GA3 Sprays Research Articles

Effect of Integrating Plant Growth Regulators and Micronutrients on Growth, Phenology and Seed Yield of Fenugreek (Trigonella foenum-graecum L.)

An experiment was conducted during Rabi 2019-20 at College of Agriculture, Indore (Madhya Pradesh) to investigate the effects of Plant Growth Regulator (PGRs) and Micro-nutrient Application on Growth, Quality, and Seed yield of Fenugreek (Trigonella foenum-graecum L.). The nine treatments consisted of different levels of PGRs i.e. GA3 and NAA with micro-nutrient (Mixol) which contain zinc, iron, manganese copper, boron and molybdenum including control (No use of PGRs and micro-nutrients) viz. T1 = 50 ppm GA3 seed treatment + Mixol 1.0%, T2 = 100 ppm GA3 seed treatment + Mixol 1.0%, T3 = 50 ppm GA3 foliar spray + Mixol 1.0%, T4 = 100 ppm GA3 foliar spray + Mixol 1.0%, T5 = 25 ppm NAA seed treatment + Mixol 1.0%, T6 = 50 ppm NAA seed treatment + Mixol 1.0%, T7=25 ppm foliar spray + Mixol 1.0%, T8 = 50 ppm NAA foliar spray + Mixol 1.0% and T9 = Control. Data were collected on different growth characters (Plant height and number of branches), Phonological attributes (Days to first flowering, days taken to 50% flowering and days to taken seed maturity) and yield characters (Seed yield per plant (g), seed yield t/ha, number of pods per plant, length of pod (cm), number of seeds per pod) of fenugreek. Based on results of one year experimentation, foliar spray of GA3 at 100 ppm + mixol 1.0% was found the best treatment compared with respect to plant growth and seed yield of fenugreek.

Overexpression of the Poa pratensis GA2ox gene family significantly reduced the plant height of transgenic Arabidopsis thaliana and Poa pratensis

Gibberellin (GAs) is an important plant hormone that plays a key role in plant growth and development. Gibberellin 2-oxidase (GA2ox) catalyzes the inactivation of biologically active GA or their direct precursors. In this study, five GA2ox genes were isolated from the wild type Poa pratensis ‘Baron’, named PpGA2ox3, PpGA2ox4, PpGA2ox5, PpGA2ox8, and PpGA2ox9. Phylogenetic tree analysis showed that PpGA2ox3, PpGA2ox4, PpGA2ox5, and PpGA2ox8 belong to class I GA2ox genes, while PpGA2ox9 belongs to class III GA2ox genes. They expressed in all tissues of Poa pratensis, in each plant tissue and growth stage, the expression patterns were different. After GA3 spraying treatment, the expression of each gene showed different patterns. Subcellular localization showed that PpGA2ox3 was located in chloroplasts, while PpGA2ox5 and PpGA2ox9 were located in the cytoplasm. When PpGA2ox3 and PpGA2ox9 were overexpressed in Arabidopsis thaliana, they all led to a typical dwarf phenotype, as well as low plant height, small leaves and late flowering. Similarly, when they overexpressed in P. pratensis, the transgenic plants also exhibited a dwarf phenotype with a lower leaf length/width ratio. Hormone analysis suggested that these dwarfing traits might be caused by a decrease in GA4 content. These studies indicated that the PpGA2ox gene family played an important role in studying the mechanism of plant dwarfism and also had the potential to become important genes for the breeding of P. pratensis.

