The Influence of Salinity and Temperature on Seed Germination in Salicornia bigelovii

Seeds of Salicornia bigelovii were germinated at 4.4°C, 15.5°C, and 26.6°C in saline solution containing from 0% to 8.08% sea salt. At 4.4°C, germination was delayed until the 26th day, but the final germination per cent was high in all salinities. At 15.5°C, germination was delayed until the 19th day, and the germination per cent was higher in the higher salinities. At 26.6°C, the germination began within one day and the germination per cent was higher at the lower salinities. With the exception of 26.6°C data, the maximum germination occurred at a sea salt concentration at 4.04 % which is very close to the salinity of the sea.     

Studies on an Alkaline Proteinase of Aspergillus sydowi

An alkaline proteinase of Aspergillus sydowi (Bainier et Sartory) Thom et Church has been purified approximately 4.5-fold from a culture filtrate by fractionation with ammonium sulfate, treatment with acrynol and Alumina gel C_γ, and DEAE-Sephadex column chromatography. The purified proteinase obtained as needle crystals was monodisperse in both the ultracentrifuge and the electrophoresis on polyacrylamide gel.

The optimum pH and temperature for the activity were 8.0 and 40°C, respectively. Fifty per cent of the activity was lost at 45°C within ten minutes and 95% at 50°C. At 5°C, the enzyme was highly stable at the range of pH 6 to 9. None of metallic salts tested promoted the activity, but Zn⁺⁺, Ni⁺⁺ and Hg⁺⁺ were found to be inhibitory. Sulfhydryl reagent, reducing and oxidizing reagents tested except iodine had no effect on the activity, but potato inhibitor, DFP and NBS caused a marked inhibition.

The alkaline proteinase from Aspergillus sydowi was markedly protected from inactivation by the presence of Ca⁺⁺ in the enzyme solution. The protective effect of Ca⁺⁺ was influenced remarkably by the pH values of the enzyme solution, i.e., optimum concentrations of Ca⁺⁺ for the protective effect at pH 7.1, 7.5 and 7.8 were 10^?2, 10^?3 and 10^?4 M, respectively. Conversely, at higher pH values such as 9.0, Ca⁺⁺ accelerated the rate of inactivation. There was a parallelism between the loss in activity and the increase in ninhydrin-positive material in the enzyme solution.

The proteinase acted on various denaturated proteins, but not on native proteins. In digestion of casein by the proteinase, 92% of nitrogen was turned into soluble form in 0.2 m trichloroacetic acid solution, with 14~17% of peptide bonds being hydrolyzed. Casein hydrolyzed with the Asp. sydowi proteinase was further hydrolyzed by Pen. chrysogenum, B. subtilis or St. griseus proteinases, which further increased the free amino residues in the reaction mixtures. On the contrary, the Asp. sydowi proteinase reacted only slightly on casein hydrolyzed by the above-mentioned proteinases.     

Peptide mapping of protein bands from polyacrylamide gel electrophoresis by chemical cleavage in gel pleces and re-electrophoresis

A simple method has been developed for peptide mapping of protein bands obtained by polyacrylamide gel electrophoresis. The procedure is based on selective acid hydrolysis of aspartyl-prolyl bonds which occur in proteins with an average frequency of 1 per 400 amino acid residues. A gel piece containing the protein to be analyzed is soaked with 75% formie acid. For the subsequent incubation at 37°C for 24 h the gel piece is immersed in liquid paraffin. After removal of formic acid by lyophilization the gel piece is rehydrated in buffer and placed into the sample well of a second polyacrylamide gel on which the generated peptides are electrophoretically separated.     

Partial characterization and antimicrobial activity of peptides from <Emphasis Type="Italic">Amburana cearensis</Emphasis> seeds against phytopathogenic fungi and yeasts

The aim of this work was to study the antifungal action of a protein and peptide-rich fraction from Amburana cearensis seeds. Initially, proteins were extracted from seed flour in phosphate buffer and re-extracted with 1 M lithium chloride. The products obtained from both extractions were precipitated with ammonium sulfate at 70% saturation, and the precipitates were re-suspended in distilled water, heated at 80°C for 15 min and clarified by centrifugation at 12,000×g. The obtained fractions from both extractions were dialyzed, recovered by lyophilization and visualized in Tris–Tricine/SDS gel electrophoresis. The fractions obtained were rich in proteins of low molecular weight and were submitted to antifungal assays. Fraction S4 (extraction with phosphate buffer) inhibited the fungi, Colletotrichum lindemuthianum, Fusarium oxysporum, Fusarium solani, Candida albicans and Saccharomyces cerevisiae. Fractions P2 (re-extraction with lithium chloride) had a low or non-inhibitory effect on the fungi tested.     

