Doses Of Plant Growth Regulator Research Articles

Combined Pretreatment with Bioequivalent Doses of Plant Growth Regulators Alleviates Dehydration Stress in Lactuca sativa

Plant hormones regulate adaptive responses to various biotic and abiotic stress factors. Applied exogenously, they trigger the natural plant defense mechanisms, a feature that could be implemented in strategies for supporting crop resilience. The potential of the exogenous cytokinin-like acting compound (kinetin), the auxin analogue 1-naphtyl acetic acid (NAA), abscisic acid (ABA) and the ethyleneprecursor 1-aminocyclopropane-1-carboxylic acid (ACC) to mitigate dehydration was tested on Lactuca sativa (lettuce) grown on 12% polyethylene glycol (PEG). Priming with different blends containing these plant growth regulators (PGRs) applied in bioequivalent concentrations was evaluated through biometric measurements and biochemical analyses. The combined treatment with the four compounds exhibited the best dehydration protective effect. The antioxidative enzyme profiling of the PGR-primed individuals revealed increased superoxide dismutase (SOD), catalase and peroxidase activity in the leaves. Immunodetection of higher levels of the rate-limiting enzyme for proline biosynthesis (delta-pyroline-5-carboxylate synthase) in the primed plants coincided with a significantly higher content of the amino acid measured in the leaves. These plants also accumulated particular dehydrin types, which may have contributed to the observed stress-relieving effect. The four-component mix applied by spraying or through the roots exerted similar stress-mitigating properties on soil-grown lettuce subjected to moderate drought.

Effect of Plant Growth Regulators on Growth, Yield and Quality of Tomato (Lycopersicon esculentum L.)

The present investigation was carried out at the Department of Horticulture, Naini Agricultural Institute, Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh during Kharif 2021-22 with a view to identify the effects of different doses of plant growth regulators on growth, yield and quality of Tomato variety TMTH-288. The experiment was laid in Randomized block design with 13 treatments and 3 replications with different combination in nano fertilizers. Under this experiment, overall, 13 combinations was taken including control. PGRs comprised of GA3, 2,4-D, Triacontanol and NAA were given. According to the current research, the current study found that the use of plant growth regulators (PGRs) had a significant positive impact on the growth and yield of tomato. Among the treatments tested, T3 (GA3 40 ppm) showed the most favorable results in terms of plant height, early flowering and maturing. It also demonstrated superior performance in terms of fruit weight, polar and radial length of fruit, number of fruits per plant, and yield per plant.

EFFECT OF PLANT REGULATORS ON OIL RATIO AND FATTY ACID COMPOSITION OF PEANUT (Arachis hypogaea L.)

Plant growth regulators are organic substances that are synthesized naturally within the plant, and controlled the physiological events, can be transported from where they are formed to other parts of the plants, and can show their effects even at very low concentrations. In this study, it was aimed to determine the effect of different doses of plant growth regulators in different growth stages on oil content and fatty acid compositions of peanut (Arachis hypogaea L.). A total of twelve different treatments were preferred with different chemicals such as gibberallic acid (GA3), mepiquat-chloride (MC), and seaweed (SW) in different growth stages (beginning bloom (BB), full bloom (FB) and beginning bloom + full bloom (BB+FB)). The highest oil content was obtained in MCFB200 (55.46%) treatment, while the lowest was obtained in GA3BB20 (45.44%) treatment. Oleic acid ratio varied from 50.33% to 59.25%, and all treatments were higher than that of the control group. The highest and lowest linoleic acid ratios were observed in SWBBFB100 (26.72%) and GA3FB10 (19.52%) treatments, respectively. MCFB200 and GA3FB10 treatments could be recommended for the highest oil ratio and the highest oleic acid ratio, respectively.