Effect of GA3 and Nutrient Sprays on Growth of Kokum (Garcinia indica Choisy) Seedlings

An experiment was conducted at the College of Horticulture, Dapoli, during the year 2023 - 2024. The study was conducted using a Randomized Block Design with eight treatments, each replicated three times and the treatments included T1- GA3 @ 250 ppm, T2- GA3 @ 300 ppm, T3- GA3 @ 350 ppm, T4- 19:19:19 @ 0.5%, T5- 19:19:19 @ 1%, T6- 19:19:19 @ 2%, T7- 19:19:19 @ 2.5% and T8- Control with the aim to evaluate the influence of GA3 and nutrient sprays on the growth of kokum seedlings and to identify the optimal concentrations that would enhance growth and grafting success. The highest seedling height (28.53 cm), number of leaves (19.87), girth at collar region (3.44 mm) number of nodes (8.07) and internodal length (2.09 cm) were recorded in treatment T3 i.e. spraying with GA3 @ 350 ppm. The highest survival percentage of seedlings (96.00%), minimum number of days for obtaining 80 percent graftable seedlings (142.33 days), overall percentage of graftable seedlings (90.00%) and maximum percentage of graft success (94.82%) found in treatment T3.

Synergistic Effects of Microbial Gibberellic Acid and Vitamins on Onion (Allium cepa L.) Yield, and Quality in Low-Fertility Soil

Onion is one of the most popular vegetables that play a major role in boosting immunity against diseases. As a result of the successive population increase, many farmers resort to excessive use of chemical plant growth enhancers to increase the crop's productivity, which causes many health and environmental problems and reduces the sustainability of the soil. Microbial phytohormones and vitamins are safe, eco-friendly, and effective natural solutions to increase the crop's productivity and maintain the soil health at the same time. To our knowledge, until know there is no information about the roles of microbial gibberellic acid (GA3), and vitamins on the growth and quality traits of onions. Two field experiments were conducted during two consecutive winter seasons in a sandy calcareous soil farm. Two treatments were in the main plot (without and with microbial GA3), and six were in the sub-plot (control, chemical thiamine, ascorbic acid, riboflavin, and microbial ascorbic acid and riboflavin). Plant growth parameters including plant height, fresh weight, leaf number, bulb diameter, and neck diameter were recorded. Onion yield and their quality traits of sugar content, protein, antioxidants, vitamin C, phenols, flavonoids, and NPK were measured. The major findings revealed that plants treated with applications of microbial GA3 or vitamin treatments significantly improved the onion yield, phenotypic, physiological, and biochemical characteristics in both seasons. In the majority of the measured parameters, the microbial ascorbic acid treatment outperformed the other vitamin treatments. The combination of foliar microbial GA3 spray and vitamins, especially microbial ascorbic acid, and microbial riboflavin, produced the high onion yield, growth and quality traits of plant height, number of leaves, fresh weights, bulb diameter, sugar content, vitamin C, total antioxidants, total phenols, and flavonoids during both seasons. The application of microbial GA3 in combination with microbial vitamins as foliar spraying are promising eco-friendly, cheap, plant bio-stimulators that could be used safely in the field, especially under low-fertility soil, for good growth, yield, and high-quality onions.

Optimization of Flowering and Fruit Development in Ber (Ziziphus mauritiana L.) cv. Umran using Fertilizers, Micronutrients, and Bioregulators

In order to investigate the effect of fertilizers, micronutrients and bioregulators on flowering and fruit growth and developments on ber (Ziziphus mauritiana L.) cv. Umran, an experiment was carried out during 2019/2020 cropping season at the Fruit Research Station, Imalia, Department of Horticulture JNKVV Jabalpur. The study used a factorial design using randomized complete block design (RCBD), with three replications and a total of twelve treatment combinations that included bioregulators, micronutrients, and fertilizers either separately or in various combinations. The application of treatment T4 [RDF (N:P:K)+Foliar spray of GA3 + NAA (50 ppm+50 ppm)] was found to be significantly superior as compared to other treatments for flowering parameter in respect to induce early flower bud formation, based on the results obtained in this study. It takes 22 days to induce the earliest flowering after spray, and it takes 8.67 days to achieve 50% flowering. The earliest date of flower bud initiation was found with the T11 [RDF (N:P:K)+ NPK -18:18:18 (1.0%) + ZnSO4 (0.5%) + Borax (0.3%)] which showed to be the best for fruit growth and development characteristics, including specific gravity (1.047), fruit weight (36.52 g), fruit volume (36.56 ml), fruit length (4.53 cm), and fruit diameter (3.50 cm).With regard to practically every fruit growth and development attribute, the treatment T10 was found to be the second best.