An androgen binding protein in the testis cytosol fraction of adult rats. Comparison with the androgen binding protein in the epididymis

The cytosol fraction of rat testicular homogenates contained a specific androgen binding protein (t-ABP), indistinguishable from, the androgen binding protean in. the epididymis(e-ABP) in terms of its chromatographic behaviour by gel filtration, sedimentation rate, mobility on polyacrylamide electrophoresis and steroid specificity(5α-diaydrotestosterone(DHT) > testosterone > estradiol-17β > parogesterone and estradiol-17α).The stability of t-ABP as well was similar to that of e-ABP. The aBP-DHT complexes were stable between pH 6.5–10, exhibiting the highest degree of binding between pH 8–9. The binding activity persisted after heating at 50°C for 30 min., whereas heating at 60°C for 30 min. completely destroyed the binding. DHT did not significantly increase the stability towards pH and temperature denaturation. Binding activity was not reduced by 1 mM p-chloro-mercuri-phenyl-sulphonate (PCMPS), whereas similar treatment with 1 nM N-ethyl-maleimide(NEM) or 1 mM Ellman's reagent reduced it by some 10–50 per cent. Exposure to 10 mM β-mercaptoethanol(βME) reduced the binding by 60–70 per cent. These studies strongly indicate that t-ABP and e-ABP are identical proteins.Hemicastration for 4 weeks eliminated the ABP from the epididymal cytosol fraction on the castrated side, indicating that this protein is produced by the testis.     

Bench scale conversion of 3-cyanopyidine to nicotinamide using resting cells of <Emphasis Type="Italic">Rhodococcus rhodochrous</Emphasis> PA-34

The nitrile hydratase (NHase, EC 3.5.5.1) activity of Rhodococcus rhodochrous PA-34 was explored for the conversion of 3-cyanopyridine to nicotinamide. The NHase activity (∼18 U/mg dry cell weight, dcw) was observed in 0.1 M phosphate buffer, pH 8.0 containing 1M 3-cyanopyridine as substrate, and 0.75 mg of resting cells (dry cell weight) per ml reaction mixture at 40°C. However, 25°C was more suitable for prolonged batch reaction at high substrate (3-cyanopyridine) concentration. In a batch reaction (1 liter), 7M 3-cyanopyridine (729 g) was completely converted to nicotinamide (855 g) in 12h at 25°C using 9.0 g resting cells (dry cell weight) of R. rhodochrous PA-34.     

MEASUREMENT OF THE RATE OF ACETYLCHOLINE DIFFUSION THROUGH A BRAIN SLICE AND ITS SIGNIFICANCE IN STUDIES OF THE CELLULAR DISTRIBUTION OF ACETYLCHOLINESTERASE

The rate of ACh diffusion through a 0·8 mm thick slice from the surface of the rat cerebral cortex, under aerobic conditions at 37°C, was determined by bathing the intact surface of the slice (compartment A) with ACh containing buffer and determining the concentration of ACh in buffer bathing the cut surface of the slice (compartment B). With 1 or 5 mM-ACh in compartment A no ACh was detectable in compartment B within 3 h unless at least 95 per cent of the AChE, as assessed on homogenates, was inhibited. With a given level of AChE inhibition, the rate of ACh diffusion was dependent on its concentration in compartment A. With 1 mM-ACh in compartment A the difference between the rates of hydrolysis of ACh during diffusion through slices with an AChE inhibition of 98·3 and 99·4 per cent, as assessed by AChE assays of homogenates made from the slices, was only 6 per cent of the difference between the rates of hydrolysis of 1 m-ACh by the homogenates of that part of the slices through which diffusion took place. For 5 mM-ACh and levels of 95 and 99·2 per cent inhibition the corresponding value was 10-3 per cent. Since the concentration of ACh must fall across the slice it is not possible to calculate from these figures the number of enzyme sites involved in the hydrolysis during diffusion, i.e. the concentration of extracellular AChE. The implications of these observations are discussed, particularly in relation to studies of the release of ACh from the cerebral cortex in vivo     

Osmoconditioning as a Means of Counteracting the Ageing of Pepper Seeds during High-temperature Storage

