fruit length. The experimental group subjected to the combined treatment of 30% pruning and 10 µM AUX + 10 µM GA3 showed the most noteworthy levels of vitamin C, fruit weight, and fruit thickness. The groups that received the 10 µM GA3 and 20 µM AUX + 10 µM GA3 treatments exhibited the most favorable fruit flavor. According to the research results, the implementation of hormonal treatments 10 µM AUX and 10 µM AUX + 10 µM GA3 in combination with a 30% pruning strategy resulted in the most advantageous yield of bell peppers.

Effects of post-shooting sprays and bunch covering on yield attributes of Willium banana (Musa paradisiaca L.)

This research investigates the synergistic effects of post-shooting sprays and bunch covering materials on the growth, development, and yield of Willium banana (Musa paradisiaca L.). Gibberellic acid (GA3) at 100 mg/l emerges as a potent post-shooting spray, significantly enhancing bunch length, finger length, girth of finger, bunch weight, and overall fruit yield. The study highlights the pivotal role of GA3 in promoting both cell division and elongation, contributing to increased fruit size and weight. Non-woven material bag covering proves superior in creating an optimal microclimate, fostering enhanced air circulation, temperature control, and light interception. This material significantly boosts finger length, girth, bunch weight, and fruit yield. These findings provide valuable insights for banana cultivation, emphasizing the strategic use of GA3 and appropriate covering materials to optimize environmental conditions and hormonal balance for improved crop outcomes. The study contributes to the evolving field of banana cultivation practices and offers practical implications for enhancing fruit quality and yield.

Enhanced germination of seeds native to Brazil: A comparative analysis between free and nanoencapsulated gibberellic acid in Dyckia sp. (Bromeliaceae)

ABSTRACT Brazil is home to a great diversity of species of the genus Dyckia. However, many of these species are threatened due to habitat destruction and predatory exploitation. An alternative to conserving these plants is sexual propagation using plant regulators to stimulate germination. Gibberellic acid (GA3) is an effective regulator in this process, but its instability and ease of degradation pose challenges. Therefore, nanoencapsulation of GA3 could be used to protect the molecule and allow controlled release. In this study, the effects of different doses of GA3 were evaluated on the germination of four species: D. cabrerae, D. dusenii, D. pottiorum and D. walteriana. The first stage consisted of soaking the seeds in different concentrations of GA3, in which the species D. dusenii and D. walteriana showed significant responses to GA3, with an increase from 35% to more than 60% germination. However, the species D. cabrerae and D. pottiorum responded positively to GA3 only in vegetative growth parameters. In the second stage, the use of nanoparticles of alginate/chitosan (NP ALG/CS) and chitosan/tripolyphosphate (NP CS/TPP) containing GA3 was compared with free GA3 and with NPs without GA3. It was verified that the use of nanoencapsulated GA3 resulted in a more efficient germination response in D. walteriana seeds, using smaller doses of the regulator (between 0.75 mg · L−1 and 1.0 mg · L−1), mainly with the ALG/ CS NPs. Therefore, the use of GA3 is recommended for D. dusenii and D. walteriana, and for the latter, nanoparticles containing ALG/CS-GA3 allow a reduction in the required dose.

Aplikasi Asam Giberelin(GA3) dan Naftalenacetate (NAA) untuk Menstimulasi Pertumbuhan Tanaman Philodendron xanadu

