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Tef [Eragrostis tef (Zucc.) Trotter] and finger millet [Eleusine coracana Gaertn] are staple cereal crops in Africa and Asia with several desirable agronomic and nutritional properties. Tef is becoming a life-style crop as it is gluten-free while finger millet has a low glycemic index which makes it an ideal food for diabetic patients. However, both tef and finger millet have extremely low grain yields mainly due to moisture scarcity and susceptibility of the plants to lodging. In this study, the effects of gibberellic acid (GA) inhibitors particularly paclobutrazol (PBZ) on diverse physiological and yield-related parameters were investigated and compared to GA mutants in rice (Oryza sativa L.). The application of PBZ to tef and finger millet significantly reduced the plant height and increased lodging tolerance. Remarkably, PBZ also enhanced the tolerance of both tef and finger millet to moisture deficit. Under moisture scarcity, tef plants treated with PBZ did not exhibit drought-related symptoms and their stomatal conductance was unaltered, leading to higher shoot biomass and grain yield. Semi-dwarf rice mutants altered in GA biosynthesis, were also shown to have improved tolerance to dehydration. The combination of traits (drought tolerance, lodging tolerance and increased yield) that we found in plants with altered GA pathway is of importance to breeders who would otherwise rely on extensive crossing to introgress each trait individually. The key role played by PBZ in the tolerance to both lodging and drought calls for further studies using mutants in the GA biosynthesis pathway in order to obtain candidate lines which can be incorporated into crop-breeding programs to create lodging tolerant and climate-smart crops.

The application of exogenous paclobutrazol (PP 333 ) can improve the ability of winter warming to promote flowering in Chaenomeles speciosa , but the underlying mechanism is unclear. In this study, the cultivar ‘Changshouguan’ was sprayed with different concentrations of PP 333 during flower bud differentiation, and the changes in the anatomical structures and physiological characteristics of the flower buds during the differentiation process, as well as the growth state of the flower buds and the effect on flowering promotion after winter warming treatment, were comprehensively investigated. The results showed that different concentrations of PP 333 could advance the flowering time of ‘Changshouguan’ by 15–24 d under the warming treatment and increase the flowering duration to 17 d compared with those under the warming treatment alone (CK), and 1000 mg/L was the best treatment. Compared with the CK treatment, the PP 333 treatment decreased the contents of indole acetic acid (IAA) and gibberellic acid (GAs) and increased the contents of zeatin ribosides (ZRs) and abscisic acid (ABA), thus changing the balance of hormones during flower bud differentiation. The inflection point (low point) of the curve shapes of the ZRs/GAs and ZRs/IAA ratios appeared significantly earlier, which showed a pattern consistent with soluble sugar and protein content and antioxidant activity. Interestingly, the above changes also corresponded to earlier flowering times during the warming process. Taken together, these results indicate that spraying an appropriate concentration of PP 333 in the early stage of ‘Changshouguan’ flower bud differentiation promotes the early differentiation of flower buds and early flowering under winter warming treatment by altering their endogenous hormone content and homeostasis and changing their physiological state. The key to maintaining a relatively long flowering period in plants in the PP 333 treatment group after flowering promotion was the increased accumulation of sugars and proteins.

The production of mini shallot bulbs from true seed offers potential advantages for efficient propagation and high-quality seed systems. This study evaluated the responses of shallot growth and bulb miniaturization to planting density and paclobutrazol root-dipping under greenhouse conditions. The experiment was arranged in a split-plot design with three planting densities (100, 200, and 300 plants m-²) as main plots and four paclobutrazol concentrations (0, 150, 300, and 450 mg L-¹) as subplots. Growth traits, yield components, biochemical attributes, and geometric characteristics were analysed using ANOVA, regression, and correlation analyses. Paclobutrazol temporarily reduced plant height and leaf number during early growth but did not significantly affect bulb size, bulb weight, or pigment composition at harvest. In contrast, planting density markedly influenced plant morphology and yield distribution. Increasing density significantly decreased bulb diameter, fresh weight, and biomass per plant, while increasing the proportion of mini bulbs and single-bulb formations. Leaf pigment stability across treatments indicated no evidence of physiological stress associated with either factor. Regression analysis further showed that planting density exhibited stronger predictive relationships with yield parameters than paclobutrazol concentration. Overall, the findings indicate that bulb miniaturization in true-seed shallot is primarily associated with planting density rather than paclobutrazol application, highlighting high-density planting as a practical approach for mini-bulb production systems.