Sweet pepper seeds were osmotically conditioned in 0.4 M mannitolsolution for 4 d (at 25 °C, in darkness) before or afterstorage at 35 °C for up to six months, and their germinationand viability was compared with that of untreated seeds storedunder the same conditions. Seeds that had been osmoconditionedprior to storage retained a high rate of germination and germinatedto a high final percentage (from 80 to 50 per cent) at both15 and 25 °C throughout the storage period. By contrast,both the rate and total level of germination of untreated pepperseeds declined rapidly at both germination temperatures, andby three months of storage the total level of seed viabilitywas already less than 10 per cent. Seeds that were first storedat 35 °C, and then osmoconditioned just prior to germination,showed a decline in germinability which when tested at 25 °Cwas the same as for untreated seeds, while tested at 15 °Coccurred at a slightly slower rate than for untreated seeds. It is evident that osmoconditioning prior to storage, in additionto the acceleration of germination, resulted in a dramatic delayof the ageing rate, thus increasing considerably the longevityof seeds. On the other hand, osmoconditioning after storagedid not seem to have any significant effect on seed viability,though it enhanced the germination rate. Capsicum annuum, sweet pepper, seed, germination, osmoconditioning, priming, storage, viability, ageing, longevity     

Use of low temperature and high K+ incubation media for in vitro tissue preparation for X-ray microanalysis

Incubation of tissue slices in physiological buffers gives rise to significant changes in the intracellular ion concentrations, which may disturb subsequent X-ray microanalysis. In the present study it was attempted to design incubation conditions that retain the in vivo conditions better. The following variables were investigated: (1) exchange of Na⁺ in the incubation medium for K⁺, and exchange of Cl^–for the less permeable gluconate anion; (2) incubation at 4°C rather than at 37°C; and (3) addition of dextran to the incubation medium. Brief exposure (a few seconds) of liver slices to a buffer causes changes in the intracellular Na, Cl and K concentrations, depending on the ionic composition of the buffer. Incubation in a normal physiological (high NaCl) buffer at 37°C results in a further increase of Na and Cl and a further decrease in K in liver cells. The changes reach a maximum at 30 min and the concentrations then remain stable throughout a 2-h incubation. Incubation in sodium gluconate medium or addition of dextran to the physiological buffer somewhat reduces the changes in the intracellular ion composition (compared to the standard physiological incubation medium). Incubation in potassium gluconate medium results in a decrease in cellular Na and an increase in K. Quantitative morphological studies show that tissue oedema is observed to the same extent in hepatocytes incubated in sodium gluconate, potassium gluconate and physiological buffer containing 10% dextran. However, these buffers cause significantly less cell oedema than the physiological (high NaCl) buffer. Incubation of liver, cerebral cortex or submandibular gland slices in physiological (high NaCl) solutions at 4°C for 4 h caused a more extensive increase in Na⁺ and decrease in K⁺ than incubation at 37°C for 2 h. This suggests inhibition of the Na⁺, K⁺-ATPase under these conditions. As compared to incubation at 37°C for 2 h, tissues incubated in potassium gluconate buffer at 4°C for 4 h have a cellular K concentration closer to the in situ value. Cholinergic stimulation of tissue slices from cerebral cortex and submandibular gland at room temperature for 1 min shows the best physiological response in tissue slices preincubated at 4°C for 4 h in high KCl, potassium gluconate and high NaCl, in this order. The response can, however, only be seen, when cholinergic stimulation is carried out in a standard physiological buffer with a high NaCl concentration. It is concluded that in vitro storage of tissue for X-ray microanalysis is best carried out at 4°C in a solution with a high K⁺ concentration.     

Effect of temperature and cold stratification on seed germination of the Mediterranean wild aromatic Clinopodium sandalioticum (Lamiaceae)

A germination study was carried out on seeds of Clinopodium sandalioticum (Bacch. & Brullo) Bacch. & Brullo ex Peruzzi & Conti (Lamiaceae), a wild aromatic plant endemic to Sardinia. Seeds were incubated at a range of constant (5–25°C) and an alternating temperatures regime (25/10°C), with 12 hours of irradiance per day. The results achieved at 10°C were also compared with those obtained after a period of cold stratification at 5°C for three months. Final seed germination ranged from ca. 28% (5°C) to ca. 72% (25/10°C). A base temperature for germination (T_b) of ca. 5°C and a thermal constant for 50% germination (S) of 89.3°Cd were identified and an optimal temperature for germination (T_o) was estimated to be comprised between 20 and 25°C. Cold stratification negatively affected seed viability and germination at 10°C. Although a typical “Mediterranean germination syndrome”, could not be detected for C. sandalioticum seeds, these results were coherent with those previously reported for other Mediterranean Lamiaceae species.     

