Carbohydrate Supply Research Articles

Interactions of H2 and carbon metabolism in moderating nitrogenase activity of the Gunnera/Nostoc symbiosis

Nitrogenase activity in the Gunnera Nostoc symbiosis is shown to respond dramatically to the addition of glucose. H2 can replace glucose in stimulating nitrogenase activity, but there is no H2 stimulation in the presence of excess glucose. Net hydrogen evolution is strongly stimulated by addition of glucose. We postulate that carbohydrate supply and uptake hydrogenase can moderate the apparent activity of nitrogenase by supplying reductant and/or ATP. The recycling of a large proportion of the electron flux in nitrogenase through uptake hydrogenase maintains a high level of potential nitrogenase ready to take advantage of an influx of carbohydrate.

The Effect of the Accumulation of Carbohydrate and Organic Nitrogen on Nitrogen Fixation (Acetylene Reduction) of Faba Bean cv. Fiord

Plants of faba bean cv. Fiord were grown under controlled conditions, without mineral N, in coarse river sand. Twenty-five days after sowing when plants had at least eight fully opened leaves and were nodulated and actively fixing N2, half were topped and kept debudded for 21 d. Changes in dry weight, N2 fixation (acetylene reduction activity), soluble carbohydrate, starch, soluble N and total N in plants were monitored over the period.Both debudded and control plants grew and accumulated dry matter. Debudding resulted in a significant increase in the concentration of soluble carbohydrate, starch and soluble N. but had only a small effect on the total N concentration. A strong positive linear relation between total plant weight and N content of both control and debudded plants showed that even under conditions of excess supply of carbohydrate, faba beans have little capacity to store N. Soluble N accumulated in debudded plants presumably because less N was needed for the formation of new tissues than in control plants. AR continued to increase throughout the experiment in control plants but declined in debudded plants from 6 to 13 d after debudding and remained low until the end of the experiment. The decline was associated with an increase in available carbohydrate and in soluble N. The results of this experiment are consistent with a feed back control of N2 fixation by the soluble pool of N.

Causes of Growth Reduction in Elongating and Expanding Leaf Tissue of Sugarcane Under Saline Conditions

Plants of sugarcane, cv. Co 1148, were subjected to salinisation with 200 milliequivalents L-1 of Cl- -type salts mixture (having Na+, Ca2+ and Mg2+ as 3 :1:1 and Cl- and SO42- as 4:1 on a milli- equivalent basis) for two weeks or more during the tillering phase. Soluble sugar concentrations increased by 55% in the blades of recently matured leaves (source tissues) and by nearly 225% in the elongating sheath bases (sink tissues) as a result of salinisation. Leaf elongation within 3 h of desalin- isation was much faster than for the non-saline controls. The accumulated sugars also dropped in the rapidly elongating sheath bases by 43% during this period after desalinisation. Further, the drop in sugar levels upon desalinisation was of greater magnitude in the more rapidly growing sheath bases. The present studies indicate that even though the supply of carbohydrates from the source tissues is reduced, the sink tissues are not able to make use of these sugars under saline conditions. As Na+ and Cl- concentrations did not change within 3 h of desalinisation, the ions themselves did not appear to affect metabolic activities of the sink tissues; this suggestion is further supported by the utilisation of accumulated sugars within 3 h of desalinisation.

Planting density effects on dry matter partitioning and productivity of sunflower hybrids

Abstract Dry matter partitioning and yield formation are key points for successful simulation of seed yield. The response of dry matter partitioning and yield of sunflower (Helianthus annuus L.) to plant population was studied in field experiments performed at Cordoba, Spain in 1990 and 1991. Four hybrids (SW-101, Arbung E353, Sungro 385 and S530) were grown under irrigation at plant populations ranging from 0.5 to 10 plants m−2. The hybrids differed in the durations of the emergence-floral initiation (FI) and FI-anthesis periods but not in the duration of seed filling. The responses of biomass, seed number and yield to planting density were dependent on the hybrid. The leaf partitioning coefficient decreased and the head partitioning coefficient increased with increasing plant population, suggesting that the head has a priority for dry matter partitioning. The number of seeds per head changed with plant population through changes in the number of flowers and in the fertility ratio of the central part of the capitulum. Single-seed mass decreased with increasing planting density while the amount of oil per seed was little affected, showing the dependence of oil accumulation on factors other than carbohydrate supply. Seed yield response to planting density followed a saturation-type curve with the plateau around 4.5 t ha−1, indicating that potential yields under irrigation can be achieved by using short-cycle cultivars if plant population is high enough. Increasing potential yield of the sunflower should focus on the improvement of the harvest index of the long-cycle hybrids.

