Morphogenetic Effects on Vegetative Plants of Poa pratensis L. of 6-Azauracil, (2-Chloroethyl)- phosphonic acid, and (2-Chloroethyl) trimethyl-ammonium chloride and their Interaction with Gibberellic Acid

Fresh and dry weights and leaf size of Poa pratensis were reducedwhen treated with 6-azauracil (AzU), (2-chloroethyl)phosphonicacid (CEPA), or (2-chloroethyl)trimethylammonium chloride (CCC).AzU and CEPA inhibited epidermal cell division without inhibitingcell elongation, while CCC inhibited mainly cell elongationand cell division to a small extent. The ratio of blade lengthto sheath length and the blade length/width ratio were reduced,but leaf emergence and tillering were increased by AzU and CEPA.CCC affected only the latter three features. Like GA₃, CEPAinduced stem formation, but internodes were shorter. GA₃ was ineffective in preventing leaf-growth inhibition byAzU, which inhibited Ga₃-induced cell elongation. The inhibitoryeffect of CEPA on leaf growth was apparently reversed by GA₃,but this was due solely to increased cell elongation, the reductionin cell number being unaffected. Ga₃ reversed the effect ofCCC on leaf length, as well as on cell size and number. Simultaneousapplication of the inhibitors produced a complex interactionin reducing leaf length and number and size of epidermis cells.It is postulated that AzU, CEPA, and CCC have different modesof action because they have specific effects on plant growthand different effects on GA₃-induced cell elongation.     

Effects of 2-Chloroethyl Trimethylammonium Chloride (CCC) and 2-Chloroethylphosphonic Acid (CEPA) on Dry Matter Distribution in the Cowpea (Vigna Unguiculata L.)

Effects of foliar applications of CCC and CEPA on dry matterdistribution in two cowpea cultivars which exhibit differentdegrees of premature abscission of fruits were investigated.At the concentration of 0-1 mg1^–1, CCC increased stemweight in the cultivar Adzuki, but had no effect on the cv.Mala (which exhibits a relatively high degree of premature abscission).While CCC did not significantly influence root weight in Adzuki,the concentrations of 1 and 10 mg 1^–1 increased root weightin Mala. In both cultivars, the 1000 mg1^–1 treatment decreasedseed weight, with a greater decrease in Adzuki. All concentrations of CEPA, up to 1000 mg 1^–1, decreasedstem and root weights in Mala, and leaf weight in Adzuki. The10 mg1^–1 concentration increased seed weight in Mala by100 percent, and leaf weight by 28 percent, without any significanteffect on pod weight, or on the weight of the whole plant. Therewas also no increase in pod number. Overall, Mala was more responsive than Adzuki to the growthregulators, particularly CEPA. In the low concentration responses,CEPA increased seed weight not by increasing gross plant weight,but mainly by causing a change in distribution of dry matter.     

Contribution of the wheat (Triticum aestivum L.) flag leaf to grain yield in response to plant growth regulators

In West-Europe, intensive cereal management uses plant growth regulators (PGRs) especially for wheat. A green-house experiment compared the effects of two PGRs on flag leaf characteristics and yield of winter wheat. Chlormequat chloride + choline chloride (CCC) and chlormequat chloride + choline chloride + imazaquin (CCC+I) were applied to winter wheat at growth stage 5 (Feekes Large scale). CCC and CCC+I significantly increased flag leaf surface area at anthesis. Both treatments also enhanced chlorophyll content of the main stem flag leaf. The grain filling period was extended with PGR application by 2 days. CCC and CCC+I significantly increased net CO₂ assimilation rates during the flag leaf life. No effects of PGR spraying were observed on the pattern of ¹⁴C labelled assimilate distribution. Increased grain yield was due to the increase in average grain weight. The results indicate that PGR treatments increased flag leaf contribution to grain filling. The addition of imazaquin (I) to chlormequat (CCC) improved the effects of CCC.     

