bluuebunny/crossref_metadata_2025_split huggingface dataset:
LONGEVITY AND PRODUCTIVITY OF LEAVES OF A CULTIVATED ANNUAL, GLYCINEMAX MERRILL
Authors: MIYAJI KEN‐ICHI 
Published: May 2006

SummaryTo understand the structure and dynamics of the leaf population composing a canopy, a life table analysis using rates of leaf emergence, mortality and dry matter production was applied to the foliage of soybean plants grown at three densities and sown at three times.The mean leaf longevity differed greatly depending on the time of sowing, but in the early sown plants little difference was found among the leaves of lower and middle layers of the canopy in spite of the wide difference in the irradiance of the layers.The rate of net photosynthesis of upper leaves in full daylight tended to decline gradually owing to senescence in leaves older than 20 d. That of lower‐layer leaves, in very dark conditions, decreased very rapidly owing to both shading and senescence. Analyses of the survivorship curves and the time trends of net photosynthetic rates showed that lower leaves in densely planted populations survived for quite a long time after they had lost the ability to produce additional dry matter.The rate of canopy net photosynthesis tended to follow a saturation curve with the increase in the leaf area index of whole canopy. There was no optimum leaf area index that maximized canopy photosynthetic rate.
IRON REQUIREMENTS OF C3 AND C4 PLANTS
Authors: SMITH G. S. , CORNFORTH S. , HENDERSON H. V. 
Published: May 2006

SummaryPlants having the C4, photosynthetic pathway required higher concentrations of iron in the nutrient solution for maximum growth when grown in sand culture than those with the C3 pathway. There were only small differences among species in the concentration of iron required in the leaves to achieve near maximum dry matter yield. This suggests that C3 and C4 plants differ in their ability to absorb iron from the root zone. Higher concentrations of iron were required in the nutrient solution for maximum growth of both the C3 and C4 plants when nitrate, rather than ammonium nitrate, was the sole source of nitrogen. It seems likely that when nitrate was used, there was a decrease in availability of iron to the plant as a result of the increased alkalinity in the root zone. By contrast, the root zone was acidified when ammonium nitrate was applied. Iron concentrations greater than 2 to 5 μg Fe ml−1 in the nutrient solution reduced the dry matter yields of a number of plants grown with ammonium nitrate as the nitrogen source, probably because of a decrease in the absorption of phosphorus by the roots.
OBTAINING A STERILIZED SOIL FOR THE GROWTH OF ONOCLEA GAMETOPHYTES
Authors: RUBIN GAIL , PAOLILLO D. J. 
Published: May 2006

SummaryAutoclaved soils totally inhibited germination of spores of the fern, Onoclea sensibilis. Gamma‐irradiated soil sometimes allowed germination and growth, whereas germination and growth on ashed soil was entirely reproducible. All methods of sterilization produced sterile soil, but only ashing produced a medium acceptable for use in other experiments. Experiments with mineral solutions suggest that the failure of sterilized soil to support germination is due to toxic compounds rather than nutrient deficiency. Ashing the toxic soils removed the inhibitory compounds, which seemed to be related to the breakdown of organic matter during sterilization by autoclaving and gamma irradiation. On gamma‐irradiated soil, germination was promoted by removal of ethylene from the atmosphere around the spores, but subsequent growth failed, probably due to other inhibitors formed in the soil during irradiation.
STUDIES ON NITRATE REDUCTASE IN BRITISH ANGIOSPERMS
Authors: HIPKIN C. R. , Al GHARBI A. , ROBERTSON K. P. 
Published: May 2006