EFFECT OF SPACING AND FOLIAR SPRAY OF GIBBERELLIC ACID (GA3) ON GROWTH AND YIELD OF OKRA

An experiment was conducted at the Horticultural Farm of Sher-e-Bangla Agricultural University, Dhaka during March-July, 2016 to find out the best combination of plant spacing and GA3 dose for successful production of okra. The experiment consisted of two factors, Factor A: three levels of spacing, viz. S1: 60 cm × 30 cm, S2: 60 cm × 40 cm and S3: 60 cm × 50 cm and Factor B: four doses of GA3, viz. H0 (control; no GA3); H1: 50 ppm GA3; H2: 100 ppm GA3 and H3: 150 ppm GA3. The experiment was laid out in a Randomized Complete Block Design following 12 treatment combinations and replicated thrice. Results revealed that interaction effect of spacing and foliar spray of GA3 had significant positive effect on growth (plant height, leaves plant-1, branches plant-1 and leaf area), yield contributing traits (number of fruits plant-1, fruit length, fruit diameter, fruit yield plant-1 and stover yield plant-1) and yield (tha-1) of okra. Among different treatment combinations, the highest yield (19.92 t ha-1) was obtained from S3H2 combination. Based on the results of the study, it is concluded that foliar application of 100 ppm GA3 with the spacing of 60 cm × 50 cm produced the highest yield of okra as compared to other treatment combinations tested. From our present findings we can suggest that, 60 cm × 50 cm spacing with 100 ppm GA3 as foliar application would be one of the effective agronomic practices for economic production of okra.

Response of Phosphorus, Sulphur and Foliar Spray of GA3 on Nutrient Content and Uptake of Soybean [Glycine max (L.) Merrill

Background: Soybean is an important oil seed crop grown in a varied range of climate and soils in India. Phosphorous and sulphur is an important macronutrient required for plants. Their deficiency in soil is a worldwide concern for production of oil seed crops. The gibberellic acid involved in plant growth and development. Therefore, investigation was carry out to study influenced of phosphorus, sulphur and gibberellic acid on nutrient content and uptake of soybean. Methods: An experiment conducted during kharif-2020 on soybean in sub-sub split plot design with three replications. The twenty four treatment combinations were comprised viz. four levels of phosphorus (Control, 20, 40 and 60 kg ha-1), three levels of sulphur (15, 30 and 45 kg ha-1) and two levels of gibberellic acid (Foliar spray of GA3 @ 75 ppm and no spray). Result: Results revealed that application of 40 kg phosphorus ha-1 and 30 kg sulphur ha-1 is optimum dose for obtaining higher available nitrogen, phosphorus, potassium and sulphur in the soil after crop harvest, nutrient content in seed and straw and uptake of soybean crop. The foliar spray of gibberellic acid @ 75 ppm is also beneficial for improving productivity and profitability of soybean crop.

Study on the effect of foliar spray of NAA, GA3 and Ethrel on yield and yield attributing traits of ridge gourd (Luffa acutangula)

Study on the effect of foliar spray of NAA, GA3 and Ethrel on yield and yield attributing traits of ridge gourd (Luffa acutangula)

Foliar Spray of NPK and Gibberellic Acid on Growth and Yield of Chickpea Based Intercropping System

