Application Of Growth Retardants Research Articles

Studies on the Impact of Spacing, Pinching and Growth Retardants on Vegetative Growth and Flowering Behaviour of Salvia

The present investigation entitled “Studies on the impact of spacing, pinching and growth retardants on vegetative growth and flowering behaviour of Salvia” was conducted at College of Agriculture, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha during December 2021 to April 2022. The experiment was laid out in a Factorial Randomized Block Design (FRBD) with three replications, comprising of 12 treatment combinations which includes the first factor spacing with two levels i.e., S1 (20 cm x 25 cm) and S2 (25 cm x 25 cm), second factor pinching with two levels i.e., P0 (no pinching) and P1 (pinching) and the third factor application of growth retardants with three levels i.e., G0 (control), G1 (CCC @500ppm) and G2 (MH @100ppm). The findings revealed that pinching and the application of growth retardants had a greater impact on critical flowering attributes than the spacing experimented with in this study. Treatment combination S2P1G1 i.e., T11 was proved to be better and yielded significant improvements. Based on the results it was concluded that pinching and application of CCC resulted in better growth and development in salvia regarding vegetative and flowering characters. Thus, the treatment combination S2P1G1 i.e., T11 was found to be superior for vegetative growth characters like plant height, the number of branches, the number of leaves and flowering characters like the number of flower spikes per plant, length of flower spike, and length of florets.

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.

Dwarfism in Fruit Plants: A Review

In this modern era, farmers are adopting high density planting (HDP) for most of the fruit crops. Dwarfing is based on the principle of making the optimal use of vertical and horizontal space per unit time and harnessing the highest potential returns per unit of inputs and natural resources. Dwarfing in fruit crops can be accomplished through a variety of methods, including the use of dwarfing rootstock, the selection of spur type scion cultivars, use of interstock, pruning, root pruning, various training systems, girdling, scoring, bark invasion and the application of growth retardants. One strategy for promoting early fruiting, less vigour and increasing production is to utilize dwarf root stocks. The mechanism underlying dwarfing involves anatomical, physiological and biochemical changes. It has been proposed that dwarfing rootstock or interstock control tree size by regulating the auxin that passes through the rootstock or interstock’s bark. Paclobutrazol retards growth, shoot elongation and reduced internodal length by inhibiting gibberellins synthesis. Dwarfness can be imparted by the using incompatible rootstock. Dwarfing can be induced by inducing viral infection, although, it is not commercially adopted. Recombinant DNA technology has recently expanded the gene pool that can be managed to cause dwarfism and maximize benefits in horticulture crops.

Energy Productivity and Efficiency of Mungbean [Vigna radiata (L.) Wilczek] in Response to Foliar Application of Growth Retardants and Micronutrients

Energy Productivity and Efficiency of Mungbean [Vigna radiata (L.) Wilczek] in Response to Foliar Application of Growth Retardants and Micronutrients

Influence of Crop Geometries and Growth Regulators on Weed Growth and Yield of Machine Sown High Density Cotton

Field experiments were conducted at Tamil Nadu Agricultural University, Coimbatore, during Winter irrigated seasons of 2017-18 and 2018-19 to study the effect of weed growth by growth retardants on machine-sown cotton under high-density planting system. The experiment was laid out in a split-plot design, and the treatments were replicated thrice. Main plot treatments comprised of three crop geometries viz., 75 cm x 10 cm (M1), 75 cm x 20 cm (M2) and 75 cm x 30 cm (M3) and seven sub plots of foliar application of growth retardants along with one control viz., Cycocel 400 ppm (S1), Cycocel 500 ppm (S2), Mepiquat Chloride 100 ppm (S3), Mepiquat Chloride 200 ppm (S4), Maleic Hydrazide 400 ppm (S5), Maleic Hydrazide 500 ppm (S6) and Control (No Spray) (S7). Cotton genotype TCH 1819, developed for synchronized maturity exclusively to fit into high density planting system, was used as the test crop. The cotton crop was raised under raised bed and the major cultivation practices were carried out with machines namely; inclined plate planter for sowing, power weeder for weeding and drip system for irrigation and fertigation. However, harvesting was done manually. Weed infestation in cotton increased with 75 cm x 10 cm spacing compared to wider spacing. With respect to foliar application of growth retardants, there were no significant differences observed among the treatments tested during both the years of the study.

