Foliar Application Of GA3 Research Articles

Effects of Foliar Application of Gibberellic -Acid3 on the Growth and Yield of Canola (Brassica napus L.) Genotypes

Plant growth regulators play a central part in plant life. Plant hormones help to manage the equilibrium of phytohormones. Gibberellic acid, which is well known as a plant growth promoting hormone, is involved in a variety of activities related to plant growth and development. An experiment was performed at the Nuclear Institute of Agriculture, Tandojam with four promising canola genotypes in order to determine the impact of GA3 foliar application on canola growth and output during the rabi season in 2017-2018. The results showed that growth regulators levels significantly influenced the growth and yield of canola crops. It was observed that earlier days to maturity (108.39) was recorded in genotype R00-100/6, while maximum plant height (162.75), branches per plant (10.33), siliquae per plant (362.24), siliqua length (7.39 cm), seeds per siliqua (21.49), seed index (4.50 g) and seed yield (1443.08 kg ha-1) were observed with the application of GA3 5g ha-1 in SURHRAN-2012, followed by the application of GA3 6 g ha-1 genotype R00-125/12 and Rainbow (P). The results suggested that the variety SURHRAN-2012 x GA35 g ha-1 (foliar application) is comprised a suitable combination for obtaining maximum yield. Such application of GA3 is very advantageous in the field of plant development.

Effect of Gibberellic Acid and Silicon at Germination and Seedling Growth of Triticum Aestivum Grown under Salinity

Different abiotic stresses create noticeable changes in plant growth and development and plant under such condition reduced its yield. Different ions and growth regulators are very important and play key role for creation of stress tolerance in plants. This project was proposed to evaluate the performance of gibberellic acid and silicon on germination and seedling establishment stage of wheat under salinity. Experiment was completely randomized design, in which seeds were sown in petri plates, which were irrigated with different concentration of NaCl (control, 50mM and 150mM), GA3 (50ppm and 100ppm), silicon (5mM and 10mM) and combination of silicon and GA3 (50ppm GA3 x 5 mM Si and 100ppmGA3 x 10 mM Si). After 7 days experiment was terminated and shoot length, root length, fresh weight, dry weight, vigor index, RWC, RSR, SWR and RWR were measured. Shoot length, root length, Fresh weight and dry weight, Vigor index, RWC, SWR, RWR and different physiological indices were reduced with increasing salt (50mM and 150mM) as compare to control. Result indicated that different concentration of salt significantly increased RSR as compare to control plant. Further investigations revealed that under non-saline conditions application of GA3, silicon, and interactions showed increase in studied parameters except vigor index, RWR which decreased after foliar applications as compare to without GA3 and silicon applied plants. Additionally, under saline conditions foliar applications of GA3, silicon and interactions increase root length, shoot length, fresh and dry weight, RSR, RWR, SWR and stress tolerance indices. Consequently, the results suggested that these chemicals under studied doses can act as an effective strategy to cope up the deleterious effects of salt in wheat at germination and seedling growth stages.

Cadmium Toxicity Alleviation through Exogenous Application of Gibberellic Acid (GA3) in Mustard (Brassica juncea (L.) Czern.) and Rapeseed (Brassica rapa L.)

An experiment was carried out by considering adverse impact of heavy metals on human health through consumption of crops. To alleviate the adverse effects of cadmium (Cd) toxicity through foliar application of gibberellic acid (GA3), two varieties of Brassica including Indian mustard (Brassica juncea (L.) Czern.) commonly known as ‘Raya’ and rapeseed (Brassica rapaL.) as ‘Toria’ were studied. The Completely Randomized Design (CRD) was used with eight treatments including control in four replicates. Treatments were as following, T0 (control), T1 (150 μM CdCl2), T2 (50 mg/L GA3), T3 (75 mg/L GA3), T4 (100 mg/L GA3), T5 (150 μM CdCl2 + 50 mg/L GA3), T6 (150 μM CdCl2 + 75 mg/L GA3), and T7 (150 μM CdCl2 + 100 mg/L GA3). Gibberellic acid (GA3), a plant growth regulator applied exogenously. The concentration of cadmium (150 µM CdCl2) resulted in Cd toxicity affected adversely the morphological and biochemical parameters. Foliar application of GA3 (50 mg, 75 mg and 100 mg) positively influenced the various growth parameters as root length (30 cm), shoot length (129.75 cm), number of leaves (14.5), pods per plant (88) and biochemical parameters like total chlorophyll (0.19 mg/g), protein content (0.70 mg/mL), carbohydrates (0.37 mg/mL) and CAT (0.56 units/mg). Outcome indicated that GA3 reduces the harmful effects of Cd stress in both varieties. It was concluded that all growth and yield parameters of variety ‘Raya’ were better as compared to variety ‘Toria’, hence Raya recommended for large scale cultivation with GA3 under Cd stress.

