Paclobutrazol Research Articles

Assimilate Partition of Potato (Solanum tuberosum L.) as Response to Combination of Paclobutrazol and Nitrogen

Increasing the productivity of potato (Solanum tuberosum L.) can be done by increasing biological production (biomass) and the ability to convert (partition) assimilate/photosynthate into economic results (tubers). The aim of this research is to find a better combination of paclobutrazol (PBZ) application and nitrogen (N) fertilization for tuber partition assimilate of potato. The experiment was conducted in Randomized Block Design (RBD) with three replications. The treatment was consists of  nine combinations of PBZ treatments and N  fertilization as follows: 1) 3 kg PBZ/ha + 200 kg N/ha, 2) 3 kg PBZ/ha + 250 kg N/ha, 3) 3 kg PBZ/ha + 300 kg N/ha, 4) 3,5 kg PBZ/ ha + 200 kg N/ha, 5) 3,5 kg PBZ/ha + 250 kg N/ha, 6) 3,5 kg PBZ/ha + 300 kg N/ha, 7) 4 kg PBZ/ha + 200 kg N/ha, 8) 4 kg PBZ/ha + 250 kg N/ha, 9) 4 kg PBZ/ha + 300 kg N/ha. The research results showed that at the beginning of growth up to 42 DAP (day after plan), the assimilate (dry material) was directed towards stem and leaf (shoot) growth. Next, at 56 DAP to 84 DAP the assimilate is allocated for tuber growth. The combination of 4 kg PBZ/ha + 200 kg N/ha produces the largest tuber weight Keywords: Potato (Solanum tuberosum L);  nitrogen; paclobutrazol; partition assimilate

Modulating Growth and Oil Profile of Sesame (Sesamum indicum L.): Paclobutrazol and Mepiquat Chloride Impacts

AbstractSesame (Sesamum indicum L.) is an important oilseed crop with significant economic importance in many developing countries. This study rigorously investigated the impact of various applications and doses of two specific plant growth regulators, paclobutrazol (PAC) and mepiquat chloride (MC), on the development, yield components, oil content, and fatty acid composition of sesame plants across two consecutive growing seasons. The research revealed that while paclobutrazol application increased the plant height it also resulted in a slight decrease in oil content. The paclobutrazol treatment resulted in the highest seed yield (21.3 g/plant), which was significantly different from both the MC (13.1 g/plant) and PAC + MC (14.6 g/plant) treatments. In contrast, the mepiquat chloride treatment resulted in the lowest oil content. The combined application of both regulators showed intermediate effects. In addition, variations in fatty acid content were observed between applications and doses, with significant differences in saturated and unsaturated fatty acid levels. The findings provide valuable insights into the potential benefits and implications of using growth regulators in sesame cultivation, especially in the context of mechanized harvesting and oil quality optimization.

Effect of Plant Growth Regulators on Nutrient and Quality Changes in Zingiber officinale Rosc

Ginger is one of the oldest and renowned commercial spices well known for its medicinal and pharmaceutical value. Land degradation, availability of the quality rhizomes and diseases are some of the challenges faced in the ginger production. Since the productivity of a plant is influenced by a complex physiological process controlled by plant growth hormone balancing systems, the application of the growth regulators can have positive effect. Manipulating the PGR combinations and concentrations can lead to better quality and productivity in ginger. Hence, an experiment was conducted to study the effect of different plant growth regulators (PGRs) on nutrient and quality parameters in the ginger variety IISR Varada. Foliar spray of PGRs with 6-benzyl adenine purine (6-BAP), cycocel (Chlormequat chloride), gibberellic acid (GA) and paclobutrazol (PBZ) with five concentrations viz., 50ppm, 100ppm, 150ppm and 200ppm were applied 4th month after planting and water spray treated as control. Nutrients composition and biochemical components were observed on 5th month after planting and oleoresin was observed in the rhizomes after harvest. The results of pooled data over two years revealed that GA at 100 ppm recorded maximum nitrogen and chlorophyll content in leaves, potassium and protein in rhizomes. Regarding the oil content, maximum was noticed in treatment 100ppm Paclobutrazol followed by GA 100ppm.