Compact shoot architecture of Osteospermum fruticosum transformed with Rhizobium rhizogenes.

Improved compact shoot architecture of Osteospermum fruticosum Ri lines obtained through Rhizobium rhizogenes transformation reduces the need for chemical growth retardants. Compactness is for many ornamental crops an important commercial trait that is usually obtained through the application of growth retardants. Here, we have adopted a genetic strategy to introduce compactness in the perennial shrub Cape daisy (Osteospermum fruticosum Norl.). To this end, O. fruticosum was transformed using six different wild type Rhizobium rhizogenes strains. The most effective R. rhizogenes strains Arqua1 and ATCC15834 were used to create hairy root cultures from six Cape daisy genotypes. These root cultures were regenerated to produce transgenic Ri lines, which were analyzed for compactness. Ri lines displayed the characteristic Ri phenotype, i.e., reduced plant height, increased branching, shortened internodes, shortened peduncles, and smaller flowers. Evaluation of the Ri lines under commercial production conditions showed that similar compactness was obtained as the original Cape daisy genotypes treated with growth retardant. The results suggest that the use of chemical growth retardants may be omitted or reduced in commercial production systems of Cape daisy through implementation of Ri lines in future breeding programs.

New approach to increasing rice (Oryza sativa L.) lodging resistance and biomass yield through the use of growth retardants

Yield losses in rice are heavy, particularly when lodging occurs after heading. Lodging is due to the interaction between susceptibility to the lodging of the plant and external force. A major contributing factor towards lodging is the tall phenotypic characteristic of the plant. In all cases, the plant stem base is unusually weak with a reduced diameter. In rice, the application of growth retardant can reduce plant height by means of internodes retardation. This study, evaluate the use of two plant growth regulators as mepiquat chloride (N,N-dimethyl piperidinium chloride) and paclobutrazol [(2 RS, 3RS)-1-(4-chlorophenyl)-4-4-dimethyl-2(1,2,4-triazol-I-yl)-pentan-3-ol], which are synthetic plant growth regulators that showed reliable stem shortening to combat abiotic stress. The present investigation was carried out under the aegis of Bidhan Chandra Krishi Viswavidyalaya during Kharif season of 2017 to 2019 in randomized block design with four replication comprised of ten treatments which include five levels of mepiquat chloride (37.5,50, 62.5, 75 and 100 g a.i. ha -1 ), four levels of paclobutrazol (25, 50, 75 and 100 g a.i. ha -1 ) and untreated control (water only). Foliar-applied growth retardant inhibited plant growth and retarded internode and culm length but increased culm diameter. Significantly more grain yield was observed with the mepiquat chloride @ 50 g a.i. ha -1 (47.34 q ha -1 ) and was at par with the paclobutrazol @ 25 g a.i. ha -1 (44.09 q ha -1 ) and paclobutrazol @ 50 g a.i. ha -1 (45.94 q ha -1 ).The result indicated that mepiquat chloride reduced plant height and the incidence of lodging and similarly improved yield over the control by 27 q ha -1 . The highest straw yield was obtained either at paclobutrazol @ 50 g a.i. ha -1 and was at par only with the paclobutrazol @ 25 g a.i. ha -1 and statistically better to other treatments. Economics revealed that more net return (Rs. 35,421 ha -1 and B:C (1.87) observed with the mepiquat chloride @ 50 g a.i. ha -1 and was closely followed by paclobutrazol @ 25 g a.i. ha -1 and paclobutrazol @ 50 g a.i. ha -1 .

