TRANSLOCATION OF APPLIED GIBBERELLIN IN BEAN SEEDLINGS

The direction and extent of GA transport in Pinto beans has been studied. The increase in growth rate was used as a measure of the amount of GA which reached the stem apex. The evidence showed that a similar increase in stem growth occurred whether GA was applied to the first trifoliolate leaf or to the apex of the shoot, but considerably less elongation resulted when GA was applied to primary leaves. When leaves were treated with GA after remaining in darkness for extended times, no increase in stem elongation was observed; however, growth was promoted when the plants were returned to light. The time required for a sufficient amount of GA to be translocated from the leaf to increase stem growth is less than 1 hour. The maximum growth response was found when the treated leaf was left on the plant for 3 or more hours. A study of GA movement in two-branched plants was made. The untreated branch showed no growth response when GA was applied to the apex of the other branch, even if the dose of GA was 20 × greater than a saturating dose. Similar results were observed when GA was applied to the first trifoliolate leaf. Considerable GA moved from a mature leaf to the opposite shoot if this untreated branch had been defoliated. The pattern of GA movement to the opposite shoot was dependent on the position of the treated leaf on the shoot. It is concluded that the movement of applied GA is related to carbohydrate transport within the plant.     

The effects of (2RS, 3RS)-1-(4-chlorophenyl)-4, 4-dimethyl-2-(1H-1,2,4 triazol-1-yl) pentan-3-ol (Paclobutrazol:PP333) and root pruning on the growth,water use and response to drought of Colt Cherry rootstocks

The effect of (2RS, 3RS)-1-(4-Chlorophenyl)-4, 4-dimethyl-2-(1H-1,2,4 triazol-1-yl) pentan-3-ol (PP333) on the growth and transpiration of normal and root pruned colt rootstocks was measured. PP333 reduced plant height, stem diameter increment, leaf number, area and weight and stem weight. Root pruning reduced root, leaf and stem weight, and plant height in control plants. PP333 reduced both total water use and transpiration per unit leaf area and increased stomatal resistance. In control plants root pruning also reduced total water use and increased stomatal resistance. 15 days after the beginning of the experiment half the plants in all treatments were allowed to dry out. The effects of drought, i.e. reduced transpiration, growth and leaf water potentials, were smaller in PP333 treated than in control plants.     

植物生长延缓剂对盆栽月季生长发育的影响

采用不同质量浓度的3种植物生长延缓剂多效唑(PP333)、矮壮素(CCC)、缩节胺(DPC),运用叶喷和灌根两种处理方式,通过测定植株的形态指标(株高、节间长、叶片长与宽、花枝长、花梗长、花径及初花期等)和生理生化指标(叶绿素含量、光合速率、蒸腾速率、叶片酶活性及可溶性糖含量等),研究3种药剂对盆栽月季‘世纪之春’生长发育的影响。结果表明:(1)不同药剂的使用浓度和方式对盆栽月季的形态和生理指标有不同程度的影响,适宜浓度和方式处理能缩短植株节间长度来降低株高,使株型饱满,开花正常,提高观赏价值;同时可以增加叶片叶绿素含量,提高光合效率,增加叶片超氧化物歧化酶和过氧化物酶活性及可溶性糖含量,对改善盆栽月季观赏品质有重要影响;(2)叶面喷洒700mg.kg-1 PP333和灌根300mg.kg-1 PP333的调控效果最好,喷洒1 200mg.kg-1CCC和300mg.kg-1 DPC效果次之,均能达到有效降低株高和提高观赏效果的目的。     

NAA、IBA和PP333对怀山药试管苗生长发育的影响

就不同生长调节剂对怀山药试管苗生长发育的影响进行了系统的研究。结果表明 :( 1 )NAA、IBA和PP3 3 3 均能诱导根的生成 ,但根形成的时间、发生方式及发达程度均不相同。低浓度的NAA( 0 .1～ 0 .5mg.L 1)有利于根的生成 ,但高浓度的NAA(≥ 2mg .L 1)则易形成愈伤组织 ,且随着浓度的升高 ,愈伤组织化程度变大 ,根多来源于愈伤组织 ;IBA( 0 .1～ 2mg .L 1)对根的生成较为有利 ,其中以IBA 1mg .L 1的生根效果较好 ;PP3 3 3 ( 0 1～ 8mg.L 1)有利于根的生成 ,根形成的最早、最多 ,且随着浓度的升高 ,根更加粗壮发达。 ( 2 )PP3 3 3 抑制试管苗的纵向伸长生长 ,使株高降低 ,但却显著地促进了根系的发育 ,使试管苗生长健壮 ,叶色浓绿 ,叶片增多。这种效应随着PP3 3 3 浓度的升高而加强。从培养壮苗的角度来看 ,PP3 3 3 ( 2～ 4mg.L 1)是最佳浓度     

The effect of an experimental growth retardant (WL83801) on leaf growth and development in Lolium perenne L.