In Vitro Medium-Term Storage of Banana Cultivar ‘Barangan’ Using Alginate-Encapsulation Technique

In vitro medium-term storage using the alginate-encapsulation technique is essential for conserving plant genetic resources, preserving vegetatively propagated species by controlling the growth and development of explants, and maintaining plant biodiversity. The study aimed to obtain the optimum combination medium for the encapsulation of bananas and evaluate the viability of the alginate-encapsulated explants after storage. In vitro, medium- term storage of nodule-like meristem of banana cultivar ‘Barangan’ was performed using sodium alginate, paclobutrazol (PBZ), and Murashige and Skoog (MS) salt. This research consists of 3 stages: (1) Initiation and multiplication of in vitro shoots and nodule-like meristems; (2) In vitro medium-term storage of banana by encapsulation technique; (3) Regeneration of nodule-like meristem explants after in vitro storage. This research showed that the banana's number of nodule-like meristem was optimum on media supplemented with thidiazuron (TDZ) 0.22 mgL-1 and indole 3-acetic acid (IAA) 1.75 mgL-1. Encapsulation explant of nodules-like meristems using 3% sodium alginate in full and half-strength MS salt medium supplemented with PBZ 2.5 mgL-1 and incubated in liquid MS medium was able to store nodule-like meristem for six months. The color of the explants remains green, and the capsule is not damaged. Sub-culture of nodule-like meristem after storage in MS salt medium containing TDZ 0.22 mgL-1 and IAA 1.75 mgL-1 showed that nodules-like meristems could regenerate to form new shoots and nodule-like meristem three months after sub-cultured. This research concludes that encapsulated nodule-like meristem was recorded until six months of storage. PBZ was a necessary retardant in minimizing the growth during storage.

Phoshporic acid actived biochar for efficient removal of paclobutrazol and alleviating its phytotoxicity to mung bean

Using biochar to absorb organic pollutants in water and soil is a simple and efficient method. However, most biochar is typically prepared at high temperatures (>500 ℃), resulting in low yield and high production costs and hence limiting its practical applications. This study aimed to prepare biochar (P-BC) through low-temperature (280 ℃) phosphoric acid assisted pyrolysis of cotton stalks. P-BC possessed a large specific surface area (389.96 m2·g−1) and contained abundant oxygen functional groups as well as phosphorous and nitrogen nutrient elements. This study applied P-BC to remove paclobutrazol (PBZ) from water and remediate PBZ-polluted soil. The water adsorption capacity of P-BC was 192.89 mg·g−1. The adsorption mechanisms of P-BC included pore filling, hydrogen bonding, weak electrostatic effects, and π-π interactions. Adding 1 % P-BC to soil contaminated with 10 mg·kg−1 PBZ could alleviate PBZ induced phytotoxicity in mung bean seedlings, ensuring the normal growth of roots and plants.

Application of soil amendments and paclobutrazol to shorten internode and increase rice yields

This study aims to determine the role of soil amendments, Paclobutrazol (PBZ), and varieties as well as their interactions on the growth and yield of rice. This study used a randomized block design (RBD) factorial split-split plot 3 x 2 x 2 with 3 replicates. The first factor was soil amendments as the main plot which consisted of 3 levels: A1= biochar, A2= compost, A3= mixture of biochar, compost, Mycorrhiza, and Trichoderma. The second factor was the concentration of PBZ in the split plot, which consisted of 2 levels: PBZ1 = 500 ppm, and PBZ2 = 700 ppm. The third factor is the variety as a split-split plot consisting of 2 levels: V1 = Sigupai Abdya, V2 = Tangse. The results showed that soil amendments had a significant effect on grain weight, and yield potential. The best yields are found in 50 g pot−1 of compost. PBZ had a very significant effect on grain weight and yield potential. PBZ at 700 ppm, can shorten rice internodes. Varieties have a very significant effect on grain weight and yield potential. The best growth and yields were found in the treatment of 50 g pot−1 compost with PBZ at a concentration of 700 ppm using the Tangse variety.

Gibberellin-mediated far-red light-induced leaf expansion in cucumber seedlings.