Philodendron xanadu is one of the leaf ornamental plants that much liked by society. Apart from being an ornament, P. xanadu also functions as an absorbent of toxic compounds contained inside the room. The potential development of P. xanadu is quite promising because the plant is widely used for decorating rooms and garden-forming elements. The growth rate of P. xanadu which derived from the separation of saplings is very slow, where the plant height is barely increased, but the addition number of saplings is very rapid / numerous. These conditions are unfavorable when used as an ornamental plant because the beauty of the plant is not optimally expressed. To overcome this, it is necessary to conduct research on the use of gibberellic acid (GA3) and naphthalmylene acetic acid (NAA) to spur the plant growth. The purpose of this study was to determine the influence of the use of GA3 and (NAA) to the growth of P. xanadu. The study was arranged factorial (2 factors) with a group randomized environment design. As the first factor is three levels of GA3 (0, 50, and 100 mg.l-1), and the second factor is 3 levels of NAA (0, 50, and 100 mg.l-1). Each experimental treatment was repeated 4 times. The results showed that the given of NAA and GA3 concentrations of 0, 50, and 100 mg.l-1 had no effect on the growth (leaf length) and the number of saplings P. xanadu. Keywords: GA3, NAA, Philodendron xanadu

Seed Germination of Two Hybrids Obtained via Cross-Pollination between Miscanthus sinensis × Miscanthus sacchariflorus

To date, economically and energy-costly vegetative propagation using rhizomes and tissue culture are the only options for the cultivation of Miscanthus spp. Some genotypes of miscanthus produce fertile seeds, offering a valid alternative to vegetative propagation. A preliminary study has been conducted on the seeds of two hybrids of miscanthus obtained via interspecific cross-pollination between M. sacchariflorus and M. sinensis: ‘GRC14’ (maternal: M. sacchariflorus) and ‘GRC10B’ (maternal: M. sinensis). Seeds were assessed for germination traits in a laboratory (at 25 °C in the dark) just after panicle harvest, and during 1-year storage at room temperature or at 8 °C. In a second experiment, the effects of gibberellic acid (GA3) solution at different concentrations (0, 50, 100, 300, 500 ppm) on the germination of freshly matured seeds were assessed. Poor germination just after harvest (&lt;30%) indicates the occurrence of a physiological dormancy. Indeed, two months later, germination rose up to 76.7% in ‘GRC14’ and 50.8%, in ‘GRC10B’, and peaked at 95.6% in ‘GRC14’ and at 78% in ‘GRC10B’, 6 months after harvest. After a total of 12 months, germination was significantly reduced in both hybrids (≈60%). Seeds stored at room temperature lost dormancy earlier than those stored at 8 °C. Overall, germination was significantly improved by GA3, but the extent of the GA effect was genotype-dependent. In conclusion, a low establishment rate may result from direct seeding when fresh seed is used in the field. In this case, the use of GA3 is a possible strategy to ameliorate the impact of dormancy on seed germination. In the case of delayed sowings in late winter–early spring, seeds stored at room temperature after harvest may better perform than those stored at 8 °C.

Regulation of dormancy break and germination of safflower seeds: the role of GA3, light and cold temperatures.

The safflower crop is considered a great alternative for crop rotation since drought tolerance and low production cost are attractive for its choice. However, safflower seeds show dormancy soon after dispersal from the mother plant, making it difficult to successfully establish plants using newly harvested seeds. The influence of temperature, gibberellin and light/dark on dormancy break of safflower seeds during storage were investigated. In a completely randomized design, freshly harvested seeds or stored for 100 and 200 days (paper bag, 20 °C/ 60% UR) were treated with GA3 (0 and 100 µM), at 4, 10 and 25 °C, in the presence and absence of light, during the germination test. Seeds were evaluated for germination percentage, germination speed and seedling survival after 21 days. The temperature of 10 °C, in combination with GA3 (0/100 µM), or light/dark, provided the highest seed germination results, for freshly-harvested seeds and stored seeds. Collectively, these observations indicate that dormancy was not affected by gibberellic acid (100 µM GA3) and the germination results at 21 days were significantly higher, in relation to the use of GA3, under light or dark. Recently harvested seeds could efficiently germinate at 10 °C in the dark, while seeds dry-stored at 20 °C had decreased germination percentages.

Joint metabolome and transcriptome analysis of the effects of exogenous GA3 on endogenous hormones in sweet cherry and mining of potential regulatory genes.

