bluuebunny/crossref_metadata_2025_split huggingface dataset:
The development of seed quality in spring barley in four environments. II. Field emergence and seedling size
Authors: Filho C. Pieta , Ellis R. H. 
Published: September 2008

AbstractThe field emergence ability of a total of 88 seed lots of spring barley (Hordeum vulgare L.) harvested serially during development in 2 years was compared, as was the size of the resultant seedlings. For seedsproduced in each year, field emergence and the mean dry weight of emerged seedlings were significantly greater for seed lots harvested some timeafter physiological maturity (end of the seed-filling period) than for those harvested at or before this developmental stage. This is compatiblewith results for the potential longevity of these lots. It is concluded that barley seed quality continues to increase after physiological maturity, and that the developing seeds attain maximum quality (however this is assessed) close to when the seed crop can be combine harvested. Positive correlations were detected between seedling emergence and seed dry weight (P<0.05) and between the mean dry weight of emerged seedlings and seed dry weight (P<0.005) among seed lots harvested close to when maximum quality was attained in four seed production environments.
Mechanism of seed dormancy in rice
Authors: Seshu D. V. , Dadlani M. 
Published: September 2008

AbstractDormancy in rice (Oryza sativaL.) seed is imposed by certain physical and chemical factors associated with its covering structures, i.e.hull and pericarp. The nature of these germination blocks, their mode ofaction, and processes regulating the release of dormancy are not fully understood. Of nine rice cultivars studied, Ching-shi 15, Stejaree 45, PTB10, and Mahsuri are weakly dormant, and Bansphul, Benaful, Kataktara, Dular, and N22 are dormant. Release of seed dormancy in rice by various treatments, oxidative processes and enzymic changes associated with dormancy, and parallelism between natural and artificially imposed dormancy patterns were examined. The influence of the hull in imposing dormancy was stronger and more prolonged than that of the pericarp. Application of GA3was effective in inducing germination only in weakly dormant cultivars. Dormancy was completely released in all cultivars by subjecting the seeds to moist heat treatment, by removing the hull and pericarp, and by applying GA3after dehulling. Dormant cultivars had higher O2uptake rate and peroxidase activity and lower amylase and dehydrogenase activities than the weakly dormant ones. Hull removal substantially decreased peroxidase activity but enhanced amylase and dehydrogenase activities. Nonanoic acid (C90), a short-chain saturated fatty acid (SCSFA), when exogenously applied to non-dormant seeds imposed dormancy. Dry heat treatment or presoaking in 0.01mKNO3or 0.1mH2O2was very effective in releasing SCSFA-imposed dormancy. Amylase activity was greatly reduced by treatments with nonanoic acid (C90) or ABA. Considering earlier reports and results of the present study, it is proposed that seed dormancy in rice is regulated both by the presence of SCSFAs and ABA in the hull and the pericarp. The relative significance of these substances in cultivars of tropical and temperate origins and its implications in terms of ecogeographic adaptability are discussed.
The effect of soaking injury in bean seeds on protein synthesis in embryonic axes
Authors: Pretorius Johan C. , Small J. G. Chris 
Published: September 2008

AbstractThe capacity for protein synthesis in embryonic axes of Phaseolus vulgaris L. cv. Top Crop seeds was reduced markedly by soaking in airsaturated and CO2-saturated water. The former treatment induces soaking injury while the latter treatment prevents injury. After soaking, the capacity for protein synthesis in axes of seeds soaked in air-saturated water declined and the pattern of synthesis remained almost similar to that at the time of termination of soaking. However, the capacity and pattern of protein synthesis in axes of seeds soaked in CO2-saturated water recovered subsequent to soaking and approached that of non-soaked seeds.
Leakage of K, Mg, Cl, Ca and Mn from imbibing seeds, grains and isolated seed parts
Authors: Lott John N. A. , Cavdek Vandy , Carson Joanne 
Published: September 2008