Our experiments explored the effects of far-red (FR) light on cucumber (Cucumis sativus L. 'Zhongnong No. 26') seedling growth. Our results indicated that FR light significantly promoted the growth of cucumber seedlings. Specifically, it promoted the accumulation of shoot biomass and the elongation of internodes and leaves (except the first leaf at the bottom). Further analysis showed that FR light had no effect on the accumulation contents of abscisic acid (ABA) and auxin (IAA) in seedling leaves. Still, it significantly caused the increase of the gibberellin (GA3, GA4, and GA7) contents and the decrease of GA1 content, which suggested that the leaf expansion progress under FR light may be primarily related to GA. Therefore, the cucumber seedling leaf expansion response to GA was evaluated under different light sources. The exogenous spraying of different GA4/7 contents significantly promoted the leaf expansion of cucumber seedlings under white light, while the GA biosynthesis inhibitor paclobutrazol (PAC) significantly promoted the expression of GA hydrolytic genes (GA2ox2 and GA2ox4) and decreased the content of endogenous active GA, which inhibited the leaf expansion induced by FR light. As expected, the combination of exogenous GA4/7 and PAC restored the growth promotion effect of FR light on cucumber seedling leaves. It increased the contents of endogenous active GA (GA1, GA3, GA4, and GA7), and the expression trend in GA synthetic/hydrolytic-related genes was the opposite of that of PAC was applied alone. All of the above results indicated that FR light regulates leaf expansion progress in cucumber seedlings through GA.

Effect of Photoperiod and Gibberellin on the Bolting and Flowering of Non-Heading Chinese Cabbage

Non-heading Chinese cabbage (cabbage) is an essential green leafy vegetable, and bolting and flowering are necessary for reproduction. However, further research is needed to study the effect of photoperiod on the bolting and flowering of cabbage, particularly on the development of the stem. In this study, we performed phenotypic analysis and measured endogenous gibberellin levels in the cabbage. We carried out these experiments under four different photoperiodic treatments, 12 h (light)/12 h (dark), 14 h (light)/10 h (dark), 16 h (light)/8 h (dark), and 18 h (light)/6 h (dark). The results showed that the time of bolting and flowering gradually decreased with increasing light duration. The development of stems was optimal under the 16 h (light)/8 h (dark) photoperiod treatment, and the same result was obtained via cytological observation. In addition, the changes in the endogenous gibberellin3 (GA3) content under different photoperiodic treatments were consistent with the development of stems and peaked at 16 h (light)/8 h (dark). At the same time, qRT-PCR analysis showed that the relative expression of the key gibberellin synthase genes, BcGA3ox2 and BcGA20ox2, exhibited upregulation. When treated with exogenous GA3 and its synthesis inhibitor, paclobutrazol (PAC), exogenous gibberellins significantly promoted bolting; conversely, gibberellin inhibitors suppressed the bolting, flowering, and stem elongation of cabbage. Therefore, the photoperiod may regulate cabbage bolting by regulating endogenous GA3.

Gibberellins involved in fruit ripening and softening by mediating multiple hormonal signals in tomato.

The phytohormone ethylene is well known for its important role in the ripening of climacteric fruit, such as tomato (Solanum lycopersicum). However, the role and mode of action of other plant hormones in climacteric fruit ripening regulation are not fully understood. Here, we showed that exogenous GA treatment or increasing endogenous gibberellin content by overexpressing the gibberellin synthesis gene SlGA3ox2 specifically in fruit tissues delayed tomato fruit ripening, whereas treatment with the GA biosynthesis inhibitor paclobutrazol (PAC) accelerated fruit ripening. Moreover, exogenous ethylene treatment cannot completely reverse the delayed fruit ripening phenotype. Furthermore, exogenous GA treatment of ethylene signalling mutant Never ripe (Nr) or SlEBF3-overexpressing lines still delayed fruit ripening, suggesting that GA involved in fruit ripening partially depends on ethylene. Transcriptome profiling showed that gibberellin affect the ripening of fruits by modulating the metabolism and signal transduction of multiple plant hormones, such as auxin and abscisic acid, in addition to ethylene. Overall, the results of this study provide new insight into the regulation of gibberellin in fruit ripening through mediating multiple hormone signals.

Productivity and Econometric Analysis of Leguminous Monkey-nut (Arachis hypogaea L.) as Influenced by Growth Retardant