A field experiment was carried out during rabi seasons of 2019-20 and 2020-21 at Birsa Agricultural University, Ranchi, Jharkhand. The experiment was laid out in split-plot design with 3 replications. The treatments were comprised of 9 main plots, viz., sole chickpea, sole wheat, sole linseed, sole safflower, sole mustard, chickpea + wheat (6:3), chickpea + linseed (6:2), chickpea + safflower (6:2), chickpea + mustard (6:2) and 3 sub-plots viz., water(control), foliar spray of 1% NPK (19:19:19) and GA3 (100 ppm). Results revealed that maximum values of growth parameter (like plant height, dry matter accumulation), yield attributes (like number of pods, capsules, capitula, siliqua/plant and spikes/m2, 100-seed weight in chickpea and 1000-seed weight), grain and straw yield as well as harvest index were recorded under chickpea+ mustard (6:2). With regards to different foliar spray treatments, the maximum values for the above-mentioned parameters were found to be higher under the foliar spray of GA3 (100 ppm) at 45 days after sowing during both the years of experimentation.

Micronutrient and Metabolic Profiling of Strawberry Cultivars Grown in Subtropical Conditions: A Review

Strawberry is most economically important fresh and processed fruits, consumed both for its pleasant flavor and its nutrient content. Due to the fruit’s high concentration of antioxidants and phytochemicals, eating strawberries has been linked to maintain good health and preventing the development of chronic diseases. The following information has been compiled from previous year research papers, which contain valuable insights into the health benefits, nutritional status and effects of strawberries. Balanced nutrition is needed by delicate strawberry plants so it’s important to maintain the nutritional status for better growth, yield and quality of strawberry fruits. Although strawberries are a highly perishable fruit and cannot be kept for an extended amount of time, several wrapping techniques have preserved the fruit’s quality when kept at ambient temperature. Disorder like albinism can be corrected with proper spacing and spray of borax and GA3. One step toward helping farmers maximize their profits is the notion of waste utilization in horticultural crops. Therefore, the goal of doubling farmer’s income by minimizing their after-harvest losses and enhancing the demand of perishable cultivable fruit crops is achieved. This review paper showing different practices related to strawberry like its propagation, metabolites and health benefits, biochemistry of fruit ripening, effect of micro and macronutrients on strawberry’s growth, yield and quality.

Influence of Foliar Spray with Urea and GA3 on Some Vegetative Growth Characteristics of Mandarin Saplings cv.Clementine.

The experiment was conducted in the lath house affiliated with the College of Agriculture / University of Anbar to investigate the effect of foliar spray of urea and GA3 on some vegetative growth traits of mandarin saplings cv. Clementine, during the period from April 2021 to December 2021, spraying urea(46% N) included 0(spray with distilled water as control), 4, 8 and 12 g.l-1 ; on the other hand, spraying GA3 included 0(spray distilled water as control), 30 and 60 mg.l-1 . The results showed that urea spray significantly increased all vegetative traits, especially 12 g.l-1 , compared to the control. In the same context, GA3 at 60 mg.l-1 spray increased all vegetative growth characteristics, like plant height, leaves number increment, leaves area, shoot number, shoot length and rootstock diameter increment, compared to the lowest value in control. Keywords: Foliar Spray, Urea, Nitrogen, GA3, Vegetative Growth, Mandarin.

Effect of ethrel and gibbrellic acid on bio-chemical changes and productivity of sugarcane (Saccharum species hybrid complex)