Summary In vivo nitrate reductase (NR) activity was measured in the leaves of plants from woodland, wooland‐edge and open (ruderal) communities. Nitrate reductase activity was highest in the youngest fully‐expanded leaves of all plants sampled. Nitrate reductase activity in populations from woodland and woodland‐edge increased after feeding with nitrate; feeding with Mo had no significant effect. During the day NR activity in plants from each community increased to a maximum near the middle of the photoperiod and then decreased. These daily changes are discussed in terms of the possible regulatory roles of light and the transport of nitrate to the shoot.
THE RESPONSE OF ACHILLEA MILLEFOLIUM L. (YARROW) TO SHADING
Authors: BOURDÔT G. W. , SAVILLE D. J. , FIELD R. J. 
Published: May 2006

SummaryGrowth analysis was used to assess the response of vegetative rosettes of Achillea millefolium L. (yarrow) to shading in the range of full daylight irradiance to a relative level of irradiance (r.l.i.) of 0–064. As functions of time, SLA, LWR, NAR and RGR showed more or less pronounced ontogenetic drifts which interacted with r.l.i. As functions of total dry weight, these interactions were greatly diminished. At dry weights from 1.53 to 4.0 g, the response of RGR to shading was characterized by a plateau between full daylight and approx. 0.40 r.l.i. owing to increases in SLA and LWR compensating for a reduction in NAR. Relative growth rate then fell steeply to a compensation point of O.o37 r.l.i. It was concluded that A. millefolium is considerably tolerant of shading and an ecological interpretation is given.
STUDIES ON THE BIOLOGY OF SENECIO VULGARIS L. SSP. DENTICULATUS (O. F. MUELL) P. D. SELL
Authors: KADEREIT JOACHIM W. 
Published: May 2006

SummaryExperimental evidence and evidence obtained from herbarium material suggest a pronounced difference in the biology of Senecio vulgaris L. var. vulgaris and ssp. denticulatus (O. F. Muell.) P. D. Sell. Whilst var. vulgaris is a plant of ruderal habitats, which can complete its life cycle in a very short time and can be found flowering all year round, ssp. denticulatus is a winter annual with an Atlantic–Mediterranean–montane distribution, which is strictly coastal outside the Mediterranean. It shows strong seed dormancy, which seems to be regulated by one major gene, and requires substantially more time to complete its life cycle than var. vulgaris. There is also some evidence that the reproductive potential of ssp. denticulatus is smaller than that of var. vulgaris. It seems likely that the ruderal var. vulgaris evolved from forms similar to ssp. denticulatus.
THE EFFECTS OF FLUCTUATING CONCENTRATIONS OF SULPHUR DIOXIDE ON THE GROWTH OF PINUS SYLVESTRIS L. AND PICEA SITCHENSIS (BONG.) CARR
Authors: GARSED S. G. , RUTTER A. J. 
Published: May 2006

SummaryPlants of Pinus sylvestris and Picea sitchensis, initially at the end of their third growing season, were grown for 2 years and 1 year, respectively, in regimes of fluctuating sulphur dioxide (SO2) concentration. The four fluctuating regimes had mean concentrations of about 100 μg m−3 and peak concentrations of either 300 to 400 μg m−3 or 750 to 900 μmg m−3,* combined with durations of high concentration which were either short (mean ∼ 5 h) and frequent, or long (mean ∼ 20 to 30 h) and infrequent. Their effects were compared with a constant concentration of about 100 μg m−3 and with clean air.In the first year of treatment, effects on dry weight increment consisted of depressions in the root only, but marked chlorosis, necrosis and abscission of the leaves of Picea sitchensis were caused by SO2, while the leaves of Pinus sylvestris were hardly affected. By the end of the second year of treatment (Pinus sylvestris only) dry weight increase of the whole plant had been reduced by 14% in the constant concentration and in fluctuating regimes with peaks of short duration, and by 22% in regimes with peaks of long duration. All the SO2 treatments caused early fall of 3‐year‐old leaves during the second year of treatment of this species.A comparison of the treatments with the characteristic regime of fluctuating concentration in those parts of Britain where the mean annual ground level concentration of SO2 is around 100 μg m−3, leads to the conclusion that the main effect of this regime is attributable to its mean, rather than its peak concentration.
AMINO ACID AND AMIDE METABOLISM IN THE HULLS AND SEEDS OF DEVELOPING FRUITS OF GARDEN PEA, PISUM SATIVUM
Authors: MURRAY D. R. , CORDOVA‐EDWARDS MARIA 
Published: May 2006