Modification of growth habit of Majestic potato by growth regulators applied at different times

The effect of gibberellic acid, CCC (2-chloroethyltrimethylammonium chloride) and B 9 (N-dimethylaminosuccinamic acid) was studied on growth of potato plants in pots. Growth was analysed on four occasions and changes in habit defined in terms of internode lengths, leaf areas and growth of lateral branches. Soaking seed pieces for 1 hr. in GA solution caused six internodes to elongate greatly, an effect not prevented by CCC applied when the shoot emerged from the soil. The effects on internode extension were determined by the length of the interval between GA treatment and CCC treatment. Treatment at emergence with CCC shortened all internodes and more CCC applied 4 weeks later had no effect. Late application of CCC or B9 shortened the top two lateral branches, usually very long in untreated plants. The regulators affected leaf growth differently from internode growth: usually growth regulators had less effect on leaf growth. Effects on growth depended on when the regulators were applied. Treatment with GA alone inhibited bud development at higher nodes than in untreated plants; when followed by late treatment with CCC, lateral growth at higher nodes was also less. CCC retarded development of lateral branches especially when applied early. B9 had a similar effect to CCC applied late. When regulators retarded growth of lower laterals, upper laterals often grew more than in untreated plants. Treatments did not affect the number of leaves on the main stem at first but later GA hastened senescence. GA increased the number of leaves on lateral stems, and the effect was enhanced by CCC. CCC alone increased the number of first- and second-order lateral leaves. GA lengthened and CCC shortened stolons. The effect of CCC persisted throughout the life of the plant. CCC or B 9 shortened stolons whenever applied. CCC hastened tuber initiation but slowed tuber growth. CCC at first retarded formation of lateral tubers but had no effect on the ultimate numbers of lateral and terminal tubers. The value of E (net assimilation rate) did not alter with time. CCC applied at emergence increased E, probably because it hastened tuber initiation and temporarily increased sink capacity. Although tubers formed earlier with CCC, their growth was slower and their demand for carbohydrate was also less. The increase in second-order laterals in CCC-treated plants indicates that they utilize carbohydrate that would normally go to tubers. This experiment also demonstrates that crowding leaves by shortening stems did not diminish E, possibly because another over-riding process (bigger sinks) offsets the effect of shading.     

Effects of growth regulators, CCC and B9, on some potato varieties

The effects of CCC and B 9 on the growth habit of potato differed between varieties. CCC diminished stem lengths and dry weight more than Bo because CCC was applied early when shoots emerged from the soil, but B 9 was applied about 3 weeks later when several leaves had formed. In some varieties lateral stem growth was increased by treatment and in others decreased. There was an inverse relation between main stem and lateral stem growth so that varieties with vigorous main stem growth had poor lateral growth and vice-versa. Treatment with the growth-regulators diminished leaf dry weight of main stem leaves less than leaf area, but the degree of magnitudes of the changes depended on the variety. Both regulators lessened net assimilation rate. Net assimilation rate and dry matter per unit area of leaf were inversely related, possibly because accumulation of substances in leaves decreases photosynthesis. Stolon dry weight was positively correlated with main stem leaf area. There was a direct relation between stem length and tuber dry weight, suggesting that tuber initiation occurs at different stem lengths in different varieties. Tubering was earliest in Epicure and latest in King Edward. Epicure had the greatest tuber weight and smallest stem length.     

Effect of two plant growth retardants on steviol glycosides content and antioxidant capacity in Stevia (Stevia rebaudiana Bertoni)

Two greenhouse experiments were conducted to study the effect of two plant growth retardants, Chlorocholine chloride (CCC) and Paclobutrazol (PBZ), on growth, Steviol glycosides (SVglys) content and antioxidant capacity in Stevia (Stevia rebaudiana Bertoni). Five concentrations of CCC (0, 250, 500, 750 and 1,000 ppm) and PBZ (0, 6, 12, 18 and 24 ppm) with three replications were applied to Stevia plants as treatments based on completely randomized design. CCC was sprayed on Stevia shoots, but PBZ was applied as a drench. The obtained results showed that CCC reduced plant height but improved leaf and stem dry weight, especially with 750 ppm concentration. Total SVgly content and consequently SVglys yield were significantly reduced by CCC application, and 1,000 ppm of CCC concentration was more effective than other treatments. PBZ had no effect on Stevia height while it significantly enhanced stem and dry weight at 12 ppm. Moreover, PBZ remarkably increased total SVglys contents, SVglys yield, and Rebaudioside A/Stevioside ratio. Total antioxidant capacity significantly varied with CCC and PBZ and the highest activity was obtained with 1,000 and 12 ppm of CCC and PBZ, respectively. The results of these experiments indicated that, although CCC and PBZ are plant growth retardants and act as anti-gibberellins, only CCC reduced plant height and SVglys production in Stevia. On the contrary, PBZ at 12 ppm concentration, improved Stevia growth, SVglys production, and antioxidant capacity.     

