Photosynthate Partitioning into Starch in Soybean Leaves: II. IRRADIANCE LEVEL AND DAILY PHOTOSYNTHETIC PERIOD DURATION EFFECTS

Two photosynthetic periods and photosynthetic photon flux densities (PPFD) were used to study the relationship between the rate of photosynthesis and starch accumulation in vegetative soybean leaves (Merr. cv Amsoy 71). Plants grown in short daily photosynthetic periods (7 hours) had higher rates of CO₂ fixation per unit leaf dry weight and of leaf starch accumulation than plants grown in long daily photosynthetic periods (14 hours) irrespective of PPFD. CO₂ fixation rates per unit leaf area were similar in 7-hour and 14-hour plants grown at low PPFD but were highest in 14-hour plants at the high PPFD. When single leaves of 14-hour plants were given 7-hour photosynthetic periods, their rates of starch accumulation remained unchanged. The programming of starch accumulation rate and possibly of photosynthetic rate by the length of the daily photosynthetic period is apparently a whole-plant, not an individual leaf, phenomenon. Programming of chloroplast starch accumulation rate by length of the daily photosynthetic and/or dark periods was independent of PPFD within the ranges used in this experiment.     

Photosynthetic Carbon Metabolism in Leaves and Isolated Chloroplasts from Spinach Plants Grown under Short and Intermediate Photosynthetic Periods

Responses of foliar and isolated intact chloroplast photosynthetic carbon metabolism observed in spinach (Spinacia oleracea cv Wisconsin Bloomsdale) plants exposed to a shortened photosynthetic period (7-hour light/17-hour dark cycle), were used as probes to examine in vivo metabolic factors that exerted rate determination on photosynthesis (PS) and on starch synthesis. Compared with control plants propagated continuously on a 12-hour light/12-hour dark cycle, 14 to 15 days were required, subsequent to a shift from 12 to 7 hours daylength, for 7-hour plants to begin to grow at rates comparable to those of 12-hour daylength plants. Because of shorter daily durations of PS, daily demand for photosynthate by growth processes appeared to be greater in the 7-hour than in the 12-hour plants. The result was that 7-hour plants established a 1.5- to 2.0-fold higher total PS rate than 12-hour plants.

Intact chloroplasts isolated from the leaves of 7-hour plants (7-h PLD) displayed 1.5- to 2.0-fold higher PS rates than plastids isolated from 12-hour plants (12-h PLD). Plastid lamellae prepared from 7- and 12-h PLD isolates displayed equivalent rates of ferredoxin-dependent ATP and NADPH photoformation indicating that electron transport processes were not factors in the establishment of higher 7-h PLD PS rates. Analyses, both in leaves as well as intact PLD isolates, of dark to light transitional increases in Calvin cycle intermediates, e.g., ribulose-1,5-bisphosphate (RuBP) and 3-phosphoglycerate (3-PGA), as well as estimations of activities of RuBP carboxylase and fructose-1,6-bisphosphate phosphatase, indicated that 7-hour plant leaves displayed higher PS rates (than 12-hour plants), because there was a higher magnitude of activity of the Calvin cycle.

Although both the foliar level of starch and sucrose, as well as starch synthesis rate, often was higher in 7-hour compared with 12-hour plant foliage, the higher 7-hour plant total PS rates indicated that maximal sucrose and starch levels did not mediate any `feedback' inhibition of PS. The higher 7-hour plant foliar and PLD PS rates resulted in higher glucose-1-P levels as well as a higher ratio of 3-PGA:Pi, both factors of which would enhance the activity of chloroplast ADP-glucose pyrophosphorylase, and which were attributed to be causal to the higher starch synthesis rates observed in 7-hour plant foliage and PLD isolates.

     

Diurnal Pattern of Translocation and Carbohydrate Metabolism in Source Leaves of Beta vulgaris L

Transitions in carbohydrate metabolism and translocation rate were studied for evidence of control of export by the sugar beet (Beta vulgaris L. Klein E.) source leaf. Steady-state labeling was carried out for two consecutive 14-hour light periods and various quantities related to translocation were measured throughout two 24-hour periods. Starch accumulation following illumination was delayed. Near the end of the light period, starch stopped accumulating, whereas photosynthesis rate and sucrose level remained unchanged. At the beginning of the dark period there was a 75-minute delay before starch was mobilized. The rate of import to the developing sink leaves at night was similar to that during the day, whereas export decreased considerably at night.

