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Salinity stress severely restricts rice growth. Prohexadione calcium (Pro-Ca) modulation can effectively alleviate salt stress in rice. In this study, we explored the effects of Pro-Ca on enhancing salt tolerance in two rice varieties, IR29 and HD96-1. The results revealed that Pro-Ca markedly enhanced root and shoot morphological traits and improved plant biomass under salt stress. Chlorophyll a and b content were significantly increased, which improved photosynthetic capacity. Transcriptomic and metabolomic data showed that Pro-Ca significantly up-regulated the expression of genes involved in E3 ubiquitin ligases in IR29 and HD96-1 by 2.5-fold and 3-fold, respectively, thereby maintaining Na+ and K+ homeostasis by reducing Na+. Moreover, Pro-Ca treatment significantly down-regulated the expression of Lhcb1, Lhcb2, Lhcb3, Lhcb5, and Lhcb6 in IR29 under salt stress, which led to an increase in photosynthetic efficiency. Furthermore, salt stress + Pro-Ca significantly increased the A-AAR of IR29 and HD96-1 by 2.9-fold and 2.5-fold, respectively, and inhibited endogenous cytokinin synthesis and signal transduction, which promoted root growth. The current findings suggested that Pro-Ca effectively alleviated the harmful effects of salt stress on rice by maintaining abscisic acid content and by promoting oxylipin synthesis. This study provides a molecular basis for Pro-Ca to alleviate salt stress in rice. [ABSTRACT FROM AUTHOR]

Prohexadione calcium (EA) and gibberellin (GA) are two different types of plant growth regulators that have different effects on the regulation of plant development. The objective of this study was to evaluate the impacts of EA and GA on rice plant growth, development and morph-physiological traits in two rice varieties: 'Huang Huazhan' and 'Guang Hong 3'. At the three-leaf seedling stage, the plants were treated with 50 mM NaCl 24 h after foliar application of EA (100 mg·L−1) and GA (1 mg·L−1). Data on morphological indexes, osmotic regulators and antioxidant activities were compared with the treatment of EA and GA on the 4th, 7th, 10th and 13th days after NaCl stress. Our data analysis showed that NaCl stress inhibited the leaf area growth of rice seedlings, altered the microstructure and disrupted the antioxidant system, ion uptake and transport balance. The significant increase in malondialdehyde (MDA) content and superoxide anion production rate (O2 · ¯) indicated that NaCl stress caused a severe oxidative stress response to rice seedlings. Treatment with EA and GA activated the antioxidant system under NaCl stress, significantly elevated superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and suppressed the increase in MDA content and the O2 · ¯ production rate. Under NaCl stress, EA and GA treatments improved the osmoregulatory balance, significantly increased soluble protein and proline contents and maintained lower Na+/K+ levels. EA and GA treatments significantly increased the K+ and Ca2+ contents, thereby maintaining ionic balance, which was favorable for maintaining the growth of rice seedlings. In this study, moth plant growth regulators maintained the growth and development of rice seedlings under NaCl stress by inducing an increase in osmoregulation and antioxidant levels, reducing the degree of membrane damage and regulating the selective uptake of ions by rice seedlings. Current findings also clarified that foliar application of EA was more effective than GA in three-leaf seedlings by enhancing the morph-physiological and antioxidant parameters under NaCl stress. [ABSTRACT FROM AUTHOR]