Growth, Sex Expression and Yield of Squash Melon (Citrullus vulgarisvar. fistulosus) as Influenced by 2(chloroethyl)phosphonic acid, 2,3,5-tri-iodobenzoic acid and (2-chloroethyl) trimethyl-ammonium chloride

Single aqueous sprays of 2(chloroethyl)phosphonic acid (CEPA) 250, 500 and 1000 mg/1; 2,3,5-triiodobenzoic acid (TIBA) 25, 50 and 100 mg/1; and (2-chloroethyl) trimethyl-ammonium chloride (CCC) 250, 500 and 1000 mg/1 were applied to squash melon (Citrullus vulgaris Schrad. var. fistu-losus Stocks.) at the 2–3 leaf stage. Though the final length of the main axis and number of lateral branches were not affected by any treatment, CEPA retarded growth of young plants by reducing the internodal length. It did not change the flowering pattern but delayed flowering and reduced the production of both pistillate and staminate flowers. However, it increased the per cent femaleness as a result of comparatively more suppression of staminate flowers. The TIBA 25 and 50 mg/1 and CCC 500 mg/1 did not affect the staminate flower production but increased the pistillate flowers, which increased the per cent femaleness. The CEPA decreased while both TIBA 25 and 50 mg/1, and CCC 500 mg/1 increased the number of fruits per plant and the yield. The mode of action of the chemicals has been discussed.     

The Effects of Foliar Applications of (2-Chloroethyl)-trimethylammonium Chloride on Leaf Area and Dry Matter Production by the Brussels Sprout Plant

When CCC was applied as a spray to the leaves of Brassica oleraceaL. (Brussels sprout) grown in pots, plant height and mean internodelength were reduced. The effects appeared more slowly and wereless pronounced than those previously observed when CCC hadbeen applied to the soil; other differences were that root growthwas not inhibited, stem weight was only significantly reducedat the highest rate of application (2 per cent), and stomatalnumber per unit area of lower leaf epidermis was not affected.In common with soil applications, leaf thickness, stem diameter,and the percentage moisture contents of the leaves were allincreased by foliar applications.In a further experiment theprogress of wilting was observed in untreated plants and inplants treated with CCC applied either to the leaves or to thesoil. The rates of water loss and the moisture contents of theleaf laminae of the treated plants, after a period of wilting,were not significantly different from the controls. The treatedplants, however, looked less ‘wilted‘ for the changein angle of the leaf lamina to the stem was less and their leaveswere therefore held more upright.     

Effects of Chlorocholine Chloride and Water Regime on Growth, Yield, and Water Use of Spring Wheat

When CCC was applied as a spray to the leaves of Brassica oleraceaL. (Brussels sprout) grown in pots, plant height and mean internodelength were reduced. The effects appeared more slowly and wereless pronounced than those previously observed when CCC hadbeen applied to the soil; other differences were that root growthwas not inhibited, stem weight was only significantly reducedat the highest rate of application (2 per cent), and stomatalnumber per unit area of lower leaf epidermis was not affected.In common with soil applications, leaf thickness, stem diameter,and the percentage moisture contents of the leaves were allincreased by foliar applications.In a further experiment theprogress of wilting was observed in untreated plants and inplants treated with CCC applied either to the leaves or to thesoil. The rates of water loss and the moisture contents of theleaf laminae of the treated plants, after a period of wilting,were not significantly different from the controls. The treatedplants, however, looked less ‘wilted‘ for the changein angle of the leaf lamina to the stem was less and their leaveswere therefore held more upright.     

