Effect of tetcyclacis and chlormequat applied to seed on seedling growth of triticale cv. Lasko

The growth of triticale seedlings from seeds treated with three concentrations of the plant growth regulators (PGRs), tetcyclacis and chlormequat, with or without drying after soaking was studied. Both tetcyclacis and chlormequat inhibited shoot growth. They reduced shoot:root ratios, first by restricting shoot growth (one week after treatment) and later by boosting root growth (eight weeks after transplanting). At the concentrations used tetcyclacis was a more active PGR than chlormequat and promoted tiller production. Drying, after soaking, promoted root growth, retarded the elongation growth of seedlings and enhanced some of the effects of the PGRs. Analyses of regressions between those growth characteristics significantly influenced by PGRs and the concentration revealed a quadratic relationship.     

Response of Eucalyptus nitens seedlings to gibberellin biosynthesis inhibitors

The plant growth regulators (PGRs) paclobutrazol, chlormequat chloride and prohexadione where applied to 11 month old seedling of Eucalyptus nitens to examine their relative effects on precocious flowering, growth and levels of GA20 and GA1 in the shoot apex. Paclobutrazol was most effective in reducing growth and levels of GA20 and GA1 in the seedlings followed by chlormequat chloride with prohexadione being least effective. Paclobutrazol and chlormequat chloride reduced both GA20 and GA1 levels by similar degrees, but prohexadione reduced GA1 levels considerably more than GA20 levels. None of these PGRs was effective in promoting precocious flowering. This suggests that there is an extra level of reproductive control operating in juveniles of this species compared to those of the closely related species E. globulus previously found to flower precociously in response to similar paclobutrazol treatments.     

Effects of the plant growth regulator chlormequat on plant form and yield of triticale

Three field experiments were conducted in order to evaluate the effect of application of the plant growth regulator chlormequat on growth and yield of the cereal triticale. Application of chlormequat resulted in shorter triticale plants as a result of restricted elongation of the upper internodes of the stem. These shorter plants produced a lower weight of straw and were more resistant to lodging. In two experiments chlormequat application led to no statistically significant increase in triticale grain yield; in a third yield was increased. Chlormequat consistently increased the number of grains per ear but this was offset to some extent by a lower mean grain weight. Yield was closely correlated with the number of grains per m². Leaf senescence was delayed by chlormequat. The results are consistent with the hypothesis that chlormequat can increase yield potential.     

Effect of an organo - mercurial fungicide, chlormequat and decenylsuccinic acid on frost hardiness and seedling diseases of oats

Treating oat seeds of ten cultivars with an organo-mercurial fungicide (Ceresan) and a dust formulation of the growth regulator chlormequat (2% a.i.) increased survival of seedlings growing under natural and simulated winter conditions. Treatment increased frost hardiness in less-hardy cultivars, increased soluble sugars in stem base tissues and protected them from attack by soil fungi. It also increased root length in some cultivars but did not affect leaf area. Foliar applications of 10^-3 m decenylsuccinic acid did not increase frost hardiness and also increased disease on stem base tissues. The possibility that sugar concentration may influence frost- and disease-resistance of seedlings is discussed.     

渐狭叶烟草组培苗生根条件优化及在基因转化中的应用

针对渐狭叶烟草(Nicotiana attenuata)组培苗生根困难的问题，本研究测试了不同浓度萘乙酸(NAA)、吲哚丁酸(IBA)、吲哚乙酸(IAA)、嘧啶醇、矮壮素、生根粉及活性炭等外源添加物对组培苗生根的影响。结果表明，对照处理的组培苗在90 d内基本不生根；不同浓度矮壮素处理也不能诱导组培苗生根；而合适浓度的NAA、IBA或IAA处理均能较好地诱导组培苗生根，其中0.8 mg·L^-1 IBA不仅具有较好的诱导生根效果，生根率达72.73%，且根及地上部分均生长良好。进一步测试发现0.8 mg·L^-1 IBA处理对转基因组培苗具有良好的生根效果，20 d后生根率达60%以上，而对照组未生根；经伤口诱导和0.8 mg·L^-1 IBA处理，40 d内总生根率可达90%以上。该研究为高效获得渐狭叶烟草转基因生根苗提供了解决方案，也为渐狭叶烟草作为烟草属模式植物的研究提供了便利。     