The Effect of Temperature and Moisture Content on the Longevity of Seed of Ulmus carpinifolia and Terminalia brassii

Seeds of the Smooth-leafed Elm (Uimus carpinifolia) and of thetropical forest tree Terb (Terminalia brassii) were stored hermeticallyand sampled at intervals for periods of up to two years. Bothspecies possess ‘orthodox’ seed (increasing longevityis observed as either moisture content or temperature are reduced)within the temperature ranges from — 13 to 52°C (Elm)and from —4 to 42°C (Terb) and within the moisturecontent ranges from 3 to 19 per cent (Elm) and from 5 to 14per cent (Terb) on a fresh weight basis. Elm seed stored at—75°C showed the expected relationship between longevityand moisture content, but did not differ significantly in longevityfrom seed kept at — 13°C when moisture contents wereheld constant. Probit analysis of the relationship between germinationpercentage and time was performed for each storage environment,yielding a slope from which the standard deviation of the distributionof seed deaths over time () was calculated. Standard deviationvalues were used in turn to determine the values of constantsin a viability equation which had previously been applied toseed of barley, chickpea, cowpea and soybean. The equation,which gave a good fit to the results obtained, can be used topredict viability for seed in storage over a wide range of environmentalconditions. Some limitations to the applicability of the viability equationwere defined. At 22 per cent and higher moisture contents Elmseed survived longer than predicted. Furthermore, all Elm andTerb seed was killed quickly on placing in —75°C at22 and 20 per cent moisture content respectively, but high viabilitywas retained for several days at 19 and 17 per cent respectively.Practical implications of the results are discussed. Uimus carpinifolia Gleditsch, Smooth-leafed Elm, Terminalia brassii Exell, Terb, seed longevity, seed storage, moisture content, temperature     

Purification of a Latent Form of Polyphenoloxidase from La France Pear Fruit and Its Pressure-activation

A latent form, mostly soluble, of polyphenoloxidase of La France pear fruit (Pyrus communis) was purified to homogeneity by ammonium sulfate fractionation and anion-exchange chromatography with DEAE-Sephadex A-25 and then DEAE-Toyopearl 650M, followed by gel permeation chromatography with Toyopearl HW-55s. The addition of 10% glycerol to the eluting buffer was needed for purification. The purified latent enzyme seemed to be a monomeric protein; the molecular weight was estimated to be 70,000 by gel permeation chromatography and 65,000 by SDS–polyacrylamide gel electrophoresis. The enzyme was activated by pressurization at 400 MPa or higher or by treatment with SDS. The highest activity was obtained by pressurization at 600 MPa and 20°C for 6 h.     

Influence of post-flowering temperature on seed development, and subsequent performance of crisp lettuce

Crisp lettuce plants cv. Saladin were grown from the time they started flowering, at 20/10°C (16 h day, 8 h night), 25/15°C and 30/20°C in glasshouses on two occasions in 1985. Yields of seed increased from, on average, 15 g to 27 g and then fell to 20 g per plant with progressive increases in temperature. The number of mature florets per plant increased with temperature but the number of seeds per mature floret was lower at 20/10°C and 30/20°C than at 25/15°C. An increase in temperature reduced mean seed weight by up to 45%, seed volume by 15%, cell numerical volume density (N_v) by 27% and the number of cells per seed by 39%. Percentage seed germination reached a maximum early in seed development at the stage when the pappus appeared through the involucral bracts. Differences in percentage germination and vigour of seeds (slope test) from different temperatures were accounted for largely by the effects on mean seed weight. However, when germinated at 30°C seeds produced at 30/20°C germinated more readily than those produced at 25/15°C or 20/10°C. Seed vigour gradually increased with an increase in the length of storage after harvest, reaching a maximum after 260 days. In general, seeds produced at 25/15°C exhibited a greater variation in numbers of seeds per floret, N_v, seed weight, times of seedling emergence, seedling and mature head weight than seeds produced at lower or higher temperatures.     