Carbohydrate and mineral nutrition of orange fruitlets in relation to growth and abscission

Carbohydrate and mineral nutrition was studied in relation to abscission in fruitlets from leafy inflorescences of the Washington navel orange (Citrus sinensis [L.] Osbeck). Differences in the growth rate of the fruitlets permitted to predict abscission several weeks in advance. This allowed characterization of early differences in composition and behaviour of persisting and abscising fruitlets.Inflorescences with persisting fruitlets accumulated more mineral elements than inflorescences with abscising fruitlets, and for the phloem‐mobile elements the excess accumulation was allocated to the fruitlets. Starch accumulated in the inflorescence leaves during early fruitlet growth, and this accumulation was enhanced by the persisting fruitlets despite their higher growth rate and mobilizing ability. The relations between the fruitlets and the inflorescence leaves cannot be explained totally in terms of source sink relationships; a hormonal regulation of the leaves by the fruitlets is postulated.Acid invertase activities and hexose concentration in the pericarp were higher in the abscising fruitlets. The lower early growth rate of these fruitlets is thus not caused by a limitation in carbohydrate supply. It seems more related to carbohydrate utilization, probably hormonally mediated, as demonstrated by the higher dependence on hormone supply for the growth in vitro of the endocarp explants.

Effects of Ambient CO2 Concentration on Growth and Nitrogen Use in Tobacco (Nicotiana tabacum) Plants Transformed with an Antisense Gene to the Small Subunit of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase.

Growth of the R1 progeny of a tobacco plant (Nicotiana tabacum) transformed with an antisense gene to the small subunit of ribulose-1,5-carboxylase/oxygenase (Rubisco) was analyzed under 330 and 930 [mu]bar of CO2, at an irradiance of 1000 [mu]mol quanta m-2 s-1. Rubisco activity was reduced to 30 to 50% and 13 to 18% of that in the wild type when one and two copies of the antisense gene, respectively, were present in the genome, whereas null plants and wild-type plants had similar phenotypes. At 330 [mu]bar of CO2 all antisense plants were smaller than the wild type. There was no indication that Rubisco is present in excess in the wild type with respect to growth under high light. Raising ambient CO2 pressure to 930 [mu]bar caused plants with one copy of the DNA transferred from plasmid to plant genome to achieve the same size as the wild type at 330 [mu]bar, but plants with two copies remained smaller. Differences in final size were due mostly to early differences in relative rate of leaf area expansion (m2 m-2 d-1) or of biomass accumulation (g g-1 d-1): within less than 2 weeks after germination relative growth rates reached a steady-state value similar for all plants. Plants with greater carboxylation rates were characterized by a higher ratio of leaf carbon to leaf area, and at later stages, they were characterized also by a relatively greater allocation of structural and nonstructural carbon to roots versus leaves. However, these changes per se did not appear to be causing the long-term insensitivity of relative growth rates to variations in carboxylation rate. Nor was this insensitivity due to feedback inhibition of photosynthesis in leaves grown at high partial pressure of CO2 in the air (pa) or with high Rubisco activity, even when the amount of starch approached 40% of leaf dry weight. We propose that other intrinsic rate-limiting processes that are independent of carbohydrate supply were involved. Under plentiful nitrogen supply, reduction in the amount of nitrogen invested in Rubisco was more than compensated for by an increase in leaf nitrate. Nitrogen content of organic matter, excluding Rubisco, was unaffected by the antisense gene. In contrast, it was systematically lower at elevated pa than at normal pa. Combined with the positive effects of pa on growth, this resulted in the single-dose antisense plants growing as fast at 930 [mu]bar of CO2 as the wild-type plants at 330 [mu]bar of CO2 but at a lower organic nitrogen cost.

