Concentrations Of Paclobutrazol Research Articles

The Effect of Paclobutrazol and Types of Nitrogen (N) Fertilizer on The Growth and Yield of Long Bean (Vigna sinensis L.)

Long bean is the one of the most widely consumed vegetables both fresh and processed. The market demand for long beans is rising, but their production remains limited. This study aims to investigate how different concentrations of paclobutrazol and various types of nitrogen fertilizers affect the growth and yield of long bean plants. The research was conducted in Dander Village, Dander District, Bojonegoro Regency, East Java. The study employed a factorial Randomized Block Design (RBD) with two factors: the concentration of paclobutrazol (P0 = control, P1 = 150 ppm, P2 = 200 ppm, P3 = 250 ppm) and the type of nitrogen fertilizer (N0 = NPK control, N1 = Urea, N2 = ZA, N3 = KNO3). Variables to observed included plant length, number of leaves, flowering age, number of pods, pod weight, number of seeds, and fruit set. The results showed that the combination of 150 ppm paclobutrazol and KNO3 nitrogen fertilizer produced the best results in terms of the fastest flower emergence at 29 days after planting (HST) and the highest pod weight of long beans at 43.00 grams per plant. Keywords: Paclobutrazol, Various Nitrogen Fertilizers, Growth, Yield, Long Beans (Vigna sinensis L.)

Effects of Paclobutrazol on Reproductive and Vegetative Traits of Phalaenopsis Join Grace 'TH288-4'.

Phalaenopsis is the most popular potted plant worldwide. However, its typically long stalks often lead to increased shipping costs and risks. This study investigates the effectiveness of varying the concentration, timing, and frequency of paclobutrazol (PP333) applications on shortening the stalk of Phalaenopsis Join Grace 'TH288-4'. Concurrently, it also examines the potential for producing visually appealing and single-flower potted phalaenopsis products by means of truncation. Mature phalaenopsis plants were moved to a cool room in the seventh week to induce flowering. Four experimental groups were established based on different PP333 application schedules: the control (CK) group, with reverse osmosis water application in the second week; the T2 group, with a single application in the second week; the T2T3 group, with applications in both the second and third weeks; and the T7T8 group, with applications in the seventh and eighth weeks. The PP333 concentrations used were 250, 500, 750, and 1000 mg·L-1, applied as foliar sprays. The results showed that the shortest stalks, measured from the base to the first flower, were observed in the T2 group treated with PP333 at 750 mg·L-1 and in the T2T3 group with PP333 at 500, 750, and 1000 mg·L-1. These treatments resulted in stalk lengths of 19.18-22.17 cm, which are 67.2-71.6% shorter than the controls. PP333 application had minimal effect on the stalk diameter, pedicel length, flower width, length, and length/width ratio. However, root diameter was thicker in plants treated with PP333 compared with the control plants. For producing single-flower phalaenopsis, a foliar spray of 750 mg·L-1 PP333 is recommended approximately a month before moving the plants to cooler conditions, followed by truncation, retaining only the first flower. As a result, this study establishes a PP333 treatment protocol for phalaenopsis, offering a strategy to effectively shorten the stalks.

Effect of biochar composition and paclobutrazol concentration on growth and yield of G1 Medians cultivar potato seeds in Jatinangor medium plain

Potato seed production in the medium plain is necessary to avoid environmental damage and the limited area of potato seed production in the high plain. The effort to increase the production of G1 potato seeds on the medium plain is the evaluation of the biochar composition and concentration of paclobutrazol that can increase the production G1 potato seeds cv Medians in the medium plain of Jatinangor. The research was conducted from August to December 2022 at the Ciparanje Experimental Field. Jatinangor. Faculty of Agriculture. Universitas Padjadjaran. The experiment used a Factorial Randomized Block Design (RBD). The first factor was the biochar composition: m1 (100% compost), m2 (80% compost + 20% rice husk biochar), m3 (80% compost + 20% coconut shell biochar), and m4 (80% compost + 10% biochar husk rice + 10% coconut shell biochar). The second factor was the paclobutrazol concentration: p1 (without paclobutrazol), p2 (100 ppm paclobutrazol), and p3 (150 ppm paclobutrazol). The experimental results showed that there was no reaction effect of biochar compositions and paclobutrazol concentrations on the growth and yield of G1 potato seeds. The application of 80% compost + 20 % rice husk biochar gave significantly higher yields than treatment without biochar. The number of tubers was 6.29 knol per plant and the tuber weight was 66.80 g per plant. Application of 100 ppm paclobutrazol resulted in lower plant height, gave the number of tubers was 6.39 knol per plant, tuber weight per plant was 63.34 g higher than without paclobutrazol and produced more seed tubers with S class.