Comparative potency of different plant growth retardants in cell cultures and intact plants

A comparison of the efficiency of a broad range of plant growth retardants on cell division growth of 13 cell suspension cultures is presented. The results show that (1) the new plant bioregulator tetcyclacis (NDA) is the compound with the highest activity in inhibiting cell division of all cultures tested, and (2) cell cultures react species-specifically to various compounds. Significant correlations between the results from suspension cultures and intact seedlings of the same plant species demonstrate the usefulness of cell cultures for identifying substances with a growth-regulating potency. Futhermore, the usefulness of cell cultures for establishing structure-activity relationships was shown with structural analogues of chlormequat and mepiquat chloride.     

The effect of chlormequat chloride formulated with choline chloride on the height and yield of winter wheat

Twenty-one field trials were conducted on commercial crops of winter wheat from 1976 through to 1978, with a mixture of 460 g chlormequat chloride and 320 g choline/litre at rates ranging from 0.67 kg to 2.07 kg of chlormequat chloride/hectare. The mean increase in grain yield in the absence of lodging following treatment with chlormequat chloride was 0.31 t/ha, with a greater yield increase where lodging occurred on untreated controls. Chlormequat chloride when applied in mixture with carbendazim fungicide usually resulted in yield increases which were less than the sum of the increases from the two products applied separately. Yield increases following the use of chlormequat chloride were usually greater when used in a traditional system of wheat growing than when used in the Laloux system. Effects of chlormequat chloride on crop height were poorly determined in the dry season of 1976 but there were consistent reductions up to 1.15 kg a.i./ha in 1977. Crop height was reduced by 1.61 kg of chlormequat chloride/ha in 1978.     

Comparative potency of different plant growth retardants in cell cultures and intact plants

A comparison of the efficiency of a broad range of plant growth retardants on cell division growth of 13 cell suspension cultures is presented. The results show that (1) the new plant bioregulator tetcyclacis (NDA) is the compound with the highest activity in inhibiting cell division of all cultures tested, and (2) cell cultures react species-specifically to various compounds. Significant correlations between the results from suspension cultures and intact seedlings of the same plant species demonstrate the usefulness of cell cultures for identifying substances with a growth-regulating potency. Futhermore, the usefulness of cell cultures for establishing structure-activity relationships was shown with structural analogues of chlormequat and mepiquat chloride.     

Effect of imazaquin on absorption,translocation, and pattern of distribution of chlormequat chloride in winter wheat

The role of imazaquin in the absorption, translocation, and distribution of chlormequat chloride in CYCOCEL^* CL has been studied in winter wheat. Three treatments were applied to the 5th leaf of the main stem at growth stage 5 (Feekes Large scale): (1)¹⁴C-chlormequat chloride, (2) CYCOCEL^* CL containing¹⁴C-chlormequat chloride, and (3) CYCOCEL^* CL containing¹⁴C-imazaquin. Tracing of the radioactivity was followed in the treated leaf, main stem, tillers, and roots. Results showed that more than 85% of the radioactivity absorbed remained in the treated leaf. Ten days after the application of chlormequat chloride alone, 94.4% of the¹⁴C-chlormequat was found in the treated leaf, 2.9% in the main stem, 1.2% in the tillers, and 1.4% in the root system versus 88.2, 8.2, 2.1, and 1.4%, respectively, for the chlormequat chloride plus imazaquin treatment. It was concluded that imazaquin increases the mobility and the pattern of distribution of chlormequat chloride in the plant.     