AbstractInstrumental neutron activation analysis (NAA) was used to quantify the amounts of K, Mg, Cl, Ca and Mn leaked into water from imbibing dry seeds, dry fruits and isolated seed parts. A number of intact monocot and dicot dry seeds or fruits were studied as were some isolated parts such as testa, endosperm and embryo. All samples studied leaked detectable amounts of the five elements measured but the amounts leaked varied greatly. In most cases K was leaked in greater amounts than the other elements while Mn was leaked least. The leakage of Ca was highest from isolated seed coats and from mericarps of three umbelliferous species. Comparisons of the amount of element leaked with the total amount of that element present in the starting material showed that leakage, especially of K, represents a substantial loss of mineral nutrient reserves. The degree of leakage of elements did not appear to be closely related to the types of organic storage reserves present.
The development of seed quality in spring and winter cultivars of barley and wheat
Authors: Ellis R. H. , Filho C. Pieta 
Published: September 2008

AbstractSeed development and changes in germination ability and longevity were monitored in two spring and two winter cultivars of each of barley (Hordeum vulgare L.) and wheat(Triticum aestivum L.). Physiological maturity (end of the seed-filling period) occurred between 31 and 41 d after 50% anthesis in the eight cultivars, at which time seed moisture contents had declined naturally to 40–49% (wet basis). Most seeds were able to germinate (in 28 d tests at 10°C) following enforced desiccation at this time (normal germination varied from 83% in one cultivar of winter wheat to 97% in one of spring wheat).Potential seed longevity continued to increase after physiological maturity. The intervalbetween physiological maturity and the time when seeds attained maximum potential longevity varied between 3 and 21 d; maturation drying had reduced seed moisture contents to 16–28% (wb) at this time. The results for all eight cultivars contradict the hypothesis that maximum seed quality is attained at physiological maturity and thereafter declines. The term physiological maturity is potentially misleading, therefore; mass maturity is more appropriate to describe this developmental stage. It is shown that the results of accelerated ageing or controlled deterioration tests may provide misleading conclusions in seed quality development studies if the single storage treatment chosen is inappropriate.
Effects of controlled deterioration and osmopriming on protein synthesis of cauliflower seeds during early germination
Authors: Fujikura Yuzo , Karssen Cees M. 
Published: September 2008

AbstractProfiles of proteins synthesized in vivo in radicle tips were compared among unaged, artificially aged (controlled deterioration: 10% moisture content at 42°C for 3 weeks), osmoprimed (−1.5 MPa polyethylene glycol 6000 at 20°C for 1 week), and artificially aged and subsequently osmoprimed cauliflower (Brassica oleracea L.) seeds. Germination and initiation of incorporation of 35S-methionine into radicle tips were delayed by controlled deterioration. Osmopriming accelerated these processes and also alleviated the delays. The labelled proteins were analysed by two-dimensional gel electrophoresis and fluorography. Proteins were found whose expression correlated with the rate of germination, and was reduced by controlled deterioration but enhanced by osmopriming. Subsequent osmopriming reversed the effect of controlled deterioration and even caused an enhancement up to the level of unaged osmoprimed seeds. These proteins appeared to be related to processes preceding visible germination. In unaged seeds, formation of the proteins in the radicle tip began upon imbibition but decreased towards visible germination. On silver-stained gels, one of the proteins was shown to be mobilized by the time of radicle protrusion, while all were found in dry seeds. Proteins whose pronounced expression was observed only after both treatments were also found.
The effect of soaking injury in bean seeds on aspects of the oxidative pentose phosphate pathway in embryonic axes
Authors: Pretorius Johan C. , Small J. G. Chris 
Published: September 2008

