Influence of Sink-Source Interaction on Dry Matter Production in Tomato

Sink-source ratio in tomato was manipulated, in six glasshouseexperiments, by fruit pruning (trusses pruned to two to sevenfruits immediately after fruit set of each truss), truss pruning(removal of every other truss at anthesis) and truss pruningin plants with two shoots. Periodic destructive harvest wereconducted for about 100 d after flowering of the first truss.Dry matter production was not influenced by sink-source ratio,whereas dry matter distribution between fruits and vegetativeparts was greatly affected. The fraction of dry matter distributedto the fruits at the end of the fruit pruning experiments (F_fruits)could be described accurately as a saturation-type functionof number of fruits retained per truss (N_f): F_fruits = 0.660(l-e^-0.341N_f). Specific leaf area and internode length decreasedand plant leaf area increased when sink-source ratio was reduced.Removal of every other truss at anthesis did reduce dry matterpartitioning into the fruits, but it did not influence internodelength. Plant development (number of visible leaves at the endof the experiments) was not influenced by sink-source ratio.In four experiments some plants were pruned to one fruit pertruss. Final dry matter production was 8-24% lower for theseplants, compared with plants with more than one fruit per truss.This was, at least party, the result of less light interceptionby these plants, which had strongly curled leaves pointing downwards. Results indicate that effects of sink demand on dry matter productionper unit of intercepted radiation and probably on leaf photosyntheticrate in commercial tomato production can be ignored.Copyright1995, 1999 Academic Press Dry matter production, feedback control, glasshouse, growth analysis, Lycopersicon esculentum, pruning, sink demand, sink-source ratio, tomato     

Effects of pod removal on the transport and accumulation of abscisic Acid and indole-3-acetic Acid in soybean leaves

Concentrations of abscisic acid (ABA) and indole-3-acetic acid (IAA) in the second most recently expanded trifoliolate leaf were determined during reproductive development of soybean (Glycine max [L.] Merr cv `Chippewa 64'). The concentration of ABA in leaves was constant during most of the seed filling period until the seeds began to dry. The concentration of IAA in the leaves decreased throughout development. Removal of pods 36 hours prior to sampling resulted in increased concentrations of ABA in leaves during the period of rapid pod filling but had little effect on the concentration of IAA in leaves. ABA appears to accumulate in leaves after fruit removal only when fruits represent the major sink for photosynthate.

ABA and IAA moving acropetally and basipetally in petioles of soybean were estimated using a phloem exudation technique. ABA was found to move mostly in the basipetal direction in petioles (away from laminae). IAA, primarily in the form of ester conjugate(s), was found to be moving acropetally (toward laminae) in petioles. The highest amount of IAA ester(s) was found in petiole exudate during the mid and late stages of seed filling. Removal of fruits 36 hours prior to exudation reduced the amount of IAA ester recovered in exudate, suggesting that fruits were a source of the IAA conjugate in petiole exudate.

     

Auxins,ABA and gibberellin-like activity in abscising and non-abscising flowers and pods of Vicia faba L.

Abscission probability varies among floral positions within inflorescences of Vicia faba L. Flowers from proximal positions have a greater chance to develop into mature pods than flowers from more distal positions which normally abscise either as older flowers or as young pods. In three field experiments with the indeterminate single stem variety Herz-Freya, changes in the contents of extractable auxins, abscisic acid (ABA) and gibberellins in flowers and pods during their development, and their possible influence on abscission were investigated.Inflorescences at different positions along the stem were divided into the two proximal and the remaining fruits. The content of all three hormones was at a low level during flower development, increased greatly in parallel with dry matter accumulation in the young pods, and then decreased to maturity. The first hormone to increase in the fruits was auxin and this took place when abscission from the distal positions began. ABA and gibberellins at this time were still at a low level. This ontogenic course of hormone production was very similar in fruits of both positions within an inflorescence, but in flowers and young pods from proximal positions, auxin content in most inflorescences was greater than in those from the abscising distal positions. No such positional differences were observed with ABA and gibberellins. Decapitation of the plants reduced flower and pod drop from the remaining reproductive nodes. Although decapitation resulted in less abscission among distal flowers and young pods from these nodes, it did not affect the ontogenic course of auxin and ABA production in these fruits.     