No effect of the plant growth regulator, chlormequat, on boar fertility

Chlormequat is a commonly used plant growth regulator in agriculture. Defined levels of chlormequat residue are allowed in food and an acceptable daily intake is defined for humans. However, there are results in the literature suggesting that a daily intake below the acceptable level for human is detrimental for mammalian reproduction. In the present experiment we investigated the effect of chlormequat at levels up to that acceptable for humans on reproduction in male pigs. Chlormequat (also known as chlorocholine chloride (CCC)) was mixed into the diet and given to the experimental animals at three levels (three treatment groups), i.e. 0 mg CCC/kg BW per day (Control), 0.025 mg CCC/kg BW per day and 0.05 mg CCC/kg BW per day. Eight mother sows per treatment group were used in the experiment. From the day of insemination, the mother sows received the experimental diets. The piglets were weaned at 4 weeks of age and two boar littermates continued on the same treatment as the dam until maturity and delivery of semen for in vitro fertilization (IVF) and in vivo fertilization. Semen volume, sperm concentration and fraction of live sperms were not (P 0.46) detrimentally affected by chlormequat intake. The fraction of oocytes developing to more than the one-cell stage at day 5 after IVF was not (P = 0.88) detrimentally affected by chlormequat intake. Chlormequat intake did not detrimentally affect the fraction of gilts being pregnant after one insemination (P = 0.65) or the number of embryos in the pregnant gilts (P = 0.36). Serum chlormequat concentration was 0.9 μg/kg in the 0.025 mg CCC/kg BW per day group and 1.8 μg/kg in the 0.05 mg CCC/kg BW per day group, but was below the detection limit in control animals. In conclusion, the plant growth regulator chlormequat could not be proven to be detrimental to the selected reproduction traits in male pigs. This is in contrast to existing results from the male mouse.     

Effect of imazaquin on absorption, translocation, and pattern of distribution of chlormequat chloride in winter wheat

The role of imazaquin in the absorption, translocation, and distribution of chlormequat chloride in CYCOCEL^* CL has been studied in winter wheat. Three treatments were applied to the 5th leaf of the main stem at growth stage 5 (Feekes Large scale): (1)¹⁴C-chlormequat chloride, (2) CYCOCEL^* CL containing¹⁴C-chlormequat chloride, and (3) CYCOCEL^* CL containing¹⁴C-imazaquin. Tracing of the radioactivity was followed in the treated leaf, main stem, tillers, and roots. Results showed that more than 85% of the radioactivity absorbed remained in the treated leaf. Ten days after the application of chlormequat chloride alone, 94.4% of the¹⁴C-chlormequat was found in the treated leaf, 2.9% in the main stem, 1.2% in the tillers, and 1.4% in the root system versus 88.2, 8.2, 2.1, and 1.4%, respectively, for the chlormequat chloride plus imazaquin treatment. It was concluded that imazaquin increases the mobility and the pattern of distribution of chlormequat chloride in the plant.     

Foliar Uptake and Movement of Chlormequat in Cereals: Influence of Dose and Addition of Related Chemicals

Increased amounts of chlormequat applied to leaves of barleyand wheat resulted in a greater proportion being taken up andmoving to the tips of treated leaves. Combined foliar applicationwith certain other amines also increased uptake and movementof chlormequat - choline and glycine betaine were particularlyeffective - but a few others had the reverse effect. Ammoniumand sodium salts of acetic, butyric and hydrochloric acids alsoincreased movement of ¹⁴C-chlormequat Hordeum vulgare L., barley, Triticum aestivum L., wheat, chlormequat, foliar uptake     

Modification of Leaf Formation by Cytokinin and Chlormequat (CCC) in Vitis

Application of the cytokinin, 6-(benzylamino)-9-(2-tetrahydropyrany1)-9H-purine(PBA, 1mM) and 2-chloroethyl trimethyl ammonium chloride (chlormequat;3 mM), a growth retardant, to grapevines induced the formationof fused leaves (two laminae and two petioles) and double leaves(two separate petioles each with a single lamina). Double leaveswere found in Vitis vinifera L. seedlings, in Vitis ripariaand in Muscadinia (Vitis) rotundifolia. In some of the treatedvines, leaves arose with opposite phyllotaxy. Other anomaliesincluded production of two opposite axillary buds in axils ofopposite leaves and production of two tendrils per node. Sometendrils grew into shoots. In Muscat of Alexandria, applicationof GA₃ (3 µM, 15 µM), followed by an applicationof chlormequat (0.4 mM, 1.2 mM), led to a marked reduction inthe extension growth of axillary shoots. Vitis vinifera L., Vitis riparia, Muscadinia (Vitis) rotundifolia, grapevines, leaf formation, cytokinin, chloromequat     