Characterization of sugar moieties and oligosaccharide sequences in the distal intestinal epithelium of the rainbow trout by means of lectin histochemistry

Lectin histochemical study was performed on the distal intestinal mucosa of the rainbow trout. A panel of 25 biotinylated leetins for detection of sugar residues and oligosaccharide sequences of glycoconjugates on Bouin's solution‐fixed paraffin embedded sections were used as probes. The avidin‐biotin‐peroxidase complex (ABC) was used to visualize the binding sites of lectins. A rich supply of carbohydrates was detected in this gut mucosal region. Marked differences in lectin labelling of goblet cells and enterocytes (absorptive cells) probably reflect various functional activities. The results are compared with those (scarce) obtained from other teleosts. Species differences in carbohydrate residue composition may be related to various feeding habits. The roles of posterior intestinal glycoconjugates in host‐parasite interaction, macromolecular ingestion and immunological implications are discussed.

Characterization of sugar moieties and oligosaccharide sequences in the distal intestinal epithelium of the rainbow trout by means of lectin histochemistry

Lectin histochemical study was performed on the distal intestinal mucosa of the rainbow trout. A panel of 25 biotinylated leetins for detection of sugar residues and oligosaccharide sequences of glycoconjugates on Bouin's solution-fixed paraffin embedded sections were used as probes. The avidin-biotin-peroxidase complex (ABC) was used to visualize the binding sites of lectins. A rich supply of carbohydrates was detected in this gut mucosal region. Marked differences in lectin labelling of goblet cells and enterocytes (absorptive cells) probably reflect various functional activities. The results are compared with those (scarce) obtained from other teleosts. Species differences in carbohydrate residue composition may be related to various feeding habits. The roles of posterior intestinal glycoconjugates in host-parasite interaction, macromolecular ingestion and immunological implications are discussed.

Interactive effects of high temperature and elevated carbon dioxide concentration on cowpea [Vigna unguiculata(L.) Walp.

ABSTRACTLimitations in carbohydrate supplies have been implicated as a factor responsible for reproductive failure under heat stress. Heat stress affects two stages of reproductive development in cowpea [Vigna unguiculata(L.) Walp.], and genotypes are available with tolerance and sensitivity to heat during these different stages. The objectives of this study were to determine the responses of these cowpea lines to ambient and elevated [CO2], under heat stress and optimal temperature, and test whether differences in carbohydrate supplies due to genotypes, CO2enrichment and heat stress are associated with differences in sensitivity to heat during reproductive development. Plants were grown in reach‐in growth chambers and subjected to day/night temperatures of either 33/20 or 33/30°C, and [CO2] levels of either 350 or 700 μmol mol‐1. Under intermediate night temperature (33/20°C), all lines set substantial numbers of pods. Under high night temperature (33/30°C) with either ambient or elevated [CO2], one heat‐sensitive line produced no flowers and the other set no pods, whereas the heat‐tolerant line abundantly set pods. High night temperature reduced the overall carbohydrate content of the plants, especially peduncle sugars, and caused decreases in photosynthetic rates. The high pod set of the heat‐tolerant line, under high night temperature, was associated with higher levels of sugars in peduncles compared with the heat‐sensitive lines. The heat‐tolerant line accumulated substantial shoot biomass, exhibited less accumulation of starch in leaves, and possibly had less down‐regulation of photosynthesis in response to CO2enrichment and heat stress than the heat‐sensitive lines. Elevated [CO2] resulted in higher overall carbohydrate levels in heat‐sensitive lines (starch in leaves, stems and peduncles), but it did not increase their heat tolerance with respect to flower production or pod set. Heat‐induced damage to floral buds and anthers in the sensitive lines was associated with low sugars levels in peduncles, indicating that heat had greater effects on assimilate demand than on leaf assimilate supply. The heat‐tolerant line was the most responsive genotype to elevated [CO2] with respect to pod production under either high or intermediate temperatures.

Effects of leaf blast on growth and production of a rice crop

Rice crops grown under irrigated conditions were inoculated withPyricularia oryzae during early growth stages to study the effect of leaf blast on yield formation. The inoculations led to severe epidemics of leaf blast around maximum tillering, characterized by the presence of typical blast lesions and an accelerated senescence of heavily infested leaf tissue. Leaf blast led to a prolonged tillering and a delay in flowering and maturity. Crop growth rate and leaf area formation declined sharply during establishment of the disease and continued to be reduced till maturity. This resulted in a marked reduction of total dry matter production and grain yield. Dry matter distribution was not affected. Leaf blast reduced spikelet number, 1000 grain weight, and the fraction filled grains. From this last observation it was concluded that the reduction in grain yield was exclusively source determined. Nitrogen uptake of the inoculated crops before flowering was reduced compared to the N uptake of the control crop, but shoot N content of the inoculated crops at flowering was higher. Uptake of nitrogen after flowering was negligible in both healthy and inoculated crops. Redistribution from vegetative tissue was therefore the main source of N for grain growth. The higher N content of the shoot organs in the inoculated crops during ripening led to the conclusion that the reduced N uptake was not responsible for the yield reduction observed. Consequently, the reduction in grain yield was solely determined by a reduced carbohydrate supply.