The present study was conducted during the spring seasons of 2015–16 to 2017–18 to investigate the effects of application of ethrel and gibbrellic acid on growth, yield and sucrose content of spring planted sugarcane in order to work out its potential to be used as germination and growth enhancer in subtropical region. The treatments viz., planting of setts after overnight soaking in water, T2 ; planting of setts after overnight soaking in 50 ppm ethrel solution, T3 ; planting of setts after overnight soaking in 100 ppm ethrel solution, T4 ; T1 + GA3 spray @ 35 ppm at 90, 120 and 150 DAP, T5 ; T2 + GA3 spray @ 35 ppm at 90, 120 and 150 DAP, T6 ; T3 + GA3 spray @ 35 ppm at 90, 120 and 150 DAP, T7 and T4 + GA3 spray @ 35 ppm at 90, 120 and 150 DAP, T8 were compared with T1 (conventional planting/farmers practice treatment). Sugarcane growth, yield, and quality parameters were significantly influenced by various treatments. Owing to enhanced reducing sugars, acid invertase (AI), indole acetic acid oxidase (IAAO) and superoxide dismutase (SOD) activity in treated setts, planting of setts after overnight soaking in 50 ppm ethrel solution resulted in higher germination count at 10, 20, 30, 40 and 50 days after planting (DAP). Planting of setts after overnight soaking in 50 ppm ethrel solution + GA3 spray @ 35 ppm at 90, 120, and 150 DAP resulted in a greater plant population at all stages of growth, which was responsible for a higher number of millable canes at harvesting. Treatment planting of setts after overnight soaking in 50 ppm ethrel solution + GA3 spray @ 35 ppm at 90, 120 and 150 DAP recorded higher leaf area index at 180 and 240 DAP. Similarly, treatment (T7 ) also recorded higher shoot and root dry weight at 120, 180, 240 and 300 DAP. Net assimilation rate during 120–180 DAP (5.78 g/m2 /day) and 180–240 DAP (3.95/m2 /day) were also recorded highest in treatment T7 . Similarly, planting of setts after overnight soaking in 50 ppm ethrel solution + GA3 spray @ 35 ppm at 90, 120 and 150 DAP recorded higher cane yield (101.2 t/ha) and net returns (166.25 × 103 `/ha) with a benefit: cost ratio of 1.31 which was significantly higher than farmers practice and planting of setts after overnight soaking in water. Thus, planting of setts after overnight soaking in 50 ppm ethrel solution + GA3 spray @ 35 ppm at 90, 120 and 150 DAP should be adopted to obtain the maximum productivity and profitability by spring sugarcane.

Modulating Effect of PGRs on Growth and Biochemical Traits in Rice (Oryza sativa L.) under Salt Stress

An investigation was conducted to study the effect of plant growth regulators on rice (variety Sarju-52) grown under sodic conditions, during the kharifseason 2018 at the students’ instructional farm of ANDUA&T, Kumarganj, Ayodhya. The experiment was laid out in randomized block design with nine treatments and three replications, with different concentrations and modes of application of plant growth regulators (PGRs). The PGRs were applied as follows- seed priming of GA3 @25 ppm & 50 ppm and SA @ 10 ppm & 25 ppm, and foliar application of GA3 and SA, each @ 100 ppm & 200 ppm at 30 (DAT), along with untreated control. Seed priming was done for 12 hours in different concentrations of PGRs. Thirty five days old seedlings were transplanted to the field from the nursery. Observations were recorded on various growth parameters such as plant height, number of tillers, dry biomass/hill, relative water content and biochemical parameters like chlorophyll, and TSS, at 30, 60 and 90 DAT and at maturity (harvesting stage). Both seed priming and foliar application of PGRs positively influenced the growth characters, chlorophyll content, and total soluble sugars. Moreover, foliar spray of GA3 @200 ppm was found to have a more pronounced effect in improving the yield of the variety studied, among all the treatments, under sodic conditions. It can be concluded that foliar spray of GA3 @ 200 ppm is effective in improving the growth and yield of rice grown under salt stress.