Effect of prohexadione calcium on vegetative growth, yield and scab development on ‘Sinap Orlovskii’ apple trees

There are many apple orchards in the Russian Federation where trees were trained with volumetric canopies; the vigor of these canopies must be suppressed. Prohexadione calcium (calcium 3-hydroxy-5-oxo-4-propionyl-cyclohex-3-enecarboxylate) was developed to inhibit the gibberellins biosynthesis to reduce vegetative growth. The study was done in the commercial orchard of “Planeta sadov” LLC in Michurinck district of Tambov Region (53°02’11.9 “N 40°29’29.9 “E). This research was aimed to evaluate the influence of prohexadione calcium on the length of one-year shoot growth, yield, and scab development on trees of vigorous apple cultivar ‘Sinap Orlovskii,’ planted 6 x 4 m (418 tr. ha-1). After 1.25 + 1.25 g ha-1 prohexadione calcium double treatment, the length of one-year shoots was 1.96 (2019) and 1.60 (2020) times less than Control 1 (without prohexadione calcium application and hand pruning) and 2,00 times less than in hand pruning treatment. The application of prohexadione calcium inhibited apple tree height and reduced the average height growth rate by 10.7% (2019) and 17.0% (2020). Growth retardant treatments stimulated significant yield increases and improved the commercial value of fruits. The enhance of scab protection improved under the influence of prohexadione calcium treatments. The application of growth retardant increased the alternate bearing index.

EFFECT OF SOME GROWTH RETARDANTS AND PINCHING ON GROWTH AND FLOWERING OF POTTED Jacobinia carnea PLANT

This work was carried out during the two consecutive seasons of 2016/2017 and 2017/2018 in the Experimental lathe house of Horticulture Dept., Faculty Agric., Benha University, Kalubia Governorate, Egypt to study the effect of paclobutrazol (PP333), cycocel (CCC) and pinching treatments as well as their combinations on growth and flowering of potted Jacobinia carnea plant. After one month from repotting process (mid-March during the two seasons), the plants were arranged into two groups; the first one was lifted without pinching, while the second group was subjected to pinching treatment by removing 1cm from the seedling top, then all plants of the two groups were subjected to three sprays with paclobutrazol at 50, 75 and 100 ppm and cycocel at 1000, 2000 and 3000 ppm plus tap water as control at one month intervals. The obtained results showed that all pinched plants received growth retardants treatments were shorter than those received growth retardants without pinching in the two seasons. Anyhow, the highest values of branches number/ plant, leaves number/plant, leaf area/plant, leaves fresh and dry weights/plant, flowers number / plant, fresh and dry weights of flowers / plant and show value were scored by those subjected to pinching treatment and sprayed with pp333 at 100 ppm in the two seasons. Moreover, all tested application of growth retardants and pinching as well as their combinations increased root growth parameters of jacobinia plants, with superior for the high concentration of PP333 or CCC in the two seasons.

An overview of canopy management in cashew (Anacardium occidentale L.)

Being a tree crop of commercial importance, the productive performance of cashew is greatly influenced by how best its canopy is architectured for harnessing maximum benefits in terms of yield. The initial training is crucial for the development of photosynthetically efficient canopy in cashew as in other perennial fruit trees. Pruning of dead wood and crisscross branches can alone increase the yield by 30-40 per cent. The dwarf rootstocks also play a role in manipulating the canopy in cashew, wherein, canopy containment and yield were influenced by such rootstocks. By resorting to soil application of growth retardants like paclobutrazol, cashew canopy could be successfully contained to suit high density planting system. The studies on planting geometry has indicated the advantage of high density planting in enhancing profitability of cashew orchards in the initial years of plantation. The advantages of rejuvenation as well as top working techniques are also discussed in this aper.

An overview of canopy management in cashew (Anacardium occidentale L.)