Dihydrogibberellin improves grain yield and lodging resistance of direct seeded rice

AbstractDihydrogibberellin (DIH) is an eco‐friendly and low‐toxic regulator with immense potential for application in the current rice industry, specifically for increasing yield and lodging resistance. However, limited research has been conducted to explore the impact of DIH on the yield and lodging resistance of direct‐seeded rice (DSR, Oryza sativa L.). Therefore, a 2‐year field experiment was conducted to evaluate the effects of spraying different concentrations of 5% DIH emulsifiable concentrate on DSR during the tillering (1) and jointing (2) stages. Three concentrations of DIH were used: 27 (DIH27), 54 (DIH54), and 108 g ha−1 (DIH108). The commonly used paclobutrazol concentration in rice production (112.5 g ha−1) was compared and a clear water treatment was used as control (CK). The results of the experiment showed that the DIH treatments increased the DSR yield by 1.22%–22.64% and reduced lodging index by 8.9%–54.2% compared to the CK treatment. Additionally, the DIH treatments resulted in significant reductions in the length of the 1–3 basal internodes and plant height, as well as increases in the diameter and culm wall thickness of internodes. Moreover, the DIH treatments also led to higher dry matter percentages in stalks and leaf sheaths, as well as increased lignin and cellulose content. Furthermore, the best effect of DIH application was observed at the jointing stage in terms of increasing yield and lodging resistance. Therefore, this research demonstrates that the application of DIH to DSR at the jointing stage can be an effective strategy for increasing yield and improving lodging resistance.

Effect of spraying with different concentrations of the growth regulator paclobutrazol on the yield characteristics of three varieties of oat crop Avena sativa L.

The experiment was conducted at the Research Station of the College of Agriculture, University of Basrah,located north of Basrah city, during the winter season of 2022-2023, in a loamy soil. The study aimed toinvestigate the response of three varieties of oats (Avena sativa L.) to foliar spraying with differentconcentrations of the growth regulator paclobutrazol. The study included three oat varieties (Ganzania,Shafa, and CarlIoup) under the influence of spraying three concentrations of paclobutrazol (25, 50, and100 mg/L) and a control treatment. The interaction between the two factors was also studied. Thespraying was carried out in two stages, the first at the beginning of branching, and the second after threeweeks from the first spray.The experiment was arranged using a randomized complete block design(RCBD) with three replicates. The results showed the superiority of the paclobutrazol treatment (50 mg.l-1), which recorded the highest averages for most of the studied yield characteristics, as the lowestaverage number of panicles m-2was recorded at 458.05 dalia - and the highest average number of grainsper dalia was 55.45 grains g-1, and the highest average weight was recorded. 1000 grains amounted to37.33 g, while the Ganzania variety was superior in terms of the number of days and the number ofgrains in of panicl and 1000 grains amounted to 458.05 and amounted to 55.45 grains in of panicl-1 and 34.93 g and its components, protein content in grains, and chlorophyll in leaves were studied. Theresults showed the superiority of the paclobutrazol treatment (50 mg/L), which recorded the highestmeans for most of the studied growth traits. It had the lowest average plant height, reaching 70.75 cm. Italso recorded the highest average chlorophyll content, reaching 143.90 mg/100 g, and the highest averagefor the number of tillers, reaching 488.97 tillers/m². Additionally, it recorded the highest average for stemdiameter, reaching 4.49 mm.