Starch accumulation and degradation seemed to be initiated in response to the level of illumination. Cessation of starch accumulation before the end of the light period was initiated endogenously. Exogenous control appeared to be mediated by the level of sucrose in the source leaf while endogenous control seemed to be keyed to photoperiod or photosynthetic duration.

     

The response and recovery of nitrogen fixation activity in soybean to water deficit at different reproductive developmental stages

Soybean (Glycine max [L.] Merr.) N₂ fixation is a primary plant mechanism responsible for meeting plant-N demand during seed development. Nitrogen fixation is recognized as a drought-sensitive mechanism; however, N₂ fixation response to water deficit and N₂ fixation recovery at different reproductive stages are not well documented. We tested the hypothesis that water deficit during late reproductive stages would inhibit N₂ fixation and lead to the breakdown of essential leaf proteins and an inability to recover N₂ fixation. Acetylene reduction activity (ARA) and N redistribution response to a 5-d drought period at flowering (R2), early seed fill (R5), and late seed fill (R6) were evaluated in one genotype (Hendricks, maturity group 0). Control plants maintained high rates of nodule activity until late seed fill. Plants drought stressed at R2 and R5 recovered ARA after rewatering and in some cases had higher nitrogenase activity than control plants during mid-seed fill. Recovery of ARA on plants stressed at R2 and R5 was associated with higher shoot N concentration than control plants at maturity. Drought stress at R6 reduced ARA, and the inability to recover ARA after stress alleviation at R6 resulted in decreased individual seed mass, which was likely caused by an acceleration of leaf N redistribution and a shorter seed-fill period. Results emphasized the importance of soybean N₂ fixation during late seed development on seed yield and that the ability to recover N₂ fixation following drought is dependent upon crop developmental stage.     

Photosynthate Partitioning into Starch in Soybean Leaves: I. Effects of Photoperiod versus Photosynthetic Period Duration

Photosynthesis, photosynthate partitioning into foliar starch, and translocation were investigated in soybean plants (Glycine max (L.) Merr. cv. Amsoy 71), grown under different photoperiods and photosynthetic periods to determine the controls of leaf starch accumulation. Starch accumulation rates in soybean leaves were inversely related to the length of the daily photosynthetic period under which the plants were grown. Photosynthetic period and not photoperiod per se appears to be the important factor. Plants grown in a 14-hour photosynthetic period partitioned approximately 60% of the daily foliar accumulation into starch whereas 7-hour plants partitioned about 90% of their daily foliar accumulation into starch. The difference in starch accumulation resulted from a change in photosynthate partitioning between starch and leaf residual dry weight. Residual dry weight is defined as leaf dry weight minus the weight of total nonstructural carbohydrates. Differences in photosynthate partitioning into starch were also associated with changes in photosynthetic and translocation rates, as well as with leaf and whole plant morphology. It is concluded that leaf starch accumulation is a programmed process and not simply the result of a limitation in translocation.     

C-Photosynthate Partitioning and Translocation in Soybeans during Reproductive Development

Partitioning and translocation of ¹⁴C-photosynthates were examined during flowering and seed maturation in soybean (Glycine max [L.]Merr.) plants to quantify allocation to sugars, amino acids, organic acids, and starch and to study transport of C and N from leaves to reproductive sinks. The trifoliolate leaf at the eighth node was exposed to steady state levels of ¹⁴CO₂ for 2 hours, followed by immediate extraction and identification of radioactive assimilates in the fed leaf blade, tissues of the transport path (e.g. petiole and stem), and fruits if they were present. About one-third of the total ¹⁴C recovered from the leaf blades was in starch until late pod-filling, after which the proportion dropped to 16%. Sugars comprised 70% to 86% of the recovered ¹⁴C from soluble assimilates of the source leaf, with highest proportions occurring during late flowering and early pod-filling. Amino acids accounted for 8% to 17% of the ¹⁴C recovered from the soluble fraction, and were most evident during early flowering and mid to late pod-filling. The ¹⁴C-organic acids comprised from 3% to 14% of the soluble ¹⁴C-assimilates in leaves. Petioles consistently contained a higher percentage of recovered radioactivity in sugars (87-97%) and a lower percentage in amino acids (3-12%) than did leaf blades. ¹⁴C-Amino acids in petioles attained their highest levels during mid and late pod-filling, while ¹⁴C-organic acids comprised 2% or less of the recovered radioactivity after pod initiation. The distribution of ¹⁴C-assimilates in the internode below the source leaf was similar to that found in petioles. A comparison of the above data to calculated C and N requirements for seed development suggests that ¹⁴C-amino acids derived from current photosynthesis and translocated from source leaves supply at least 12% to 48% of the seed N depending on the stage of pod-filling.     