INFLUENCE OF ORGANIC MANURES AND GIBBERELLIC ACID ON GROWTH AND YIELD OF STRAWBERRY (Fragaria X ananassa DUCH.)

A field experiment was conducted to study the effect of organic manures and growth regulators on the growth and yield of two varieties of strawberry namely ‘Sweet Charlie’ and ‘Winter Dawn’. Six treatments were taken combining three organic manures viz. Vermicompost @ 3.0 t/ha, Mustard oil cake @ 1.0 t/ha and Neem cake @ 1.0 t/ha and two concentrations of gibberellic acid (GA3) viz. 75 ppm and 100 ppm along with a control. Foliar application of GA3 was carried out at 40 and 60 days after planting whereas organic manures were applied as basal dose. Results of the study suggested that higher doses i.e. 100 ppm of GA3 along with vermicompost exhibited more vegetative growth whereas 75 ppm GA3 resulted in higher fruit set and yield in both the varieties. It was found that vermicompost @ 3.0 t/ha combined with 100 ppm GA3 recorded the highest plant height (24.7 cm and 21.4 cm) and numbers of leaves per plant (46.0 and 68.7) in both Sweet Charlie and Winter Dawn varieties, respectively. Whereas, highest fruit diameter (3.3cm and 3.4cm), fruit length (4.6cm and 4.8cm), fruit weight (18.2 g and 17.9 g), number of fruits per plant (24.6 and 32.0), yield per plant (447.8 g and 572.1 g) and yield per hectare (18.80 t and 24.03 t) were recorded under vermicompost @ 3.0 t/ha in combination with 75 ppm GA3 in both Sweet Charlie and Winter Dawn varieties, respectively. It was observed that Winter Dawn variety produced a 28.0% higher yield as compared to Sweet Charlie under the best treatment i.e. vermicompost @ 3.0 t/ha in combination with 75 ppm GA3.

Plant Growth Regulators Modify Fruit Set, Fruit Quality, and Return Bloom in Sweet Cherry

Sweet cherry (Prunus avium L.) is a valuable fruit crop worldwide. Farmers’ incomes are closely related to fruit quantity and quality, yet these can be highly variable across years. As part of a broader project for optimizing fruit set and fruit quality in sweet cherries, this study was conducted to evaluate the potential of various plant growth regulators (PGRs) for improving fruit set and fruit quality. Cytokinins, gibberellins, auxin, and polyamines were used as treatments. Treatments were applied as foliar sprays at full bloom to ‘Bing’ and three low-productivity genotypes, ‘Regina’, ‘Tieton’, and ‘PC8011-3’. We assessed the fruit set, fruit quality, and return bloom from each treatment. 4-chlorophenoxyacetic acid (4-CPA) increased fruit set by 53% and 36% in ‘Bing’ and ‘Tieton’, respectively. The combination of gibberellin (GA)3 + GA4/7 was more effective for improving fruit set than other isomers of gibberellin alone. Cytokinin treatments had slight adverse effects or no effect on fruit set except for CPPU. In ‘PC8011-3’, both N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) and 4-CPA enhanced fruit set by ≈81% and 100% compared with untreated control. The response of cherry trees to polyamine sprays depended on the properties of the cultivars and the treatment concentration. Foliar application of GA3, GA4/7, or N-phenyl-N'-(1, 2, 3-thiadiazol-5-yl) urea (TDZ) in ‘Bing’ trees has negative effects on return bloom, whereas GA1 can increase the yield and flower buds. These results suggest that PGRs may have varied effects on sweet cherry fruit set and that more work is needed to develop practical programs for improving yield security.