Characterization of γ-glutamyltranspeptidase in the liver of the frog: 3. Response to freezing and thawing in the freeze-tolerant wood frog Rana sylvatica

The freeze tolerant wood frog Rana sylvatica was studied to determine the impact of the freezing and thawing of this frog on the activity of γ-glutamyltranspeptidase in the liver. On exposure to ?2·5°C, for 1, 12 and 24 h, frogs were found to be cool, covered with ice crystals and frozen, respectively. Thawing for 24 h at 4°C recovered the frogs completely. A 45 per cent decrease in the liver weight: body weight ratio was notable after 1 h at ?2·5°C, suggestive of an early hepatic capacitance response. A glycemic response to freezing was observed: blood glucose levels exhibited a 55 per cent decrease after 1 h at ?2·5°C on cooling; a 10·5-fold increase after 12 h at ?2·5°C on the initiation of freezing; and a 22-fold increase after 24 h at ?2·5°C in the fully frozen state. Blood glucose levels remained elevated four-fold in the thawed state. Plasma insulin levels were increased twofold in the frozen state and 1·8-fold in the thawed state, while plasma ketone levels were increased 1·8-fold in the frozen state and 1·5-fold in the thawed state. Plasma total T₃ levels were decreased by 22 per cent in the frozen state and normalized on thawing. In homogenates and plasma membranes isolated from the livers of Rana sylvatica, the activity of γ-glutamyltranspeptidase was found to be elevated at all stages of the freeze–thaw process. After 1, 12 and 24 h at ?2·5°C, activities were increased 2·5-, 2·3-, 2·4-fold respectively in the homogenates and 2·5-, 2·2-, 2·4-fold respectively in the plasma membranes. After thawing, activities were still increased 1·9-fold in both homogenates and plasma membranes. In homogenates prepared from the kidneys of Rana sylvatica, the activity of γ-glutamyltranspeptidase was increased 1·4-fold after 1 h at ?2·5°C after which it returned to normal. The role of thyroid hormone in producing the increase in γ-glutamyltranspeptidase in the liver of Rana sylvatica in response to freezing is discussed as is the significance of the enzyme increase in terms of hepatic cytoprotection and freeze tolerance.     

Sterile Germination Requirements of Seeds of Some Water Plants

A sterile germination study with seeds of some common phanerogamic water plants showed almost 100 per cent germination for seeds of Alisma plantago–aquatica, Baldellia ranunculoides and Nymphaea alba. Seeds of Potamogeton lucens could be germinated to about 40 per cent, seeds of Polygonum amphibium germinated sporadically while those of Cladium mariscus could not be germinated at all. Freshly harvested seeds of Alisma and Baldellia showed an ability to germinate at both 20°C and 35°C. A stratification period of one month at +4°C gave germination of all species tested, with the exception of Cladium. Potamogeton germinated in light only, the other species both in light and darkness. Treatment times for surface sterilization in disinfectants are given.     

Changes in the rates of protein synthesis in the brain of goldfish at various temperatures.

Intraperitoneal injections of [¹⁴C] tyrosine suspension into goldfish produced a relatively constant specific activity of free tyrosine in the brain over an 8 hour experimental period. This made the measurement of the rate of cerebral protein synthesis in this time period possible. The increase of protein-bound [¹⁴C] tyrosine was linear with time and occured in most protein fractions. In the absence of a net increase of protein it was an indicator of the rate of cerebral protein turnover. Rates of incorporation of tyrosine into brain proteins were 0.52 per cent/hour at 34° and 0.026 per cent/hour at 10°, i.e., the rate at 34° was about 20-fold that at 10°. Temperature gradients of protein turnover were similar in fish and rat brain.     

Assessing seed priming,sowing date,and mulch film to improve the germination and survival of direct‐sown Miscanthus sinensis in the United Kingdom