Induction of direct organogenesis in Blackberry (Rubus fruticosusL.) using leaf explants

This study is to establish the best conditions for in vitro propagation by inducing direct organogenesis of “Thornfree” blackberry (Rubus fruticosusL.) using different doses of plant growth regulators, which affect the regeneration of shoots in compound nutrient medium of mineral salts Murashige and Skoog (MS). Young leaves were used as explants. In the initiation phase, plant material necessary for the experiment was obtained, using an MS nutrient medium enriched with 0.5 mg. l-1of BAP, after 30 days’ leaves were obtained that were introduced in regeneration medium where the effect of BAP (1 and 2 mg. l-1) was evaluated in combination with AIA (0.5 mg. l-1) and TDZ (0.5 mg. l-1). The highest number of shoots with an average of 6.40 and oxidation percentage of 7.41% was achieved. In the proliferation phase no significant statistical differences were observed, however, the optimum performance attained for the number of buds was obtained with a concentration of 2 mg. l-1of BAP, having an average shoot-length of 6.10 cm and a rooting percentage of over 80%.

Development of an efficient in vitro regeneration system in Costus speciosus - an important herbal insulin plant

Costus speciosus is being rapidly eliminated in its natural habitats in India and driven to a nearly threatened degree of extinction because of non-selective collection and over-exploitation. The commercial cultivation of C. speciosus is impeded owing to its poor seed viability, reduced germination rate, and weak rooting potential of vegetative cuttings. As costus could not be multiplied rapidly by conventional propagation methods, in-vitro regeneration technology was experimented with to standardize explants in addition to the combinations of plant growth regulators (PGRs) to fortify the growing media that helps to produce the enormous number of plants in a shorter duration. Several kinds of explants viz., leaves and nodes were cultured into the Murashige and Skoog (MS) medium reinforced with different combinations and doses of PGRs. A higher frequency (51.67 ± 1.7%) of the regenerated adventitious shoot was obtained from nodal segments cultured onto MS medium fortified with 0.5 mg/l Thidiazuron (TDZ) and 2.0 mg/l of 6-benzyl amino purine (BAP). TDZ in combination with BAP and Indole-3-acetic acid (IAA) exhibited a remarkable effect on shoot multiplication and elongation. Further, MS medium with 0.5 mg/l TDZ, 1.0 mg/l 2, 4-dichlorophenoxyacetic acid, and 0.5 mg/l IAA yielded a great range of callus initiation (86.66 ± 1.6%) from leaf explants. Leaf-derived callus results in the greatest shoot regeneration (56.66 ± 1.7%) response on TDZ (0.5 mg/l) and BAP (1.0 mg/l) reinforced MS medium. Elongated shoots from node and callus cultures when inoculated with the MS medium reinforced along with 1.0 mg/l of IAA and 0.5 mg/l of Indole-3-butyric acid (IBA) produced optimum rooting (88.33 ± 1.66%). The rooted young plantlets were effectively acclimatized to the environmental climate and their greenhouse survival rate was 85%.

Determination of Optimal Doses of Plant Growth Regulators for In vitro Propagation of Four Potato Varieties (Solanum tuberosum) in Niger

Aims: The main limitation of the production of potatoes (Solanum tuberosum L.) in Niger is the external dependence on the supply of quality seeds. In the context of a national potato seed system, one of the critical phases is the rapid in vitro multiplication of virus-free good quality potato plantlets. Fifteen hormonal combinations were formulated and tested to determine a suitable hormonal combination and optimum concentrations for the in vitro production of a high number of plantlets for four farmer-preferred varieties in Niger (ATLAS, PAMELA, STEMSTER and YONA).
 Study Design: A completely randomized design (CRD) was employed to reveal the performance of four potato varieties, as affected by fourteen combinations of NAA and BAP with four replications. Results of the study were subjected to the analysis of variance, and significant differences among treatments were determined using GENSTAT12.01. Segregation between means was made according to the Student Newman-Keuls test, at 5% threshold.
 Place and Duration of Study: The experiment was carried out at the laboratory of Biotechnology and plant improvement of the institute of radio-isotopes in the University Abdou Moumouni of Niamey, in Niger (latitude 13°29' North and longitude 2°10' Est), for 28 days.
 Methodology: Uninodal stem explants of in vitro plantlets were cultured on full-strength Murashige and Skoog media (MS) supplemented with fourteen different combinations of α-Naphthalene Acetic Acid NAA (0; 0.25; 0.50; 1.0; 2.0 mg/l) and Benzyl Amino Purine BAP (0; 0.25; 0.50 mg/l), for 28 days.
 Results: Statistical analysis of the results showed that the variety and hormonal significantly influenced the height of the plant, the number of leaves and number of roots. Treatments with NAA alone without BAP stimulated rhizogenesis. From a NAA concentration of 0.25 to 0.5 mg/l there is a proliferation of the roots and from 1 mg/l there is an increase in roots length. PAMELA and ATLAS cultivars showed better root production.