Improving Seed Productivity of Garlic By Using Nitrogen, Potassium Fertilization and Some Growth Regulators تحسين إنتاج تقاوى الثوم بإستخدام التسميد النيتروجينى والبوتاسى وبعض منظمات النمو

Two field experiments were conducted under Egyptian conditions at Kaha Vegetables Research Farm, Horticulture Research Institute, Agriculture Research Centre to study the effect of the high nitrogen and potassium levels and two growth regulators, Cytokinin at 2.5 ppm and Gibberellic Acid (GA3) at 100 ppm on the growth and seed yield of garlic (Allium sativum L.) cv. Sids 40. The obtained results showed that increasing nitrogen and potassium fertilizer up to 150 % NK. of the recommended rate (120 kg N + 72 kg K2O fed-1), significantly improved most studied growth traits (plant length, number of leaves, leaf area, total fresh weight, total plant dry weight), bulb characters, chemical constituents, yield, and yield components. Moreover, 150 % NK combined with GA3 + CPPU foliar spraying resulted in the highest average bulb weight, average glove weight and bulb. The obtained results confirm that garlic seed yield could be improve by N, K nutrition and foliar application of GA3 and CPPU.

Exogenously applied GA3 promotes plant growth in onion by reducing oxidative stress under saline conditions

Onion (Allium cepa L.) is a biennial crop of high commercial value in Pakistan. Onion is considered as salt sensitive plant species. The present investigation was carried out to investigate the effect of salinity on onion and its alleviation through exogenously applied gibberellic acid (GA3; 100 mg L-1). Foliar application of GA3 (100 mg L-1) was applied on onion seedlings grown under three levels (0, 2 or 4 dS m-1) of salinity after 45 days of sowing. Results revealed that growth parameters and total soluble protein (TSP) contents declined with increase in soil salinity level. While, antioxidant enzyme activities (CAT, SOD and POD) were increased with salinity. However, exogenously applied GA3 significantly enhanced the plant growth and TSP in onion seedlings. Interestingly, CAT, SOD and POD concentration decreased with GA3 application which depicts stress alleviation in saline stressed onion plants due to GA3. It was concluded that the growth of onion could be enhanced to some extent by the application of GA3 under salinity stress.

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%.

Response of plant growth regulators and multi micronutrient on growth, yield and quality of chrysanthemum cv. Ratlam selection

The present experiment entitled “Interaction Response of Plant growth regulators and Multi micronutrient on Growth, Yield and Quality of Chrysanthemum cv. Ratlam Selection” was carried out at Jamuvadi Farm, Department of Horticulture, College of Agriculture, Junagadh Agricultural University, Junagadh, during October 2018 to February 2019 and October 2019 to February 2020. The experiment was laid out in Randomized Block Design with Factorial concept (FRBD) consisting two factors with three replications. The treatment comprised with five plant growth regulators and three treatments of multi micronutrient. The results indicated that the foliar application of GA3 @ 150 ppm with multi micronutrient (grade-IV) @ 0.75% foliar spray at 30 & 45 DAT after transplanting in addition to recommended dose of fertilizers (120: 60: 60 kg/ha NPK) produced better growth and yield characters viz., plant height, plant spread, number of branches, stem thickness, number of flowers per plant, number of flowers per plot, weight of single flower, flower yield per plot and flower yield per hectare as well as quality characters viz., vase life of cut flowers, shelf life of loose flowers, in situ longevity of flowers, flower stalk length and flower diameter in chrysanthemum cv. Ratlam Selection.

Growth and Yield of Squash Influenced by Leaf Pruning and Gibberellic Acid (GA3)

The experiment was conducted at Sher-e-Bangla Agricultural University's Horticulture Farm, Sher-e-Bangla Nagar, Dhaka-1207, to determine the effect of pruning and GA3 on squash growth and yield over the period from November 2017 to February 2018 Three levels of pruning as P0 = No pruning (control), P1 = 1st pruning at 20 DAT (1st and 2nd leaves) and P2 = 2nd pruning at 30 DAT (3rd and 4th leaves) and four levels of GA3foliar application as G0 = No GA3 (control), G1 = 100 ppm GA3, G2 = 200 ppm GA3 and G3 = 400 ppm GA3 considered for the present study. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Considering growth parameters, pruning treatment had a significant effect on growth, yield contributing parameters and yield of squash except for stem base diameter and individual fruit weight. Regarding GA3 treatments, growth and yield parameters were significantly influenced except fruit diameter. In terms of the combined effect of pruning and GA3 treatments, all the studied growth and yield parameters were significantly influenced. The highest stem length (64.73 cm), number of leaves plant-1 (23.59), stem base diameter (2.09 cm), number of male flower plant-1 (8.69), number of female flower plant-1 (7.52), total number of fruits plant-1 (5.74), fruit length (22.42 cm), fruit diameter (6.15 cm), individual fruit weight (507.66 g), dry weight of fruit (6.61%), weight of fruits plant-1 (2914.33 g) and fruit yield ha-1 (29.14 t) were also found from the treatment combination of P1G1 compared to the other treatment combination. Hence, we can summarize that 1st pruning at 20 DAT (1st and 2nd leaves) with 100 ppm GA3 given the maximum output in terms of yield compared to other treatments.