Gibberellin (GA) is an important phytohormone that can participate in various developmental processes of plants. The study found that application of GA3 can induce parthenocarpy fruit and improve fruit set. However, the use of GA3 affects endogenous hormones in fruits, thereby affecting fruit quality. This study mainly investigates the effect of exogenous GA3 on endogenous hormones in sweet cherries. The anabolic pathways of each hormone were analyzed by metabolome and transcriptome to identify key metabolites and genes that affect endogenous hormones in response to exogenous GA3 application. Results showed that exogenous GA3 led to a significant increase in the content of abscisic acid (ABA) and GA and affected jasmonic acid (JA) and auxin (IAA). At the same time, the key structural genes affecting the synthesis of various hormones were preliminarily determined. Combined with transcription factor family analysis, WRKY genes were found to be more sensitive to the use of exogenous GA3, especially the genes belonging to Group III (PaWRKY16, PaWRKY21, PaWRKY38, PaWRKY52, and PaWRKY53). These transcription factors can combine with the promoters of NCED, YUCCA, and other genes to regulate the content of endogenous hormones. These findings lay the foundation for the preliminary determination of the mechanism of GA3's effect on endogenous hormones in sweet cherry and the biological function of WRKY transcription factors.

Method development for the investigation of Mn2+/3+ , Cu2+ , Co2+ , and Ni2+ with capillary electrophoresis hyphenated to inductively coupled plasma-mass spectrometry.

The lifetime of lithium ion batteries (LIBs) decreases under continuous cycling due to various degradation processes, such as dissolution of transition metals (TMs) from the electrodes. Therefore, suitable methods to analyze the oxidation states of TMs are mandatory to better understand the dissolution mechanisms of TMs from positive and negative electrodes (LIBs). To investigate the dissolution of Mn2+ and Mn3+ in electrolytes of LIBs, a previously implemented capillary electrophoresis (CE) method with UV/Vis spectroscopy detection was further developed with the aim of higher sensitivities and additional detection of other dissolved divalent TMs such as Co2+ , Ni2+ , and Cu2+ . Therefore, inductively coupled plasma-mass spectrometry was applied instead of UV/Vis for detection. This also allows the use of Ga3+ instead of the previously used Cu2+ as an internal standard, which solves the limitation of this method for cycled LIBs due to copper dissolution from the copper-based current collector. The CE buffer based on sodium diphosphate as complexing agent for the stabilization of Mn3+ and cetyltrimethylammonium bromide as dynamic capillary wall modifier was optimized in terms of concentrations and pH. Finally, both manganese species and Co2+ , Ni2+ , and Cu2+ could be analyzed within 15min. With this improved method, the dissolution of TMs in LIBs for positive electrode materials such as LiNi0.5 Mn1.5 O4 (LNMO) or LiNix Coy Mnz O2 (NCM, x+y+z=1) can be studied in future in more detail.

Temperature and GA3 as Modulating Factors in the Biosynthesis of Alkaloids during Imbibition and Early Development of Annona x atemoya Mabb. cv. ‘Gefner’ Seedlings

Alkaloids are products of the specialized metabolism of plants and temperature is a factor capable of modulating their biosynthesis. Species of the Annonaceae family biosynthesize alkaloids and present dormancy in their seeds, which can be overcome with the use of gibberellins. Therefore, the aim of this work was to evaluate whether temperature variations and the use of gibberellin in seeds affect the production of alkaloids during germination and early development of Annona x atemoya Mabb. cv. ‘Gefner’ seedlings. Results showed that the temperature of 30 °C associated with imbibition in water caused an increase in the production of total alkaloids and liriodenine and that the use of gibberellin decreased production. In addition, it was possible to identify the presence of nine other alkaloids with organ-specific distribution. The presence of none of them was induced by the effect of temperature or gibberellic acid. Therefore, it could be concluded that temperature variation and the use of GA3 alter the biosynthesis of alkaloids, with high temperature causing increased concentration, but the use of GA3 reducing production.