Seed tuber production of potato from stem cuttings, planting densities, and paclobutrazol concentrations

Rapid multiplication of potato seed using cuttings is a pivotal strategy for ensuring seed availability. This study aimed to elucidate the interactive effects of node number, paclobutrazol concentration, and planting density on seed potato and cutting productions. The study consisted of two experiments. The first experiment evaluated two genotypes (Granola and PKHT-6) with one or two nodes per cutting. The second experiment investigated planting density (one, three, or five plants per polybag) and paclobutrazol concentration (0, 15, 30, and 45 mg L-1). Notably, node number did not significantly influence cutting success, despite genotype-specific and interactive effects on vegetative parameters like plant height, stem diameter, leaf number, and root length. Planting density had no statistically significant impact on all vegetative parameters but demonstrably affected all production parameters. Conversely, paclobutrazol concentration significantly affected all vegetative parameters and influenced all production parameters except tuber weight per plant. From the results of this research, the use of single cutting is more recommended because it will obtain more plant material compared to two-node cuttings. Thus, in a more global context of potato development, this has the potential to increase the production of potato seeds from cuttings twice as much as the current seed production. The use of three plants/polybags is more recommended since it will produce more tuber but not different with five plants, and the use of paclobutrazol 15 mg L-1 is also recommended to increase the number of tubers. In this way, the production costs of G0 potato seeds can be reduced so that the availability of G0 potato seeds will be more guaranteed and affordable. Keywords: Granola; PKHT-6; rapid multiplication; tuber production

Effect of Paclobutrazol and GA4+7 on Post-Harvest Storage of Dragon Fruit [Hylocereus costaricensis (Web.) Britton and Rose

Dragon fruit undergoes rapid senescence during storage. This study identified the synergistic effect of Paclobutrazol and GA4+7 with different concentrations on the postharvest quality and shelf life of dragon fruits stored at ambient conditions. This study was conducted in completely randomized design. Dragon fruits were treated with different concentration of Paclobutrazol and GA4+7 and stored at ambient temperature for 13 days. Changes in fruit’s physiological loss of weight, firmness, total soluble solid, titrable acidity, and ascorbic acid were periodically recorded. The results indicated that the Paclobutrazol treated with 200mg significantly reduced the decrease of physiological loss of weight, firmness, total soluble solids, titrable acidity and ascorbic acid content. The results showed that Paclobutrazol treated with 200mg is the most effective treatment than GA4+7 for improving the postharvest quality and prolong the shelf life of dragon fruits when stored at ambient condition.

Response of growth, yield, and seeds quality of G0 potato on different potassium fertilizer doses and retardant concentrations in Jatinangor medium land

This study aims to determine the best interaction of potassium (K) fertilizer dose and retardant concentration on the growth, yield, and seed quality of G0 potato grown in the medium land of Jantinangor. The experiment was conducted at Screen House Station Ciparanje, Jatinangor, Faculty of Agriculture Universitas Padjadjaran from November 2022 until January 2023 at an elevation of ± 685 meters above sea level. The experimental design used was the Factorial Randomized Block Design (RBD). The first factor was the K fertilizer dose including 50%, 100%, and 150%. The second was the retardant concentration including without retardant, 100 ppm paclobutrazol, 100 ppm prohexadione-Ca, and 150 ppm prohexadione-Ca. The experimental results showed that there was an interaction effect between the K dose and retardant concentration. The interaction effect of 150% K and 100 ppm prohexadione-Ca showed the highest percentage of L class seed tuber and the lowest tuber weight loss. Independently, 150% K improved growth rate, number of tubers (6.67 knol/plant), and weight of tubers (73.33 g/plant). Independently, 100 ppm paclobutrazol concentration increased the chlorophyll content index. 150 ppm prohexadione-Ca concentration suppressed leaf area and plant height but increased stomatal conductance, fast emergence shoot time, and shoot length. 100 ppm prohexadione-Ca concentration produced the highest number of tubers and the weight of tubers, i.e., 6.78 knol/plant and 74.33 g/plant, respectively.