Influence of SA, GA3 and Pinching on Growth and Flowering in Verbena

A field experiment was conducted to find out effect of salicylic acid (SA), GA3, pinching and their interaction on the growth and flowering attributes of verbena × hybrida. Three concentration each of GA3 (100,150 and 200 ppm) and SA (100, 150 and 200 ppm) was foliar sprayed at 21 days after transplanting to run-off stage and pinching was done at 40 days with three replications set in Randomized Block Design. Pinching treatment recorded significantly maximum no. of primary branches/plant, stem diameter, fresh weight and dry weight of leaves, fresh leaf biomass, leaf area, flower longevity, fresh weight of flower, no. of spikes/plant and peduncle length. However, no. pinching treatment recorded maximum plant height, early bud initiation and early flowering. Spraying of GA3 100 ppm resulted in early bud initiation. GA3 150 ppm recorded fresh weight of leaves, fresh leaf biomass and bud cluster diameter. However, maximum plant height, leaf area, no. of spikes/plant and peduncle length was observed with GA3 at 200 ppm. Among various doses of salicylic acid, SA 100 ppm recorded maximum stem diameter. Early flowering, maximum fresh and dry weight of flower was seen with SA 150 ppm. SA 200 ppm resulted in maximum no. of primary branches/plant and flower diameter. Significant effect of interaction between pinching and plant growth chemicals (GA3 and SA) was observed in most of the growth and flowering attributes.

GA3 Treatment Delays the Deterioration of 'Shixia' Longan during the On-Tree Preservation and Room-Temperature Storage and Up-Regulates Antioxidants.

Gibberellic acids had been proven to improve the fruit quality and storability by delaying deterioration and maintaining the antioxidant system. In this study, the effect of GA3 spraying at different concentrations (10, 20, and 50 mg L-1) on the quality of on-tree preserved 'Shixia' longan was examined. Only 50 mg L-1 GA3 significantly delayed the decline of soluble solids (22.0% higher than the control) and resulted in higher total phenolics content (TPC), total flavonoid content (TFC), and phenylalanine ammonia-lyase activity in pulp at the later stages. The widely targeted metabolome analysis showed that the treatment reprogrammed secondary metabolites and up-regulated many tannins, phenolic acids, and lignans during the on-tree preservation. More importantly, the preharvest 50 mg L-1 GA3 spraying (at 85 and 95 days after flowering) led to significantly delayed pericarp browning and aril breakdown, as well as lower pericarp relative conductivity and mass loss at the later stages of room-temperature storage. The treatment also resulted in higher antioxidants in pulp (vitamin C, phenolics, and reduced glutathione) and pericarp (vitamin C, flavonoids, and phenolics). Therefore, preharvest 50 mg L-1 GA3 spraying is an effective method for maintaining the quality and up-regulating antioxidants of longan fruit during both on-tree preservation and room-temperature storage.

Exogenous applications of gibberellic acid modulate the growth, flowering and longevity of calla lily

Calla lily (Zantedeschia aethiopica (L.) Spreng.) is an important ornamental crop used in garden landscapes, floral arrangements, and medicinal applications. Gibberellic acid (GA3) is actively involved in cell elongation, growth, physiology, and flowering. In addition, it is an environmentally-friendly compound which can be applied to plants to increase the ornamental production. Therefore, the present study was designed with three GA3 spray times viz., single, double and triple spray and five exogenous applications of gibberellic acid concentrations viz., 0, 25, 50, 100, and 200 mg L−1 with factorial randomized block design. Results revealed that the interaction effect of combinations of two time applications of GA3 at 100 mg L−1 induced higher growth parameters over control. Significantly higher physiological parameters viz., photosynthetic rate (14.3 μmol m−2s−1), number of stomata (26.5 mm−2), stomatal conductance (0.28 mmol m−2s−1), and transpiration rate (3.6 mmol m−2s−1) were reported when plants were treated twice with 100 mg L−1 GA3. Similarly, among flowering traits, days to flower were significantly low in plants treated two-time spray at GA3 100 mg L−1 (169.8 days). The number of flowers in the double spray at GA3 100 mg L−1 treatment increased by 11.3 and 23.7% over triple spray and control, respectively. Vase life was also significantly higher in plants treated with double spray at GA3 100 mg L−1 (6.3 days). The regression equation and correlation matrix indicated a strong relationship between growth, flowering and GA3 concentrations up to 100 mg L−1. The PCA analysis revealed that the calla lily crop is positively affected by spray timing and GA3 treatments. In the context of vegetative, reproductive, and longevity parameters of the crop, a dual spray of 100 mg L−1 GA3 can be recommended to small scale farmers and commercial growers as an alternative technique for promoting growth, yield and improving the ornamental value for commercial level production.