Nutritional Regulation of Postruminal Digestive Enzymes in Ruminants

Nutritional regulation of digestive enzymes has received limited study in ruminants. Comparable studies with non-ruminants report adaptations occurring in pancreatic and mucosal enzyme concentrations and synthesis in response to increased consumption of carbohydrate, lipid, or protein. Adaptations in carbohydrases apparently are mediated through changes in blood glucose and insulin, and changes in lipase are mediated through changes in circulating β-hydroxybutyrate. Increased synthesis and secretion of pancreatic proteases apparently are mediated directly through luminal effects of protein, possibly through a messenger peptide. Available information for ruminants suggests that pancreatic α-amylase concentration increases with increased energy intake, but not with increased carbohydrate intake, independent of energy. This result may indicate an adaptation mechanism similar to that of nonruminants, one that is mediated through increased glucose turnover, not intestinal carbohydrate supply alone. Increased intake of energy or increased intestinal supply of carbohydrates results in little or no increase in mucosal carbohydrases in the ruminant. Comparable data for effects of changing intestinal supply of protein are limited to the developing ruminant. Experiments involving lipid feeding are not available, but duodenal lipid infusion decreases pancreatic lipase secretion. Ruminant data are inadequate to predict accurately an adaptive response to feeding any diet.

Control of root growth: effects of carbohydrates on the extension, branching and rate of respiration of different fractions of wheat roots

Rates of extension, numbers of laterals and rates of respiration were measured in different fractions of wheat (Triticum aestivum L. cv. Alexandria) roots following changes in carbohydrate supply. The supply of carbohydrate was varied by selective pruning and exogenously fed sugars. Pruning shoots to a single leaf (leaf‐pruning) reduced the rate of O2 uptake by intact roots. Rates were not stimulated by shortterm feeding of sucrose (25 mM), but were stimulated by the uncoupler p‐trifluoro‐methoxy(carbonylcyanide)phenylhydrazone (FCCP). Feeding glucose to roots of leaf‐pruned and non‐pruned plants for 16–24 h increased the rate of O2 uptake. It is concluded that respiration is under fine control by adenylates and coarse control by carbohydrate supply, with carbohydrates regulating directly the rate of some energy consuming process(es). These energy consuming processes are located in growing tissue fractions. Feeding glucose to leaf‐pruned and non‐pruned plants increased rates of O2 uptake in seminal root tips, the zone of developing lateral primordia and mature root sections with elongating laterals, but had no effect on mature sections from which the laterals had been excised. Leaf‐pruning reduced the extension rate of seminal axes and first‐order laterals when measured over 24 h. Feeding glucose to roots from the time of pruning increased the rate, but did not fully restore it to control values. Pruning roots to a single seminal axis (root‐pruning) and feeding glucose to non‐pruned plants had no effect on the extension rate of the seminal axis or its laterals over this time period, although rates were increased by root‐pruning when measured over 3 days. The number of lateral root primordia was reduced by leaf‐pruning and increased by root‐pruning and feeding glucose. The results are discussed in terms of the role of carbohydrates in the control of root growth and branching.

Effect of shade stress on growth, morphology, and carbon dynamics of loblolly pine branches

Shade treatments were applied to the terminal portions of branches in loblolly pine trees to test whether portions of branches were autonomous with respect to carbohydrates. The shade treatments reduced light by 50% and 72% compared with full sun conditions resulting in significant reductions in net photosynthesis. Branch growth (branch diameter and length, branch and needle biomass) decreased significantly within the shaded portion of the branch. Branch and needle morphology were also affected by shading. Lateral branches subtending terminal shoots were labelled with 14C 2 times during the growing season. No movement of 14C into the terminal portions of the branch was evident during the first growth flush. However, during the second flush of growth small but statistically significant amounts of 14C were imported into the terminal portion of the shaded branches from subtending laterals. It was concluded that loblolly pine shoots were usually autonomous with respect to carbohydrate supply, but that carbohydrate movement into the terminal shoot from subtending foliage could occur under conditions of very high stress.