The experimental growth retardant WL83801, applied as a root drench, had a rapid and persistent effect in retarding the growth and development of leaves in L. perenne. Leaves of the main shoot were greatly reduced in length, were broader, and appeared faster than in control plants. The rate of extension of individual leaves was greatly reduced in retarded plants but still followed a diurnal pattern that closely corresponded with temperature. There was evidence that leaf extension was far less responsive to temperature in treated plants. At the cellular level WL83801 had no significant effect on leaf blade cell number, thus reductions in leaf length were associated with the retardation of cell elongation. Changes in leaf structure were also observed. These changes in the pattern of leaf growth and development are discussed in relation to the primary mode of action of the growth retardant in interfering with gibberellin biosynthesis.     

How periodic growth pattern and source/sink relations affect root growth in oak tree seedlings

Seedlings of Quercus pubescens were grown in root boxes to study the growth pattern of the root system in relation to shoot development. Shoot growth was typically rhythmic. Root elongation was also periodic, in contrast to several previous reports on other Quercus species. Both taproot and lateral root elongation were depressed during expansion of the second leaf flush, with a more pronounced response of lateral root growth. Apical diameter of the taproot followed comparable but less prominent trends than taproot elongation. Modifying source/sink relationships through various defoliation treatments altered the root growth pattern. Ablation of source organs (mature leaves or cotyledons) amplified the decrease in root growth concomitant with leaf expansion. Root growth recovery was even more difficult when both cotyledons and mature leaves had been removed. Ablation of sink aerial organs (young leaves) initially suppressed competition for growth between the shoot and the root, and then caused a gradual decrease in lateral root growth. Antagonism between maximum leaf expansion and root growth reduction during the second flush, and various responses of seedlings with modified source/sink relationships, raise an hypothesis of mutual competition for carbohydrates. The gradual decrease in lateral root growth after ablation of young leaves suggests a long-term carbohydrate limitation, or auxin limitation as auxin sources have been removed.     

锌和铁缺乏对枳生理指标、矿物质含量及叶片超微结构的影响

采用营养液培养法,研究了缺锌(0μmol·L-1 Zn2+)、缺铁(0μmol.L-1 Fe-EDTA)条件下柑橘砧木枳的生理胁迫反应.结果表明:1)锌、铁缺乏使枳生物量与根系活力均显著下降,叶片与根系中的SOD活性明显上升;叶片与根系中的POD活性在缺锌下显著增高,但在缺铁胁迫下显著降低;缺锌处理的根系CAT活性显著上升,但缺铁处理下的CAT活性与对照无显著差异.2)缺铁处理的根部K、Mg、P含量及缺锌处理的地上部K含量均显著降低;缺铁处理的根部和地上部Zn、Cu含量以及缺锌处理的根部Fe、Mn及地上部Mn含量均显著增高.3)叶肉细胞超微结构变化显著,缺铁胁迫下细胞器受损程度较重,如叶绿体、线粒体空泡化严重,叶绿体膜及类囊体片层模糊,质体小球明显增多,无淀粉粒;而缺锌处理时叶绿体基粒片层排列松散、数目明显减少,质体小球明显增多.     

Effects of imazamethabenz on the main shoot growth and tillering of wild oat (Avena fatua L.)

Foliar application of imazamethabenz at sublethal doses of 100 and 200 g a.i./ha to wild oat plants at the two-leaf stage without tillers greatly inhibited the growth of the main shoot but increased tillering. The near cessation of sheath and the main stem elongation indicated that the major effect of imazamethabenz on the main shoot was inhibition of intercalary growth. Low doses of imazameth-abenz treatment resulted in more leaves (including leaf primordia) in the main stem but did not affect mature first and second leaves. Sublethal doses of imazamethabenz only briefly inhibited tiller growth. A later increase in tillering in treated plants resulted from the stimulated resumed growth of tillers and the increased initiation of tiller buds. Such enhanced tillering mainly resulted from the release of apical dominance due to the inhibition or cessation of the main stem growth with imazamethabenz treatment. Both doses of imazamethabenz (100 and 200 g a.i./ha) significantly reduced the biomass of shoots and roots, but increased the ratio of roots/ shoots dry weight.     