Prohexadione calcium (EA) and gibberellin (GA) are two different types of plant growth regulators that have different effects on the regulation of plant development. The objective of this study was to evaluate the impacts of EA and GA on rice plant growth, development and morph-physiological traits in two rice varieties: ‘Huang Huazhan’ and ‘Guang Hong 3’. At the three-leaf seedling stage, the plants were treated with 50 mM NaCl 24 h after foliar application of EA (100 mg·L−1) and GA (1 mg·L−1). Data on morphological indexes, osmotic regulators and antioxidant activities were compared with the treatment of EA and GA on the 4th, 7th, 10th and 13th days after NaCl stress. Our data analysis showed that NaCl stress inhibited the leaf area growth of rice seedlings, altered the microstructure and disrupted the antioxidant system, ion uptake and transport balance. The significant increase in malondialdehyde (MDA) content and superoxide anion production rate (O2·¯) indicated that NaCl stress caused a severe oxidative stress response to rice seedlings. Treatment with EA and GA activated the antioxidant system under NaCl stress, significantly elevated superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and suppressed the increase in MDA content and the O2·¯ production rate. Under NaCl stress, EA and GA treatments improved the osmoregulatory balance, significantly increased soluble protein and proline contents and maintained lower Na+/K+ levels. EA and GA treatments significantly increased the K+ and Ca2+ contents, thereby maintaining ionic balance, which was favorable for maintaining the growth of rice seedlings. In this study, moth plant growth regulators maintained the growth and development of rice seedlings under NaCl stress by inducing an increase in osmoregulation and antioxidant levels, reducing the degree of membrane damage and regulating the selective uptake of ions by rice seedlings. Current findings also clarified that foliar application of EA was more effective than GA in three-leaf seedlings by enhancing the morph-physiological and antioxidant parameters under NaCl stress.

Abstract Feathering in apple nursery trees is a critical operation used to increase the quality of planting material. Plant growth regulators (PGR) could be used to form feathers in apple nursery trees. The main goal was to study the impact of different PGR and concentrations on feathering promotion in different nursery apple trees. The study had three different trials where the specific aims were to study the impact of: i) different rates of 6-benzyladenine (6-BA); ii) different PGR (6-BA and 6-BA + GA4+7) on feathering promotion, and; iii) 6-BA on feathering promotion and prohexadione calcium (P-Ca) on trunk thickening under greenhouse conditions. Both 6-BA and 6-BA + GA4+7 were effective inducing feathering in the different cultivars tested. 6-BA reduced final young plants grafted height only in one out of three seasons, reducing an average of 15 and 10 cm on ‘Early Red One’ and ‘Fuji’ apple nursery trees, respectively. P-Ca reduced tree growth rate 4-5 weeks after sprayed, but the difference did not persist until the end of the season. Trunk diameter was not affected by the different plant growth regulators and concentrations tested. 6-BA alone or in combination with GA4+7 is an efficient tool to feathering formation in different nursery apple cultivars and conditions.

Prohexadione calcium (Pro-Ca), as a growth retardant, can effectively alleviate the damage of salt stress to plants. In order to explore the effects of NaCl stress on the physiological characteristics and panicle traits of rice plants as well as the alleviating effect of Pro-Ca at the booting stage, we performed pot experiments on two rice cultivars: conventional rice 'Huanghuazhan' and hybrid rice 'Xiangliangyou900'. Rice plants were treated with 0.3% NaCl 48 hours after Pro-Ca (100 mg L-1) treatment to study the effects of Pro-Ca on the physiological characteristics of the leaves and panicles, as well as the panicle and yield traits of rice under salt stress. Our analysis indicated that NaCl treatment inhibited the morphological growth parameters and photosynthetic efficiency, destroyed the antioxidant defense systems of leaves and panicles, increased soluble protein and proline in both rice cultivars. Foliar application of Pro-Ca significantly increased the leaf area, uppermost internode length, panicle length, panicle weight, number of primary branches, number of grains per panicle, seed setting rate and yield under salt stress. Pro-Ca application significantly affected chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and apparent mesophyll conductance (AMC) in NaCl-treated rice cultivars compared with NaCl treatment alone. Moreover, Pro-Ca also increased ascorbic acid (AsA) content, enhanced superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activity, and further increased the accumulation of soluble protein and proline in leaves and panicles. These results illustrated that foliar application of Pro-Ca at the booting stage could alleviate the damage caused by NaCl stress by regulating the physiological and metabolic processes of rice plants, thereby enhancing the stress resistance of the plants, increasing total rice yield in salt stress conditions. [ABSTRACT FROM AUTHOR]