SummaryPea plants (Pisum sativum L. cv. Melbourne Market), each with a single developing pod, were pulse‐fed with [l4C]glutamine supplied through the cut stem. Hull and seed tissues were removed after a suitable interval (usually 24 h) and frozen for later analysis. The fruit received substantial label at all stages analysed (from 12 to 31 d after full blossom). Except at the youngest stage, most of the label recovered from the fruit was present in the seeds. The distribution of label in soluble metabolites of the hull, seedcoats, embryo sac liquid and embryo was determined by paper chromatography and radioautography. The results confirm that glutamine is utilized as a major source of carbon by pea embryos throughout their development.
AMINO ACID AND AMIDE METABOLISM IN THE HULLS AND SEEDS OF DEVELOPING FRUITS OF GARDEN PEA, PISUM SATIVUM II. ASPARAGINE
Authors: MURRAY D. R. , CORDOVA‐EDWARDS MARIA 
Published: May 2006

SummaryPea plants (Pisum sativum cv. Melbourne Market), each with a single developing pod, were pulse‐fed with [14C]asparagine supplied through the cut stem at stages ranging from 12 to 31 d after full blossom. The hull and seed tissues were removed after 24 h and frozen for later analysis. The hull retained a higher proportion of the total label in the fruit than the enclosed seeds until after 19 d, i.e. until the total nitrogen content of the hull had begun to decline. The distribution of label in soluble metabolites of the hull, seedcoats, embryo sac liquid and embryo was determined by paper chromatography and radioautography. The results confirm that the metabolism of asparagine is more rapid in the seedcoats than in the hull. In the youngest stages, label from the seedcoats is transmitted to the embryo sac mainly in forms other than asparagine, notably as glutamine, alanine and sucrose.
INFLUENCE OF VESICULAR–ARBUSCULAR MYCORRHIZA ON THE HYDRAULIC CONDUCTIVITY OF ROOTS OF TWO CITRUS ROOTSTOCKS
Authors: GRAHAM J. H. , SYVERTSEN J. P. 
Published: May 2006

SummaryCarrizo citrange (CC) and sour orange (SO) seedlings were grown in a low phosphorus (P) sandy soil and either inoculated with Glomus intraradices Schenck & Smith or fertilized with soluble P. Mycorrhizal seedlings had nutritionally sufficient levels of leaf P, non‐mycorrhizal plants of similar size were P‐deficient. The root–shoot ratio of both rootstocks was reduced by mycorrhizal colonization, but root hydraulic conductivity per unit root length of mycorrhizal CC and SO was more than twice that of non‐mycorrhizal seedlings under well‐watered conditions. Mycorrhizal plants also had significantly higher transpiration rates when standardized on a root length basis, and greater transpiration appeared to be related to the increased conductivity of roots. Flow of water to roots via hyphae alone could not account for the greater water uptake by mycorrhizal roots. Apparently, mycorrhizal enchancement of P nutrition was primarily responsible for the greater conductivity of roots since no differences were found between root hydraulic conductivity of mycorrhizal and non‐mycorrhizal CC of equal P status under well‐watered conditions.
THE EFFECT OF ROOT DENSITY, INOCULUM PLACEMENT AND INFECTIVITY OF INOCULUM ON THE DEVELOPMENT OF VESICULAR–ARBUSCULAR MYCORRHIZAS
Authors: ABBOTT L. K. , ROBSON A. D. 
Published: May 2006