Effect of Foliar Spraying of Gibberellins and Brassinolide on Cadmium Accumulation in Rice.

Cadmium (Cd) is one of the heavy metals that contaminate rice cultivation, and reducing Cd contamination in rice through agronomic measures is a hot research topic. In this study, foliar sprays of gibberellins (GA) and brassinolide (BR) were applied to rice under Cd stress in hydroponic and pot experiments. After foliar spraying of GR and BR, the biomass of rice plants grown in either hydroponics or soil culture was significantly higher or even exceeded that in the absence of Cd stress. In addition, photosynthetic parameters (maximum fluorescence values), root length and root surface area, and CAT, SOD and POD activities were significantly improved. The MDA content decreased in the shoots, suggesting that the application of GR and BA may have enhanced photosynthesis and antioxidant function to alleviate Cd stress. Furthermore, the BR and GA treatments decreased the Cd content of rice roots, shoots and grains as well as the Cd transfer coefficient. Cd chemical morphology analysis of rice roots and shoots showed that the proportion of soluble Cd (Ethanol-Cd and Water-Cd) decreased, whereas the proportion of NaCl-Cd increased. Analysis of the subcellular distribution of Cd in rice roots and above ground showed that the proportion of Cd in the cell wall increased after foliar spraying of GA and BR. The results indicate that after foliar application of GA and BR, more of the Cd in rice was transformed into immobile forms and was fixed in the cell wall, thus reducing the amount in the seeds. In summary, foliar sprays of GA and BR can reduce the toxic effects of Cd on rice plants and reduce the Cd content in rice grains, with GA being more effective.

Exogenous hormone application regulates dwarf mutant plant height in Sophora davidii (Franch.) Skeels by changing endogenous hormone levels

Dwarf mutants are valuable materials for investigating plant gene function and developing new crop varieties. In the present study, dwarf mutant (D-CK) and wild-type (W-CK) Sophora davidii (Franch.) Skeels plants foliarly sprayed with distilled water were used as controls, and dwarf mutants were treated with different concentrations of gibberellin A3 (GA3; 20, 40 and 60 mg L-1), brassinosteroid (BR; 12.5, 25 and 50 mg L-1); and auxin indole-3-acetic acid (IAA; 12.5, 25 and 50 mg L-1) to study the changes in plant height at 20, 40 and 60 d after exogenous hormone spraying. The changes in endogenous contents of IAA, GA3, BR, abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) and IAA:ABA ratio in the dwarf mutant plants were also measured at 20, 40 and 60 d after exogenous hormone application. The dwarf mutants reverted to the W-CK height phenotype after 60 d of exogenous spraying with different concentrations of GA3 and BR (except 50 mg·L-1), but after exogenous spraying with IAA, dwarf mutants did not revert to the W-CK height phenotype. Compared with D-CK plants, endogenous GA3, BR and IAA contents in dwarf mutant plants increased to some extent with exogenous spraying of GA3, BR and IAA. The results indicated that exogenous spraying of different concentrations of GA3 and BR regulated S. davidii plant height by promoting the secretion of endogenous GA3, BR, IAA and SA and inhibiting endogenous ABA secretion in dwarf mutant. The height of mutants was sensitive to exogenous GA3 and BR but not to exogenous IAA.