In 2020, a greenhouse experiment was conducted to investigate the suppression of annual bluegrass (Poa annua), which is a difficult weed to manage in cool-season in turfgrass mixtures on football pitches. The efficacy of prohexadione calcium (Pc), ethephon (Eth) and Pseudomonas fluorescens against P. annua, Lolium perenne and Poa pratensis was tested, as the latter two most commonly occur in turfgrass mixtures on football pitches. Mesotrione (Mes) was used as a positive control, and nontreated grass was used as a negative control. Only a single grass species was sown in each pot. Treatments were randomly distributed for two experiments conducted separately: first – unmown grass before the beginning of spraying and second – grass mowed before the beginning of spraying. In both experiments, plant height and the number of tillers were measured/counted several times during the growing season. In both experiments, grasses were sprayed six times with Pc, Eth and P. fluorescens, while Mes was applied twice. Based on the performed study, the efficacy of the tested products is connected to grass species and whether the grass was mowed/cut before spraying. It has been detected in the present study that spraying with Pc could reduce the height of annual bluegrass, while spraying with P. fluorescens has reduced the number of tillers. Spraying was more effective on grasses that were mowed/cut before the beginning of spraying. Mes should cause severe damage to annual bluegrass but without confirmation in this study. Results of this study have indicated that the application of Pc and P. fluorescens can inhibit the spread of annual bluegrass in football pitches; however, testing their effectiveness against P. annua under field conditions should be performed as well.

Foliar sprays of growth regulators have commercial potential for improving the performance of some of the parameters associated with alternate bearing in pecan trees. The objective was to evaluate the behaviour of alternate bearing through analysis of seasonal variations in buds and leaflets of non-structural carbohydrates (glucose, fructose, sucrose, and starch), mineral nutrients (N-total, P, K+, Ca2+, Mg2+, Fe2+, Cu2+, Mn2+ and Zn2+), yield components (nut weight per kilogram and kernel percentage) and oxidative metabolism (superoxide dismutase, hydrogen peroxide, catalase, guaiacol peroxidase and antioxidant capacity) in cv. Wichita pecan trees in response to foliar applications of gibberellic acid (50 mg L−1), calcium prohexadione (500 mg L−1) or thidiazuron (10 mg L−1). The experiment was of a completely randomized experimental design with five replicates. Foliar growth regulator (GRs) sprays help maintain the concentration of non-structural carbohydrates in the leaflets and buds between the evaluation years. With the exception of K+ (12.9 and 10.9 g kg−1) and Zn2+ (45.1 and 30.5 mg kg−1), the GRs did not show any effects on the concentrations of the foliar mineral nutrients. The results suggest foliar sprays of gibberellic acid improve the performance of parameters associated with alternate bearing, including oxidative metabolism. [ABSTRACT FROM AUTHOR]

ABSTRACT Carya illinoinensis (Wangenh.) K. Koch. is a deciduous fruit species with high economic impact and nutritional value that exhibits alternate bearing behavior. In this study, the concentration of foliar nutrients, non-structural carbohydrates and yield were evaluated in cultivar Western Schley pecan in response to the foliar application of gibberellic acid (50 mg L-1 GA3), prohexadione calcium (500 mg L-1 PCa) and thidiazuron (10 mg L-1 TDZ).The statistical analysis reveals that between agricultural cycles, the treatments showed no variation in the foliar concentration of nitrogen total (N-total), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), copper (Cu), manganese (Mn) and non-structural carbohydrates (fructose, glucose, sucrose and starch). However, the application of PCa showed no significant effect on the concentration of phosphorus (P) (1.5 and 1.9 g kg-1). On the other hand, the concentration of zinc (Zn) (27.0-60.1 mg kg-1) showed a significant difference between years, with no effect due to the application of growth bioregulators. The trees treated with GA3 minimized alternate bearing by presenting similar values (12.4 and 15.3 kg tree-1) of yield. Likewise, the applied treatments did not affect the nut weight per kilogram (kg) (5.5-6.8 g) and kernel percentage (56.5-60.8). These data provide a new perspective on the complex nature of alternate bearing production in cultivar Western Schley pecan and are interpreted to indicate that alternate production could be regulated by carbohydrate reserve, nutrient concentration, and gibberellins.