Influence of chlorocholinechloride and ethrel on chlorophyll content and the “epinastic response” of the primary leaf of wheat seedlings

Wheat seedlings were cultivated in nutrient solutions containing 10^-3 M CCC, 10^-3 M CEPA or 5 × 10^-4 M CCO and CEPA, respectively. CCC applied alone or mixed with CEPA increased chlorophyll content per unit fresh matter but had no influence on the epinastio response of the primary leaf. In contrast, CEPA had no influence on chlorophyll content but greatly increased the epinastic response. The different response to the application of these substances with regard to chlorophyll content ha been claimed in a previous paper to be due to their different effect on cell extension and cell division. The epinastic response of the primary leaf suggests that ethylene participates in the reaction chain of CEPA effect on plant tissues.     

Suppression of floral induction inBryophyllum daigremontianum by a growth retardant

Summary Flower formation in the long-short-day plantBryophyllum daigremontianum induced by the shift from long to short day is fully suppressed by applying the growth retardant CCC [(2-chloroethyl)-trimethylammonium chloride]via the roots during short day treatment at a level of at least 1 g per plant. At the same time CCC applications strongly reduce the internode length, but the rate of leaf formation does not seem to be affected. CCC also causes the production of more anthocyanin in the leaves.Gibberellin A₃ appliedvia the apices and youngest leaves at a dose of 1.5 g per plant, completely overcomes the inhibition of flower formation caused by CCC. Ten times higher quantities are needed for a complete reversal of the reduction in stem elongation.The growth retardant CCC seems to keep the level of physiologically active GA below that which is normally required for floral initiation and stem elongation. Thus, the results are in agreement with the hypothesis that a high GA level is necessary for the production of floral stimulus inBryophyllum daigremontianum.With 2 Figures in the TextThis work was supported by the National Science Foundation, grants G-16408 and G-17483.     

Response of Cowpeas to Salinity and (2-Chloroethyl) trimethyl-ammonium Chloride (CCC)

Recent investigations have demonstrated that the growth retardant, (2-chloroethyl) trimethyl-ammonium chloride (CCC) inhibits several aspects of vegetative growth. In solution culture experiments, reduction in plant growth and dry matter production was confirmed in cowpeas, Vigna unguiculata L, (cv. Makueni II), when treated with CCC. The growth retardant had negligible effect on the rate of transpiration per unit leaf area although it slightly increased the relative water content of leaves. Stomatal opening was suppressed by CCC treatment but the number of stomata per unit leaf area was increased by the growth retardant. Variations in mineral element content (K, Ca, N and Na) of shoots are presented and discussed in relation to CCC treatment.     

Persistent effects of seedling treatment on growth of sugar beet in pots

Further evidence is provided that the environment of sugar-beet seedlings, or growth substances applied to seedlings, continues to influence growth when the plants are later in other environments. Sugar-beet seeds were germinated at 20 °C in 8, 16 or 24 h photoperiods of constant light intensity, i.e. with different amounts of total radiation. When the seedlings had two leaves (15–18 days old) they were transferred to large pots in the glasshouse. Some seedlings were treated with (2-chloroethyltrimethylammonium chloride) either sprayed on the leaves or applied to the soil, at different times. The treatments affected areas of individual leaves throughout the growing period; plants raised in 24 h photoperiod had the largest leaves, and those in 8 h photoperiod the smallest. Consequently, 24 h plants had most dry matter and 8 h plants least. Plants given most radiation produced leaves fastest and CCC applied early increased the rate, but as the leaves were smaller, except late in 1967, and died sooner, the leaf area duration was less and so yields were less. CCC applied later did not affect leaf production. There was no interaction between amount of radiation and CCC treatment. Twenty-four hour plants had the greatest net assimilation rate (E) early. CCC decreased E early, but increased it later and more when sprayed on the leaves than when applied to the soil. Some factor, possibly pot size, eventually restricted growth and probably diminished the effect of the treatments applied to the seedlings.     