Paclobutrazol Residues in Recirculated Water in Commercial Greenhouses

Reusing irrigation water has technical, environmental, and financial benefits. However, risks are also associated with the accumulation of agrochemicals, in addition to ions, plant and food safety pathogens, and biofilm organisms. In this project, we measured the concentration of paclobutrazol (a persistent and widely used plant growth regulator) in recirculated water in greenhouses producing ornamental plants in containers. Solutions were collected from catchment tanks at nine commercial greenhouses across seven states in the United States in Spring and Fall 2014. Paclobutrazol was detected in all samples, with differences observed by season, greenhouse operation, paclobutrazol application method, and irrigation method. Across operations, the residual concentration of paclobutrazol was higher in spring for most greenhouses (ranging from 0 to 1100 µg·L−1) compared with the fall (ranging from 0 to 8 µg·L−1). The spray-drench application method resulted in the highest residual concentrations (up to 35 µg·L−1), followed by substrate drench (up to 26 µg·L−1) and foliage spray (concentrations under 3 µg·L−1). Residual concentrations were higher with overhead irrigation (up to 35 µg·L−1) compared with subirrigation systems (up to 15 µg·L−1). Our results indicate that paclobutrazol is likely to be a growth retardant risk in greenhouse operations recirculating water. A clear understanding of the risks associated with recirculated water intends to support the development and implementation of risk management strategies to ensure and promote safe use of recirculated water in greenhouses. Overall, the most effective preventative strategy is to ensure the use of the minimum amount of the a.i. necessary per unit of space and time.

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.

Response of off-season strawberries (Fragaria sp.) production under the effects of paclobutrazol and drought stress

Strawberry (Fragaria sp.) is a fruit crop harvested seasonally with the peak season from August to November while the off-season harvest is January to June with limited harvest. The purpose of this study was to find the concentration of paclobutrazol and the level of drought stress for off-season strawberry production. This research conducted on April to July 2023. The experiment used a factorial Randomized Block Design consisting of 2 factors and 3 replications with 16 treatment combinations. The first factor was paclobutrazol consisting of four levels, namely P0 = control, P1 = 10,000 ppm, P2 = 20,000 ppm and P3 = 30,000 ppm and the second factor was the level of drought stress consisting of four levels i.e. C0 = 100% field capacity, C1 = 80% field capacity, C2 = 60% field capacity and C3 = 40% field capacity. The results showed that paclobutrazol accelerated flowering time, increased fruit set, leaf relative water content, root length, chlorophyll content, but decreased the number of fruits formed, harvested fruits, fruit diameter, harvested fruit weight, weight per fruit, root oven dry weight, percentage of fallen fruits and total soluble solids. Drought stress level increased leaf relative water content, root length, root oven dry weight, percentage of fallen fruit, percentage of fruit set, but decreased number of flowers formed, fruits harvested, weight of fruits harvested, weight per fruit, fruit diameter, total soluble solids, chlorophyll content and delayed flowering time.

Effects of paclobutrazol seed priming on seedling quality, photosynthesis, and physiological characteristics of fragrant rice

BackgroundPaclobutrazol is widely used in the agricultural field. This study investigated the effects of seed priming with different concentrations of paclobutrazol on seedling quality, 2-acetyl-1-pyrroline (2-AP, a key aroma component of fragrant rice) biosynthesis, and related physiological and biochemical indicators in fragrant rice seedlings.ResultsThe experiment is being conducted at the College of Agriculture, South China Agricultural University. In the experiment, three concentrations of paclobutrazol (Pac 1: 20 mg·L−1; Pac 2: 40 mg·L−1; Pac 3: 80 mg·L−1) were used to initiate the treatment of fragrant rice seeds, while water treatment was used as a control (CK). The results showed that compared with CK, paclobutrazol treatment reduced plant height, increased stem diameter, and increased fresh and dry weight of aromatic rice seedlings. Moreover, paclobutrazol treatment also increased the seedlings’ photosynthetic pigment content and net photosynthetic rate.ConclusionsThis study demonstrates that paclobutrazol primarily increases the content of proline by reducing the content of glutamate and down-regulating the expression of P5CS2, thereby promoting the conversion of proline to the aromatic substance 2-AP. Under the appropriate concentration of paclobutrazol (40 mg·L−1~80 mg·L−1), the seedling quality, stress resistance, and aroma of fragrant rice can be improved.