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pecan [Carya illinoinensis (Wangenh.) K. Koch.] is a deciduous species with high economic importance and nutritional value that exhibits alternate bearing. The mitigation of alternate bearing through the floral initiation of pistillate flowers is very important to improve the yield and nut quality. The aim of this research was to evaluate the effect of the application of some growth bioregulators on the yield and nut quality in pecan. The application of gibberellic acid (GA3 - 50 mg L-1), thidiazuron (TDZ - 10 mg L-1) and prohexadione calcium (PCa - 500 mg L-1) was carried out during two years (2017 and 2018) on young Western Schley pecan trees from an orchard located in Chihuahua, Mexico. The foliar application of growth bioregulators minimized alternate bearing by maintaining the number of fruits set before harvest between the evaluation years. Between the evaluated production cycles, the data obtained indicate that the application of growth bioregulators affected the yield, although the nut weight per kilogram remained similar with TDZ (5.6 and 5.7 g). PCa was the best treatment for both parameters. Likewise, significant variation in the alternate bearing index with respect to the control was observed. On the other hand, the kernel percentage showed the best behavior between years and treatments with the use of GA3 and PCa. The use of the evaluated growth bioregulators could be an agronomic management strategy to minimize alternate bearing in Western Schley pecan trees. [ABSTRACT FROM AUTHOR]

BACKGROUND: The obligatory sunflower root parasite Orobanche cumana Wallr. deprives its host of essential nutrients, resulting in a dramatic reduction in yield and biomass. A post-emergence application with an imidazolinone herbicide on an imidazolinone-tolerant sunflower is highly effective against O. cumana. The herbicide inhibits the enzyme acetohydroxy acid synthase and consequently, growth of the parasite is inhibited, although the sunflower survives the treatment through mutations in the target enzyme. Interestingly, field studies have shown that a combined application of an imidazolinone herbicide with prohexadione resulted in reduced emergence of O. cumana compared with the sole application of the herbicide. The aim of this study was to investigate whether prohexadione is herbicidal to O. cumana. RESULTS: Prohexadione was rapidly distributed within the sunflower, reaching the roots, the site of O. cumana attack, as early as 6 h after application (HAA) on sunflower leaves. A direct impact of prohexadione on O. cumana germination was investigated and a half-maximal inhibitory concentration (IC50) of 84 μM prohexadione was found. In addition, the inhibition of germination by prohexadione was terminal, meaning that O. cumana seeds died after prohexadione contact as soon as they were primed for germination. Additionally, excretion studies showed that a small proportion of the applied prohexadione was excreted by sunflower roots. CONCLUSION: We show that prohexadione is an inhibitor of O. cumana germination and that the growth regulator is found in sunflower roots shortly after application. We hypothesize that prohexadione is excreted in sufficient amounts from the sunflower roots, therefore having a direct impact on O. cumana germination. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to evaluate the effect of different aminoethoxyvinilglycine (AVG), thidiazuron (TDZ) and prohexadione calcium (P-Ca) rates sprayed at different timings on fruit set, yield, and fruit quality of ‘Rocha’ pear trees in different climatic conditions of Southern Brazil. The study was performed in two commercial orchards located in São Joaquim, SC (2015/2016) and Antônio Prado, RS (2016/2017). Plant material consisted of ‘Rocha’ pear trees grafted onto Pyrus calleryana and quince rootstock ‘BA29’ in São Joaquim and Antônio Prado, respectively. Treatments consisted of AVG, TDZ and P-Ca sprayed at different rates and timings. Trunk cross-sectional area increase, fruit set, thinned fruit, fruit per tree, yield, average fruit weight, projected yield, yield efficiency, fruit length, fruit diameter, L/D ratio, seed number, flesh firmness, and soluble solids content were assessed. Fruit set and yield were consistently increased by AVG in all experiments. Fruit set was not affected by P-Ca and was significantly decreased by TDZ. However, yield was positively affected by P-Ca 100 mg L–1 sprayed at full bloom + 7 days after full bloom and TDZ 10 mg L–1 at full bloom. Fruit size was consistently increased by TDZ.