Effects of Plant Growth Regulators Including Micro-nutrients on Fruit Set and Yield of Mandarin in Dhankuta District of Nepal

The study evaluated foliar applications of three plant growth regulators, viz. GA3 @ 20ppm; 2,4-D @ 15ppm; and NAA @ 50ppm; alone and their combinations including three plant micro-nutrients, viz. B @ 0.4% + Zn @ 0.2% + Ca @ 1% in order to determine the best foliar spray of growth hormones and plant nutrients for the increased fruit set and yield of mandarin. The foliar sprays were applied five times, started from full-bloom until late September (pre-harvest stage). The experiments were conducted in Dhankuta, Nepal during 2019 and 2020. The highest bloom fruit set of 6.1% was recorded at the foliar application of GA3 20ppm + NAA @ 50ppm, compared to the control treatment of 4.6%. Likewise, there were significant effects of plant growth regulations and micro-nutrients applications on the fruit drops across the fruit growing periods. The foliar application of GA3 + 2,4-D + micronutrients resulted in the lowest fruit drop during the months of June (63.9%), July (65.9%), and September (20.8%), as opposed to the control treatment's fruit drops of 77.6, 80.4, and 41.5%. In addition, the fruit drops occurred at the foliar sprays of GA3 + 2,4-D were statistically at par with the GA3 + 2,4-D + micro-nutrients. Also, the GA3 + 2,4-D + micronutrient spray treatment had the largest number of fruits (995 nos.) and total fruit weight (64.2 kg) per tree, which were considerably higher than the control by 201.5 and 175.5%, respectively. To sum up, a combined foliar application of gibberellic acid, 2,4-D and micro-nutrients is recommended for improving the fruit set, retention and yield of mandarin.

Influence of Foliar Application of Growth Regulators on Vegetative Growth and Flowering Of Chrysanthemum

The pot experiment was conducted at the Floriculture field of Horticulture Research Centre (HRC), Bangladesh Agricultural Research Institute (BARI), Gazipur during August 2020 to May 2021 to evaluate the foliar spray of gibberellic acid (GA3), benzyl adenine (BA) and naphthalene acetic acid (NAA) on growth and flowering traits of chrysanthemum (Chrysanthemum morifolium). The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. Four weeks old seedlings of chrysanthemum genotype CM-019 (flower class: Pompon and flower colour: Orange yellow) were transplanted in pot keeping under natural sunlight. The aqueous solution of GA3, BA and NAA @ 100 and 200 ppm of each were sprayed on the flower plants at monthly interval starting after one month of transplantation of seedlings along with control (water). The results revealed that vegetative growth and flowering parameters were significantly influenced by plant growth regulators. Maximum number of leaves per plant (50.0) and leaf area per plant (7.5 cm2) were recorded from the spraying of BA @ 100 ppm closely followed by BA @ 200 ppm (48.0 and 7.0 cm2/plant) and GA3 @ 100 ppm only for number of leaves (47.0/plant). Spraying of GA3 @ 100 ppm produced the tallest plant (70.0 cm) and the highest plant spread (23.0 cm). Number of flowers (26.0/plant), flower size (7.8 cm), average weight of stalk (37.0 g) and vase life (15.0 days) were also found maximum from the application of GA3 @ 100 ppm, closely followed by GA3 @ 200 ppm (23.5/plant, 7.2 cm, 36.0 g, 14.0 days) and NAA @ 100 ppm (18.5/plant, 7.0 cm, 36.0 g, 13.0 days) and irrespective of concentrations, BA failed to improve these characters. GA3 @ 100 ppm recorded maximum length of stalk (37.5 cm) and rachis (29.0 cm), which was identical with GA3 @ 200 ppm (34.6 cm and 25.0 cm), and BA @ 100 ppm gave the lowest length of stalk and rachis. GA3 also caused faster initiation of flowering, whereas NAA and BA delayed it. GA3 @ 100 ppm took the minimum days to flowering (50.0 days) was observed when plants were sprayed with GA3 @ 100 ppm whereas it was maximum (69 days) from BA @ 100 ppm treatment. It can be concluded that GA3 @ 100 ppm provided the best results for obtaining better vegetative growth of plants, maximum number of cut blooms with longer stalk as well as bigger flower size with prolonged vase life in chrysanthemum.
 Bangladesh J. Agril. Res. 47(1): 69-80, March 2022