Optimization of Potato Cuttings of Granola Kembang Cultivars with the Application of Auxin and Paclobutrazol for Tuber Production

Optimization of Potato Cuttings of Granola Kembang Cultivars with the Application of Auxin and Paclobutrazol for Tuber Production

Cultivo de abobrinha sob estresse salino e aplicação exógena de paclobutrazol

ABSTRACT Salinity is considered an obstacle to the production system that limits the growth and yield of crops around the world. Therefore, it is essential to develop strategies to minimize the effects of salinity and increase yield, especially in the semi-arid region of the Northeast, which has limited water resources of good quality for irrigation. The objective was to evaluate the effects of applying paclobutrazol on zucchini crop under salt stress. The experiment was conducted in a greenhouse, in a randomized block experimental design, in a 2 × 5 factorial scheme, with two salinity levels of irrigation water (0.6 and 4.0 dS m-1) and five concentrations of paclobutrazol - PBZ (0; 2; 4; 6 and 8 g L-1), and with four repetitions. Application of 8 mg L-1 PBZ increases stem diameter in zucchini under irrigation of 4.0 dS m-1. Chlorophyll b and total chlorophyll contents increase with PBZ concentration of 4 mg L-1 and irrigation of 0.6 dS m-1. PBZ concentration of 4 mg L-1 increases the relative water content while reducing electrolyte leakage in zucchini under salinities of 4.0 and 0.6 dS m-1 respectively. Root, stem and leaf dry mass of zucchini increases when plants are irrigated with water of 0.6 dS m-1 and subjected to PBZ concentration of 8 mg L-1. PBZ concentrations do not attenuate the effects of salinity on leaf area, crown volume and diameter, vegetative vigor index, chlorophyll a and carotenoids.

Interactive effects of NPK fertilizer and paclobutrazol concentration on growth and yield of hanjeli (Coix lacryma-jobi L.)

The balance between growth and crop yield can be manipulated by exploiting nutrient and retardant interactions. This study is aiming to assess the effects of various combinations of NPK 16-16-16 fertilizer in different doses, along with the application of multiple concentrations of paclobutrazol on the growth and yield of hanjeli. This experiment was carried out in the experimental field of Ciparanje, Faculty of Agriculture Universitas Padjadjaran, Jatinangor, Sumedang from February 2021 to August 2021. This research was conducted in a split-plot design with three replications. The main plot consisted of 200 kg/ha (n1), 250 kg/ha (n2), and 300 kg/ha (n3). The subplot consisted of 2000 ppm (p1), 3000 (p2), and 4000 ppm (p3). The results show that there were interaction effects between different doses of NPK fertilizer and paclobutrazol concentrations on plant height and 100-grain weight. The best combination came from the application of 200 kg/ha NPK fertilizer with 3000 ppm of paclobutrazol, which gave higher results in plant height and 200 kg/ha NPK fertilizer with 2000 ppm of paclobutrazol on 100-grain weight.

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.

Pengaruh Teknik Hardening dan Konsentrasi Paclobutrazol terhadap Pertumbuhan Planlet Krisan (Chrysanthemum sp.) pada Tahap Aklimatisasi