Light effects on development of an indeterminate plant

The peanut (Arachis hypogaea L.) plant is indeterminate in growth habit and day-neutral with respect to flower initiation. The Spanish-type cultivar used in this study begins flowering 3 to 4 weeks from planting under optimum environmental conditions. In this study, irradiance and photoperiod were used to alter the development of the peanut plant. Plants grown at low irradiance (300 microeinsteins per square meter per second) had the same number of leaves as the plants grown at high irradiance (500 microeinsteins per square meter per second), but they had a larger leaf surface area and were taller than plants grown at the high irradiance. However, flowering and other reproductive components (pegs, pods, and seeds) were reduced at low irradiance. Comparison of 8-, 12-, and 16-hour photoperiods at the high irradiance showed that the 16-hour photoperiod produced the largest amount of vegetative, but least amount of reproductive components. The plants grown at 8-hour photoperiod had one-third as much total leaflet area as plants grown at 16 hours, but six times more weight of mature seeds. The larger amount of photosynthetic surface (leaf area) did not result in more reproductive growth. The results indicate that the peanut plant may readily redistribute its available assimilates between vegetative and reproductive growth in response to irradiance and photoperiod.     

Photoperiodic Regulation of Photosynthate Partitioning in Leaves of Digitaria decumbens Stent

In leaves of pangolagrass (Digitaria decumbens Stent.), the proportion of photosynthate partitioned into starch adjusts to a change in daylength within 24 hours. After a single 14-hour long day, the relative starch accumulation rate is approximately 50% of that under 7-hour short days. This rapid response was exploited to study the light requirement for the perception of changes in daylength. It was found for short day-grown plants that: (a) 7-hour daylength extensions with dim white light (below the light compensation point for photosynthesis); (b) 7-hour daylength extensions with dim far red light (wavelengths greater than 690 nanomoles); or (c) 0.5-hour night-break irradiations with bright white light were all capable of producing about one-half of the effect of a 7-hour daylength extension with bright light. However, long periods of bright light were not required for a complete effect, since a 7-hour shifted short day (i.e. beginning 7 hours later than usual) was as effective as a 14-hour-long day itself. There was also a critical daylength between 11 and 12 hours for the transition between short-day and long-day partitioning patterns. Photoperiod determination depends, at least in part, on a nonphotosynthetic photoreceptor sensitive to both visible and far red irradiation. The duration of the photosynthetic period, as shown in experiments with low-pressure sodium lamps, does not by itself determine the response to daylength.     

Ozone affects gas exchange, growth and reproductive development in Brassica campestris (Wisconsin fast plants)

Exposure to ozone (O(3)) may affect vegetative and reproductive development, although the consequences for yield depend on the effectiveness of the compensatory processes induced. This study examined the impact on reproductive development of exposing Brassica campestris (Wisconsin Fast Plants) to ozone during vegetative growth. Plants were exposed to 70 ppb ozone for 2 d during late vegetative growth or 10 d spanning most of the vegetative phase. Effects on gas exchange, vegetative growth, reproductive development and seed yield were determined. Impacts on gas exchange and foliar injury were related to pre-exposure stomatal conductance. Exposure for 2 d had no effect on growth or reproductive characteristics, whereas 10-d exposure reduced vegetative growth and reproductive site number on the terminal raceme. Mature seed number and weight per pod and per plant were unaffected because seed abortion was reduced. The observation that mature seed yield per plant was unaffected by exposure during the vegetative phase, despite adverse effects on physiological, vegetative and reproductive processes, shows that indeterminate species such as B. campestris possess sufficient compensatory flexibility to avoid reductions in seed production.     

Adenylate and nicotinamide nucleotides in developing soybean seeds during seed-fill

Profiles of adenylate and nicotinamide nucleotides in soybean seeds were determined during seed-fill. The ATP content per seed increased during the early seed-filling stages to a level of 10 to 12 micrograms per seed. Seed ATP decreased after 40 days of development and reached its lowest level of less than 1 microgram at maturity. The ATP:ADP ratios were relatively constant at all seed development stages. Sharp increases in AMP levels during the late seed-fill stages were paralleled with a disappearance of ATP and ADP pools resulting in a reduced seed energy charge. Energy charge varied from the highest value of 0.78 at mid-seed-fill to less than 0.10 at maturity.     