Effect of (2-Chloroethyl)phosphonic Acid on CCC-Induced Delay of Fruit Ripening

(2-Chloroethyl)phosphonic acid (CEPA) which is known to releaseethylene in plant tissue, and (2-chloroethyl)trimethylammoniumchloride (CCC) were applied to ripening tomato and red pepperfruits. CEPA enhanced and CCC inhibited chlorophyll degradationand carotenoid formation. The inhibitory effects of CCC on fruitripening were counteracted by CEPA treatment. These resultsand those of other authors on gibberellin action in fruit ripeningsuggested that both CCC and gibberellin may interfere with theaction of ethylene in ripening fruit.     

Effects of 2-Chloroethylphosphonic Acid on Growth, Plastid Pigments, and Sucrose Translocation in Radish

2-Chloroethylphosphonic acid (CEPA) caused a significant declinein chlorophyll content of radish plant within 5 d of treatment.Such effects were greater when plants were treated at the two-than at the four-leaf stage. In early treated plants, concentrationof CEPA increasing from 20 mg/1 progressively increased leafweight, while decreasing root (radish) weight. A concentrationof 10 mg/1, applied at the three-leaf stage, increased leafand root weights by 27 and 30 per cent respectively in the cultivar‘Cavalier’. Similar responses were obtained withthe cultivar ‘Cherry Belle’. While Cavalier showeda discrete 10 mg/1 optimum, ‘Cherry Belle’ exhibiteda range of concentrations (10-40 mg/1) optimal for growth. At relatively high concentrations, early application of CEPAcaused inverse changes in sucrose-¹⁴C in the leaves and theroot, so that decreased retention by leaves was accompaniedby increased transport to roots. Low concentrations of CEPAappear promising for growth stimulation in root-crop plants.     

Growth of bean and tomato plants as affected by root absorbed growth substances and atmospheric carbon dioxide

Summary Bean and tomato plants were grown in solution culture root media containing pre-determined concentrations of gibberellin A₃ (GA), 1-naphthaleneacetic acid (NAA), N⁶-benzyladenine (BA), (2-chloroethyl)trimethylammonium chloride (CCC), and at atmospheric levels of 300 and 1000 ppm of CO₂. Net assimilation rates (NAR), relative growth rates (RGR), leaf area ratios (LAR), root to top dry weight ratios (R/T) and changes in dry weight, size, and form of each organ were recorded.Gibberellin had no effect on RGR of either plant species but increased the NAR of tomatoes at 1000 ppm CO₂. Total dry weight was only slightly affected by GA but root growth and R/T were markedly depressed. CCC had no effect on NAR, but decreased RCR and LAR. Root growth of beans and R/T in both plants were promoted by CCC. NAR and RGR were strongly inhibited by BA and NAA. Inhibition of stem and leaf growth by CCC and NAA was greater than that for roots; thus, R/T ratios were increased. Root branching was promoted by NAA.High (1000 ppm), compared to the low (300 ppm), atmospheric levels of CO₂ generally promoted root growth and produced an increase in the R/T, both in the absence and presence of chemical treatment. The multiplicity of effects of the rootabsorbed chemical growth substances and CO₂ on growth and photosynthesis is discussed.Journal article No 3883 of the Michigan Agricultural Experiment Station.NATO Fellow, University of Pisa, Italy.     

Effect of CCC and glycine betaine on growth and growth-substance content of primary leaves of dwarf Frenchbean (Phaseolus vulgaris L.)

CCC (2-chloroethyltrimethylammonium chloride) decreased growth of primary leaves and stem internodes above the hypocotyl of dwarf French bean, probably because it decreased the amount of auxin produced by interaction between tryptophan and phenolic esters in the primary leaves. Growth of leaves was less affected than that of stems, and the gibberellin content of the primary leaves, previously shown to be associated with their expansion, was unaffected by CCC. CCC delayed death of the primary leaves, the breakdown of chlorophyll, and the increase in auxin associated with death of bean leaves. CCC had less effect on the growth of leaf discs, probably because they are not sites of growth-substance production. Glycine betaine, a quaternary ammonium compound similar to CCC, did not affect growth of bean plants, their metabolism of growth substances or the longevity of their primary leaves, but inhibited growth of leaf discs, probably directly.     