The increasing interest and demand for chrysanthemum plants affect their economic value, which causes the quality of chrysanthemum plants to be demanded from all sides. One of the efforts to meet the needs of chrysanthemum plants in a short time is tissue culture. However, the acclimatization stage becomes a critical stage that threatens the presentation of chrysanthemum plantlets. This study aimed to determine the interaction between hardening techniques and paclobutrazol concentration on the growth of chrysanthemum plantlets at the acclimatization stage. This research was conducted in the Green House of the Tissue Culture Laboratory of Jember Polytechnic from November 2022 to January 2023. This study used a factorial complete randomized design (CRD) repeated 4 times. The first factor is the hardening technique consisting of 2 levels, H0 (no hardening), and H1 (hardening). The second factor is paclobutrazol concentration which consists of 3 levels, P1 (10 ppm), P2 (15 ppm), and P3 (20 ppm). Observational data were statistically analyzed using ANOVA, if the results showed significantly different effects then continued with the BNT test at the 5% level. The results showed that the hardening treatment had a significantly different effect on leaf color with a score of 3.5. Treatment with a paclobutrazol concentration of 20 ppm had a significantly different effect on increasing plant height by 2.71 cm and increasing the number of leaves by 1.38. This suggests that paclobutrazol and hardening treatment are needed at the acclimatization stage of chrysanthemums.

The effect of varieties of true shallot seed and paclobutrazol concentrations on growth and production of shallot plant

The increasing demand for shallots is inversely proportional to the quality of the current production. Efforts to improve and increase quality of production are selection of good varieties and add plant regulatory substances has also become the focus of many researchers in their effect on plant growth. Therefore, research was carried out on the effect of the varieties and also plant regulatory substances namely paclobutrazol on the growth and production of shallot plants. This research was carried out at the Teaching Farm, Faculty of Agriculture, Hasanuddin University from August to November 2021. This research was carried out as a factorial experiment in a split plot design, as the main plot, namely the botanical seed varieties of shallot (v) consists of 3 varieties, namely the Lokananta varieties (v1), Maserati varieties (v2), and Sanren varieties (v3), as a sub-plot, namely the concentration of paclobutrazol consists of 4 levels, namely 0 ppm (k0), 100 ppm (k1), 200 ppm (k2) and 300 ppm (k3). The research results showed that the interaction of the Sanren varieties with paclobutrazol concentration of 100 ppm gave the best results on the weight of fresh stover per plant (26.04 g), weight of dry stover per plant (19.23 g) and production per hectare (9.20 ton/ha). The Sanren varieties gave the best results on chlorophyll a (387.23 μmol.m−2), chlorophyll b (187.12 μmol.m−2), total chlorophyll (564.14 μmol.m−2) and number of tubers (1.81). Paclobutrazol concentration of 100 ppm gave the best results on plant height (43.07 cm) and number of leaves (6.24 strands), while paclobutrazol concentration of 200 ppm gave the best results on tuber diameter (23.13 mm) and paclobutrazol concentration of 300 ppm gave the best results on the number of tubers (1.54).

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.

Paclobutrazol in the in vitro conservation of cassava genotypes

In vitro germplasm conservation allows to extend the interval between subcultures without compromising the viability and genetic integrity of the plant, ensuring a backup of genotypes with high phytosanitary quality. Thus, this study aimed to verify the effect of four concentrations of Paclobutrazol® in inducing minimum growth in five Manihot esculenta accessions from the in vitro Active Germplasm Bank of Embrapa Cassava and Fruits. An experiment was installed using the Murashige and Skoog medium without addition and added with four concentrations of Paclobutrazol® (0.10, 0.20, 0.30, and 0.40 mg L-1), in five in vitro accessions of M. esculenta: BRS Jari (BGM 2041), Cigana (BGM 0264), BRS Poti Branca (BGM 2017), TME 14, and BRS Novo Horizonte. The statistical design was completely randomized in a 5 x 5 factorial scheme, with 15 repetitions. After 120 days of cultivation, the following variables were evaluated: plant height (cm), number of green leaves, number of senescent leaves, number of mini-cuttings, number of shoots, and fresh and dry mass of shoots and roots (mg). Paclobutrazol® caused a reduction in plant height and gain in root mass for all accessions, in addition to preserving the number of green leaves and decreasing leaf senescence for most genotypes. There was a strong dependence of the genotype in relation to the concentration of Paclobutrazol®. The concentration of 0.20 mg L-1 showed potential in the in vitro conservation of M. esculenta genotypes.