Foliar Paclobutrazol Application Suppresses Olive Tree Growth While Promoting Fruit Set

In some agricultural practices, application of plant growth regulators is very useful as an efficient means to modulate olive tree vigour to optimize fruit production. However, the physiological mechanisms underlying these effects are still poorly understood. Here, we evaluated the effectiveness of paclobutrazol, chlormequat and prohexadione on the modulation of vegetative growth and fruit set, with a special emphasis on the underlying effects exerted by phytohormones, in one-year-old olive trees (Olea europea cv. Arbosana). Paclobutrazol and chlormequat were tested using both foliar spraying and soil irrigation, while prohexadione was applied by foliar spraying only, and all treatments were compared to a control. Among treatments, paclobutrazol and chlormequat were the most effective in promoting vegetative growth retardation, when applied through foliar spray. Growth retardation by foliar application of paclobutrazol was associated with proline accumulation and reduced gibberellin contents in leaves. Furthermore, hormonal profiling revealed that not only all treatments were effective in reducing the endogenous contents of gibberellins, but also that the entire hormonal profiling was altered upon treatments. It is concluded that (i) various plant growth regulators can be effectively used to control olive tree growth, and (ii) paclobutrazol seems to be more efficient on vegetative growth retardation than the other tested treatments, being foliar application more effective than soil treatment.

     

Specificity and mode of action of BTS 44584 and chlormequat chloride on wheat and soybeans

The selective action of the growth retardants chlormequat chloride and BTS 44584 on the growth of wheat and soybean was investigated. Chlormequat chloride retarded the growth of wheat whether applied as a seed soak, foliar spray or soil drench, at concentrations from 10^-2 M to 10^-4 M, although effectiveness depended on the age of the plant at application. BTS 44584 retarded the growth of wheat only when applied to the seeds. In soybeans, chlormequat chloride did not retard elongation growth when applied as a seed soak but showed some effects when applied as a foliar spray and more especially as a soil drench. Irrespective of the type of application, treatment with BTS 44584 retarded growth of soybeans. Thus, the selective action of the two compounds was not solely related to different species but also to timing and mode of application.     

Factors affecting the uptake of chlormequat into cereal leaves

The effects of site of application, growth environment, droplet size, and formulation adjuvants on the retention and uptake of ¹⁴C-chlormequat by wheat cv. Avalon and barley cv. Sonja have been examined using solutions applied by a micro-sprayer. Wheat plants retained a higher proportion of droplets on initial impaction than barley irrespective of growth stage, site of application or formulation. Leaf retention increased approximately two-fold with increase in surfactant concentration (0·03·0–3% w/v) or decrease in droplet size (200-125 μm) but declined markedly with age of leaf. Uptake, which was greater into wheat than barley, increased with increase in surfactant concentration, growth temperature and droplet size, with a combination of decrease in irradiance plus a rise in soil moisture, and after exposure to simulated dew. Droplet reflection increased and chlormequat uptake declined when the fungicide preparations Bavistin and Radar replaced Agral 90 in the spray mixtures. Droplets impacted more readily and spread more extensively over the damaged surfaces of field grown leaves. Both tissue combustion and autoradiography showed that chlormequat translocated readily only in immature tissues.     