Efficacy of various doses of salicylic acid, naphthalene acetic acid and gibberellic acid on vegetative growth and pod yield of broad bean (Vicia faba L.)

To investigate the efficacy of various doses of plant growth regulators on vegetative growth and pod yield of broad bean (Vicia faba L.), a field experiment was accomplished at Vegetable Research Farm, B.H.U., Varanasi during the winter season of 2019-20. Ten treatments were evaluated in randomized block design with three replications. Results indicated that the growth parameters like plant height, number of branches/plant significantly increased with foliar spray of gibberellic acid followed by NAA and salicylic acid. The yield attributes like pod width, fresh pod weight, number of pods/plant as well as fresh pod yield significantly enhanced by NAA followed by gibberellic acid and salicylic acid with various concentrations, respectively. The foliar spraying of 120 ppm GA3 tended to produce plant with maximum height (116.4 cm), number of branches/plant (6.3), pod length (7.5 cm), number of seeds/pod (4.6) as well as early 50 % flowering (57.3 days) whereas, spraying of 40 ppm NAA exhibited the maximum pod width (1.3 cm), fresh pod weight (4.6 g), number of pods/plant (87.5) as well as fresh pod yield (105.0 q ha-1) as compared to other treatments. The maximum net return (Rs. 337326.5 ha-1) was recorded with 40 ppm NAA with B: C ratio of 3.65 followed by 30 ppm NAA and 20 ppm NAA. The lowest net income (Rs. 162382.5 ha-1) and B: C ratio (1.76) was obtained from control. The spraying of NAA was found superior in terms of yield and yield attributes as well as benefit cost ratio followed by GA3 and salicylic acid.

Efficacy of various doses of salicylic acid, naphthalene acetic acid and gibberellic acid on vegetative growth and pod yield of broad bean (Vicia faba L.)

To investigate the efficacy of various doses of plant growth regulators on vegetative growth and pod yield of broad bean (Vicia faba L.), a field experiment was accomplished at Vegetable Research Farm, B.H.U., Varanasi during the winter season of 2019-20. Ten treatments were evaluated in randomized block design with three replications. Results indicated that the growth parameters like plant height, number of branches/plant significantly increased with foliar spray of gibberellic acid followed by NAA and salicylic acid. The yield attributes like pod width, fresh pod weight, number of pods/plant as well as fresh pod yield significantly enhanced by NAA followed by gibberellic acid and salicylic acid with various concentrations, respectively. The foliar spraying of 120 ppm GA3 tended to produce plant with maximum height (116.4 cm), number of branches/plant (6.3), pod length (7.5 cm), number of seeds/pod (4.6) as well as early 50 % flowering (57.3 days) whereas, spraying of 40 ppm NAA exhibited the maximum pod width (1.3 cm), fresh pod weight (4.6 g), number of pods/plant (87.5) as well as fresh pod yield (105.0 q ha-1) as compared to other treatments. The maximum net return (Rs. 337326.5 ha-1) was recorded with 40 ppm NAA with B: C ratio of 3.65 followed by 30 ppm NAA and 20 ppm NAA. The lowest net income (Rs. 162382.5 ha-1) and B: C ratio (1.76) was obtained from control. The spraying of NAA was found superior in terms of yield and yield attributes as well as benefit cost ratio followed by GA3 and salicylic acid.