Direct sowing of Miscanthus seed could lower crop establishment costs, and increase the rate of grower uptake and biomass supply for the emerging bio‐economy. A replicated field trial was conducted at two contrasting UK sites: Aberystwyth (ABR) in mid‐Wales and Blankney (BLK) in Lincolnshire. These sites encompass the west–east meteorological gradient in the United Kingdom where the growing season at ABR is cooler and wetter while BLK is warmer and drier. Primed and unprimed Miscanthus sinensis seeds were sown directly onto the soil surface with and without a clear biodegradable mulch film, at nine dates interspersed from May to October. Average daily mean soil surface temperatures measured over the first 2 months after sowing under the mulch film were higher than control plots (2.7°C ABR and 4.2°C BLK). At both sites, the film covering also affected soil volumetric moisture relative to uncovered control plots (?3% ABR and 8% BLK), demonstrating the negative impact of mulch film when sowing on dry soil. Over nine sowings, seed germination at ABR under film varied between ?28% and +18% of germination under control conditions. Seedlings from the first three sowings at both sites under film had sufficient physiological maturity to survive the first winter period. At BLK, mulch film significantly increased tiller count and height in both the first and second years after sowing. At ABR, where temperatures were lower, film covering significantly increased tiller height but not count. Water priming had no significant effect on seed viability or germination in the field tests. Base temperatures for germination of primed and unprimed seeds on a thermal gradient plate were 7.0°C and 5.7°C, respectively, with a ± 1.7°C confidence interval. Based on our results for M. sinensis in the United Kingdom, we recommend the sowing of unprimed seed in May under film and only when the soil is moist.     

The viability and survival of sporozoites of Eimeria in vitro

Some factors affecting excystation and viability of sporozoites of several species of Eimeria from chickens were examined in vitro. Chicken embryos or cultured kidney cells were inoculated with sporozoites in order to assess viability.Sporozoites of E. tenella survived in phosphate buffer (P.B.S.) containing 0·9 per cent NaCl for 14 days. Some sporozoites survived in solutions containing up to 16 per cent NaCl for 3 days at +4°C. Sporozoites of E. maxima and E. acervulina survived for only 27 h in phosphate buffer containing 1 or 2 per cent NaCl.Sporozoites of E. brunetti, E. maxima, and E. acervulina var: mivati were released rapidly from sporocysts in vitro, but survived for relatively short periods in PBS at 4°C. However, the addition of serum or gelatine to these solutions increased survival to at least 96 h.The viability of sporozoites after freezing and storing in liquid nitrogen was best when 12 per cent dimethyl sulphoxide (DMSO) was added to the sporozoite suspensions. P.B.S. with DMSO was less suitable than the other solutions used and serum or gelatine with the DMSO, was needed to increase survival. Increasing the density of sporozoites in the frozen stabilates did not increase survival.     

The Effect of Desiccation on the Longevity of Seeds of Araucaria hunsteinii and A. cunninghamii

Seeds of Araucaria hunsteinii K. Schum. dried quicker at 29°Cthan at 19°C and quicker with the seed-coat removed thanwhen intact; seeds enclosed in polyethylene bags increased inmoisture content. At 15°C, seeds in a flow of air driedquicker than seeds in a box with silica gel, which in turn driedquicker than seeds in a box with no desiccant. No loss of germinationability occurred on drying fresh seed from 53 to about 32 percent moisture content (fresh weight basis); during further desiccationthe percentage germination was related to percentage moisturecontent in the form of a sigmoid curve, culminating in a completefailure to germinate at approximately 14 per cent moisture content.A consistent relationship was observed for all treatments andthe mean critical moisture content for seed death (failure togerminate) was near 23 per cent. Excised embryos grew on 1 percent agar but died if previously subjected to 14 h of desiccationat 15°C. In contrast, no relationship was found between germination andmoisture content of A. cunninghamii D. Don on desiccation from21 to 7 per cent moisture content. Possible causes for the observeddifference in response to desiccation are discussed and methodsfor seed storage are considered. Araucaria hunsteinii, Klinkii pine, Araucaria cunninghamii, Hoop pine, desiccation, seed longevity, storage of seeds     

The stimulatory effect of uracil and 5-bromouracil on the seed set inPapaver somniferum L.

A study was made concerning the effect of the analogues of nucleic acid components upon the seed set inPapaver somniferum L. For the experiments flowers one day after anthesis were used, as the pollination taking place at this flower age had previously been found to be most efficient for the seed set. The solutions of analogues in a 10 per cent sucrose were applied by injecting them into the ovaries three hours prior to pollination. Damage to the ovary by the injection reduces the seed set by about two thirds. In comparison with control flowers, into which only a sucrose solution was injected, 5-bromouracil at a concentration of 5.2×10^?4 M increases the seed set by about 70 per cent. Uracil brings about the same degree of promotion. The same concentration of 5-bromodeoxyuridine has no significant effect on the seed set. When applied simultaneously with uracil it suppresses its stimulating effect completely. The equimolar mixture of uracil and bromouracil did not cause any significant increase in the number of seeds in the capsules, either.