Being a tree crop of commercial importance, the productive performance of cashew is greatly influenced by how best its canopy is architectured for harnessing maximum benefits in terms of yield. The initial training is crucial for the development of photosynthetically efficient canopy in cashew as in other perennial fruit trees. Pruning of dead wood and crisscross branches can alone increase the yield by 30-40 per cent. The dwarf rootstocks also play a role in manipulating the canopy in cashew, wherein, canopy containment and yield were influenced by such rootstocks. By resorting to soil application of growth retardants like paclobutrazol, cashew canopy could be successfully contained to suit high density planting system. The studies on planting geometry has indicated the advantage of high density planting in enhancing profitability of cashew orchards in the initial years of plantation. The advantages of rejuvenation as well as top working techniques are also discussed in this aper.

Morphophysiological changes by mepiquat chloride application in Eucalyptus clones

First study of mepiquat chloride as a growth regulator in Eucalyptus. Application of mepiquat chloride in Eucalyptus clones at planting may promote drought resistance. The reduction of available areas has pushed Eucalyptus away to marginal areas with low water availability. Management practices such as the application of growth retardants may have potential to modify plant morphological and physiological features, increasing their drought tolerance. Trying to understand the drought tolerance mechanisms of Eucalyptus clones, the objective of this work was to evaluate the effects of different mepiquat chloride (MC) concentrations to Eucalyptus clones on morphological and physiological changes. Commercial clones of E. grandis × E. urophylla hybrid were planted in 20 L pots in a complete randomized block design with eight replications and four treatments. The treatments consisted of three concentrations of MC: 250, 500 and 1000 mg L−1 of MC. The control treatment consisted of a non-MC application (0 mg L−1 of MC). Evaluations of morphological and physiological parameters were carried out for 35 days after the MC application. Results indicated morphophysiological changes after the MC application. Eucalyptus clones increased root dry mass (RDM), total dry mass (TDM), number of leaves and secondary branches, and decreased height. MC application modified the physiological plant system improving intrinsic water use efficiency (WUEi) and SPAD index, and decreasing transpiration rates (E) and stomatal conductance (gs). RDM, TDM, E, WUEi and SPAD index improved when 250 and 500 mg L−1 MC concentration were applied. Our results suggest that MC application may promote drought resistance to Eucalyptus clones.

Effect of chemicals, PGRs and pruning on morpho-physiological parameters in mango under high density planting

Investigations on the effect of canopy management in mango (Mangifera indica L) cv Alphonso using chemicals, different growth regulators and pruning methods under high density planting were conducted during 2015–2016. The treatments were evaluated in terms of changes in morpho-physiological attributes. Among eight treatments, soil drenching of paclobutrazol registered the lowest canopy diameter and length and highest girth of shoots. The chlorophyll a, b and total chlorophyll contents and SPAD value of the leaves were significantly improved by the application of growth retardants particularly paclobutrazol and chlormequat chloride. Specific leaf weight was markedly improved by the application of growth retardants. Statistically superior soluble protein content and maximum level of total phenolics were observed in paclobutrazol applied trees followed by triple spray of chlormequat chloride at pre-flowering stage (Dec 2015).

Elucidation of the factors affecting poor flowering in litchi (Litchi chinensisSonn.) and measures to overcome

It is a major concern of litchi growers in many locations that yields are often irregular and frequently below the trees bearing capacity. Poor litchi flowering is a worldwide problem, especially in regions where the weather during the induction period is too worm. Induction of flowering in litchi requires an average minimum temperature of approximately 10-14°C for 4-12 weeks, depending on the cultivars. Variation in time of panicle emergence, panicle development, and anthesis among the cultivars in relation to seasonal progressions in temperature affect the fruit set. Experimental evidence suggest that temperature above 15°C increased vegetative growth and reduced or eliminated flowering. However, the temperature above which flowering fails is still not clear, nor is the time that the plants needs to grow at lower temperature for successful flower induction. It has also been suggested that not only is low temperature needed for induction, but also water stress throughout the autumn and winter. Six weeks autumnal water stress was reported to cause a significant increase in flowering of 'Mauritus' and 'Floridian' litchi in Israel. Gibberellins inhibits flowering in litchi and counteracts the flower-inducing influence of low temperature, while treatments such as cincturing, root pruning and application of growth retardants reverse the inhibitory effects of high temperature. It is believed that the conversion of vegetative bud to panicle in litchi is dependent on changes in content of endogenous growth substances. This paper discussed the various factors influencing the flowering in litchi and available technology to overcome.