植物生长调节剂影响沙田柚内源激素水平的研究

研究了植物生长调节剂优康唑和CPPU对沙田柚生理落果期间幼果和新梢叶片内源IAA、GA1 3和ABA水平的影响.研究结果表明:优康唑处理降低新梢叶片内源IAA和GA1 3水平,提高细胞分裂素含量.优康唑对叶片ABA含量和(IAA GA1 3 CTKs)/ABA比值影响不明显;优康唑处理下幼果IAA、GA1 3和ABA含量均有不同程度的下降,以GA1 3下降幅度最大.果实中CTKs含量和CTKs/ABA比例上升,结合优康唑和CPPU促进沙田柚座果的效应,提示细胞分裂素对座果有重要作用,而CTKs/ABA比例升高有助于缓解生理落果;CPPU处理降低果实ABA含量,提高果实CTKs水平和CTKs/ABA比值.这可能是CPPU促进座果和果实膨大的生理基础.     

Do Genetic Make-up and Growth Manipulation Affect Tomato Fruit Size by Cell Number,or Cell Size and DNA Endoreduplication?

This work investigated the link between genetic and developmental controls of fruit size and composition. On two isogenic lines (CF12-C and CF14-L), differing by fruit weight and sugar content quantitative trait loci (QTLs) identified previously, basal and tip fruits were characterized at anthesis and at maturity through their growth, dry matter and sugar content, number and size of cells and nuclei DNA content. The influence of competition was assessed by removing either basal or tip ovaries at anthesis. On an intact inflorescence, CF12-C fruits grew less than CF14-L fruits, with 1.67 fewer cell layers and similar cell size, suggesting that genes controlling cell division may be responsible for this fruit size variation. Truss thinning masked the QTL effect on fruit size, mainly by reducing the difference in cell number between the two lines and by promoting cell expansion in tip fruits, so that fruit growth was similar at both positions and for both lines. Thus, in these lines, cell number exerts a control on final fruit size only when there is competition among fruits. Different responses of basal and tip fruits after flower removal suggested that this treatment induced changes in hormonal relationships within the truss. No fixed relationship between DNA endoreduplication and cell size was found, as while cell size and dry matter and sugar contents differed with tomato lines, fruit position and truss size, endoreduplication patterns were the same. CF12-C fruits had a higher dry matter (+0.3% of fresh weight) and carbohydrates (+8% of dry matter) content than CF14-L fruits. The percentage dry matter was independent of truss size but decreased slightly from basal to tip fruits.     

How do salinity and water stress affect transport of water,assimilates and ions to tomato fruits?

The study was conducted in order to determine whether water stress affects the accumulation of dry matter in tomato fruits similarly to salinity, and whether the increase in fruit dry matter content is solely a result of the decrease in water content. Although the rate of water transport to tomato fruits decreased throughout the entire season in saline water irrigated plants, accumulation rates of dry matter increased significantly. Phloem water transport contributed 80–85% of the total water transport in the control and water-stressed plants, and over 90% under salinity. The concentration of organic compounds in the phloem sap was increased by 40% by salinity. The rate of ions transported via the xylem was also significantly increased by salinity, but their contribution to fruit osmotic adjustment was less. The rate of fruit transpiration was also markedly reduced by salinity. Water stress also decreased the rate of water transport to the tomato fruit and increased the rate of dry matter accumulation, but much less than salinity. The similar changes, 10–15%, indicate that the rise in dry matter accumulation was a result of the decrease in water transport. Other parameters such as fruit transpiration rates, phloem and xylem sap concentration, relative transport via phloem and xylem, solutes contributing to osmotic adjustment of fruits and leaves, were only slightly affected by water stress. The smaller response of these parameters to water stress as compared to salinity could not be attributed to milder stress intensity, as leaf water potential was found to be more negative. Measuring fruit growth of girdled trusses, in which phloem flow was inactive, and comparing it with ungirdled trusses validated the mechanistic model. The relative transport of girdled as compared to ungirdled fruits resembled the calculated values of xylem transport.     