Background: Groundnut (Arachis hypogaea L.) holds significant importance as a staple food legume and a key economic crop, serving as a valuable source of edible oil and protein in India. However, its full yield potential is often hampered by excessive vegetative growth, which leads to suboptimal yields. With this background, a field experiment was conducted at the Perunthalaivar Kamaraj Krishi Vigyan Kendra in Puducherry during 2020 and 2021. The objective was to investigate the influence of different concentrations and timing of paclobutrazol (PBZ) application on the growth and yield of groundnut. Methods: The experiment was laid out in a split-plot design with three replications, six main plot treatments (Including PBZ concentrations of 25, 50, 100, 150, 200 ppm and a control) and three sub-plot treatments (Involving single sprays at 30 days after emergence (DAE), single sprays at 50 DAE and double sprays at 30 and 50 DAE). Result: The results revealed that the application of paclobutrazol at different concentrations had a positive effect on reducing plant height during the later stages of growth, particularly when a double spray was applied at 30 and 50 DAE. Notably, the application of paclobutrazol at a concentration of 200 ppm in groundnut cultivation proved to be economically viable, resulting 29% increase in pod yield compared to the control group. Specifically, PBZ at 200 ppm, with a double spray, significantly boosted the total pod yield to 2724 kg ha-1. Furthermore, the correlation and regression analyses indicated a positive relationship between growth and yield.

Impact of paclobutrazol on storage root number and yield of sweet potato (Ipomoea batatas L.)

Increasing storage root number is an important way to improve the yield of sweet potato. Here, two-year field experiments were conducted to study the effect of 0 (CK), 10, 20 and 30 mg kg−1 paclobutrazol (PBZ) on the phytohormones and lignin biosynthesis, and root growth and yield of sweet potato. The current study found that PBZ10 decreased the concentration of phytohormones gibberellin 3 (GA3), indole acetic acid (IAA) and abscisic acid (ABA) in the subterranean stem, whereas increased the concentration of zeatin riboside (ZR) and methyl jasmonate (MeJA), resulting in lower root length, volume and tip number at 3 and 5 days after planting (DAP). At 5 DAP, PBZ10 decreased GA3, MeJA and ABA concentration in adventitious root, and increased IAA and ZR concentrations, resulting in increased root length, volume, tip number and surface area at 10 DAP. By 5–30 DAP, PBZ10 decreased the concentration of GA3 and ABA in potential storage roots and increased the concentration of IAA, ZR and MeJA, thus increasing root number. At 10–20 DAP, PBZ10 decreased the lignin concentration in the potential storage root along with the expression of IbEXP1 and the enzymatic activities of phenylalanine ammonialyase, 4-coumaric acid CoA ligase and peroxidase, which are involved in the regulation of lignin biosynthesis, resulting in increased potential storage root diameter; interestingly, the opposite pattern was observed by 25–30 DAP. Then, PBZ10 increased the SR number at 40 DAP, and the yield of sweet potato at harvest time, and no PBZ was detected in SRs of PBZ10. But excessive concentration of PBZ is unfavorable to root development and led to a decrease of yield. These results indicated that a moderate PBZ (10 mg kg−1) application could reasonably regulate phytohormones and lignin biosynthesis, then increase storage root number and yield of sweet potato.

Determination of Ten Plant Growth Regulators in Bean Sprouts by Mixed Solid Phase Extraction Columns Separation and LC-MS/MS

(1) Background: Plant growth regulators (PGRs) can accelerate growth or improve the quality and quantity of bean sprouts but are forbidden to use in bean sprout cultivation, as the sprouting process’s increased chemicals will disturb the PGRs analysis. This article aimed to increase the accuracy and level of sensitivity of the LC-MS/MS method for the simultaneous analysis of 10 PGRs after mixed solid phase extraction (SPE) purification. (2) Methods: An LC-MS/MS detection method for 10 kinds of PGRs was established based on ESI ionization in the positive ion mode for 6-furfurylaminopurine (6-KT), paclobutrazol (PBZ), indole-2-acetic acid (IAA), and indole-3-butyric acid (IBA) and in the negative ion mode for gibberellin A3 (GA3), 2,4-dichlorophenoxy acetic acid (2,4-D), 4-chlorophenoxyacetic acid (4-CPA), forchlorfenuron (FCF), thidiazuron (TDZ), and 6-benzyl adenine (6-BA). (3) Results: The 10 PGR compounds were detected within a concentration range of 1.0–50 ng/mL. The average recovery was 68.3–97.3% with relative standard deviations (RSD) of 4.6–15.2% (n = 6); the limit of detection (LOD) and limit of quantification (LOQ) were found to be 2 and 5 ng/g, respectively. PGRs were surveyed in 36 soybean sprouts and 33 mungbean sprouts; the results showed that 4-CPA and IAA were detected in 10 soybean sprouts and 10 mungbean sprouts, respectively. Five samples contained both 4-CPA and IAA. (4) Conclusions: The established method is simple, rapid, accurate, and highly sensitive for the detection of PGR residues in bean sprout products.