SummaryWe examined, in three glasshouse experiments, the development of vesicular‐arbuscular (VA) mycorrhizas formed by Glomus fasciculatum (Thaxter sensu. Gerd.) Gerd. & Trappe on Trifolium subtẽrraneum L. in relation to plant denser and inoculum quantity. The effect of inoculum placement on the formation of mycorrhizas on Medicago truncatula Gaertn. by another Glomus sp. was studied in a fourth experiment. More mycorrhizal root was formed by Glomus sp. when inoculum was dispersed throughout the soil than when it was localized either near the top or bottom of the pot. The absolute rate of mycorrhiza formation was initially more rapid with localized inoculum. However, a greater weight of mycorrhizal root was subsequently obtained with dispersed inoculum as roots continually intercepted propagules. Infection by G. fasciculatum spread deeper in one soil than in two others, perhaps reflecting differences in root growth and density associated with differences in phosphorus status of the soils for plant growth. The weight of roots which became infected increased with increasing plant density, but not when shoot growth was greatly decreased due to competition between plants. The relative rate of mycorrhizal infection remained unaffected by treatments in each experiment. When a low root density and a high inoculum level were combined, the amount of roots which became infected was greater than expected. These conditions favoured a longer exponential phase in the development of infection.
EFFECTS OF LIME, PHOSPHORUS, AND ADDITION OF VESICULAR–ARBUSCULAR (VA) MYCORRHIZAL FUNGI ON INDIGENOUS VA FUNGI AND ON GROWTH OF ALFALFA IN A MODERATELY ACIDIC SOIL
Authors: KUCEY R. M. N. , DIAB GAMAL ELDIN S. 
Published: May 2006

SummaryThe effects of inoculation with vesicular–arbuscular mycorrhizal (VAM) fungi on alfalfa (Medicago sativa L.) growth and phosphorus uptake were studied in a moderately acidic loess soil with four levels of added lime. Inoculation of alfalfa with VAM fungi from soils of pH 7.2 to 7.5 resulted in increased dry matter production at pH of 6.4 to 7.5, but not at pH of 5.4 to 6.1. Addition of lime and/or phosphorus always increased growth of alfalfa. Root colonization by indigenous mycorrhizal fungi was inhibited at the highest pH levels but root colonization by added fungi was stimulated at higher pH levels and inhibited at the lower pH levels.
THE DISTRIBUTION OF PERENNIAL RYEGRASS GENOTYPES IN SWARDS
Authors: McNEILLY T. , ROOSE M. L. 
Published: May 2006

SummaryThe number and spatial distribution of perennial ryegrass (Lolium perenne L.) genotypes in 4 pastures were estimated by sampling single tillers from points 5 cm apart on an 11 × 11 grid. Three electrophoretic loci were used initially to determine the genotype of each tiller.Three 10‐year‐old sown swards contained at least 36–43 different genotypes per 0.25 m2 quadrat (10% of the number sown) while a 40‐year‐old pasture contained only 5 genotypes per 0.25 m2 quadrat. The cut sward had a greater proportion of its area occupied by a few large genotypes than the swards grazed by sheep or cattle.The importance of age, management, and other factors influencing genotypic diversity in swards is discussed.
THE ECOLOGY OF SPECIES, FAMILIES AND COMMUNITIES OF THE CONTEMPORARY BRITISH FLORA
Authors: GRIME J. P. 
Published: May 2006

SummaryIt is argued that detailed studies of the functioning of populations cannot by themselves lead to an understanding of British vegetation. Several complementary lines of investigation are required to explore the role of past and present interactions between habitat templet and plant characteristics. Strategy concepts provide a framework in which to assemble information from such diverse fields of ecological research, and recent results suggest that the present ecologies of populations, species, families and communities remain strongly conditioned by patterns of ecological specialization which predate the development of the post glacial flora.
INTERNAL SPREAD OF FUNGI INOCULATED
Authors: BODDY LYNNE , RAYNER A. D. M. 
Published: May 2006