Effect of Plant Growth Regulators Giberellic acid (GA3) And Salicylic Acid (SA) on Growth and Yield of Carnation (Dianthus caryophyllus) under Naturally Ventilated Polyhouse

The present investigation entitled “Effect of plant growth regulators Gibberellic Acid (GA3) and Salicylic Acid (SA) on the growth and yield of carnation under naturally ventilated polyhouse”, was carried out during November, 2021 to April 2022 in, Naturally Ventilated Polyhouse, Department of Horticulture, Naini Agricultural Institute, SHUATS, it was concluded that the plant growth regulators treatments rendered their significant effect on almost all the growth, flowering and yield characters as well as quality of carnation. The treatment T3 i.e. application of GA3 @ 200 ppm was found superior in terms of Plant height (102.27cm), number of leaves (203.67), number of shoots (7.67), internodal length (7.73cm), number of internodes per shoot (17), bud length (10cm), bud diameter (2.87cm), flower diameter (6.80cm), flower length (5.67cm), flower stalk length (96.93cm), vase life (10.33), number of cut flower stalks per plant (7.00) and number of cut flower stalks per square meter (175). However, plants treated with SA @ 120ppm took minimum days for bud initiation (112.67 days) and the days taken to bud opening (24.67). Among the different treatments the highest Gross return (Rs/200m2) (7,00,000), Net return (441565), benefit cost ratio (2.70) was obtainedunder the use of GA3 @ 200 ppm (T3).

Effects of Foliar and Soil Application of Gibberellic Acid (GA3) at Different Growth Stages on Agronomic Traits and Yield of Rice (Oryza sativa L.)

Use of Gibberellic acid (GA3) application in rice cultivation for increasing the grain yield is well documented. However, improper and untimely use of GA3 could result in poor response to GA3 application. This study was aimed at to investigate the timing of application during different growth stages and mode of application of GA3 on the growth and yield of MR219, a popular Indica rice variety, released by Malaysian Agricultural Research and Development Institute (MARDI). Two commercial GA3 formulations, namely ProGibb SG containing 40% GA3 and ProGibb silica Granule containing 0.1% GA3 were used for foliar and soil application, respectively. GA3 was applied at late tillering stage and at 10-30% panicle heading stage. Interestingly, GA3 application as foliar spray during the early reproductive stage, ie at 10-30% panicle heading stage enhanced the grain yield significantly, recording over 27% grain yield increase over the untreated control. Moreover, two applications of GA3 at 7 days&amp;rsquo; interval has consistently given higher grain yield than single application. However, there is no significant difference in flag leaf characteristics, one thousand grain weight and milling qualities among different treatments. Our study has clearly illustrated that foliar application of GA3 at weekly interval at 10-30% panicle heading stage, can increase rice grain yield significantly.

Chrysin abrogates gibberellic acid-induced testicular oxidative stress and dysfunction via the regulation of antioxidants and steroidogenesis- and apoptosis-associated genes.