AbstractSubmerging Phaseolus vulgaris cv. Top Crop seeds in air-saturated water for 16 h markedly depresses subsequent germination. This is termed soaking injury. Soaking injury does not occur in seeds soaked in CO2-saturated water. Previous studies have shown that soaking injury can be alleviated by drying seeds or removing seed coats. Submergence therefore leads to a situation in bean seeds which is similar to secondary dormancy.As with dormant seeds, C6/C1 ratios of embryonic axes of seeds soaked in air-saturated water remained high (0.8–1.0) during and after soaking. This was paralleled by low activities of glucose-6-phosphate dehydrogenase (EC.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44). In axes of seeds soaked in CO2-saturated water and in unsoaked seeds C6/C1 ratios declined steadily during soaking/imbibition and reached values of around 0.3 after germination. Slight increases ofglucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities occurred in the pre-germination phase. This was followed by a massive increase after radicle emergence. Synthesis of the plastid isoenzymes was a post-germinative event.It appears that soaking injury depresses protein synthesis. Lack of oxidative pentose phosphate pathway activity appears to be a causative factor in soaking injury.
Lipid autoxidation and seed ageing: putative relationships between seed longevity and lipid stability
Authors: Ponquett R. T. , Smith M. T. , Ross G. 
Published: September 2008

AbstractOn the premise that seed ageing may be largely a result of free-radical lipid autoxidation, a study was made of the relationship between lipid stability and longevity in seeds of soybean (Glycine max), lentil (Lens culinaris), mungbean (Vigna radiata), chickpea (Cicer arietinum), broadbean (Vicia faba), pea (Pisum sativum), lettuce (Lactuca sativa), and tomato (Lycopersicon esculentum). Seed lipids were examined for α-, γ- and δ-tocopherols, and levels of unsaturated and saturated fatty acids. Using this information, analysis was attempted using linear, multiplicative or exponential models to correlate aspects of lipid stability with seed longevity values from the published literature. No statistically significant correlations could be found between longevity and total lipid unsaturation, tocopherol levels or two protection formulae obtained from the oil chemistry literature. When values for tomato were excluded, a good correlation (r = 0.89, P = 0.007) was obtained using a multiplicative regression model for levels of linolenic acid per unit of total tocopherols in relation to longevity. Possible factors contributing to a lessening of the relationship between lipid stability and seed longevity are discussed.
Transport of nutrients into developing seeds: a review of physiological mechanisms
Authors: Wolswinkel P. 
Published: September 2008

AbstractAfter synthesis in the vegetative parts of the plant, assimilates are translocated to fruits through xylem and phloem. Research on factors controlling nutrient transport into developing seeds via the phloem has been stimulated by the development of the empty seed coat technique.There is a consensus that as assimilates are transported from maternal tissues to filial tissues they are delivered to the extracellular space (the apoplast) separating the two generations, prior to uptake from the apoplast into the tissues of the embryo or endosperm. The empty seed coat technique has been used for the study of several aspects of nutrient transport into seeds, e.g. metabolic control and turgorsensitive transport. The osmotic environment of seed tissues has a strong effect on assimilate transport into empty seeds. Several lines of evidence suggest that one of the main ‘secrets’ of the high sink strength of developing seeds, at least in many taxonomic groups of dicotyledons, is that the sink end of the phloem pathway is ‘bathed’ in an apoplast solution with a high concentration of osmotically active solutes. Data on maize do not fit this pattern. A turgor homeostat mechanism may help to maintain high solute concentrations in the seed apoplast. The apoplast environment of seed tissues may also stimulate synthesis of storage proteins and be involved in the prevention of precocious germination. In addition to the osmotic environment, other factors influencing sink strength are discussed. Some aspects of solute transformation during transport through seed tissues are described.
Regulation of protein synthesis in germinating wheat embryos under polyethylene glycol and salt stress
Authors: Dell'Aquila A. , Spada P. 
Published: September 2008