Physiological quality of seeds of white oat cultivars in response to trinexapac-ethyl application

The aim of this study was to assess the effect of the growth retardant trinexapac-ethyl on the physiological quality of seeds of different grain white oat cultivars in two growing environments. The experiments were carried out in Londrina and Maua da Serra, Parana State, Brazil. The experimental design was a randomized block design in a 4 × 2 factorial scheme with four replications. Treatments consisted of four white oat cultivars (IPR Afrodite, IPR Artemis, URS Corona, and URS Guria), with and without growth retardant application. Trinexapac-ethyl was applied by foliar spraying in a dose of 125 g a.i. ha−1 at the stem elongation stage between the first and second perceptible node. The following parameters were assessed: germination, first germination count, length and dry matter of seedling shoot and root, accelerated aging, electrical conductivity, emergence rate index, seedling emergence in sand, one-thousand-seed weight. At the end of the study, Londrina and Maua da Serra presented a production potential white oat seed with germination above the standards for the species. Trinexapac-ethyl application reduced seed vigor of the cultivars IPR Afrodite and IPR Artemis produced in Londrina and Maua da Serra, respectively.

DAMINOZIDE APPLICATION METHOD EFFECT ON GROWTH AND CONTENTS OF OLEANDRIN AND RUTIN OF OLEANDER (NERIUM OLEANDER L.)

This study included one factor with four growth retardant application methods of daminozide at 500 mg.l-1 concentration (without addition, sapling base soaking, drench, and spraying methods) on oleander sapling four months age. The experiment was conducted in a lath-house, Department of Horticulture and Landscaping, College of Agriculture, Tikrit University, during the growing season of 2016. The experiment was designed in a complete randomized design with three replications. The results showed that daminozide applications caused a significant effect in growth characteristics. Drench application gave less plant height 62.87 cm. Spray application resulted in the highest chlorophyll content (10.61 mg.g-1 fresh weight). Highest content of oleandrin was 0.25 mg.g-1 and 47.82 mg.kg-1 of rutin to sapling base soaking treatment.

THE INFLUENCE OF BUSH FORMATION IN RED BEET ON SEED PRODUCTIVITY AND SOWING QUALITIES

It is necessary not only to possess the technology to grow seeds but also to have knowledge of plant biology in particular crop, and sowing qualities of its seeds. The particular place where seeds are forming on the mother plant has much influence on qualities of sowing seed material. The influence of the development of red beet plant bush on seed productivity, monogermity and sowing qualities of seeds was estimated in Rostov oblast. The main stalk pruning and application of plant growth retardants had an effect on the structure of red beet bush. In variants given in seed plants, the third type of branching prevailed due to lack or oppression of main stalk. Consequently, the seed yield and proportion of single fruit formation rose. It was also shown that due to treatment of plants with growth retardant ‘Floron’ at the stage of waxen maturity significantly improved the seed germination as compared with control variant. As a result of the study it was shown that the mechanical pruning of main stalk and application of growth retardants had affected on the structure of seed red beet bush increasing the yield mono-seed compounds as well as had improved the yield and seed quality of monogerm red beet.

Effect of Pinching and Growth Retardants on Growth and Flowering in African Marigold Cv. Pusa Narangi Gainda