Effects of varied water regimes on root length,dry matter partitioning and endogenous plant growth regulators in sunflower (Helianthus annuus L.)

Abstract

A field experiment was conducted to quantify the effect of varied water regimes on root length, partitioning of dry matter and plant growth regulators by using sunflower genotypes differing in maturity and drought tolerance. Significant depressing effect of drought stress was evident on traits (i.e., reproductive dry matter, leaf area index and cytokinin concentrations in leaves). However, root/shoot, reproductive/vegetative ratios and Abscisic acid (ABA) concentration were found to increase under drought stress. Drought stress also changed the dry matter accumulation pattern of genotypes. In most cases it reduced the days to reach the maximum peak showing early senescence.

ABA was identified as a multi-functional plant growth regulator under drought stress, causing early senescence of plants and translocation of assimilates to the roots and reproductive part while root growth under drought stress was explained by the indole-acetic acid (IAA) concentrations. Maintaining higher cytokinin contents were involved in accumulation of higher reproductive dry matter under drought stress. Although ABA and IAA were both involved in the development of defense responses during the adaptation and survival to drought stress but higher productivity under drought stress was only realized through maintaining higher cytokinin contents.     

Concentrations of abscisic Acid and indoleacetic Acid in cotton fruits and their abscission zones in relation to fruit retention

An experiment was conducted with field-grown cotton (Gossypium hirsutum L.) to determine the effects of drought and an increase in available photosynthate on the abscisic acid (ABA) and indoleacetic acid (IAA) contents of 3-day-old bolls and their abscission zones. Photosynthate availability was manipulated by removing about two-thirds of the plants to permit increased irradiance, and thus photosynthesis, in the plant canopy. The demand for photosynthate was decreased by removing all bolls from the remaining plants. The thinning and defruiting operations were performed about 3 weeks after first flower. Control plants were neither thinned nor defruited. Effects of water deficit were observed by making three harvests at different times during a 2-week irrigation cycle. Increasing the availability of photosynthate increased boll retention, but had relatively little effect on the concentrations of ABA and IAA in bolls. However, it did increase the concentration of IAA in abscission zones. Water deficit increased the ABA content of bolls and abscission zones and decreased the IAA content of bolls and abscission zones. Across all treatments, the IAA content of abscission zones was positively correlated, and the ABA content of bolls was negatively correlated, with boll retention. The results indicate that stresses change the hormonal balance in ways that are consistent with observed increases in fruit abscission.     

Effects of treatments potentially influencing the supply of assimilate on its partitioning in sugarcane.

Two pot experiments and one field experiment were conducted on sugarcane to assess the effects of treatments expected to change total carbon assimilation on the partitioning of assimilate. In the first experiment pots of cultivars CP and N14 were arranged to simulate normal field spacing. At 5 months, plants were partially defoliated or left intact. In the subsequent four months, defoliation resulted in a small (not significant) decrease in total dry mass increment; it increased the proportional partitioning of assimilates to leaves in N14, whilst in CP it increased the proportional partitioning to stems. In both cultivars defoliation increased proportional allocation to non-structural dry matter, and thus sucrose, in the stem. In the second experiment pots of cv. CP were grown at normal spacing for 4 months, then left untreated, shaded, or placed further apart. During the subsequent four months shading decreased total dry matter increment, but increased proportional partitioning to the stems, and within stems to non-structural dry matter, and so sucrose. Widened spacing increased total assimilation, but decreased proportional allocation to stems; partitioning within the stems was not affected. In the field experiment plants of both cultivars were partially defoliated at 6 months, or left intact. Defoliation resulted in only a very small decrease in stem dry mass increment during the subsequent four months (leaves were not measured). Within the stem partial defoliation caused proportionally increased partitioning to non-structural dry matter, hence to sucrose. The results suggest that sucrose storage receives priority in the allocation of assimilate, rather than representing the accumulation of assimilate not required for vegetative growth.     