AbstractWheat seeds were imbibed in solutions of polyethylene glycol (PEG) and NaCl, and embryo water content and incorporation of [35S]methionine into proteins were determined. Both osmotica reduced water uptake and protein synthesis, though these were immediately resumed upon removal of stress. Results ofin vivolabelling of newly synthesized proteins showed differences in the synthesis of many polypeptides when embryos that had imbibed in water passed from the radicle pre-emergence phase to early growth. The synthesis of a group of proteins associated with radicle emergence was reduced during imbibition in PEG or NaCl. All the major proteins of the pre-germination phase were produced in PEG-treated embryos, while some new polypeptides (‘salt stress’ proteins?) were actively synthesized in salt-treated embryos. Upon removal of PEG or NaCl, synthesis of proteins common to the phase of early embryo growth increased, while specific saltimbibition proteins disappeared. These findings are consistent with the hypothesis that biochemical processes leading to radicle emergence can be affected by osmotic stress and are likely to be damaged by severe stress.
Histo-differentiation and molecular biology of developing cereal endosperm
Authors: Olsen O.-A. , Potter R. H. , Kalla R. 
Published: September 2008

AbstractTo elucidate the molecular aspects of cereal endosperm development, a good understanding of the histo-differentiation process is necessary. Reviewing the extensive history of lightand electron-microscopic investigations has revealed similarities between cereals with respect to cell ontogeny. Thus, using barley as a model and taking into account many developmental mutants in this and other species, a model for endosperm differentiation is proposed. Based on this model, molecular studies on endosperm gene-regulation are discussed and the available techniques for further investigations are considered.
Influence of plating density, sucrose and light during development on the germination and vigour ofMedicago sativaL. somatic embryos after desiccation
Authors: Anandarajah K. , McKersie B. D. 
Published: September 2008

AbstractSomatic embryo quality is an important aspect of artificial or synthetic seed production and is dependent on proper morphological development and deposition of sufficient storage reserves to support early growth of the seedling. The abilities of a somatic embryo to survive desiccation and to establish a rapidly growing seedling were used as estimates of quality and were dependent on a number of factors during the elongation and maturation phases of somatic embryo development. Embryo quality was significantly enhanced when the sucrose content of the elongation and maturation media was increased to 50 g I−1from 30 g I−1. This increased dry weight to >2 mg embryo−1suggesting greater deposition of storage reserves. Higher sucrose concentrations were inhibitory and reduced survival after desiccation and seedling vigour. An optimum number of embryos can be supported on one Petri plate; the number was controlled by the plating density of the embryogenic cell clusters spread on the elongation medium. This optimum was dependent to some extent on the sucrose content of the medium, indicating that sucrose had a nutritive effect on embryo development and not solely an osmotic effect. Light intensity was another critical factor. Intensities > 75 μmol m−2s−1photosynthetic photon flux density (PPFD) at the elongation stage of development blocked globular-stage somatic embryo development. Maturing somatic embryos were far less sensitive to high light intensities and development was more rapid at 150 μmol m−2s−1PPFD. Light quality was manipulated by covering plates with filters that selectively transmitted certain regions of the visible spectrum. All filter treatments reduced embryo yield and quality compared with embryos developing under fullspectrum light; varying the light spectrum does not seem to be a viable method of enhancing somatic embryo quality.
DNA synthesis in osmoprimed leek (Allium porrumL.) seeds and evidence for repair and replication
Authors: Ashraf M. , Bray C. M. 
Published: September 2008

AbstractOsmopriming of leek seeds (Allium porrumL.) in PEG 6000 solution (−10 bars) at 15°C for 14 days leads to reductions in both the spread of germination and mean time to germination, especially in low-vigour seed lots.In vivomethyl [3H]-thymidine pulse-labelling studies have demonstrated constant and low levels of DNA synthesis in leek embryo tissue during the osmopriming treatment. DNA synthesis during osmopriming was not inhibited by aphidicolin, an inhibitor of nuclear DNA replication. Replicative and repair-type DNA synthesis was investigated using BND-cellulose chromatography and these studies revealed that about 30% of the DNA synthesis after 1 day of priming was of a repair-type. DNA repair-type synthesis contributed to approximately 20% of the [3H]thymidine incorporated into DNA during the rest of the priming period in embryo tissue from both high-vigour and low-vigour seed lots. After 1 day of germination following priming, enhanced levels of both replicative and repair-type DNA synthesis were demonstrated. The replicative type of DNA synthesis detected in leek embyros during the priming period was not inhibited by aphidicolin and appears to represent a significant level of mitochondrial DNA synthesis. DNA synthesis could be detected in both nuclei and mitochondria of leek embryo tissue during the osmopriming treatment in the absence of any detectable cell division.
Relief of thermoinhibition in Grand Rapids lettuce seeds by oxygen plus kinetin and their effects on respiration, content of ethanol and ATP and synthesis of ethylene
Authors: Small J. G. Chris , Schultz Colleen , Cronje Elbie 
Published: September 2008