GA3 is widely used as a growth stimulant in agricultural regions. The long-term use of GA3 can cause organs damage. Chrysin is a flavonoid found in nature that is commonly used to treat organ toxicity. In this study, we examined the effect of chrysin on the testes function of GA3-affected rats. A total of 24 male Wistar rats were divided into 4 groups. Saline was given to the control group. The chrysin group was given orally 50 mg/kg/BW of chrysin in saline. The GA3 group received a daily oral gavage of GA3 (55 mg/kg/BW). The protective group (chrysin + GA3) was given chrysin and GA3 as those described in chrysin and GA3 groups. There were an increase in MDA levels in the serum and testicular tissue of GA3-treated group. Catalase, GSH, and SOD levels were all lowered in the GA3-treated rats. Chrysin dramatically reduced the harmful effects of GA3 by restoring reproductive hormone levels, altered sperm parameters, and antioxidant capabilities. Furthermore, GA3 reduced the quantitative expression of steroidogenesis genes StAR and 3-HSD, as well as Bcl2 genes, while it increased the apoptotic marker BAX; all were alleviated by the pre-administration of chrysin. The pre-administration of chrysin protected the GA3 group from spermatogenic vacuolation, interstitial edema, necrosis, and depletion. Chrysin inhibited oxidative stress and modulated antioxidant activity, as well as apoptosis-/anti-apoptosis-related mediators in the testes. Chrysin has the potential to repair GA3-induced testicular dysfunctions. This suggests that chrysin is preferable as a medication to mitigate GA3-induced oxidative damage in the testes. PRACTICAL APPLICATIONS: Chrysin has the potential to repair GA3-induced testicular dysfunctions. This suggests that chrysin is preferable as a medication to mitigate GA3-induced oxidative damage in the testes.

Effect of Foliar Feeding of Nutrients and Gibberellic Acid on Yield and Quality of Mango (Mangifera indica L.) Fruits cv. Dashehari

Background: Mango is national fruit of India and it is suffering with many problems in cultivation among which fruit drop is major which leads to low production. So, the application of nutrients and plant growth regulators would be helpful to minimize fruit drop and to get better yield with quality fruits. The aim of the present study to study the effect of foliar feeding of nutrients and gibberellic acid on yield and quality of mango (Mangifera indica L.) fruits cv. Dashehari. Methods: This study was conducted at Horticulture Farm, Rajawala and in PG Laboratory of Doon (PG) College of Agriculture Science and Technology, Camp Road, Selaqui, Dehradun during the years 2017-2018 with the use of GA3 (100 ppm), Urea (1.5%) and Boron (0.2%) alone and in combinations, these all were compared with control treatment. Result: All the treatments used were found better to improve the yield and quality of fruit but the treatment combination of Boron (0.2%) + Urea (1.5%) + GA3 (100 ppm) was found significantly effective to increase the fruit retention, fruit yield, fruit length, fruit width, fruit weight, total soluble solids, ascorbic acid and sugars. However, fruit drop and titrable acidity were drastically decreased while the fruit volume was found non-significant.

Comparative effects of gibberellic acid, salicylic acid and Bacillus subtilis on oxidative stress marker and antioxidant potential of Musa sapientum Linn

Banana (Musa sapientum) as a major fruit is widely cultivated for its nutritional and therapeutic properties. Thus, to avoid wastage, there is a need to increase its shelf life. In this study, banana fruits were dipped into the solutions of salicylic acid (SA), gibberellic acid (GA3), Bacillus subtilis (BS) and BS with SA or GA3, respectively, and control in distilled water. The SA, GA3 and BS effects on postharvest treatment of banana was investigated at 0, 3 and 6 day. This study compared the effects of GA3, SA or BS and their combined treatment on antioxidant properties of banana. The results showed that the use of GA3, SA and BS individually or in combination significantly (p ≤ .05) increased the antioxidant properties of the fruits. Decreased titratable acidity and weight loss in the treated groups show the effectiveness of postharvest treatments. Therefore, the results of (GA3 and BS) combined effect is a promising postharvest treatment for banana fruits.