Ameliorative Effect of Chlormequat Chloride and IAA on Drought Stressed Plants of <Emphasis Type="Italic">Cymbopogon Martinii</Emphasis> and <Emphasis Type="Italic">C. winterianus</Emphasis>

Responses of Cymbopogon martinii and C. winterianus to drought stress and chlormequat chloride and IAA application are compared. These two species are important source of essential oil production in drought regions. For both species and their cultivars relative water content (RWC), herbage yield and oil amount decreased under drought, while oil biosynthesis increased. Oil concentration increased significantly under drought in C. winterianus while peroxidase activity increased in C. martinii. Amount of geraniol increased under drought stress in C. martinii while citronellal and geraniol accumulation decreased in C. winterianus. Ameliorative effects of chlormequat chloride and IAA were observed in drought stressed plants of both species. Herbage yield increased significantly in chlormequat chloride and IAA treated stressed plants of C. winterianus, while oil concentration increased in C. martinii. Ameliorative effect of IAA in increasing oil yield was significant in drought stressed plants of both the species. Changes in various morpho-physiological traits indicated that chlormequat chloride and IAA can partially alleviate the detrimental effect of drought in these aromatic grasses.     

Relationships between xanthoxin,phototropism, and elongation growth in the sunflower seedling Helianthus annuus L.

For phototropic curvature of a green sunflower seedling, only the hypocotyl has to be illuminated; the tip and cotyledons are not involved in stimulus perception. The etiolated seedling is phototropically insensitive, illumination of only the hypocotyl renders it sensitive. It is concluded that the photoreceptor is located within the responding organ. In curving seedlings, the endogenous indoleacetic acid (IAA) remains evenly distributed. However, the inhibitor, xanthoxin (Xa), accumulates on the illuminated side. The degree of phototropic response is generally related to the concentration of Xa. The amount of phototropic curvature is independent of the rate of elongation growth, the former can be changed without affecting the latter, and vice versa. The data conflict with the Cholodny-Went theory, whereas they support the hypothesis of Blaauw that the phototropic reaction is caused by the local accumulation of a growth-inhibiting substance on the irradiated side.Abbreviations CCC chlormequat, (2-chloroethyl)trimethylammonium chloride - GA₃ gibberellic acid - IAA indole-3-acetic acid - Xa xanthoxin     

The effects of mechanically-induced stress in plants — a review

Mechanically-induced stress (MIS) occurs naturally in plants as the aerial parts are moved, usually by wind, but also by such agents as rain and animals. It can be induced indoors by various actions such as rubbing or bending the stem or shaking or brushing the entire shoot. The most noticeable effect of MIS is a reduction in stem, leaf or petiole length invariably resulting in plants which are smaller and more compact than unstressed controls. However, the response of other variables can often differ between species and there may be either increases or decreases in stem or petiole diameter, root: shoot weight ratio, chlorophyll content or drought resistance. Why species should differ in this way, and what is the endogenous control mechanism for MIS responses, are inanswered questions. Ethylene, which increases as a result of MIS in several species may cause some MIS responses such as increased stem diameter, epinasty or a change in sex expression. However, evidence suggests that MIS retardation of extension growth may equally be due to lower or supraoptimal auxin levels or lower gibberellin levels.The uses in the field of the growth promoter gibberellin or the growth retardant chlormequat chloride (CCC) appear to be examples of respectively reversing or stimulating MIS growth response. MIS may be applied indoors if short compact plants are needed, either for aesthetic purposes as with floral crops, or if hardier and more manageable plants are needed, such as seedlings for transplanting in the field. Much more research is needed to estimate the importance of MIS in the field and to assess how such knowledge may be used to improve crop yield.     

Use of the plant growth regulator chlormequat chloride to control the aphid Hyperomyzus lactucae on black currants

A single application of chlormequat chloride at 2500 ppm reduced the density of Hyperomyzus lactucae on black currants below that at which damage was caused. This treatment had no short-term effects on the aphid predators present, but did affect interactions between the aphids, their host and the predators. There were no effects on yield in the year of the experiment, but in the following year bushes which had been treated gave considerably higher yields. This increase was attributed both to direct action of the chlormequat chloride and to indirect effects through the reduction of aphid density. Prospects for the use of plant growth regulators as dual-function compounds in integrated control programmes are discussed.