Foliar sprays of growth regulators have commercial potential for improving the performance of some of the parameters associated with alternate bearing in pecan trees. The objective was to evaluate the behaviour of alternate bearing through analysis of seasonal variations in buds and leaflets of non-structural carbohydrates (glucose, fructose, sucrose, and starch), mineral nutrients (N-total, P, K+, Ca2+, Mg2+, Fe2+, Cu2+, Mn2+ and Zn2+), yield components (nut weight per kilogram and kernel percentage) and oxidative metabolism (superoxide dismutase, hydrogen peroxide, catalase, guaiacol peroxidase and antioxidant capacity) in cv. Wichita pecan trees in response to foliar applications of gibberellic acid (50 mg L−1), calcium prohexadione (500 mg L−1) or thidiazuron (10 mg L−1). The experiment was of a completely randomized experimental design with five replicates. Foliar growth regulator (GRs) sprays help maintain the concentration of non-structural carbohydrates in the leaflets and buds between the evaluation years. With the exception of K+ (12.9 and 10.9 g kg−1) and Zn2+ (45.1 and 30.5 mg kg−1), the GRs did not show any effects on the concentrations of the foliar mineral nutrients. The results suggest foliar sprays of gibberellic acid improve the performance of parameters associated with alternate bearing, including oxidative metabolism.

Abstract: The objective of this work was to evaluate the effect of different techniques to modify grape cluster architecture on the incidence and severity of botrytis bunch rot, as well as on the viticultural performance of the 'Sauvignon Blanc' grapevine (Vitis vinifera). Associated with fungicides, four treatments were tested: control, 30 ppm gibberellic acid sprayed at full bloom, 1,000 ppm prohexadione calcium sprayed at full bloom, and berry thinning at the stage of beginning of berry touch. The experiment was carried out in the 2015, 2016, and 2017 vintages. Clusters were treated with fungicides during the stages of full bloom, beginning of berry touch, veraison, and around 15 days before harvest. Berry thinning does not cause losses in the yield and quality of 'Sauvignon Blanc', and, despite having little effect on cluster architecture, is effective in reducing the incidence and severity of Botrytis cinerea. Prohexadione calcium improves grape phenolic maturation, is effective in reducing the incidence and severity of B. cinerea, and reduces cluster compactness by decreasing berry diameter. The application of gibberellic acid spray at full bloom is not recommended because it decreases yield and bud fertility and increases berry susceptibility to B. cinerea infection.

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Copyright of Progress in Plant Protection is the property of Institute of Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aims: The overall objective of this study was to investigate the effect of the growth regulator Prohexadione Calcium (ProCa) on the production of Tempranillo vines in La Rioja, the vinification and the sensory profile of wines obtained from treated grapes. Methods and results: Prohexadione calcium was applied to Tempranillo vines from Rioja Baja at preblooming in years 2004 and 2005. A number of rows were not treated and they were used as controls. Vinification was carried out at an experimental winery. Oenological parameters were determined. A sensory analysis was performed on the obtained wines. The results showed that crop yield was reduced in treated vines. As regards the fermentation process, slight differences were observed in the case of the treated Tempranillo grapes in comparison to the control. The sensory analysis revealed different organoleptic characteristics in the wines obtained from treated grapes in comparison to those produced from the untreated ones. Conclusion: The growth regulator Prohexadione calcium can be used as an alternative to bunch thinning. Improved sanitary conditions of grapes are observed. The treatment at preblooming produces a reduction in berry size and weight. An improvement in sensory characteristics and wine quality is observed, as a consequence of reduced production. Significance and impact of study: ProCa as a growth regulator may be an option for a quality vitiviniculture. No previous studies have been published on applications of ProCa in grapevines in either Europe or in cv. Tempranillo. Additionally, studies with other varieties have not demonstrated sensory improvements in wines obtained from treated vines.

The objective of this study was to evaluate the quality of seeds and yield of winter wheat under different retardants application. The two years field trials on winter wheat were carried out in the Institute of Plant Protection - National Research Institute in Poznan (Poland). Treatments consisted of trinexapac-ethyl, chlormequat and prohexadione calcium applied in mixtures with paraffin oil adjuvant or organosilicone surfactant in BBCH 31 growth stage of winter wheat. No lodging occurred in any experimental year. The retardants had varying effect on the quality parameters of wheat grain. The highest fluctuations in the content of protein, gluten and the Zeleny value were observed after the application of chlormequat chloride. Starch content in wheat grain, regardless of the retardant application method, was negatively correlated with others grain quality parameters evaluated in the experiment. Depending on the year of study and weather conditions, increased or decreased wheat quality. [ABSTRACT FROM AUTHOR]