Effects of fully open-air [CO2] elevation on leaf ultrastructure, photosynthesis, and yield of two soybean cultivars

The objective of this study was to investigate the effect of elevated (550 ± 17 ??mol mol^?1) CO₂ concentration ([CO₂]) on leaf ultrastructure, leaf photosynthesis and seed yield of two soybean cultivars [Glycine max (L.) Merr. cv. Zhonghuang 13 and cv. Zhonghuang 35] at the Free-Air Carbon dioxide Enrichment (FACE) experimental facility in North China. Photosynthetic acclimation occurred in soybean plants exposed to long-term elevated [CO₂] and varied with cultivars and developmental stages. Photosynthetic acclimation occurred at the beginning bloom (R1) stage for both cultivars, but at the beginning seed (R5) stage only for Zhonghuang 13. No photosynthetic acclimation occurred at the beginning pod (R3) stage for either cultivar. Elevated [CO₂] increased the number and size of starch grains in chloroplasts of the two cultivars. Soybean leaf senescence was accelerated under elevated [CO₂], determined by unclear chloroplast membrane and blurred grana layer at the beginning bloom (R1) stage. The different photosynthesis response to elevated [CO₂] between cultivars at the beginning seed (R5) contributed to the yield difference under elevated [CO₂]. Elevated [CO₂] significantly increased the yield of Zhonghuang 35 by 26% with the increased pod number of 31%, but not for Zhonghuang 13 without changes of pod number. We conclude that the occurrence of photosynthetic acclimation at the beginning seed (R5) stage for Zhonghuang 13 restricted the development of extra C sink under elevated [CO₂], thereby limiting the response to elevated [CO₂] for the seed yield of this cultivar.     

SOYBEAN GROWTH RESPONSES TO ENHANCED LEVELS OF ULTRAVIOLET-B RADIATION UNDER GREENHOUSE CONDITIONS

Soybean (Glycine max [L.] Merr. cv. Essex) was grown in an unshaded greenhouse under three levels of biologically effective ultraviolet-B (UV-B_BE) radiation (effective daily dose: 0, 11.5 and 13.6 kJ m^–2) for 91 days. Plants were harvested at regular intervals beginning 10 days after germination until reproductive maturity. Mathematical growth analysis revealed that the effects of UV-B radiation varied with plant growth stage. The transition period between vegetative and reproductive growth was the most sensitive to UV-B radiation. Intermediate levels of UV-B had deleterious effects on plant height, leaf area, and total plant dry weight at late vegetative and reproductive stages of development. Specific leaf weight increased during vegetative growth but was unaffected by UV-B during reproductive growth stages. Relative growth, net assimilation, and stem elongation rates were decreased by UV-B radiation during vegetative and early reproductive growth stages. Variation in plant responses may be due in part to changes in microclimate within the plant canopy or to differences in repair or protection mechanisms at differing developmental stages.     

Studies on Genetic Male-Sterile Soybeans : II. Effect of Nodulation on Photosynthesis and Carbon Partitioning in Leaves

Soybean (Glycine max L. Merr.) germplasm, essentially isogenic except for loci controlling male sterility (ms₁) and nodulation (rj₁), were developed to study the effects of reproductive development and nitrogen source on certain aspects of photosynthesis. Plants were sampled from flowering (77 days after transplanting) until maturity (150 days after transplanting). With all four genotypes, net carbon exchange rates were highest at flowering and declined thereafter. Photosynthetic rates of the sterile genotypes (nodulated and non-nodulated) declined more rapidly than the fertile genotypes, and after 105 days, both sterile genotypes maintained low but relatively constant carbon exchange rates (<3 milligrams CO₂/gram fresh weight per hour). Photosynthetic rates and starch accumulation (difference between afternoon and morning levels) declined with time. The sterile genotypes attained the highest morning starch levels, which reflected reduced starch mobilization. After 92 days, the proportion of photosynthetically fixed carbon that was partitioning into starch (relative leaf starch accumulation) in the sterile genotypes increased dramatically. In contrast, relative leaf starch accumulation in the fertile genotypes remained relatively constant with time. Throughout the test period, all four genotypes maintained leaf sucrose levels between 5 and 15 micromoles glucose equivalents per gram fresh weight.