Einfluss von Chlorcholinchlorid und Ethrel auf Zellteilung und Zellstreckung bei Primärblättern von Weizenkeimpflanzen

Both chlorcholinchloride and ethrel are used as growth retardants in cereal cultivation. Wheat seedlings were cultivated in nutrient solutions containing 10^-3M CCC, CEPA or 5 × 10^-4M CCC and CEPA, respectively. The epidermis of full-grown primary leaves was analysed. CCC relatively equally decreases the length of leaves and long epidermal cells, whereas CEPA mainly inhibits cell division. Leaf growth is always a little more inhibited than the number of stomata and trichomes is reduced by CCC or CEPA. This results in an increased frequency of stomata and trichomes by about 14 to 16 per cent. This means that retardants can strongly influence the length of leaves and the length or number of long epidermal cells but, due to the mechanism of programmed determination, the frequency of stomata and trichomes is kept constant within relatively narrow limits. Furthermore it can be concluded that long epidermal cells function as pace-makers in the growth of leaves of monocotyledonous plants.      

Vegetative Growth Responses of Pea Plants to CCC and Phosfon in Relation to Phosphorus Nutrition

The effects of 2-chloroethyltrimethylammonium chloride (CCC)and 2,4-dichlorobenzyl-tributylphosphonium chloride (Phosfon)on the growth of pea plants in sand culture at two rates ofapplied phosphorus (P), were studied in controlled-environmentgrowth chambers. CCC at 1 and 10 mg/1, and to a lesser degreePhosfon at 0.1 mg/1, stimulated growth. CCC at 1000 mg/1 andPhosfon at 100 mg/1 retarded growth, due mainly to shortenedstems. The magnitude of such effects depended on the level ofapplied P. Reductions in plant height by the 1000 mg/1 CCC treatmentwere 13 and 50 per cent respectively at the high (160 mg/1)and low (8 mg/1) rates of applied P. Similar decreases due to100 mg/1 Phosfon were 30 and 57 per cent respectively. At thehigh P rate, both CCC and Phosfon had no significant effecton total uptake of P, or on relative distribution in the leaf,stem, and root. At the low P rate, the root, relative to leafand stem, retained more P, at a CCC concentration of 1000 mg/1.With Phosfon at 100 mg/1 relative leaf P content increased whilethat of the stem and root decreased. Phosfon was more activethan CCC in terms of the concentration required to cause a givenmagnitude of growth effect.     

Effects of exogenously applied growth regulators on shoot growth of inbred lines of Plantago major differing in relative growth rate: differential response to gibberellic acid and (2-chloroethyl)-trimethyl-ammonium chloride

The possibility of modulating shoot growth charaeteristics of seedlings of two inbred lines of Plantago major L., differing in relative growth rate (RGR), by exogenously applied 6-benzylaminopurine (BA), α-naphthalene acetic acid (NAA), (gibberellic acid (GA₃) and (2-chloroethyl)-trimethyl-ammonium chloride (CCC) was investigated. BA completely inhibited growth of the shoot at a concentration of 1 m M , while lower concentrations had no effect. NAA reduced growth of the shoot at 10 ü M , while 1 m M completely inhibited growth. Addition of 10 μ M GA₃ or higher stimulated shoot fresh weight up to 20% and leaf area up to 30% for the slow growing inbred line (W9), but less for the fast growing line (A4). Application of 1 m M CCC, an inhibitor of gibberellin metabolism, reduced growth of both inbred lines, but to a larger extent in the fast growing seedlings.
The lower shoot growth of W9 was associated with a lower specific leaf area (SLA) and a higher dry matter percentage of the shoot, as compared with A4. NAA reduced growth by reducing SLA and increasing leaf thickness, but the percentage dry matter of the leaves was unaffected. Stimulation of the shoot growth by GA₃ application was associated with higher SLA and lower dry matter percentage. Application of CCC had opposite effects on SLA and dry matter percentage as compared with GA₃. GA seems to be involved in the regulation of at least part of the genetic difference in RGR in Plantago major .