辣椒杂种一代生化特性与农艺性状的灰色关联分析

用灰色关联分析方法研究了辣椒雄性不育杂种一代农艺性状与单株产量间、花蕾、叶片中生化物质含量与农艺性状间关系的密切程度。结果表明,农艺性状与单株产量问关联度的大小顺序依次为株幅、株高、果长、结果数、单果质量、第一花节位、果宽和侧枝数,花蕾中生化物质含量与农艺性状问总体关联度的大小顺序依次为可溶性糖、可溶性蛋白质、过氧化物酶活性、脱落酸、生长素、游离脯氨酸和玉米素,叶片中生化物质含量与农艺性状问总体关联度的大小顺序依次为可溶性糖、过氧化物酶活性、游离脯氨酸、脱落酸、生长素、玉米素和可溶性蛋白质。     

Analytical studies on the responses of sunflower (Helianthus annuus) to various defoliation treatments

The effects of defoliation treatments on plant growth in sunflower (Helianthus annuus) were studied in the field. Four defoliation treatments, 0 (control), 37.4, 56.1 and 93.4% of the total leaf dry weight, were applied to plants that had small third leaves. Decreased leaf weight/whole plant weight (F/W) ratios in defoliated plants rapidly recovered to almost the same ratio as that observed in the control within 12 to 16 days after defoliation according to the degree of defoliation. The mechanism involved in the recovery of the F/W ratio in defoliated plants mainly consisted of three parameters: enhancement of (1) carbon distribution ratios in the leaves, (2) photosynthetic activity in the remaining leaves, and (3) retranslocation of carbon from the stem and/or roots to leaves. Inhibitive effects of defoliation on relative growth rate and net assimilation rate were seen at an early stage, but subsequently both rates became larger in defoliated plants than in controls. Defoliated plants tended to show rapid development and expansion of new leaves, and to show increased specific leaf area and protein synthesis in individual leaves. The sugar content of leaves in defoliated plants was higher than that in controls, while the content in both stem and roots was lower. These responses seem to be advantageous for development of the photosynthetic system. Heights of defoliated plants were clearly depressed according to the degree of defoliation, and this was attributed largely to differences in the elongation rates of the internodes resulting from defoliation.     

嫁接的西瓜果实发育过程中叶和果实蔗糖代谢的一些特性

嫁接瓜果实发育过程中,叶内蔗糖含量和干物质积累显著高于自根瓜,自根瓜和嫁接瓜的叶中蔗糖含量与酸性转化酶（AI）、蔗糖磷酸合酶（SPS）活性均呈显著正相关;嫁接瓜果实中蔗糖含量显著低于自根瓜,SPS活性和果实中糖分的跨液泡膜运输能力亦较自根瓜低;自根瓜和嫁接瓜叶的干物质积累与叶中AI和SPS活性、果实AI活性呈显著负相关,与液泡膜H^＋-ATPase活性呈显著正相关。     

2种石蒜生长发育期鳞茎内源激素的动态变化

应用酶联免疫吸附测定法（ELISA）研究了石蒜与中国石蒜不同生长发育期鳞茎内源激素质量摩尔浓度的动态变化,分析了内源激素与2种石蒜生长发育的关系。结果表明,花芽分化前期2种石蒜鳞茎IAA浓度较低,而iPAs、ABA与GAs浓度较高;临近抽葶IAA浓度均有所增加,而iPAs与Zrs、ABA与GAs浓度均降到极值。花期ABA、GAs与ZRs浓度均有所回升,说明高浓度的ABA与GAs对2种石蒜的开花可能起正向调控的作用,但对叶生长的协同规律不明显。内源激素比例分析表明,ZRs/IAA、GAs/IAA、ABA/GAs三者比例高有利于2种石蒜的花原基分化,三者比例低则有助于2种石蒜的叶生长。     

IAA level and dry matter accumulation at different positions within a wheat ear

Dry matter accumulation and IAA level of grains in various positions within the wheat ( Triticum aestivum L. cvs Solo and Kolibri) ear were investigated during the grain filling period. Main shoot ears were partitioned into basal, central and apical regions and further into proximal and distal grains. Results from a two-year experiment with two wheat cultivars of different grain size are presented. The IAA level increased rapidly from about 8 until 20 to 30 days after anthesis, and then decreased dependent upon year and cultivar. The differences in IAA levels, both among spikelets in different regions of the ear (i.e. basal, central and apical) and also among florets within a spikelet (i.e. proximal and distal), were positively correlated with the differences in dry matter accumulation. Although the correlations held true within cultivars in a particular year, differences in dry matter between cvs Solo and Kolibri or differences from year to year were not well correlated with the corresponding changes in IAA levels. Possible interactions between dry matter accumulation and IAA levels are briefly discussed.     