A study on the effect of pinching and application of growth retardants on growth and flowering in African marigold cv. 'Pusa Narangi Gainda' was carried out in the experimental field of Division of Floriculture and Landscaping, Indian Agricultural Research Institute, New Delhi. Treatments comprised pinching, CCC applied at 1000ppm, 1500ppm or 2000ppm, MH at 500ppm, 1500ppm or 2000ppm; B-9 at 500ppm, 750ppm or 1000ppm, and a Control (no pinching). CCC at 2000ppm recorded minimum plant height (46.0cm), maximum plant-spread (56.0cm) and maximum number of branches (19.0), whereas, maximum plant height (67.0cm), minimum plant-spread (29.66cm) and minimum number of branches (5.33) were recorded in Control (non-pinching). As for flowering and yield, application of CCC at 2000ppm recorded maximum flowering-duration (25.33 days), number of flowers per plant (40), single-flower weight (119.46g), flower yield per plant (408.10g), flower yield per unit area (17.83t/ha) and seed yield per plant (17.80 g), Maximum flower diameter (7.93cm) was recorded with application of CCC 2000ppm, whereas, minimum was recorded with pinching (6.2cm). Spray of growth retardants enhanced flower yield compared to that in Control (no pinching). Maximum shelf-life of flower was recorded with CCC 2000ppm (3.66 days), whereas, minimum was recorded with pinching and non-pinching (2.33 days). Thus, application of CCC at 2000ppm is superior to other treatments tested for increasing flower yield in marigold.

Influence of growth retardant on growth and development of Euphorbia pulcherrima Willd. ex Klotzsch

This study was undertaken to evaluate the influence of single foliar flurprimidol treatment on morphology and transpiration of ‘Roman’ and ‘Freedom Red’ poinsettias. The growth retardant flurprimidol (Topflor 015 SL) was applied once as a foliar spray at concentrations of 5, 10 or 15 mg × dm<sup>-3 </sup>when lateral shoots were about 5 cm in length. Single foliar flurprimidol treatment was sufficient to inhibit stem elongation of both poinsettia cultivars. The degree of growth inhibition depended on cultivar and growth retardant concentration. As compared to the control, the shoots of flurprimidol treated ‘Roman’ and ‘Freedom Red’ plants were up to 44% and 37% shorter, respectively. The desirable plant heights for ‘Roman’ and ‘Freedom Red’ poinsettias were obtained with flurprimidol at concentrations of 5 and 10 mg × dm<sup>-3</sup>, respectively. The shoots of flurprimidol sprayed poinsettia were also more rigid and aligned relative to each other and thus the bracts on the plant were placed on the same level. The diameters of growth retardant treated poinsettias were up to 13% narrower. The leaf areas, petiole lengths, fresh and dry weights of ‘Roman’ and ‘Freedom Red’ poinsettias treated with flurprimidol were substantially smaller as compared to the control. The bract diameters of both poinsettia cultivars were only slightly affected by growth retardant application. Plants exposed to flurprimidol had also intensified green leaf pigmentation. There was almost no abscission of the oldest leaves in the low portions of growth retardant treated plants, compared to those of the control ones. Flurprimidol had no effect on transpiration rate per unit leaf area and stomatal conductance in both poinsettia cultivars. No phytotoxicity was observed in flurprimidol treated plants. Chemical name used: α-(1-methylethyl)-α-[4-(trifluromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol).

A potential retardant for lodging resistance in direct seeded rice (Oryza sativa L.)

Sinniah, U. R., Wahyuni, S., Syahputra, B. S. A. and Gantait, S. 2012. A potential retardant for lodging resistance in direct seeded rice ( Oryza sativa L.). Can. J. Plant Sci. 92: 13–18. Yield losses in rice are heavy, particularly when lodging occurs after heading. A major contributing factor towards lodging is the tall phenotypic characteristic of the plant. In rice, application of growth retardant can reduce plant height by means of internode retardation. In this study, paclobutrazol at 50, 100 and 200 ppm was applied as a foliar application at panicle initiation on MR 219 and MR 84 cultivars and its effects on growth, lodging resistance and yield were studied. Foliar-applied growth retardant inhibited plant growth and retarded internode and culm length but increased culm diameter. All treated plants had higher bending resistance compared with the control. A significant positive correlation was observed between increased culm diameter and stem bending resistance (r=0.885). Histological studies showed greater compaction of parenchyma cells with thickening of parenchyma cell walls. Treatments with either 50 or 100 ppm paclobutrazol gave significant retardation of internodes and gave higher stem bending resistance with significant increase in yield.