In this experiment, the effect of prohexadione calcium on the cold resistance physiological index of tobacco seedlings were investigated with a tobacco variety YY87. The results showed that compared with the control spraying deionized water under low temperature, spraying prohexadione calcium could induce the resistant of tobacco seedlings suffering low temperature. Under conditions of low temperature stress, spraying prohexadione calcium made the increase of membrane lipid peroxidation product malondialdehyde( MDA) content slowly, increase proline content, weaken the inhibition of SOD, POD, CAT activity under cold stress, enhance enzymes activity; Slowing the decomposition of chlorophyll, chlorophyll fluorescence parameters of tobacco leaves under low temperature stress significantly increased, reduce the influence of low temperature on photosynthesis of plant leaves; While improving root activity, decrease inhibitory effect of low temperature on biomass accumulation of tobacco seedlings, improve cold resistance of tobacco seedlings, thus promote the growth of tobacco seedlings. [ABSTRACT FROM AUTHOR]

Prohexadione calcium (Pro-Ca), as a growth retardant, can effectively alleviate the damage of salt stress to plants. In order to explore the effects of NaCl stress on the physiological characteristics and panicle traits of rice plants as well as the alleviating effect of Pro-Ca at the booting stage, we performed pot experiments on two rice cultivars: conventional rice ' Huanghuazhan ' and hybrid rice ' Xiangliangyou900 '. Rice plants were treated with 0.3% NaCl 48 hours after Pro-Ca (100 mg L -1 ) treatment to study the effects of Pro-Ca on the physiological characteristics of the leaves and panicles, as well as the panicle and yield traits of rice under salt stress. Our analysis indicated that NaCl treatment inhibited the morphological growth parameters and photosynthetic efficiency, destroyed the antioxidant defense systems of leaves and panicles, increased soluble protein and proline in both rice cultivars. Foliar application of Pro-Ca significantly increased the leaf area, uppermost internode length, panicle length, panicle weight, number of primary branches, number of grains per panicle, seed setting rate and yield under salt stress. Pro-Ca application significantly affected chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and apparent mesophyll conductance (AMC) in NaCl-treated rice cultivars compared with NaCl treatment alone. Moreover, Pro-Ca also increased ascorbic acid (AsA) content, enhanced superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activity, and further increased the accumulation of soluble protein and proline in leaves and panicles. These results illustrated that foliar application of Pro-Ca at the booting stage could alleviate the damage caused by NaCl stress by regulating the physiological and metabolic processes of rice plants, thereby enhancing the stress resistance of the plants, increasing total rice yield in salt stress conditions., Competing Interests: The authors declare there are no competing interests., (©2023 Huang et al.)

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Đổ ngã là yếu tố quan trọng làm giảm năng suất, phẩm chất hột và làm cho thu hoạch lúa khó khăn. Việc bón nhiều phân đạm làm cho lúa vươn lóng và dễ đổ ngã. Đề tài này đã khảo sát ảnh hưởng của prohexadione calcium lên sự giảm đổ ngã trên lúa ở các mức bón phân đạm khác nhau. Kết quả cho thấy khi xử lý prohexadione calcium (10g ai/ha) ở 65 ngày sau khi sạ hoặc xử lý 2 lần ở 50 và 65 ngày sau khi sạ với mức phân đạm 90, 120 và 150kg N/ha có tác dụng làm giảm đổ ngã. Nếu bón phân đạm hơn 90kg N/ha thì lúa dễ đổ ngã và năng suất cũng không tăng. Bón 90kg N/ha và có xử lý prohexadione calcium ở 65 ngày sau khi sạ hoặc xử lý 2 lần ở 50 và 65 ngày sau khi sạ đã làm giảm đổ ngã và góp phần tăng năng suất lúa. Kết quả phân tích cho thấy prohexadione calcium ức chế sinh tổng hợp gibberellin nội sinh, điều này đã làm giảm chiều dài tế bào, chiều dài lóng thân, chiều cao thân và làm tăng khả năng chống chịu đổ ngã trên lúa.