喷施多效唑提高麻疯树幼苗耐盐性的生理机制

研究了600 mg?L-1 PP333喷施对200 mmol?L-1 NaCl胁迫处理下麻疯树幼苗干重、含水量、叶片细胞超微结构、光合作用、叶片渗透调节能力、叶片丙二醛含量和叶片抗氧化能力的影响。结果表明：600 mg?L-1 PP333喷施处理能显著提高200 mmol?L-1 NaCl胁迫下植株的干重、根冠比和叶片含水量,同时显著降低叶片电解质外渗率（ELP）,降低叶片细胞超微结构的伤害程度,显著提高了其叶绿素含量、净光合速率、渗透调节能力、SOD酶活性和CAT酶活性,显著降低了MDA含量和POD酶活性。可见,PP333喷施能显著提高麻疯树幼苗对盐渍的适应,主要因为其提高了植株的抗氧化能力、光合作用、渗透调节能力。     

Defoliation and Regrowth in the Graminaceous Plant: The Role of Current Assimilate

Infra-red gas analysis and a quantitative radiocarbon tracertechnique were used to measure photosynthesis, and the export,distribution and utilization of current assimilate in the regrowthof leaf tissue and the growth of stem and root of partially-defoliateduniculm barley plants. After defoliation, which removed allleaf tissue above the ligule of leaf 3, the rate of photosynthesisof the remaining two older leaves fell to 90–95 per centof that of control leaves, but they exported more of their assimilatedcarbon to meristems elsewhere in the plant during the first48 h after the defoliation. The level of export from the twoolder leaves began to decline when new leaf tissue regrew fromthe shoot apex, and fell below that of the control leaves 4days after defoliation. The two older leaves supplied the assimilateused in the regrowth of new leaf tissue immediately after defoliation:previously they had exported most of their assimilate to root.There was no evidence that ‘reserves’ were mobilizedto meet the needs of regrowth at leaf meristems or, indeed,of the growth in stem and root; current photosynthesis suppliedsufficient assimilate to account for all observed growth. Ingeneral, the plants responded to defoliation with a rapid andmarked re-allocation of assimilate from root to leaf meristems,with the result that root growth was severely retarded but newleaf tissue grew at 70–100 per cent of the rate observedin control plants.     

Growth of a mangrove (Rhizophora apiculata) seedlings as influenced by GA3, light and salinity

The growth performance of Rhizophora apiculata Blume (mangrove) seedlings in the presence and absence of exogenous gibberellic acid (GA3) under different combinations of salinity and light was analyzed. Root and shoot growth responses of 75-day old seedlings in liquid-culture, were measured. It was concluded that light exhibited a significant inhibitory effect on all the growth parameters-number of primary roots, primary root length, shoot elongation, number of leaves, total leaf area; and, the GA3 treatment singly or in combinations with light, showed a significant influence on the total leaf area and primary root length.     

Kinematics and Dynamics of Sorghum (Sorghum bicolor L.) Leaf Development at Various Na/Ca Salinities (I. Elongation Growth)

In many salt-sensitive species, elevated concentrations of Ca in the root growth media ameliorate part of the shoot growth reduction caused by NaCl stress. The physiological mechanisms by which Ca exerts protective effects on leaf growth are still not understood. Understanding growth inhibition caused by a stress necessitates locating the leaf expansion region and quantifying the profile of the growth reduction. This will enable comparisons and correlations with spatial gradients of probable physiologically inhibiting factors. In this work we applied the methods of growth kinematics to analyze the effects of elevated Ca concentrations on the spatial and temporal distributions of growth within the intercalary expanding region of salinized sorghum (Sorghum bicolor [L.] Moench, cv NK 265) leaves. NaCl (100 mM) caused a decrease in leaf elongation rate by shortening the leaf growing zone by 20%, as well as reducing the peak value of the longitudinal relative elemental growth rate (REG rate). Increasing the Ca concentrations from 1 to 10 mM restored the length of the growing zone of both emerged and unemerged salinized leaves and increased the peak value of the REG rate. The beneficial effects of supplemental Ca were, however, more pronounced in leaves after their appearance above the whorl of encircling older leaf sheaths. Elevated Ca then resulted in a peak value of REG rate higher than in the salinized leaves. The peak value of unemerged leaves was not increased, although it was maintained over a longer distance. The duration of elongation growth associated with a cell during its displacement from the leaf base was longer in salinized than control leaves, despite the fact that the elongation zone was shorter in salinity. Although partially restoring the length of the elongation region, supplemental Ca had no effect on the age of cessation of growth. Elongation of a tissue element, therefore, ceased when a cellular element reached a certain age and not a specific distance from the leaf base.     