The activities of sucrose phosphate synthase (SPS) in leaf extracts of the four genotypes declined from 77 to 147 days. Nodulated genotypes tended to maintain higher activities (leaf fresh weight basis) than did the non-nodulated genotypes. In general, relative leaf starch accumulation was correlated negatively with the activity of SPS (normalized with leaf net carbon exchange rate) in leaf extracts for all four genotypes during early reproductive development, and for the fertile genotypes at all sampling dates. In contrast, leaf sucrose content was correlated positively with SPS activity during early reproductive development. These results suggested that a direct relation existed between the activity of SPS and starch/sucrose levels in soybean leaves. However, the interaction between these processes also may be influenced by other factors, particularly when leaf photosynthetic rates and plant demand for assimilates is low, as in the sterile genotypes.

     

Effect of methabenzthiazuron on growth and nitrogenase activity in Vicia faba

The effects of the herbicide methabenzthiazuron (175 and 220 g ha^-1) on vegetative and reproductive growth, nodulation and nitrogenase activity of Vicia faba were studied in the field under Mediterranean conditions. Nitrogenase activity of excised nodules was estimated using the acetylene reduction assay four times during the developmental period. Leaf area index, dry weight and nitrogen content of the different parts of the plants were measured. Methabenzthiazuron-treated plants showed an increase in nodulation, nitrogenase activity and vegetative growth at early pod fill. Methabenzthiazuron also caused an increase in leaf N content and fruits. These were transient effects found during early and mid pot fill. Nevertheless, plants treated with these sublethal doses of herbicide improved seed production and nitrogen content of seeds at harvest time. The stimulatory effect of methabenzthiazuron on N₂ fixation and vegetative growth seems not be related with the transient stimulatory effect on photosynthetic capacity, also caused by the herbicide, since the stimulatory effect on N₂ fixation was apparent during pod fill, when photosynthetic capacity declined and was not modified by methabenzthiazuron.     

Phenology, growth, and response to light of ciruela Mexicana (Spondias purpurea L., Anacardiaceae)

The phenology of vegetative and reproductive patterns, shoot growth, and the physiological and anatomical plasticity of leaves of ciruela mexicana (Spondias purpurea L) exposed to different ranges of light are described. Flower and fruit production occur during the dry season. Shoot elongation occurs during late spring and summer. Growth rates of S. purpurea are similar to the rates reported for fast growing plants, when growing on rocky slopes in shallow infertile soils. Leaves exposed to the highest photosynthetic photon flux (PPF) had a thicker mesophyll than leaves that developed under the shade. Midday depression of photosynthesis was observed forS. purpurea. The reduction in the rates of net CO₂ uptake was related to high temperatures, high PPF, and increased leaf starch content. Plasticity in physiological and anatomical traits as observed in S. purpurea may be advantageous in the low-resource rocky environments where it grows.     

Changes in Carbohydrate Levels in Red Kidney Bean (Phaseolus vulgaris L.) Exposed to Sulphur Dioxide

Red kidney bean (Phaseolus vulgaris L.) was exposed to variousconcentrations of SO² for 24 h (16 h light/8 h dark photoperiod)with continuous monitoring of photosynthetic and respiratoryactivity. Plants were harvested at the end of the dark periodinto samples of mature and immature leaf tissue, stems, androots for determination of sugar and starch levels. In all tissue samples the levels of total sugars were increasedby exposure to the lower concentrations of SO², but decreasedby the higher concentrations. Starch levels in leaves followeda similar trend. Increases in sugar and starch levels precededsymptoms of visible injury. Decreasing rates of photosynthesiswere correlated with increasing rates of respiration, the occurrenceof visible injury, and the depletion of sugar and starch levels.     

Starch storage in the stems of wheat plants: localization and temporal changes

Background and Aims

Carbohydrate temporarily accumulates in wheat stems during the early reproductive growth phase, predominantly as water soluble carbohydrate (WSC), and is subsequently remobilized during grain filling. Starch has also been reported as a minor storage carbohydrate component in wheat stems, but the details are lacking.

Methods

The accumulation and localization of starch in wheat stem and leaf sheath tissue over a developmental period from 6 d before anthesis to 35 d after anthesis was investigated.