SummaryThe white‐rotting basidiomycetes Exidia glandulosa, Peniophora quercina, Phellinus ferreus, Schizopora paradoxa, Stereum gausapatum and Vuilleminia comedenswere inoculated into attached living branches of oak (Quercus robur). Patterns of establishment and spread varied in relation to species, time of inoculation and location with respect to branch order and proximity of experimental girdles. Peniophora quercina, Stereum gausapatum and V. comedens readily formed localized decay columns within 6 months, but apparently failed to extend further subsequently. The other fungi either failed to establish, or spread only for limited distances, E. glandulosa preferentially colonizing bark. Longitudinal spread was often markedly facilitated within the vicinity of a girdle, although radial and tangential spread were restricted. In several instances, individuals of Peniophora quercina, Stereum gausapatum and V. comedens became established naturally within the branches. Such individuals were invariably somatically incompatible with those inoculated, and further contrasted with the latter in giving rise to columns of considerable longitudinal and radial extent.
DOES AUXIN STIMULATE THE ELONGATION OF INTACT PLANT STEMS?
Authors: HALL J. L. , BRUMMELL D. A. , GILLESPIE JANE 
Published: May 2006

SummaryContradiction exists in the literature as to the effect of exogenous auxin on the growth of intact plants, and the assumed lack of such an effect has been used as evidence that auxin does not function in regulating growth through changes in concentration. Indole‐3‐acetic acid (IAA), applied in lanolin to the third internode of intact etiolated Pisum sativum L. cv. Alaska stems, rapidly and markedly stimulated elongation, to an extent similar to that observed in excised segments. This was a short‐term effect and did not alter the final stem size attained after 24 or 50 h. Decapitated plants responded more slowly to IAA application but, again, the final size attained was similar to that of the untreated controls. The results show that changes in auxin amounts cannot be ruled out in discussions of growth regulation.
COBALT REQUIREMENT FOR NODULE DEVELOPMENT AND FUNCTION IN LUPINUS ANGUSTIFOLIUS L.
Authors: RILEY IAN T. , DILWORTH M. J. 
Published: May 2006

SummaryThe cobalt requirement for nodule development and function in Lupinus angustifolius L. ev. Uniharvest was studied in a glasshouse using a range of cobalt applications. Nodule establishment was found to be limited only by severe cobalt limitation. Bacteroid content of the nodules was the main determinant of nodule function and thus plant performance. Leghaemoglobin synthesis appeared to be more sensitive to cobalt limitation but was a less significant determinant of acetylene reduction activity. The critical root cobalt level for the normal symbiosis was 500 ng Co g−1 d. wt but a level of 300 ng Co g−1 d. wt resulted in no yield loss since there was a compensatory increase in lateral nodulation.
PLANT GROWTH RESPONSES TO VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: HAYMAN D. S. , TAVARES M. 
Published: May 2006

SummaryNine vesicular‐arbuscular mycorrhizal endophytes were assessed for their infectivity and ability to improve the growth of alpine strawberry seedlings in sterilized, low‐phosphate soils (4 and 8 mg kg−1 NaHCO3‐soluble P), limed to different pHs. At pH 4, Glomus clarum greatly stimulated plant growth, but the other endophytes except Gigaspora margarita and Glomus fasciculatum‘E3’ had little or no effect. The most efficient endophytes at pH 5 were E3, Acaulospora laevis and G. clarum. The largest plants were those growing at pH 7 and inoculated with Glomus epigaeum; A. laevis and G. clarum were ineffective at this pH. The most effective endophytes at pH 6 and 7 were G. epigaeum, Glomus mosseae, E3, Glomus caledonium and Gigaspora heterogama, although results varied slightly between soils. Most endophytes infected well at all pHs, even where they did not enhance plant growth. In studies of this nature plant growth is affected by different pHs, soil P levels and the inoculum used. Nevertheless these data show clearly that different endophytes vary enormously in their symbiotic effectiveness at different soil pHs. The practical implications of these results are discussed.
HERMAPHRODITES AND SUBHERMAPHRODITES IN A REPUTEDLY DIOECIOUS PLANT,CIRSIUM ARVENSE(L.)SCOP.
Authors: KAY Q. O. N. 
Published: May 2006