Background GRAS are plant-specific transcription factors that play important roles in plant growth and development. Although the GRAS gene family has been studied in many plants, there has been little research on the GRAS genes of Tartary buckwheat ( Fagopyrum tataricum ), which is an important crop rich in rutin. The recently published whole genome sequence of Tartary buckwheat allows us to study the characteristics and expression patterns of the GRAS gene family in Tartary buckwheat at the genome-wide level. Results In this study, 47 GRAS genes of Tartary buckwheat were identified and divided into 10 subfamilies: LISCL, HAM, DELLA, SCR, PAT1, SCL4/7, LAS, SHR, SCL3, and DLT. FtGRAS genes were unevenly distributed on 8 chromosomes, and members of the same subfamily contained similar gene structures and motif compositions. Some FtGRAS genes may have been produced by gene duplications; tandem duplication contributed more to the expansion of the GRAS gene family in Tartary buckwheat. Real-time PCR showed that the transcription levels of FtGRAS were significantly different in different tissues and fruit development stages, implying that FtGRAS might have different functions. Furthermore, an increase in fruit weight was induced by exogenous paclobutrazol, and the transcription level of the DELLA subfamily member FtGRAS22 was significantly upregulated during the whole fruit development stage. Therefore, FtGRAS22 may be a potential target for molecular breeding or genetic editing. Conclusions Collectively, this systematic analysis lays a foundation for further study of the functional characteristics of GRAS genes and for the improvement of Tartary buckwheat crops.

Plant growth regulators are chemical substances which govern all the factors of development and growth within plants. The application of plant growth regulators to crops modifies hormonal balance and growth leading to increased yield, enhanced crop tolerance against abiotic stress and improved physiological trait of crops. Paclobutrazol (PBZ) [(2RS, 3RS)-1-(4-chlorophenyl)- 4, 4-dimethyl-2-(1H-1, 2, 4-trizol-1-yl)-pentan-3-ol], is one of the members of triazole family having growth regulating property. The growth regulating properties of PBZ are mediated by changes in the levels of important plant hormones including the gibberellins (GAs), abscisic acid (ABA) and cytokinins (CK). PBZ affects the isoprenoid pathway, and alters the levels of plant hormones by inhibiting gibberellin synthesis and increasing cytokinins level and consequent reduction in stem elongation. When gibberellins synthesis is inhibited, more precursors in the terpenoid pathway accumulate and that resulted in the production of abscisic acid. PBZ is more effective when applied to the growing media and application on the growing medium would give longer absorption time and more absorption of active ingredient than foliar spray. The application of PBZ to crops is important in reducing plant height to prevent lodging and in increasing number and weight of fruits per tree, in improving the fruit quality in terms of increases in carbohydrates, TSS, TSS/TA and decreases acidity. It further reduces evapo-transpiration and decreases plant moisture stress by enhancing the relative water content of leaf area and develops resistance in the plants against biotic and abiotic stresses. In addition, it acts as highly active systemic fungicide and used against several economically important fungal diseases. In this review, the current knowledge and possible applications of PBZ, which can be used to improve the growth, yield and quality of crops, have been reviewed and discussed. The role of PBZ to mitigate the harmful effects of environmental stresses in crops is also examined. Moreover, various biochemical and physiological processes leading to improved crop production under the effect of PBZ are discoursed in detail.

Aim: Present study aimed to assess the efficacy of paclobutrazol on vegetative growth, root traits, antomical modifications and nutrient uptake in mango. Methodology: Pot experiment was conducted in young grafted plants of Amrapali variety treated with four concentrations of paclobutrazol viz., 100 mg l-1, 200 mg l-1, 500 mg l-1 and 1000 mg l-1. The design was completely randomized with four replications and each replicate comprised of fifteen plants. Data on different parameters were recorded in randomly selected plants and mean values were presented. Results: Plant height, leaf area, internodal length, plant biomass and shoot biomass reduced by 30.8%, 32.4%, 38.2%, 38.7% and 40.4%, respectively, at higher concentration of paclobutrazol (1000 mg l-1). However, there was an increase in leaf chlorophyll content with high PBZ concentrations (1000 mg l-1). Root traits like root biomass, growth rate and primary root reduced significantly at higher PBZ concentrations, whereas tertiary roots tended to increase. The size of xylem and phloem reduced substantially at higher PBZ concentration. First principal component (PC 1) explained more than 92% of the variance signifying most of the growth attributing traits. Interpretation: The results unveiled that growth attributing traits, vascular characteristics of root and stem, and leaf nutrient status were significantly influenced by higher concentration of PBZ.