Germinability and Seedling Growth Performance of Chilli (Capsicum annuum) Seeds in Response to Different Gibberellic Acid Concentrations Pre-Treatment

Chilli seeds are always associated with physiological dormancy characteristics or endogenous dormancy that has affected their germination potential. Problems noticed on the low seed germination rate, vigour growth, further may lead to the poor seedling growth pattern of chilli crop production. Gibberellic Acid (GA3) which is usually used as a treatment solution is not a new advent of seed dormancy breaking methods for chilli. But, looking forwards to a better GA3 concentration is still needed for the discovery of this treatment potential effect on chilli seed germinability and seedling growth. Thus, this study aimed to evaluate the effect of different GA3 concentrations on seed emergence and seedling growth performance in chilli. In this experiment, chilli seeds were imbibed with 25 mg/L, 75 mg/L and 125 mg/L concentration of GA3 with three replications each; for 24 hours at room temperature (32±4°C) and the untreated seeds as a control. The data collection on final germination percentage was taken daily for 21 days after sowing. While the 15 germinated seeds were directly planted on the 5 polybags arranged in the net house of Junaidy Jonik Farm, Sabah, Malaysia. The experiment was arranged in a completely randomized design with three replications. Data were subjected to analysis of variance with SAS version 9.4 and the significant means were separated by the least significant difference test at P&lt;0.05. Significant differences were observed in the seed germinability measured; germination rate index (GRI), mean germination time (MGT) and final germination percentage (FGP), as well as on seedling vigour index (SVI) between treated and control seeds. Conversely, plant height, number of internodes, number of leaves and fresh weight of seedlings showed no significant differences among treatments. It was concluded that the use of GA3 was able to enhance chilli seeds germinability and could display a better SVI than the control. It is recommended to use GA3 treatment at 25 mg/L of concentration, as it may give an advantage to both economic and biological importance in producing higher germinability and seedling growth performance in chilli.

Germinability and Seedling Growth Performance of Chilli (Capsicum annuum) Seeds in Response to Different Gibberellic Acid Concentrations Pre-Treatment

Chilli seeds are always associated with physiological dormancy characteristics or endogenous dormancy that has affected their germination potential. Problems noticed on the low seed germination rate, vigour growth, further may lead to the poor seedling growth pattern of chilli crop production. Gibberellic Acid (GA3) which is usually used as a treatment solution is not a new advent of seed dormancy breaking methods for chilli. But, looking forwards to a better GA3 concentration is still needed for the discovery of this treatment potential effect on chilli seed germinability and seedling growth. Thus, this study aimed to evaluate the effect of different GA3 concentrations on seed emergence and seedling growth performance in chilli. In this experiment, chilli seeds were imbibed with 25 mg/L, 75 mg/L and 125 mg/L concentration of GA3 with three replications each; for 24 hours at room temperature (32±4°C) and the untreated seeds as a control. The data collection on final germination percentage was taken daily for 21 days after sowing. While the 15 germinated seeds were directly planted on the 5 polybags arranged in the net house of Junaidy Jonik Farm, Sabah, Malaysia. The experiment was arranged in a completely randomized design with three replications. Data were subjected to analysis of variance with SAS version 9.4 and the significant means were separated by the least significant difference test at P&lt;0.05. Significant differences were observed in the seed germinability measured; germination rate index (GRI), mean germination time (MGT) and final germination percentage (FGP), as well as on seedling vigour index (SVI) between treated and control seeds. Conversely, plant height, number of internodes, number of leaves and fresh weight of seedlings showed no significant differences among treatments. It was concluded that the use of GA3 was able to enhance chilli seeds germinability and could display a better SVI than the control. It is recommended to use GA3 treatment at 25 mg/L of concentration, as it may give an advantage to both economic and biological importance in producing higher germinability and seedling growth performance in chilli.

The Influence of Flower Head Order and Gibberellic Acid Treatment on the Hydroxycinnamic Acid and Luteolin Derivatives Content in Globe Artichoke Cultivars.