Interactive Effects of Gibberellic Acid and Nitrogen Fertilization on the Growth, Yield, and Quality of Sugar Beet

Two field trials were conducted during the 2014/2015 and 2015/2016 seasons at Aweesh Al-Hagar Village, center of Mansoura, Dakahlia Governorate, Egypt. A split-split-plot design with four replicates was used. The main plots were assigned three nitrogen fertilizer levels, i.e., 165, 220, and 275 kg/ha. The sub-plots were restricted to four gibberellic acid (GA3) concentrations, i.e., 0, 80, 160, and 240 mg/L, and the sub-sub plots received GA3 application twice, i.e., 60 and 120 days after planting (DAP). The results showed that both root length and diameter, root and foliage fresh weights/plant, and root and foliage yields/ha increased with the incremental level of nitrogen and/or GA3 concentration. Foliar application of GA3 and N-fertilizers also significantly decreased quality parameters including sucrose and total soluble solid (TSS) percentages. Early application of GA3 (60 DAP) had an active role on sugar beet growth, yield, and quality compared with spraying at 120 DAP. Generally, fertilizing sugar beet with 275 kg N/ha or spraying GA3 with a concentration of 160 mg/L at 60 DAP is the recommended treatment for raising sugar yield under the ecological circumstances of this research.

Technological refinement to enhance profitability in hybrid rice seed production

Rice is livelihood of majority of population in tropical and sub-tropical parts of the world. Hybrid rice varieties have been witnessed to enhance the production as well productivity over the open pollinated varieties and that’s why Indian farmers are being given preference the hybrid culture in their rice farming. If the farmers are well trained for the hybrid seed production, their income will certainly be enhanced. Keeping above facts, a series of experiments were conducted with rice hybrid NDRH2 accommodating its parental lines viz., IR58025A, IR58025B, NDR3026-3-1, along with a combination of treatments involving staggered seeding, proper application of GA3, DAP and Boric Acid, supplementary pollination, etc. measures in order to maximize the hybrid seed production. The economics of various components viz., common cost, treatment cost, cost of cultivation, gross return, net return and benefit cost (B: C) ratio of different treatments were worked out on the basis of input-output analysis. The maximum benefit: cost ratio viz., 2.56:1 and 2.60:1 during 2015 and 2017, respectively was observed with foliar application of GA3 @ 90g/ha+ DAP @ 3%+Boric acid @ 0.3% by producing hybrid seed of rice hybrid NDRH2 using CMS and fertility restorer system at 2:12 male and female planting ratio during Kharif season. Thus, these fine tuning in hybrid rice seed production technology advocated as a major profit earning enterprise which needs to be disseminated at farmer’s fields also on a mission mode in order to enhance and or double their income by 2022.

Effects of Foliar Application of Gibberellic Acid on the Salt Tolerance of Tomato and Sweet Pepper Transplants

Seed germination and early seedling growth are the plant growth stages most sensitive to salt stress. Thus, the availability of poor-quality brackish water can be a big limiting factor for the nursery vegetable industry. The exogenous supplementation of gibberellic acid (GA3) may promote growth and vigor and counterbalance salt stress in mature plants. This study aimed to test exogenous supplementation through foliar spray of 10−5 M GA3 for increasing salt tolerance of tomato and sweet pepper seedlings irrigated with increasing salinity (0, 25, and 50 mM NaCl during nursery growth. Tomato and sweet pepper seedlings suffered negative effects of salinity on plant height, biomass, shoot/root ratio, leaf number, leaf area, relative water content, and stomatal conductance. The foliar application of GA3 had a growth-promoting effect on the unstressed tomato and pepper seedlings and was successful in increasing salinity tolerance of tomato seedlings up to 25 mM NaCl and up to 50 mM NaCl in sweet pepper seedlings. This treatment could represent a sustainable strategy to use saline water in vegetable nurseries limiting its negative effect on seedling quality and production time.