• Plant growth and development are coordinated by multiple environmental and endogenous signals. Brassinosteroid (BR) and ethylene (ET) have overlapping functions in a wide range of developmental processes. However, the relationship between the BR and ET signalling pathways has remained unclear. • Here, we show that BR and ET interdependently promote apical hook development and cell elongation through a direct interaction between BR-activated BRASSINOZALE-RESISTANT1 (BZR1) and ET-activated ETHYLENE INSENSITIVE3 (EIN3). • Genetic analysis showed that BR signalling is required for ET promotion of apical hook development in the dark and cell elongation under light, and ET quantitatively enhances BR-potentiated growth. BZR1 interacts with EIN3 to co-operatively increase the expression of HOOKLESS1 and PACLOBUTRAZOL RESISTANCE FACTORs (PREs). Furthermore, we found that BR promotion of hook development requires gibberellin (GA), and GA restores the hookless phenotype of BR-deficient materials by activating EIN3/EIL1. • Our findings shed light on the molecular mechanism underlying the regulation of plant development by BR, ET and GA signals through the direct interaction of master transcriptional regulators.

Dense plant cultivation is an efficient approach to utilize the maximum inputs for increasing maize production. However, dense plant populations may prone to lodging as it results in increased plant height and reduced culm diameter; therefore, we hypothesized that weaker stems may be responsible for maize lodging. In this study, we examined the regulatory effects of paclobutrazol under two commonly used application methods (seed-soaking and seed-dressing). Seed-soaking with paclobutrazol at the rate of 0 (CK1), 200 (S1), 300 (S2), and 400 (S3) mg L−1, while seed-dressing at the rate of 0 (CK2), 1.5 (D1), 2.5 (D2), and 3.5 (D3) g kg−1 were used. Results showed that paclobutrazol improved the culm physical strength by increasing the rind penetration strength, stalk breaking strength, culm diameter, wall thickness, and dry weight per unit length of basal third internode, compared to control plants. Moreover, paclobutrazol reduced the internode length, plant height, ear height, center of gravity height and lodging rate in both growing seasons. In addition, more lignin was accumulated in the basal internode and the activities of phenylalanine ammonia-lyase (PAL), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD) and 4-coumarate: CoA ligase (4CL) increased with paclobutrazol, and their maximum values were observed in the S2 and D3 treatments, resulting in strong lodging resistance. Lignin content was positively and significantly correlated with the rind penetration strength, breaking strength of internode, and activities of PAL, 4CL, POD, and CAD, while significantly and negatively correlated with lodging percentage. The present findings suggested that 300 mg L−1 and 3.5 g kg−1 of paclobutrazol may efficiently be utilized to minimize the risk of lodging, not only by manipulating plant height but also by enhancing culm physical strength and lignin accumulation in basal internodes.

The poinsettias were cultivated years ago as medicinal and ornamental plants, too; but in the recent time are in the light of world flower assortment surprising with new shapes and colors in the cold season. The ornamental values of these plants are given by bracts which can have the same size as foliage leaves or even larger. The tendency of floral industry consists in obtaining high quality ornamental plants with superior marketable price. In these regards, the role of plant growth retardants in regulating the growth of poinsettia is important to obtain healthy, compact bushes and extended decoration period. The aim of the paper is to evaluate the effects of plant growth retardants on poinsettia. Five treatments with different retardants were applied as drench or spray. In the experiment four replicates and a total of 144 poinsettias were used. Treatments with paclobutrazol (60 mg/l sprayed), daminozide (2500 mg/l sprayed) and chlormequat chloride (1000 mg/l sprayed), showed the best results in case of marketability.

Cotton cultivars have evolved to produce extensive, long, seed-born fibers important for the textile industry, but we know little about the molecular mechanism underlying spinnable fiber formation. Here, we report how PACLOBUTRAZOL RESISTANCE 1 (PRE1) in cotton, which encodes a basic helix-loop-helix (bHLH) transcription factor, is a target gene of spinnable fiber evolution. Differential expression of homoeologous genes in polyploids is thought to be important to plant adaptation and novel phenotypes. PRE1 expression is specific to cotton fiber cells, upregulated during their rapid elongation stage and A-homoeologous biased in allotetraploid cultivars. Transgenic studies demonstrated that PRE1 is a positive regulator of fiber elongation. We determined that the natural variation of the canonical TATA-box, a regulatory element commonly found in many eukaryotic core promoters, is necessary for subgenome-biased PRE1 expression, representing a mechanism underlying the selection of homoeologous genes. Thus, variations in the promoter of the cell elongation regulator gene PRE1 have contributed to spinnable fiber formation in cotton. Overexpression of GhPRE1 in transgenic cotton yields longer fibers with improved quality parameters, indicating that this bHLH gene is useful for improving cotton fiber quality.