Study on effect of plant growth regulators on growth and yield of tomato (Lycopersicon esculentum Mill)

The experiment was conducted during Rabi season 2021-22 at Horticulture Research Farm, Barrister Thakur Chhedilal College of Agriculture & Research Station, Bilaspur, Chhattisgarh. The treatments consisted of different doses of plant growth regulators viz., control plot (T1), GA3-60 ppm (T2), GA3-80 ppm (T3), GA3-100 ppm (T4), NAA-80 ppm (T5), NAA-100 ppm (T6), NAA-120 ppm (T7), 2,4-D-5 ppm (T8), 2,4-D- 10 ppm (T9), 2,4-D-15 ppm (T10). Significantly, maximum no. of fruit 24.01 was found in T7, fruit weight 44.01 gm in T7, days of first fruit harvesting 58.14 days in T7 and highest yield 393.94 q ha-1 in T7 at harvest.

The effects of plant growth substances on the oil content and fatty acid composition of Ricinus communis L.: an in vitro study.

Ricinus communis L. (castor bean) is valued for its oil and the performance of oil is closely related to its fatty acid composition. Thus, producing oil in vitro with favored fatty acid profiles is a promising research area and may also offer industrial opportunities. In line with this, the total amount of oil and the fatty acid composition of the samples, which were endosperm and calli obtained by treatment of various doses of plant growth regulators were determined. Results showed that the type and amount of the plant growth regulator used in the media affect the fatty acid composition. In detail, the biggest change was shown by Indole-3-Acetic Acid (IAA), in general, using the plant growth regulators at 5 mgL-1, instead of 20 mgL-1, was found to have induced larger differentiations. The effect of a natural plant growth regulator (IAA) on fatty acid profiles was bigger than the synthetic ones (NAA, 1-Naphthaleneacetic acid, and 2,4 D, 2,4-Dichlorophenoxyacetic acid). The media containing 5 mgL-1 of NAA, 20 mgL-1 of NAA, 20 mgL-1 of 2,4 D, or 5 mgL-1 of 2,4 D gave similar results.

Effect of silver nitrate and growth regulators to enhance anther culture response in wheat (Triticum aestivum L.)

Application of chemical substances as stress pre-treatment factors may positively influence androgenetic responses in cereal and other crops. AgNO3 is an anti-ethylene compounds that played a significant role in combination with other chemicals for anther culture responses in cereal and other crop plants. For this study two local wheat cultivars viz. Kheri and Akbar were considered to evaluate the effect of AgNO3 and to optimize the suitable doses of plant growth regulators, amino acids and sucrose that supplemented in MS medium. Data were recorded on the basis of embryoids induction, regenerated green and albino plants. The results clearly stated that anther culture responses and its major outcomes on regeneration significantly increased with suitable dosages of chemicals. The most noteworthy increases embryo like structures and regenerated green plants accomplished by utilizing the combined effect of AgNO3 (50 mg/l) and as plant growth regulators IAA (1.0 mg/l) + kinetin (0.5 mg/l). Best embryo like structures (79.17%) and green plants (33.33%) were recorded in Kheri. The results clearly stated that reducing albinism and increasing embryos induction and green plants 50–75 mg/l silver nitrate along with optimum doses of IAA and kinetin showed very effective results in wheat.

Performance evaluation and cost estimation as compared for different paddy threshers

Growth and yield attributes of cotton were evaluated with the application of varying doses of plant growth regulators during kharif 2020. The experiment was laid out in Randomized Block Design and replicated thrice, conducted at Agricultural College Farm, Bapatla. The treatments comprised of T1: control, T2: Mepiquat chloride 50 ppm at 45 DAS; T3: Mepiquat chloride 50 ppm at 75 DAS; T4: Maleic hydrazide 30ppm at 45 DAS; T5: Maleic hydrazide 30ppm at 75 DAS; T6: Cycocel 60ppm at 45 DAS; T7: Cycocel 60ppm at 75 DAS; T8: Mepiquat chloride 50 ppm at 45 DAS and 75DAS; T9: Maleic hydrazide 30ppm at 45 DAS and 75 DAS; T10: Cycocel 60ppm at 45 DAS and 75 DAS. The results indicated that the highest drymatter accumulation at harvest and stalk yield were recorded in control plot. Maximum number of bolls plant-1, number of picked bolls plant-1 and seed cotton yield were noticed in Mepiquat chloride 50 ppm at 45 + 75 DAS which was on par with T9: Maleic hydrazide 30 ppm at 45 DAS and 75 DAS; T10: Cycocel 60 ppm at 45 DAS and 75 DAS.