Comparative Evaluation of Paclobutrazol and Rhizobacterium Variovorax sp. YNA59 Effects on Mitigating Drought Stress in Chinese Cabbage (Brassica rapa ssp. Pekinensis)

Drought has severely impacted worldwide agricultural land, resulting in substantial yield loss and abiotic pressures in crops such as Chinese cabbage. Paclobutrazol (PBZ) and plant growth-stimulating bacteria have been extensively recommended to reduce a variety of stresses in crops. Considering these facts, we used PBZ and rhizobacterium Variovorax sp. YNA59, a microbe with potential plant growth-stimulating qualities, in Chinese cabbage under drought stress and non-stressed conditions, and we observed their impacts on morphological and physiological attributes. Our findings revealed a considerable improvement in total plant biomass growth after treatment with YNA59 (28%) and PBZ (8%) under drought conditions. In contrast, negative results of PBZ were observed under normal conditions, suppressing plant growth and reducing plant biomass. The increase in physiological parameters, such as chlorophyll content, relative water content, and photochemical efficiencies of PS II, were observed in YNA59-treated plants, followed by PBZ, especially under drought. Furthermore, drought stress significantly increased the endogenous phytohormone abscisic acid level, whereas PBZ and YNA59 inoculations significantly decreased it. Antioxidant analysis revealed that PBZ and YNA increased glutathione and catalase and decreased polyphenol oxidase and peroxidase levels. These findings suggested that rhizobacterium YNA59 could be more significant for conferring water stress in the Chinese cabbage plant than PBZ.

Effects of Paclobutrazol and Mepiquat Chloride on the Physiological, Nutritional, and Morphological Behavior of Potted Icterina Sage under Greenhouse Conditions

Plant growth regulators (PGRs) are commonly used in horticulture to improve crop quality, save water, and enhance plant resilience to stress. In this study, we examined the effects of two PGRs, paclobutrazol (PBZ) and mepiquat chloride (MC), on the growth and health of Salvia officinalis ‘Icterina’, a popular ornamental and aromatic plant. Parameters such as growth and development, water status, chlorophyll levels, nutrient content, photosynthetic performance, and gas exchange were evaluated. The study took place in a greenhouse with automatic watering and three plant groups: one treated with PBZ, another with MC, and a control group (untreated). Only one application of growth retardants was made, with 0.1 L per pot of a 100 mg/L solution of PBZ, and 0.1 L per pot of a 2.5 g/L solution of MC. The results showed that both PBZ and MC treatments reduced the plant’s water consumption, with PBZ being more effective in limiting leaf growth and promoting the accumulation of substances in the leaves. Both PGRs resulted in smaller plants, reducing the need for soil and potting materials. The MC treatment improved nutrient absorption, reducing the requirement for fertilizers. When subjected to environmental stress from March to June in the greenhouse, Salvia plants benefited from the application of both PGRs, as they helped maintain photosynthetic activity. These findings contribute to improving the sustainability of nursery practices by utilizing PGRs to conserve resources and mitigate the impact of stressful environmental conditions on sage plants.

Treatment of Potted Zebra Plant and Inch Plant with Antigibberellin Plant Growth Regulators Slows Stem Elongation in an Interior Green Wall

In commercial interior green walls, plant trimming and replacement necessitated by stem elongation under low interior light levels is labor intensive and costly. Antigibberellin plant growth regulators (PGRs) may slow stem elongation and thus reduce maintenance costs in this environment. In Expt. 1, two PGRs were applied as foliar spray or drench to three spiderwort selections [two of zebra plant (Tradescantia zebrina) and one of inch plant (Tradescantia fluminensis)] immediately before installation in a green wall, each at three rates: ancymidol (ANC) foliar spray at 25, 100, and 200 mg·L−1; paclobutrazol (PBZ) foliar spray at 20, 80, and 160 mg·L−1; and PBZ drench at 1, 4, and 8 mg·L−1, along with an untreated control. In Expt. 2, 80 mg·L−1 PBZ foliar spray, 1 mg·L−1 PBZ applied via subirrigation four times, and the combination of these two treatments, was evaluated on ‘Burgundy’ zebra plant. In both experiments, plants were placed in a vertical modular tray interior green wall. Change in total stem and specific internode length were measured every 14 days after installation for 3 months to calculate growth per month. Antigibberellin application slowed internode elongation of spiderwort selections during the first month after installation. Antigibberellins were more effective in zebra plant at reducing overall stem growth rate and less so on inch plant. Across the three spiderwort selections, 25 mg·L−1 foliar spray of ANC resulted in no difference in growth rate when compared with the control, although 100 to 200 mg·L−1 foliar spray was effective. Based on the results of both experiments, moderate and high rates of PBZ, applied both as a foliar spray and drench, resulted in similar reduction in stem elongation. PBZ applied as 20 to 80 mg·L−1 foliar spray, 4 mg·L−1 drench before installation in the wall, or a combination of an 80 mg·L−1 PBZ pre-installation foliar spray and recurring 1 mg·L−1 via subirrigation (four times) were effective at growth suppression of spiderworts for at least 3 months. Even rates of PBZ of 160 mg·L−1 foliar spray or 8 mg·L−1 drench did not show phytotoxicity in treated plants and could be considered for use. We recommend a pre-installation application of 80 mg·L−1 foliar spray or 4 mg·L−1 drench for controlling stem growth across spiderwort selections. Application of antigibberellin PGRs to plants before installation in green walls slows stem growth and can contribute to reduced maintenance costs.