Effect of foliar application of gibberellic acid (GA3) on quality attributes of calendula flowers (Calendula officinalis) cv. Gitana Fiesta in Chitwan, Nepal

An experiment was conducted to study the effect of gibberellic acid (GA3) on quality attributes of calendula (Calendula officinalis L.). Single factorial experiment based on completely randomized design including 7 treatments and 3 replications was carried out. The treatments used were different concentrations of GA3 (0, 50, 100,150, 200, 250 and 300 ppm). Results showed that foliar application of GA3 had positive effect on quality of calendula flowers. First bud initiation and first flowering were recorded significantly earlier (p<0.05) if plants were sprayed with T5 (GA3@200ppm) treatment. Similarly, the study showed that the maximum flower diameter (6.43 cm) was recorded in T6 (GA3@250ppm) which was significantly similar (p>0.05) to T5 (GA3@200ppm) treatment whereas minimum flower diameter (4.19 cm) was recorded in control. Significant differences (p<0.05) among treatments were recorded in weight of flower where maximum weight of flower (3.77 gm) was recorded in T6 (GA3@250ppm), while minimum weight of flower (2.86 gm) was recorded in control plants. These results suggest that GA3 of dose 200 ppm to 250 ppm was ideal for enhancing the quality of flowers in calendula.

Synergistic effect of cytokinin and gibberellins stimulates release of dormancy in tea (Camellia sinensis (L.) O. Kuntze) bud.

Reactivation of dormant meristem in banjhi (dormant) shoots is important to enhance the quality and quantity of tea production. The field grown tea bushes were subjected to treatment with dormancy breaking agents such as potassium nitrate (KNO3), thiourea, sodium nitro prusside (SNP), the phytohormones kinetin (Kn) and gibberellins (GA). The efficacy of Kn and GA were comparatively lesser than KNO3 while the combination of Kn and GA (50 and100 ppm respectively) resulted in better dormancy reduction in tea buds. This observation was supported by our results from gene expression study where accumulation patterns of mRNAs corresponding to histones (H2A, H2B, H3 and H4), cyclins (B2, D1 and D3), cyclin-dependent kinase (CDKA), ubiquitination enzymes (FUS, EXT CE2), cyclophilin, E2F, and tubulin were analyzed during growth-dormancy cycles in tea apical buds under the influence of Kn, GA and their combinations. The level of these mRNAs was low in dormant buds, which was significantly increased by foliar application of GA and Kn combination. The present study indicated that the foliar application of GA in combination with Kn will help to improve quality and quantity of tea production by breaking dormancy and stimulating the bud growth.

Response of two seed-grown artichoke cultivars to GA3 and melatonin treatments

BackgroundGlobe artichoke Cynara scolymus L. is an important vegetable crop. Poor crop stand due to the low ratio of stumps surviving is the common problem which occurs with using vegetative parts. The current study evaluated two seed-propagated cultivars of artichoke: treated by GA3 and melatonin applications in newly reclaimed land.ResultsResults showed that Imperial Star produced higher values of vegetative growth, yield productivity, and chemical contents, compared with Romanesco cultivar. GA3 foliar application treatment ranked the first to increase vegetative growth, yield productivity, and chemical contents, followed by melatonin treatment, compared with untreated control.ConclusionIt could be concluded that the use of GA3 and melatonin were favorable for the production of both artichoke cultivars: Imperial Star and Romanesco. The highest productivity was achieved by foliar application of GA3 to Imperial Star cultivar.

Bioregulators Can Improve Biomass Production, Photosynthetic Efficiency, and Ornamental Quality of Gazania rigens L.

Gazania rigens L. is a perennial herbaceous plant that belongs to the Asteraceae family, widely used as bedding or ornamental potted plants. The environmental and economic sustainability of ornamental production can be enhanced using environmentally friendly bioregulators. A pot experiment was conducted to evaluate the influence of key bioregulators gibberellic acid ((GA3) at 50, 100 or 150 mg L−1), humic acid ((HA) at 100, 300 or 600 mg L−1), and ascorbic acid ((AA) at 50, 100 or 200 mg L−1)), on the growth, leaf gas exchange, and ornamental quality of G. rigens. The results indicated that plants treated with foliar applications of GA3, HA, or AA exhibited higher plant fresh and dry biomass, plant height, leaf area, and leaf area ratio, root-shoot ratio, root-shoot mass fractions, and number of flowers, as well as the flowers display time. All bioregulator treatments enhanced the vegetative and floral characteristics of Gazania plants. The GA3 was the most efficient at the concentration of 100 mg L−1. The highest efficacy of HA and AA treatments was observed at the higher concentrations, 600 and 200 mg L−1, respectively. These results were associated with higher photosynthetic rate (A), transpiration rate (E) as well as stomatal conductance (gs), and water use efficiency (WUE). In conclusion, the results suggest that foliar-applied bioregulators to Gazania are promising and represent sustainable strategies to enhance growth, flowering, and flower display time of Gazania plants.