IN VITRO RESPONSE BY Terminalia arjuna GENOTYPES DURING MICROPROPAGATION

Terminalia arjuna is an important tree of the medicinal and sericulture industry, commonly known as Arjun. It’s bark is rich in secondary metabolites makes this plant highly valuable in medicine industry to treat cardiovascular disease. Overexploitation due to high demand in medicine, low seed germination, limitations of the conventional method of propagation push this plant towards being endangered. To conserve germplasm of such tree species and meet the requirement in medicinal industry, some non-conventional propagation method like micropropagation has been developed. The present work highlighted the effect of three genotypes (G-1, G-2, and G-3) on tissue culture of T. arjuna situated at Jodhpur, Rajasthan, India. In vitro shoot proliferation was achieved on a modified MS medium enriched with BAP + additives. Among the tested genotypes, Genotype -1 showed maximum bud break response (100%) followed by G-3 (93.33 %) and G-2 (86.66%). Further multiplication of these shoots on modified MS medium containing BAP + NAA + additives gave 11.38±0.26 (G-1), 9.44±0.21 (G-2) and 10.22±0.32 (G-3) shoots. In vitro rooting was done by pulse treatment with IBA for 10 min prior to transfer on hormone free half strength MS medium containing 0.1% activated charcoal. Maximum in vitro rooting was obtained in G-1 (80%) followed by G-3 (71.11%) and G-2 (68.88%). In the present study, it was observed that optimum growth in all three genotypes required different doses of Plant Growth Regulator. Thus, by identifying and multiplying the best performing genotypes the gap between demand and supply of such medicinal plant can be fulfilled.

Jack beans and vetiver grass growth on iron ore tailing sediments from the Doce River dam disaster in Brazil: plant growth regulator effects under different edaphic conditions

After the greatest environmental disaster in the history of Brazil and the deposition of the iron ore tailings in alluvial regions, the process of revegetation for environmental recovery becomes essential. A greenhouse experiment was carried out to evaluate the biomass production and nutrient accumulation by jack bean (Canavalia ensiformis (L.) DC) and vetiver grass (Chrysopogon zizanioides (L.) Roberty) grown on iron ore tailings from alluvial regions under two edaphic conditions using plant growth regulators. Iron ore tailings were obtained for use as the substrate. Jack bean and vetiver plants were grown in two conditions, high water and nutrient availability and low water and nutrient availability, while using four doses (0, 0.25, 0.5, and 0.75 L ha−1) of plant growth regulators (kinetins, gibberellic acid, and indole-butyric acid) via leaf spray. The use of plant growth regulators increased the biomass production (74 and 30% of total dry mass in jack bean and vetiver grass, respectively) and the accumulation of nutrients in the shoot parts of the plants cultivated with greater water and nutritional availability. Under limiting conditions of water and nutritional availability, the jack bean with the highest dose of plant growth regulator had a greater potential for revegetation, biomass production, and inputs of nitrogen, while vetiver grass had a greater contribution in potassium bio-cycling in the areas affected by the tailings deposited in the alluvial regions of the Doce River. The performance of the jack bean stood out in the two edaphic conditions due to growth stimulations by plant growth regulators.