The EfFect of B9 upon the Structure of Leaves and Chloroplasts in Peanut plant

When peanut plants (Arachis hypogaea L.) were treated with aqueous solution of Bo (2000 ppm) by spraying application, the cells of the assimilating tissue were enlarged and the thickness of the leaves were increased. B9 promoted the development of the chloroplast, so that the number of chloroplast, grana and the lamella were increased. As a result, the volume of the “container” of chlorophyll was enlarged. In addition, the chlorophyll content of file leaves also increased after B9 treatment, there fore the leaves turned dark green.     

UV-B-induced Inhibition of Stem Elongation and Leaf Expansion in Pea Depends on Modulation of Gibberellin Metabolism and Intact Gibberellin Signalling

Information on the involvement of elongation-controlling hormones, particularly gibberellin (GA), in UV-B modulation of stem elongation and leaf growth, is limited. We aimed to study the effect of UV-B on levels of GA and indole-3-acetic acid (IAA) as well as involvement of GA in UV-B inhibition of stem elongation and leaf expansion in pea. Reduced shoot elongation (13%) and leaf area (37%) in pea in response to a 6-h daily UV-B (0.45 W m^?2) exposure in the middle of the light period for 10 days were associated with decreased levels of the bioactive GA₁ in apical stem tissue (59%) and young leaves (69%). UV-B also reduced the content of IAA in young leaves (35%). The importance of modulation of GA metabolism for inhibition of stem elongation in pea by UV-B was confirmed by the lack of effect of UV-B in the le GA biosynthesis mutant. No UV-B effect on stem elongation in the la cry-s (della) pea mutant demonstrates that intact GA signalling is required. In conclusion, UV-B inhibition of shoot elongation and leaf expansion in pea depends on UV-B modulation of GA metabolism in shoot apices and young leaves and GA signalling through DELLA proteins. UV-B also affects the IAA content in pea leaves.     

Uptake and translocation of paclobutrazol by shoots of M.26 apple rootstock

When ¹⁴C-paclobutrazol, a gibberellin synthesis inhibitor, was applied to different parts of actively-growing M.26 apple rootstock shoots it was translocated acropetally when applied to the young stem and, to a lesser extent, from the youngest unrolled leaf. Paclobutrazol was not translocated out of leaf laminae, shoot tips or from one-year-old wood but translocation occurred out of a treated petiole into the attached leaf. No basipetal translocation was detected. This translocation pattern suggested movement through the xylem.Localised application of paclobutrazol caused a reduction in shoot extension and leaf production when the young stem or shoot tip were treated; the effect decreased as older parts of the stem were treated. Treatment of laminae or petioles had only a slight effect on shoot extension and treatment of one-year-old wood was ineffective. Combined treatment of the shoot tip plus young stem was similar in effect to treatment of the complete shoot.It is suggested that paclobutrazol exerts its effects on shoot growth by inhibiting gibberellin biosynthesis in the shoot tip and the expanding leaves.The findings contribute to an understanding of the requirements for efficient orchard application of foliar sprays of paclobutrazol.     

日光温室光温因子对黄瓜叶绿体超微结构及其功能的影响

在日光温室内,研究了光温因子对黄瓜叶绿体超微结构及其功能的影响．结果表明,因季节之间光、温条件不同,日光温室黄瓜叶片显微结构和叶绿体超微结构有一定差异,1月份光照弱叶肉细胞较大,而5月份光照强叶绿体数较多．在该试验条件下,未发现叶片光合速率与叶绿体超微结构之间有直接或密切的相关性．在各生长季节其光合速率均为第4叶>初展叶>基部叶,与叶龄及各叶位的受光量有关．如果将不同叶位叶放在相同的光照下,则差异明显减少．黄瓜叶片的叶肉细胞、叶绿体和淀粉粒的大小以及叶绿体数、基粒数、基粒厚度、基粒片层数都随叶位的下降而呈增加趋势。不同品种、同品种不同生长时期的叶片显微结构和叶绿体超微结构及其功能也有一定的差异．限制日光温室冬季黄瓜光合作用的主要因素是光照弱、有效光照时数少,而在晴天温度的限制作用相对较小。阴天因光照弱而导致的室内低温则是限制黄瓜生长的关键因素．     

Leaf primordia initiation,leaf emergence and tillering in wheat (Triticum aestivum L.) grown under low-phosphorus conditions