Key Results

The region of the peduncle enclosed by the flag-leaf sheath, and the penultimate internode were the main tissues identified as containing starch, in which the starch grains localized to the storage parenchyma cells. In contrast, the exposed peduncle lacked starch grains. Starch grains were also found in the flag-leaf and second-leaf sheath. Plants grown in low-nitrogen conditions exhibited increased storage of both starch and WSC compared with plants grown in high-nitrogen supply.

Conclusions

The major accumulation and decrease of starch occurred temporally independently to that for WSC, suggesting a different functional role for starch in wheat stems. Starch reutilization concomitant with peduncle growth, and the early development of the reproductive structures, suggested a role in provision of energy and/or carbon scaffolds for these growth processes.Key words: Carbohydrate partitioning, peduncle, starch, wheat stem, storage parenchyma, Triticum aestivum     

The effects of CO2 and nutrient enrichment on photosynthesis and growth of Poa annua in two consecutive generations

We studied short- and long-term growth responses of Poa annua L. (Gramineae) at ambient and elevated (ambient +200???mol?mol^?1) atmospheric CO₂. In experiment 1 we compared plant growth during the early, vegetative and final, reproductive growth phases. Plant growth in elevated CO₂ was significantly enhanced during the early phase, but this was reversed in the reproductive phase. Seed mass and percentage germination were significantly reduced in elevated CO₂. Experiment 2 tested for the impact of transgenerational and nutrient effects on the response of Poa annua to elevated CO₂. Plants were grown at ambient and elevated CO₂ for one or two consecutive generations at three soil nutrient levels. Leaf photosynthesis was significantly higher at elevated CO₂, but was also affected by both soil nutrient status and plant generation. Plants grown at elevated CO₂ and under conditions of low nutrient availability showed photosynthetic acclimation after 12?weeks of growth but not after 6?weeks. First-generation growth remained unaffected by elevated CO₂, while second-generation plants produced significantly more tillers and flowers when grown in elevated CO₂ compared to ambient conditions. This effect was strongest at low nutrient availability. Average above- and belowground biomass after 12?weeks of growth was enhanced in elevated CO₂ during both generations, but more so during plant generation 2. This study demonstrates the importance of temporal/maternal effects in plant responses to elevated CO₂.     

Reversibility of Photosynthetic Inhibition in Cotton after Long-Term Exposure to Elevated CO(2) Concentrations

Cotton (Gossypium hirsutum L. cv Stoneville 213) was grown at 350 and 1000 microliters per liter CO₂. The plants grown at elevated CO₂ concentrations contained large starch pools and showed initial symptoms of visible physical damage. Photosynthetic rates were lower than expected based on instantaneous exposure to high CO₂.

A group of plants grown at 1000 microliters per liter CO₂ was switched to 350 microliters per liter CO₂. Starch pools and photosynthetic rates were monitored in the switched plants and in the two unswitched control groups. Photosynthetic rates per unit leaf area recovered to the level of the 350 microliters per liter CO₂ grown control group within four to five days. To assess only nonstomatal limitations to photosynthesis, a measure of photosynthetic efficiencies was calculated (moles CO₂ fixed per square meter per second per mole intercellular CO₂). Photosynthetic efficiency also recovered to the levels of the 350 microliters per liter CO₂ grown controls within three to four days.

Recovery was correlated to a rapid depletion of the starch pool, indicating that the inhibition of photosynthesis is primarily a result of feedback inhibition. However, complete recovery may involve the repair of damage to the chloroplasts caused by excessive starch accumulation. The rapid and complete reversal of photosynthetic inhibition suggests that the appearance of large, strong sinks at certain developmental stages could result in reduction of the large starch accumulations and that photosynthetic rates could recover to near the theoretical capacity during periods of high photosynthate demand.

     

Variability in growth and reproduction in F1-families of an Erophila verna population

Summary Seeds from two morphologically different groups in an Erophila verna dune population were used in a growth experiment to analyse and quantify flexibility and plasticity of growth and reproductive characteristics.A strong correlation between plant morphology and individual seed weight was shown in parents and progeny. Seeds of plants with narrow leaves were twice as heavy (H-plants) as those from plants with broad leaves (L-plants) Families of H-plants allocated ca. 10% more dry matter to the roots. These characters were fixed, presumably due to selfing. Plants of both types are characterized by a graded control function between the vegetative and the reproductive phase. Most of the families showed a single switch from vegetative to reproductive growth, two families showed even two switch periods.Between-family differentiation is interpreted as a result of multiniche selection in populations of Erophila verna. Within-family variation is disadvantageous due to low fecundity.