Some aspects of perinatal maturation and adaptation

Physiological challenges facing the perinatal individual are huge. This is partly because of the marked and abrupt change from the intrauterine to the extrauterine environment, but also because the physiological responses to that change depend upon systems whose maturation is affected markedly by birth. Perinatal maturation appears, therefore, both to precede and accompany the physiological adaptations required for neonatal survival. This review does not provide a comprehensive coverage of perinatal physiology but directs attention towards evaluating constraints on foetal and neonatal thermogenesis, especially those imposed by post-natal availability of metabolic fuels in body reserves deposited before birth and acquired in colostrum and milk after birth. The relative importance of the supply of carbohydrate from body reserves and colostrum is examined. Carbohydrate is the major rate-limiting substrate with respect to heat production. It is shown that in the normal birth environments of several species, including the horse, colostral supply of lactose is not adequate to meet the entire carbohydrate needs of the neonate. It must, therefore, draw on its body glycogen reserves to sustain the required rates of heat production during the first day after birth. Gastrointestinal maturation and growth play a major part in the initial and continued provision of substrates for general metabolism and growth. Pre-natal and post-natal development of the stomach and intestines in a number of species are considered, including their disproportionately large growth compared with the body as a whole during the first 1-3 days after birth. Possible contributions to gastro intestinal growth and body growth of milk-borne growth factors such as epidermal growth factors and the insulin-like growth factors are considered. The role, as a possible significant stimulus to gastrointestinal growth and maturation immediately after birth, of the high levels of these growth factors in colostrum is evaluated.

A Two-dimensional, Dynamic Model for Root Growth Distribution of Potted Plants

A two-dimensional mathematical model was developed to describe the time course of root growth and its spatial distribution for container-grown plants, using chrysanthemum [Dendranthema ×grandiflorum (Ramat.) Kitamura] as the model system. Potential root growth was considered as consisting of several concurrent processes, including branching, extension, and death. Branching rate was assumed to be related sigmoidally to existing root weight density. Root growth extension rate was assumed to be proportional to the existing root weight density above some threshold root weight density in adjacent cells. The senescence rate of root weight density was assumed to be proportional to existing root mass. The effects of soil matric potential and temperature on root growth were quantified with an exponential function and the modified Arrhenius equation, respectively. The actual root growth rate was limited by the amount of carbohydrate supplied by the canopy to roots. Parameters in the model were estimated by fitting the model to experimental data using nonlinear regression. Required inputs into the model included initial root dry weight density distribution, soil temperature, and soil water potential data. Being a submodel of the whole-plant growth model, the supply of carbohydrates from canopy to roots was required; the total root weight incremental rate was used to represent this factor. Rather than linking to a complex whole-plant C balance model, the total root weight growth over time was described by a logistic equation. The model was validated by comparing the predicted results with independently measured data. The model described root growth dynamics and its spatial distribution well. A sensitivity analysis of modeled root weight density to the estimated parameters indicated that the model was more sensitive to carbohydrate supply parameters than to root growth distribution parameters.

Glycogen metabolism in relation to fruit body maturation in Coprinus cinereus

During development of the fruit body of Coprinus cinereus large quantities of glycogen are accumulated in the cap and are subsequently degraded during basidiospore formation. The major increase of glycogen concentration was initiated as karyogamy became evident in normally developing fruit bodies and the onset of large-scale utilization of accumulated glycogen was a post-meiotic event. The temporal pattern of glycogen accumulation/degradation was very variable among 23 different fruit body caps when judged on a common developmental time scale. This indicates that glycogen content was not closely associated with meiosis or basidiospore formation even though glycogen degradation usually started from about the onset of the latter. Glycogen phosphorylase was the only glycogen degradation enzyme found in cap tissues. Glycogen synthase activity could be demonstrated (and increased with time) even during the phase of most rapid glycogen degradation. Analysis of glycogen contents during in vitro gill development and in sporeless, stem elongationless and cap expansionless mutants suggested that glycogen degradation was not specific for any one of these processes. Nutrient translocation occurred mainly in the ‘stem to cap’ direction and glycogen influx to the cap continued into the phase of glycogen degradation in the cap. The overall conclusion is that glycogen acts as a carbohydrate supply which cannot be linked exclusively, or even predominantly, with any one of the several processes which occur as the fruit body matures but rather serves any or all of those processes as required.