Abscisic acid mimics effects of dehydration on area expansion and photosynthetic partitioning in young soybean leaves

Abstract. Leaf area expansion, photosynthetic carbon dioxide uptake and leaf dry mass accumulation were compared for expanding leaves of well-watered soybean ( Glycine max [L.] Merr.) plants, mildly dehydrated plants and well-watered plants treated with abscisic acid (ABA). Both ABA treatment and dehydration reduced area expansion in the light and over a 24 h period without decreasing the photosynthetic rates of expanding leaves. Dry mass accumulation during the light was less in ABA-treated and water-stressed leaves than in control leaves, with no differences among treatments in leaf mass per unit of area. ABA treatment and water stress both increased export of carbon from expanding leaves in the light. ABA applied near the end of the light period also increased export of carbon during the following dark period. However, it is unlikely that decreased availability of photosynthate caused slow expansion in the ABA and dehydration treatments, because expansion rates were not slowed in plants kept in dim light, even though photosynthetic rates and dry mass accumulation rates were greatly reduced. The data suggest that ABA may mediate the effects of mild dehydration on leaf area expansion and partitioning of photosynthate.     

基于源库生长单位的温室番茄干物质生产-分配模拟

为了量化研究温室番茄果穗间干物质的分配,提高温室番茄栽培的效益,采用源库生长单位的测定方法,将经典的单叶同化物生产模型与GreenLab模型相结合,构建了干物质向源库生长单位内茎节、叶片、果实分配的动态模型,利用越冬茬、早春茬和春夏茬温室番茄各器官的干物质测定数据对模型进行了验证.结果表明:所构建的模型模拟结果与实测结果吻合性较好,不同茬口同化物生产模拟值与实测值的回归方程斜率为0.93,R~2为0.92;源库生长单位内茎节、叶片、果实以及根系的模拟值与实测值间回归方程斜率在0.85～0.89之间,其相对误差(R_e)均值分别为5.3%、5.6%、8.1%和3.6%,说明模型的模拟准确度较高,可为不同茬口温室番茄栽培管理提供理论依据和决策支持.     

Effects of fruit set sequence and defoliation on cell number,cell size and hormone levels of tomato fruits (Lycopersicon esculentum Mill.) within a truss

Fruit size within a tomato (Lycopersicon esculentum Mill.) truss depends on both fruit position in the truss and the time of pollination among fruits. In the natural pollination sequence a difference of 5 days in the pollination of proximal and distal flowers results in significant final size differences between proximal and distal fruits. These final size differences were eliminated when all flowers were pollinated simultaneously. At anthesis proximal ovaries have higher cell numbers than distal ovaries but the cell division activity and cell enlargement in both positions was similar in the first 10 days of fruit growth. Simultaneous pollination resulted in lower cell numbers in proximal but higher cell numbers in distal fruits compared to control fruits.Hormone levels in different sized fruits were measured using radioimmunoassays. Cytokinin concentration during the cell division period indicated a possible role in the regulation of cell division. With other hormones no obvious correlations were found. The results are discussed in relation to factors determining final fruit size in tomato.     

Dry matter accumulation at specific pod positions on field bean (Vicia faba L.) plants and possible relations with indoleacetic acid and abscisic acid levels

Seed weights at specific positions within inflorescences of field bean plants (Vicia faba L.) were varied by removal of flowers. The inflorescences of two regions (nodes 3+4 and nodes 5+6, counted from the bottom of the plant) were used for manipulations and investigations. The two proximal flowers of the manipulated inflorescence were removed in order to vary the development and seed weights of distal pods (see Fig. 1). Dry matter accumulation and IAA- and ABA-concentrations in seeds were investigated during the filling period. Treatment effects in both regions were similar during two seasons. The removal of proximal flowers prevented the usually observed drop of distal pods and favoured the accumulation of dry matter and IAA in seeds, whereas the variation of ABA-concentrations partly depended on interaction with season. Whether these effects contribute to a signal leading to the establishment of processes preceeding dry matter accumulation or are a consequence of such processes is questionable.     