Stomatal conductance, leaf chlorophyll content, growth, and yield of sweet pepper in response to plant growth regulators

ABSTRACTThe demand for sweet pepper (Capsicum annuum L.) is increasing because of nutrition and quality factors. Research to improve pepper yield using plant growth regulators (PGRs) has occurred, but results are not consistent. This study evaluated the effects of the PGRs naphthalene acetic acid (NAA), gibberellic acid (GA3), 4-chlorophenoxyacetic acid, Kelpak® (seaweed extract), and their combinations, on stomatal conductance, leaf chlorophyll content, and growth and yield of hydroponically grown sweet pepper. Seedling root plugs were soaked in Kelpak® at 10 mL L−1, 3 h before transplanting. Thereafter, solutions were applied to foliage with NAA at 20 mg L−1, GA3 at 15 mL L−1, and Kelpak® at 5 mL L−1 and their combinations at 15, 30, and 45 days after transplanting. PGR treatments benefitted stomatal conductance. Leaf chlorophyll content of untreated plants decreased with time compared to treated plants. Foliar application of GA3, alone, and in combination with Kelpak®, increased plant height, fresh and dry biomass, and yield compared to other treatments. Further investigation with application rates, and time of foliar application, on sweet pepper will provide a better understanding of how plants respond to PGRs.

Exogenous application of gibberellic acid and ascorbic acid improved tolerance of okra seedlings to NaCl stress

Accumulation of salts in soils has become a serious environmental threat for plant growth and causes considerable loss in yield. Okra Abelmoschus esculentus L. is an important crop and sensitive to saline stress. In the present study, to explore methods for growing okra in salty area, exogenous gibberellic acid (GA3) and ascorbic acid (AsA) were foliage applied on okra seedling under NaCl stress. The results showed that treatment with 100 mM NaCl decreased shoot length, root length, fresh weight, dry weight, contents of chlorophyll pigments and nutrient elements, enhanced levels of electrolyte leakage, H2O2, lipid peroxidation and activities of antioxidant enzymes. Treatments with 0.1 mM GA3 and/or 0.1 mM AsA could alleviated harmful effects of saline stress on okra seedlings by improving growth indicators, increasing contents of chlorophyll and carotenoids, stimulating activities of antioxidant enzymes and decreasing electrolyte leakage, H2O2 content and lipid peroxidation. Moreover, concentrations of K, Ca, Mg and Fe in leaves and roots as well as levels of osmo-protectants (proline and soluble protein) increased in response to treatment with GA3 + AsA in NaCl-stressed okra seedling. Overall, foliar application of GA3 and/or AsA demonstrated benefits to okra seedlings in salty environments. Combined application of GA3 and AsA was more effective than sole use of GA3 or AsA alone.

Growth and production of soybean (Glycine max L. Merril) varieties in response to waterlogging at vegetative (V5) growth phase by application of gibberellic acid and salicylic acid

Waterlogging can cause damage to soybean plants that can decrease the growth and yield. The objective of this research was to measure the growth and production of three soybean varieties such as Burangrang, Anjasmoro and Argomulyo, imposed on waterlogging at vegetative stage (V5) along with the application of GA3 and Salicylic acid. Waterlogging was conducted for 72 h by sinking the planting media inside a pool filled with water. Number of leaves, pod, seed and chlorophyll content were measured. The result showed that foliar application of GA3 (200 ppm) together with Salicylic acid (150ppm) for each enhanced the number of pod and seed for Burangrang soybean variety on waterlogged condition compared with normal condition. Burangrang and Anjasmoro soybean varieties gave the highest chlorophyll content on waterlogged condition after being applied by the same dose of plant growth regulators. In term of yield (number of pod and seed per plant), Burangrang soybean variety is the most promising variety to plant in waterlogged condition.