In two simultaneous experiments we examined the effects of phosphorus (P) supply on leaf area development in wheat (Triticum aestivum L.) grown in sand with nutrient solutions. In Experiment 1 we studied leaf emergence, leaf elongation, tiller emergence, shoot growth, and P uptake under four levels of P supply (mM) 0.025 (P1), 0.05 (P2), 0.1 (P3), and 0.5 (P4), and. In Experiment 2 there were two levels of P supply, P1 and P4, and we examined the effects of P on leaf primordia differentiation and leaf emergence. The phyllochron was calculated as the inverse of the rate of leaf emergence calculated from the regression of number of leaf tips (PHY-Ltip), Haun index (PHY-Haun), and as the cumulated thermal time between the emergence of two consecutive leaves (PHYtt). The plastochron was calculated from the inverse of the rate of leaf primordia initiation in the apex. P deficiency delayed the emergence of leaves on the main stem and on the tiller 1. Phosphorus deficiency increased the time from emergence to double ridge and anthesis. The final number of leaves was not affected by P. The effects of P on the value of the phyllochron were attributed to both a reduced rate of leaf primordia initiation, and to a reduced leaf elongation rate. P deficiency delayed or even suppressed the emergence of certain tillers. In this work a phosphorus deficiency that reduced shoot growth by 25% at 44 days after emergence significantly modified the structure of the plants by increasing the value of the phyllochron and delaying tillering. These results suggest that any attempt to simulate leaf area development and growth of wheat plants for P-limited conditions should include the effects of the deficiency on leaf emergence.     

多效唑对琯溪蜜柚枝梢生长和越冬期叶片糖、水分状态的影响

本试验探讨了不同浓度多效唑(PP333)对琯溪蜜抽枝梢生长和越冬期叶片淀粉、可溶性糖含量、束缚水/自由水比值的影响.结果表明,多效唑处理能提高越冬期叶片可溶性糖含量,增大束缚水/自由水比值,降低淀粉含量;多效唑处理使新梢长度、节间长度明显受抑制,新梢粗度增加,且随着使用浓度的增大作用增强.     

Distribution of assimilate during the flush cycle of growth in Theobroma cacao L.

The growth of the shoot and roots of seedling plants of cocoa (Theobroma cacao L.) under constant glasshouse conditions showed a rhythmic cycle, with the maximum growth stages of each alternating in a regular sequence. When the growth cycle of the shoot was upset by removing all new leaves immediately after unfolding, the roots showed a high constant growth rate during this period, suggesting that normally the rapidly expanding leaves exert an inhibitory influence on the roots. Conversely removal of portions of the root delayed the production of new leaves in the shoot. The level of soluble and starch carbohydrate in the mature leaves, roots and stem declined during the period of expansion of the flush leaves, but accumulated again at the end of the leaf expansion stage. It is likely that this reserve carbohydrate was remobilised and translocated to the flush leaves during their period of expansion. A large proportion of newly formed photoassimilate, as shown by the distribution of ¹⁴C radioactivity from different source leaves, was also translocated to the young leaves during expansion. The large sink created by these leaves may cause photoassimilate and reserve carbohydrate to be diverted from the roots, thereby inhibiting root growth during the stage of leaf expansion. It is suggested that the rhythmic leaf production at the apex may control the growth cycle of the roots.     

EFFECT OF 4'-CHLOROGLUTARANILIC ACID ON GROWTH AND DEVELOPMENT OF SUNFLOWER SEEDLINGS

The potential growth-regulating properties of 4'-chloroglutaranilic acid (CGA) as well as oxygen and nitrogen isosteres were examined in whole-plant bioassay systems utilizing sunflower seedling (Helianthus annuus L.). Test systems included both soil-grown plants and hydroponic studies. Foliar applications of CGA produced growth inhibition which was detectable within 24 hr and which persisted for at least 30 days. Direct application to roots produced a growth inhibition which was 15% greater than foliar applications. Foliar or root application at 10^-5 m or greater concentrations produced gross changes in leaf morphology. Total plant-height inhibition was principally associated with stem growth in an area located between primary leaves and the shoot meristem. CGA was found to be 32 % less active than IAA as a growth promoter, but was 76 % more active than IAA as a growth inhibitor; the most severely affected organ was the leaf and the least affected was the root system. Leaves from soil-grown plants treated wth a 10^-3 m foliar application of CGA possessed several abnormalities. These included an increase in thickness and dry weight, a reduction in chloroplast starch vacuoles, extractable starch, soluble hexoses, and soluble proteins.