Development of Cryopreservation Technique for Meristems of Syringa vulgaris L. Cultivars

Cryopreservation is considered to be one of the most effective methods for long-term storage of plant genetic resources, particularly for ornamental species. However, there is a very little research on cryopreservation of lilacs. In this study, for the first time the cryopreservation protocol (a variation of a pregrowth-dehydration method) was successfully applied to two cultivars of Syringa vulgaris: ‘Aucubaefolia’ and ‘Polina Osipenko’. Explants of both cultivars were able to withstand the different steps of the protocol, and high survival and regrowth percentages were obtained after exposure to liquid nitrogen (67–100% and 63–88%, respectively). The current study is mainly focused on the preculture conditions of the applied method. Based on our results, we propose the use of paclobutrazol (PBZ) with the combination of 6-benzylaminopurine (BAP) and thidiazuron (TDZ) in the preculture medium for increasing explant tolerance to subsequent dehydration and freezing. During post-LN recovery, the explants appeared morphologically normal, and after 12–16 weeks after thawing, they were propagated and cultured as normal plantlets. Therefore, the reported method is effective for long-term storage of lilac meristems and could be used to create a cryobank of achievements in lilac breeding.

Paclobutrazol and maleic hydrazide-induced growth inhibition in warm season turfgrasses through structural and physiological differences

Warm season turfgrasses are fast growing and require frequent mowing, which increases maintenance cost. Various plant growth retardants are used to reduce the growth and required amount of mowing of turfgrasses. Therefore, the present study was planned to explore the impact of paclobutrazol (PBZ) and maleic hydrazide (MH) on the growth rate and quality of warm season turfgrasses. Four turfgrasses were grown in pots at research area, MNS-University of Agriculture, Multan. Paclobutrazol (PBZ) and Maleic Hydrazide at 0.01%, 0.02%, 0.04% levels were applied through foliar application with three repeats in CRD arrangement. The data of growth, quality and anatomical attributes were evaluated. The results showed significant differences in growth and the quality of turfgrasses in response to different levels of plant growth retardants. PBZ application at 0.04% maximum reduced fresh (26%, 35%, 25%) and dry (45%, 54%, 34%) weights of shoot, root and clippings respectively in Fine Dacca turfgrass. Additionally, PBZ application decreased the amount of mowing (40%) compared to control. Fine Dacca also produced the highest visual quality turf with maximum Chlorophyll a (46.87%) and Chlorophyll b (60%) in comparison to nontreated turfgrasses. The minimum number and density of stomatal and mesophyll cells by 45%, 47% were also recorded in Fine Dacca at PBZ (0.04%) with respect to control. It is concluded that PBZ at 0.04% could be used to reduce the amount of mowing in warm season turfgrasses, which will decrease the cost of lawn maintenance and support the landscape industry.

Response of Foliar Application of GA3 and Paclobutrazol on Flowering and Vase Life of Tuberose (Polianthes tuberosa L.)