Effect of commercial plant growth regulator on the growth of dragon fruit (Hyolocereus sp) cuttings under greenhouse condition

Information is limited on the effects of commercial plant growth regulators (PGRs) on dragon fruit. Most studies on rooting effects on dragon fruit cuttings employed very high doses of plant growth regulators (PGRs), which are not deemed practical for greenhouse and field applications. This study was initiated to evaluate the responses of four genotypes of dragon fruit (‘Royal Red’, ‘Moroccan Red’, ‘Mexican White’, and ‘Hawaiian White’) during greenhouse acclimatization to diluted concentrations of commercial PGRs that are readily available in the market. A single factorial experiment on genotype effects on root and shoot responses, without PGR, was conducted. A second experiment with a 4x3x2 completely randomized design, with four genotypes, three diluted commercial PGR formulations and two exposure times as factors was also done. Root length, number of roots, number of days to first shoot emergence and number of new shoots were measured after 50 days of acclimatization in the greenhouse. In the single factorial experiment, only ‘genotype’ had an effect on number of new shoots (P<0.05). In the multifactorial experiment, all factors tested did not have significant interaction effects. However, the main effect of ‘genotype’ on number of new shoots and number of days to first shoot emergence was also significant (P<0.05). The lack of significant effect of other factors and their interactions on most growth responses suggest that it is difficult to resolve differences among the four genotypes using highly diluted commercial PGR formulations after a 50-day observation period. However, our data still suggest that the ‘Red’ genotypes are more superior than the ‘White’ genotypes in terms of shoot growth.

English

Flower and pod abortions in large quantities are commonly observed in soybean plants. In normal conditions of crop cultivation, flower abortion is commonly above 60%. Among the strategies that may promote great flower and pod set in soybean, there is the use of plant growth regulators and foliar applications of calcium. Thus, this study aimed to evaluate the effects of different doses of plant growth regulator and the calcium sprayed on the agronomic performance of soybean plants. Five doses of systemic bioregulator (cytokinin) and five doses of calcium carbonate (CaCO3) were applied in a 5 x 5 factorial arrangement with four replications field implemented in randomized block design. Soybean plant biometrics, the calcium content in different plant parts and crop yield were recorded. None of the treatments had a significant effect on the characteristics observed. The result was probably due to adequate conditions that prevailed during the soybean cropping cycle. In fact, flower and pod abortions happen when plants experience water stress during the flowering period. This lack of any treatment effect indicated the importance of regular and trustful monitoring of crop important variables to prevent routine applications of growth regulator and calcium.   Key words: Glycine max, cytokinin, calcium carbonate, plant biometrics, crop yield.

Effects of Different Doses of Plant Growth Regulators on Some Characteristics of Summer Snowflakes (Leucojum aestivum L.)

The aim of this study was to determine the effect of different doses and combinations of benzylaminopurine (BAP) and Putrescine elicitor on some plant characteristics of summer snowflake (Leucojum aestivum L.). The experiment was conducted for two years between 2017-2019 in the greenhouse of Uşak University, Faculty of Agriculture and Natural Sciences. Bulbs with ~7 cm circumference and ~9 g weight were used as a material of this study, and was constructed with randomized blocks design with 3 replications. The bulbs were treated for 24 hours before planting with 5, 10 and 15 mg/l BAP; 5, 10 and 15 mg/l Putrescine elicitor in different combinations (16 different combinations). Thereafter, all bulbs were planted in crates. In the first year, only plant height, number of leaves per bulb were recorded and at the end of the second year, the plant height, number of leaves per bulb, number of leaves per daughter bulb, number of bulbs, leaf weight, root length and weight, bulb weight, unit bulb weight, alkaloid contents were measured after removal of bulbs from the soil. According to the results, plant height ranged 19,3-30,0 cm; the number of leaves ranged 6.5 to 12.6, and the number of bulbs ranged 0.9 to 4.6. Root weight was determined between 13.4-47.1 g/parcel, fresh leaf weight ranged 12.4-49.2 g/parcel, and one bulb weight was between 3.5-14.6 g. It was determined that the bulb plant was influenced by different treatments. The maximum growth was noted with 5 mg/l Putrescine elicitor treatment that increased plant height, number of leaves per bulb each year and number of bulbs.