The article presents a study which sought to examine the effect of irrigation, day and night foliar water spraying, foliar application of calcium (Ca) and prohexadione Ca on the growth of Romaine lettuce and incidence of tipburn. The researchers conducted greenhouse trials and analyzed the impact of these practices on the lettuce's dry weight, biomass and leaf number. It was found out that frequent foliar applications of Ca reduced the number of leaves and percent leaf area with tipburn.

The low fruit set in the Southern Brazil conditions is one of the limiting factors to pear pmduction in the country. The use of plant growth regulators may minimize this problem. This study was carried out aiming to evaluate the effectiveness of different growth regulators and the combination of these substances on fruit set increase of Shinseiki Asian pears. The application of growth regulators was performed when the pears have reached the full bloom stage. The experimental design was randomized blocks with four replications of one tree, with the following treatments: I. control (no application); 2. thidiazuron (TDZ) 20mg L-1; 3. gibberellic acid (GA) 20mg L-1; 4. prohexadione calcium (PCa) 600mg L-1; 5. PCa 600mg L-1 TDZ + 20mg L'; 6. PCa 600mg L-1 + AG 20mg L-1; and 7. AG 20mg L-1 + TDZ 20mg L-1. When sprayed on full bloom stage, thidiazuron and gibberellic acid, and combinations of these substances, both at a concentration of 20mng L-1, increased significantly the fruit set and the fruit production of Shinseiki' pears. The use of prohexadione calcium, single or in combination with thidiazuron and gibberellic acid, did not increase the fruit production. [ABSTRACT FROM AUTHOR]

Abstract: The effect of Prohexadione Calcium (Pro-Ca) and daminozide was observed on the growth characteristics and endogenous gibberellin contents of Chrysanthemum morifolium R. cv Monalisa White. Three concentrations viz. 100, 200 and 400ppm of Pro-Ca and a single concentration of daminozide (800ppm) were applied three times with 7 days interval on three weeks old plant under greenhouse condition. Pro-Ca suppressed the plant length up to 30.7% while daminozide inhibited up to 27.12% at optimum concentration. The chlorophyll contents and stem diameter were higher than control, while the fresh weight and flower number insignificantly reduced with such treatments. Gibberellin (GA) analysis showed that Pro-Ca and daminozide application significantly lowered bioactive GA1 content, although the amount of its immediate precursor GA20 was fractionally higher. Bioactive GA4 content was slightly higher than the control while significant difference in GA9 was found between the plants treated with Pro-Ca and daminozide. Current study showed that both early C13 hydroxylation and non-C13 hydroxylation pathways of GA biosynthesis are operational in C. morifolium. [Copyright &y& Elsevier]

European chestnut ( Castanea sativa Mill) explants were cultured in vitro in the presence of five different cytokinins in three concentrations (benzyladenine, 2-isopentyladenine, kinetin, forchlorfenuron and thidiazuron). Benzyladenine at the concentration of 2 mg L −1 was the most effective, resulting in the highest shoot (6.0) and node number (23.05). At the rooting stage indole-3-butyric acid at 4 mg L −1 was more efficient in promoting rhizogenesis (up to 81.25%) than 1-naphthalene acetic acid (up to 65%). The most efficient plant growth regulators, at each in vitro stage, were combined with the plant growth retardants, mepiquat chloride, paclobutrazol and prohexadione calcium along with cyclanilide, in order to assess their efficacy on improving proliferation rate and/or rooting response. Mepiquat chloride at 0.1 mg L −1 when combined with bezyladenine at 2 mg L −1 resulted in significant increase of shoot and node number (5.9 and 30.6 respectively) compared to BA alone (4.65 and 26.85 respectively). The combination of mepiquat chloride at 0.01 mg L −1 or prohexadione calcium at 0.1 mg L −1 with BA also promoted the shoot number compared to control (5.7 and 5.75 respectively). Plant growth retardants did not further enhance rooting responses of chestnut explants. In conclusion, mepiquat chloride could be a valuable tool in combination with benzyladenine in order to improve multiplication rate of juvenile chestnut during the proliferation stage. [ABSTRACT FROM AUTHOR]