SummaryCirsium arvense(L.) Scop. has been thought to be completely or almost completely dioecious, with clear morphological and functional differences between males that set an average number of less than 0.1 viable seeds per capitulum and females that produce no pollen. An investigation of three populations in southern Britain showed that 15 % of the clones with polleniferous ‘male’ flowers were in fact hermaphrodite, with high or fairly high seed yields (10 to 65 seeds per capitulum) and a further 11 % were subhermaphrodites with seed yields of 2 to 10 seeds per capitulum. The flowers and capitula of the hermaphrodites and subhermaphrodites closely resembled those of typical male clones at the flowering stage, but their fruiting capitula ranged from typically male to typically female in appearance. The mean size and weight of the seeds set on hermaphrodites and subhermaphrodites were similar to those of seeds set on females, and seed viability was high in most hermaphrodites and subhermaphrodites. Some hermaphrodites had higher seed yields per capitulum than the overall mean for females. Pollen output per flower was lower in hermaphrodites than in typical males, but pollen from hermaphrodites was fertile and gave high seed‐set when used to pollinate female flowers. Hermaphrodites were self‐fertile, although seed‐sets on selfing were relatively low. In the hermaphrodites, the pollen contribution relative to that of typical males ranged from 0.24 to 0.85, and the ovule contribution relative to that of pure females ranged from 0.13 to 1.29.
METABOLIC CHANGES IN MUSTARD PLANTS ASSOCIATED WITH MOLYBDENUM DEFICIENCY
Authors: CHATTERJEE C. , NAUTIYAL N. , AGARWALA S. C. 
Published: May 2006

SummaryMustard (Brassica campestris L. var. sarson Prain cv. T42) plants were grown in refined sand at graded levels of molybdenum ranging from acute deficiency (2 × 10−5 mg 1−1) to excess (2 mg 1−1). Visible deficiency symptoms appeared at 2 × 10−1 mg 1−1 or less molybdenum. Total dry matter and seed yield were maximal at 2 × 10 1−1 mg Mo 1−1. In leaves of the deficient plants there was depression in the concentrations of DNA and RNA, protein nitrogen and activities of nitrate reductase and cytochrome c oxidase but stimulation in the activities of acid phosphatase and ribonuclease and accumulation of phosphorus and nitrate nitrogen.
DIEL AND SEASONAL CHANGES IN THE CHLOROPLAST ULTRASTRUCTURE OFDESCHAMPSIA FLEXUOSA(L.) TRIN.
Authors: ARO E.‐M. , KORHONEN P. , RINTAMÄKI E. , MÄENPÄÄ P. 
Published: May 2006

SummaryChloroplast ultrastructure was studied during the season of main growth on leaves ofDeschampsia flexuosa(L.) Trin. collected from the wild in South Finland. Corresponding leaf segments were used for concurrent measurements of the O2evolution rate, chlorophyll (chl) content and chla/bratio. No significant diel variation was observed in the content or arrangement of grana thylakoids but fluctuation was evident in the volume of starch grains. The seasonal changes in thylakoid organization were more marked. At the beginning of June higher values than in typical sun species were recorded for the ratio of the length of appressed to non‐appressed thylakoid membranes (1.8), the average number of partitions per granum (9.5) and the grana area (31 % of the chloroplast area). All these parameters increased as the season progressed, especially after the middle of July. The chl content and chla/bratio decreased until the middle of August, but later in August, after rain, new leaves had a chl content and chla/bratio as high as at the beginning of June. In contrast, chloroplast ultrastructure remained typical for this late growth period. The highest photosynthetic capacity was measured during the two first weeks in June. At the beginning of July this capacity had decreased by 61%, and stayed low until the end of the experimental period. The changes in chloroplast ultrastructure are discussed in relation to the photosynthetic activity and the composition of the chlorophyll‐protein complexes in appressed and non‐appressed thylakoid membranes.