Dry Matter Partitioning in Tomato: Validation of a Dynamic Simulation Model

A model for dynamic simulation of dry matter distribution betweenreproductive and vegetative plant parts and the distributionamong individual fruit trusses in glasshouse tomato, is validated.The model is part of the crop growth model TOMSIM and is basedon the hypothesis that dry matter distribution is regulatedby the sink strengths of the plant organs, quantified by theirpotential growth rates, i.e. the growth rates at non-limitingassimilate supply. Within the plant, individual fruit trussesare distinguished and sink strength of a truss is describedas a function of its development stage. Truss development rateis a function of temperature only. The same potential growthcurve, proportional to the number of fruits per truss, is adoptedfor all trusses. In a simple version of the model, vegetativeplant parts are lumped together as one sink with a constantsink strength. In a more detailed version, vegetative sink strengthis calculated as the sum of sink strengths of vegetative units(three leaves and stem internodes between two trusses). The model was validated for six glasshouse experiments, coveringeffects of planting date, plant density, number of fruits pertruss (pruning at anthesis), truss removal (every second trussremoved at anthesis), single- and double-shoot plants and atemperature experiment conducted in climate rooms at 17, 20or 23 °C. Daily increase in above-ground dry weight, averagedaily temperatures and number of set fruits per truss were inputsto the model. Both the simple and the more detailed model showedgood agreement between measured and simulated fraction of drymatter partitioned into the fruits over time. For the simpleversion of the model, the slope of the lines relating simulatedto measured fraction partitioned into the fruits (16 data sets),varied between 0.92 and 1.11, on average it was 1.04, implying4% over-estimation for this fraction. For the detailed modelthese numbers were slightly better: 0.89, 1.08 and 1.01, respectively.The temperature experiment revealed no important direct influenceof temperature on the ratio between generative and vegetativesink strength. Simulated truss growth curves showed reasonableagreement with the measurements, although both models over-estimated(17% on average) final dry weight of the lower trusses (truss1 –3) on a plant. Modelling dry matter partitioning basedon sink strengths of organs is promising, as it is a general,dynamic and flexible approach, showing good agreement betweenmeasurements and simulation for a range of conditions. Applicabilityof the model is, however, still limited as long as the numberof fruits per truss (flower and /or fruit abortion) is not simulated,as this is a major feedback mechanism in plant growth. Dry matter distribution; sink strength; glasshouse; model; partitioning; simulation; temperature; tomato; TOMSIM; validation     

Effect of temperature on biomass allocation in tomato (Lycopersicon esculentum)

Temperature may influence dry matter partitioning between fruits and vegetative plant parts either directly or indirectly through its influence on development, flower and/or fruit abortion. The objective of the present work was to investigate whether there is any direct effect of temperature on dry matter partitioning between fruits and vegetative plant parts in tomato. A greenhouse experiment was conducted, with alternating 3-week periods of high (23°C) and low (18°C) temperature setpoint. Dry matter partitioning during these 3-week periods was determined from destructive plant harvests at two levels of fruit pruning (3 and 7 fruits per truss). Indirect temperature effects on dry matter partitioning were excluded by fruit pruning.
On average, the fraction of dry matter distributed to the fruits during a 12-week period, starting with the flowering of the fifth truss (28 days after planting), was 0.53 (3 fruits per truss) and 0.70 (7 fruits per truss). These ratios were also calculated for every 3-week period separately and did not depend on the average temperature (18–24°C) during that period.
It is concluded that dry matter distribution in tomato is not significantly affected by temperature directly, which means that the temperature effect (18–24°C) on the generative sink strength is not much different from the temperature effect on the vegetative sink strength.