The present investigation “Response of foliar application of GA3 and paclobutrazol on flowering and vase life of Tuberose (Polianthes tuberosa L.)” was carried out was carried out in Horticulture Research Farm at the Department of Floriculture and Landscape Architecture, IGKV, Raipur, Chhattisgarh, India, 2017-18 and 2018-19. The experiment was laid out in Factorial Randomized Block Design with three replication comprising treatment combination of two PGRs (GA3 and Paclobutrazol) and two tuberose cultivars (Prajwal and Bidhan Ujjwal). Two PGR’s namely Gibberellins (GA3) and Paclobutrazol (PBZ) were taken as growth promoter and growth retardant, respectively. In this contest, an experiment was conducted to investigate the effect of different levels of growth promoter and retardant on growth, flowering and vase life of different cultivars of Tuberose. The result indicated that the vegetative growth, flowering and vase life were significantly influenced by different plant growth regulators and cultivars. The maximum plant height was recorded with cv. Prajwal (V1) as compared to cv. Bidhan Ujjwal (V2). While, minimum number days to first spike emergence (117.33 days), days to first flower opening (131.83 days) was recorded with cv. Bidhan Ujjwal. Among the growth regulators treatments GA3 150 ppm (30 and 50 DAP). However, maximum length of spike (94.72 cm), length of rachis (30.35 cm), length of florets (5.8 cm), diameter of florets (4.32 cm), Number of florets spike-1 (43.41) and Vase life (10.17 days) was recorded with cv. Prajwal. Among the growth regulators treatments GA3 150 ppm (30 and 50 DAP).

Impact of long-term application of paclobutrazol in communities of arbuscular mycorrhizal fungi and their efficiency in the development of Helianthus annuus L.

Paclobutrazol (PBZ) is a phytoregulator known for inhibiting plant vegetative growth and promoting flowering in mango crop (Mangifera indica L.). PBZ belongs to the triazole family, a group recognized by its fungicide capacity, and its application to the soil can directly influence microbial communities, however, little is known about its effects on arbuscular mycorrhizal fungi (AMF). The objectives of this work were to evaluate the impact of long-term application of PBZ on the AMF communities and to verify whether the management time affects the functionality of these communities in promoting the development of ornamental sunflower Helianthus annuus L. (var. Dwarf Double Sungold). Sampling was carried out in mango cultivation areas with a history of PBZ application that varied from no application to application for up to 15 years. For the analysis of the AMF community, the quantification of most probable number (MPN) of infective AMF propagules, abundance of glomerospores, richness, diversity, Simpson dominance, and Pielou's evenness were evaluated. The analysis of the functionality of the AMF community was based on the analysis of the variables of growth and mycorrhizal colonization. Soils with a prolonged history of PBZ application (>nine years) presented distinct AMF communities with lower abundance of glomerospores in relation to areas without PBZ application and with native Caatinga vegetation. However, the soil-inoculum of this AMF community has greater efficiency in promoting sunflower development and mycorrhizal colonization, suggesting greater functionality. It is concluded that the time of application and performance of PBZ in the soil influence the composition of the AMF community. Even with reduction of richness and diversity of AMF species in soils with a prolonged history of PBZ application, there are functional AMF communities in these soils that promoted sunflower plant growth, selecting more efficient and resistant species.

Effect of Paclobutrazol Application on Enhancing the Efficacy of Nitenpyram against the Brown Planthopper, Nilaparvata lugens.

The brown planthopper (BPH), Nilaparvata lugens, is one of the most destructive rice pests in Asia. It has already developed a high level of resistance to many commonly used insecticides including nitenpyram (NIT), which is a main synthetic insecticide that is used to control BPH with a much shorter persistence compared to other neonicotinoid insecticides. Recently, we found that an exogenous supplement of paclobutrazol (PZ) could significantly enhance the efficacy of NIT against BPH, and the molecular mechanism underlying this synergistic effect was explored. The results showed that the addition of a range of 150-300 mg/L PZ increased the toxicity of NIT against BPH with the highest mortalities of 78.0-87.0% on the 16th day after treatments, and PZ could also significantly prolong the persistence of the NIT efficacies. Further investigation suggested that PZ directly increased the content of flavonoids and H2O2 in rice and increased the activity of polyphenol oxidase, which might be involved in the constitutive defense of rice in advance. Additionally, there was an interaction between PZ and BPH infestation, indicating that PZ might activate the host defense responses. Therefore, PZ increased the efficacy of NIT against the brown planthoppers by enhancing the constitutive and inducible defense responses of rice. Our study showed for the first time that PZ could contribute to improving the control effects of insecticides via inducing the defense responses in rice plants against BPH, which provided an important theoretical basis for developing novel pest management strategies in the field.