Analysis of the cowpea agro-ecosystem in West Africa. I. A demographic model for carbon acquisition and allocation in cowpea, Vigna unguiculata (L.) Walp

A demographic canopy model for a photosensitive cowpea [ Vigna unguiculata (L.) Walp.] variety, whose growth and development is driven by temperature, solar radiation, soil phosphate, and water is presented. The dynamics of age-structured populations of leaves, shoots, roots, peduncles, and other reproductive organs having numbers and dry matter attributes is simulated by a time-varying distributed delay model with attrition. A modified functional response model from predation theory is used to estimate the daily photosynthates acquisition. Dry matter allocation is simulated by a metabolic pool model. Growth and yield formation of the plant are driven by the computed ratio between carbohydrates supply and demand. Simulation results are compared with four sets of field data. Further, the model has been used to evaluate the effect of drought stress and different levels of available phosphate in the soil. The model is designed for research purposes, to be used as a tool for further studies of the cowpea agro-ecosystem.

Carbohydrate and lipid oxidation during exercise

In this paper, evidence is put forward to suggest that sheep are well adapted to maintain a supply of carbohydrate for contracting muscle when compared to other mammals such as the human athlete. This is achieved by a remarkable ability to maintain or even elevate glucose concentration in the blood through 'feed forward' control of glucose metabolism. Glycogen, whether hepatic or muscle, is also readily utilized at work rates above the anaerobic threshold. The ability to replace glycogen is substantial in sheep which are adapted to exercise and in type IIA muscle is not greatly lower than in non-ruminant animals. Aspects of long chain fatty acid (NEFA) metabolism are also discussed. An interesting finding in sheep is the partial oxidation of NEFA to acetate during sustained exercise at above the anaerobic threshold. This represents a mechanism to increase the power of fat oxidation and deserves attention in other species.

Development, calibration and validation of a greenhouse tomato growth model: I. Description of the model

A dynamic crop growth model, TOMGRO, for an indeterminate tomato variety is presented. The model describes the phenological development and increase in dry weight of various organs (roots, stem nodes, leaves and fruits) from planting till maturity under variable environmental conditions. Phenological development is governed by genetic plant properties and environmental conditions (e.g. air temperature and CO 2 level) and expressed in a plastochron index, i.e. the current stem node number. Total dry matter accumulation is based on a quantitative description of the carbon balance, including gross CO 2 assimilation, maintenance respiration and growth respiration. Partitioning of dry matter increase over the various organs is governed by their relative sink strengh, defined on the basis of a genetically determined ‘potential’ growth rate, achieved under non-limiting carbohydrate supply. The model is both schematic and modular in set-up. This means it can be adapted easily and most of its subroutines can be replaced easily by others if better descriptions become available. It can also be combined with a more comprehensive model describing greenhouse climate and appears robust for use in procedures of economic optimization of climate conditions in greenhouses or for management purposes.

Starch-iodine staining patterns in petals of cut roses

The starch distribution pattern and decline in starch content of Sonia rose petals were examined by starch-iodine staining. Flowers were harvested and held in 150 mg/L of sodium dichloroisocyanurate (DICA) or 150 mg DICA/L + 2% (w/v) sucrose, or were left on the plant. Starch was degraded initially from the outer margins of petals, then from the interveinal area nearest the petal margins, and finally towards the petal bases. Starch was first lost from the outermost petal and then sequentially towards the innermost petals. The rate of starch degradation was slowest in flowers left on the plant, intermediate in flowers harvested and kept in DICA + sucrose, and most rapid in flowers harvested and held in DICA. Preharvest treatments applied in an attempt to vary starch deposition (i.e. shading, leaf removal, and leaf removal with girdling) did not alter the normal starch-iodine staining pattern, reduce starch concentrations, or reduce vase life. However, flower pigmentation was less intense, abnormal flower development occurred, and dry weight and starch contents were reduced, suggesting that carbohydrate supply to the developing bud was affected. Thus, starch-iodine staining of cleared petals of mature Sonia roses was not useful for identifying flowers that developed under conditions of restricted carbon supply. In petals of flowers that had been harvested and held in cool storage (0-3�C) for 7 days, starch was degraded evenly from all parts across the petal. This diffuse pattern of starch degradation was sufficiently distinctive that it may prove a useful test for determining whether flowers have been cool-stored.