Prohexadione calcium (Pro-Ca) is a novel plant growth regulator that inhibits the late stages of gibberellins (GAs) biosynthesis in plants, thus reducing the vegetative growth of the plant. Pro-Ca was applied to field-grown rice cultivar Ilpumbyeo to evaluate its effect on growth and yield components and endogenous GAs, when applied at different rates and timings. This study illustrated that Pro-Ca application decreased the internode length, stem length, panicle length, shoots fresh weight and stem lodging index, while stem breaking force was increased in all treatments. The effect of Pro-Ca was more pronounced in 20 ppm concentration than 10 ppm. The number of panicles m−2, ripened grain ratio and 1000 grain weight and milled rice yield parameters, increased with the application of Pro-Ca, though the number of grains per panicle decreased insignificantly. The endogenous bioactive GA1 contents significantly decreased with the application of Pro-Ca, as the GA biosynthesis was interrupted at later stages, when GA20 conversion to GA1 was blocked, thus drastically reducing GA1 and GA8 levels, but only insignificant changes were observed for intermediates from GA12 to GA20. The levels of the endogenous GAs in rice shoots were measured by GC-MS-SIM using 2H2-labelled GAs as internal standards. Present results also illustrated that early application of Pro-Ca was more effective than its late application for effective control of different growth parameters and thus reducing lodging in rice plants. [ABSTRACT FROM AUTHOR]

Michoacán and Nayarit are, respectively, the largest and second largest avocado-producing states in Mexico. The main harvest of the 'Hass' avocado in both states is concentrated during November to December, which saturates the market and reduces the price of fruit and grower income. The goal of this research was to manipulate vegetative and reproductive growth of the 'Hass' avocado with properly timed foliar-applied plant bioregulators (PBRs) to shift the date of flowering and harvest to the period before or after the main harvest. Effects of canopy sprays of gibberellic acid (GA3) or prohexadione calcium (a gibberellic acid biosynthesis inhibitor) applied at different stages of tree phenology on inflorescence development, time of anthesis, date of legal maturity for harvest of 'Hass' avocado fruit, yield, and fruit size were quantified. No PBR treatment influenced the time of anthesis. A single or double foliar application of GA3 (50 mg·L-1) ≈4 months (July) before the expected date of main harvest (November) resulted in 'Hass' avocado fruit reaching legal maturity (mesocarp dry matter 21.5% or greater) 24.8 to 28.2 d earlier than those of untreated control trees with no negative effect on yield or fruit size. [ABSTRACT FROM AUTHOR]

The effects of the acylcyclohexanedione-type growth retardant prohexadione calcium on seedling growth and endogenous levels of immunoreactive phytohormone-like substances in shoots of wheat (Triticum aestivum L. cv. Kanzler) and oilseed rape (Brassica napus L. ssp. napus cv. Lirajet) were studied. After treatment of seedlings with increasing retardant concentrations in hydroponics, plant height and fresh weight of shoots were reduced by up to 40%. Concomitantly, the amount of immunoreactive gibberellins decreased, on a fresh weight basis, when compared with levels in the shoots of control plants. In contrast, the levels of abscisic acid and dihydrozeatin riboside and isopentenyladenosine-type cytokinins were considerably elevated by the growth retardant. The content of 3-indoleacetic acid decreased slightly. These results suggest that, in addition to its effect on gibberellin content, prohexadione calcium also influences the levels of endogenous abscisic acid and cytokinins. [ABSTRACT FROM AUTHOR]

Hypocotyl explants of Albizzia julibrissin were placed on Gamborg's B5 medium supplemented with various levels of paclobutrazol, uniconazole, prohexadione calcium, or GA. Callus formation was evident within one week after placement of the explants on the culture media. Green nodule-like structures protruded from the distal end of the explants within 10 days and developed into shoots within a month. These shoots readily formed adventitious roots when placed on fresh culture medium. All three of the gibberellin biosynthesis inhibitors increased shoot formation compared to the control. The number of shoots per explants was increased 107, 79, and 168% by 0.3-0.4 μM paclobutrazol, uniconazole, and prohexadione calcium, respectively. In contrast to the gibberellin biosynthesis inhibitors, GA decreased shoot formation. These results indicate that modification of gibberellin status can have a strong impact on the number of shoots formed. [ABSTRACT FROM AUTHOR]