Flower head orders and the use of GA3 (gibberellic acid) treatment could be two influencing factors determining the bioactive compound levels in artichoke, but little to no information is available about their effects. In this study, we have therefore evaluated the influence of these factors on the hydroxycinnamic acid and luteolin derivative levels in three categories of artichoke: Seed-propagated open-pollinated cultivars; vegetatively propagated cultivars; and seed-propagated hybrids. The hydroxycinnamic acids and luteolin derivatives were quantified by RP-HPLC-DAD. The average flower head weight was the lowest in tertiary heads and GA3-treated artichokes, followed by secondary and main heads. Moreover, the hydroxycinnamic acid and luteolin derivatives levels were significantly higher in tertiary heads than in secondary or main heads. In addition, the GA3 treatment significantly reduced the hydroxycinnamic acid content and, in contrast, improved luteolin derivatives levels. These effects depended on the flower head order and cultivar. Knowledge of the effects of flower head order and GA3 treatment is therefore key in order to achieve the greatest health-benefits from artichoke consumption.

Exogenous Gibberellic Acid or Dilute Bee Honey Boosts Drought Stress Tolerance in Vicia faba by Rebalancing Osmoprotectants, Antioxidants, Nutrients, and Phytohormones.

The use of growth regulators such as gibberellic acid (GA3) and biostimulants, including diluted bee honey (Db-H) can improve drought tolerance in many crops, including the faba bean (Vicia faba L.). Db-H contains high values of osmoprotectants, mineral nutrients, vitamins, and many antioxidants making it an effective growth regulator against environmental stress effects. Therefore, the present study was planned to investigate the potential improvement in the faba bean plant performance (growth and productivity) under full watering (100% of crop evapotranspiration (ETc)) and drought stress (60% of ETc) by foliar application of GA3 (20 mg L−1) or Db-H (20 g L−1). The ameliorative impacts of these growth regulators on growth, productivity, physio-biochemical attributes, nutrient status, antioxidant defense system, and phytohormones were evaluated. GA3 or Db-H attenuated the negative influences of drought stress on cell membrane stability, ion leakage, relative water content, nutrient status, leaf pigments related to photosynthesis (chlorophylls and carotenoids), and efficiency of the photosystem II (PSII in terms of Fv/Fm and performance index), thus improving faba bean growth, green pod yield, and water use efficiency. Drought stress caused an abnormal state of nutrients and photosynthetic machinery due to increased indicators of oxidative stress (malondialdehyde (MDA), hydrogen peroxide (H2O2) and superoxide (O2•−)), associated with increased osmoprotectants (proline, glycine betaine, soluble sugars, and soluble protein), non-enzymatic antioxidants (ascorbic acid, glutathione, and α-tocopherol), and enzymatic antioxidant activities (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase). However, foliar-applied GA3 or Db-H mediated further increases in osmoprotectants, antioxidant capacity, GA3, indole-3-acetic acid, and cytokinins, along with decreased levels of MDA and abscisic acid. These results suggest the use of GA3 or Db-H at the tested concentrations to mitigate drought-induced damage in bean plants to obtain satisfactory growth and productivity under a water deficit of up to 40%.

Successive applications of gibberellic acid to reduce flowering of 'Montenegrina' mandarin in alternate bearing

Abstract: The objective of this work was to evaluate the number of successive applications of gibberellic acid (GA3), during the autumn-winter period, for its effect on the reduction of flowering, in the subsequent spring after periods of low fruit load (off-year), in 'Montenegrina' mandarin trees (Citrus deliciosa). Sequential applications at 40 mg L-1 GA3 were tested from one to four times, at 21-day intervals, beginning in the end of May. The experiment was carried out in a randomized complete block design, with four treatments and a control, four replicates, and one plant per experimental unit. Flowering, sprouting, types of shoots, fruit set, and fruit diameter were evaluated. The fruit set increases exponentially with the reduction of flowering intensity. The use of GA3 in two, three, or four sequential applications, from May to June, May to July, and from May to August, at 21-day intervals, reduces the intensity of flowering and sprouting of alternate bearing plants in the subsequent spring, increasing mixed shoots and reducing floral shoots. The use of four sequential applications of 40 mg L-1 GA3 promotes a great increase in the frequency of single flower terminal leafy shoots and favors the increase of fruit fixation and size.