The Response of 'Golden Delicious' Apple Grafted on M 9 and MM 106 Rootstock to Chemical Fruit Thinning

The effect of plant growth regulator in early stages of fruit development is to slow or stop the growth of lateral fruits and to cause their early drop. Two commercial plant growth regulator formulations naphthalene-acetamide (NAD) and naphthaleneaceticacid (NAA) were used. The applied doses of plant growth regulator were in accordance with the manufacturer's recommendations, for Amidthin 100-130 g/hl and Nokad 20-25 ml/hl. The first treatment was applied after full bloom, and the second when central fruit was 9-12 mm in size. The biggest effect on fruit weight and size was recorded on treated Golden Delicious fruits grafted on M 9 rootstock. It was found that minimum number of fruits per branch was on M 9 rootstock. Also, the most pronounced effect of fruit thinning regarding fruit weight and size was on trees grafted on M 9. Results showed that fruits had decreased firmness and increased dry matter content. However, it did not show significant differences in values of iodine - starch test and acid content.

Uso de reguladores de crescimento para a superação da dormência e sua influência na brotação, no florescimento e na produção da amoreira-preta

O presente trabalho foi conduzido na Fazenda Experimental São Manuel, da Faculdade de Ciências Agronômicas da UNESP, localizada no município de São Manuel-SP. Foram avaliadas amoreiras-pretas da cultivar Tupy com 1 ano de idade, conduzidas em quatro hastes, no sistema de espaldeira em T, com 1,2 metro de altura. O espaçamento utilizado foi de 0,6 m entre plantas x 4,0 metros entre linhas e a densidade de plantio de 4.166 plantas.ha-1. O delineamento experimental adotado foi o de blocos ao acaso, com 4 repetições, 15 tratamentos, e a parcela experimental composta por duas plantas, rodeadas por bordadura. Em 27 de julho de 2010, efetuaram-se a poda de produção e a quebra de dormência das plantas. Para tanto, foram testadas as seguintes doses de Dormex® (49% de cianamida hidrogenada): T1=0,0%; T2=1,5%,; T3=3,0%; T4=4,5%, e T5=6,0%, de Bioalho® (70% de extrato de alho): T6=0,0%; T7=2,0%; T8=4,0%; T9=6,0%, e T10=8,0% e de Stimulate® (0,005% de auxina, 0,005% de giberelina e 0,009% de citocinina): T11=0,0%; T12=2,0%; T13=4,0%; T14=6,0%, e T15=8,0% . Avaliaram-se a fenologia e a produtividade da amoreira-preta 'Tupy' em função dos reguladores e das doses utilizadas. A quebra de dormência efetuada com cianamida hidrogenada, nas doses de 3,0, 4,5% e 6,0%, antecipou e uniformizou a brotação e florescimento, além proporcionar os maiores valores de porcentagem de brotação e produtividade, sendo estas as melhores doses do regulador vegetal para cultura cultivada na região. Os tratamentos em que se utilizaram extrato de alho e Stimulate® apresentaram dados de brotação e produtividade muito inferiores, quando comparados aos apresentados pelos tratamentos em que se aplicou cianamida hidrogenada. Assim, fazem-se necessários novos estudos em busca de reguladores vegetais alternativos que sejam tão eficazes quanto à cianamida hidrogenada.

Efeito da aplicação de biorregulador no desempenho agronômico e produtividade da soja

The purpose of the work was to verify the effect of the application of a plant growth regulator on the agronomic traits of plants and on soybean seed yield, cultivar CD 216. The work was developed during two agricultural years (2005/06 and 2006/07). The treatments were composed by the combination of seed treatments (0 and 500 mL 100 kg-1 of seeds) with three doses of plant growth regulator (250, 375 and 500 mL ha-1) applied to the leaves in two stages of the culture’s development (V5 and R3), plus the control without application. The features evaluated were: plant height, number of seedpods per plant, yield and mass of one thousand seeds. The features of plant height and number of seedpods per plant were not influenced by the application of the plant growth regulator in the two agricultural years. In the agricultural years of 2005/06, the greater seed yield (2.927 kg ha-1) was reached with the application of 211 mL ha-1 of plant growth regulator to the leaves at the R3 stage, together with seed treatment. In the second agricultural year there was no significant difference (p > 0.05) between the treatments in seed yield, although the results were superior to those obtained in the first year. One of the basic principles to improve the efficacy of the plant growth regulator in soybean crops is an adverse climatic condition.