AbstractSeed germination of Grand Rapids lettuce (Lactuca sativa L.) was inhibited at 38°C (thermoinhibition). Thermoinhibition was totally relieved by a combination of 100% oxygen and 10 mg I−1 kinetin, to a lesser extent by a combination of oxygen and ethylene but not at all by oxygen plus GA3. The combination of oxygen with kinetin or ethylene was more effective in preventing thermoinhibition than a combination of all three hormones and CO2 in air. The beneficial effect of oxygen plus kinetin was not related to either increased production of CO2 or ethylene by the seeds. In air, germination was partially inhibited by 2-aminoethoxyvinyl glycine (AVG) or 2,5-norbornadiene (NBD) and totally inhibited by AVG plus NBD. Oxygen plus kinetin almost completely alleviated their inhibitory effects. It was concluded that oxygen plus kinetin caused seeds to bypass an ethylene requirement for germination or increased the sensitivity of seeds to ethylene. In air at 38°C, seeds exhibited a high level of ethanolic fermentation, while in oxygen plus kinetin they respired aerobically. At 38°C in air, contents of ATP and total adenylates were reduced, while in seeds treated with oxygen plus kinetin these contents were similar or higher than in 25°C controls. A similar response was also observed for adenylate energy charge. It was concluded that part of the mechanism of thermoinhibition could be the failure of ATP content to reach a sufficient level to satisfy the requirement for germination at 38°C. It appeared possible that the prevention of thermoinhibition by oxygen plus kinetin could be related to increased ATP content in seeds caused by this treatment.
Oxygen, free radical processes and seed longevity
Authors: Hendry George A. F. 
Published: September 2008

AbstractThe origin and significance of free radicals is described in the broad setting of animal and plant biology and in the specific context of seeds and seed viability. Evidence is given that free radicals play a central if not causal role in promoting molecular damage under the widest range of environmental stresses and induced ageing in mature plant tissuesIn ungerminated seeds, the evidence is less certain. The reason, we argue, is that many attempts to measure free radical processes in seeds are set not against gradients of damage or ageing (as they are in most other biological tissues) but against one of only two options, either seed germinability or mortality. Because free radical reactions differ quantitatively and qualitatively in living and dead tissues attempts to correlate radicalmediated damage with the viability of a population of seeds may be unreliable particularly when measurements are made at uncertain intervals after death. Despite this, the evidence that seeds, uniquely, are exempt from the ravages of oxygen assault is weak. Instead it ismore probable that oxygen plays a central role in seed mortality and may have significance in the evolution of seed persistence.
Non-destructive X-ray analysis ofArabidopsisembryo mutants
Authors: Bino R. J. , Aartse J. W. , van der Burg W. J. 
Published: September 2008

AbstractX-radiography is a simple, rapid and non-destructive method for analysing the morphology of embryos in dry, mature seeds ofArabidopsis thaliana.In wild type seeds, the cotyledons, hypocotyl and radicle tip can be readily distinguished. In seeds of the mutant typesknolle, keule, and the double mutantkeulelgnom, aberrations in embryo morphology can be visualized. X-radiography may therefore be useful in the isolation of embryo mutants fromArabidopsisseed samples.
Heat shock and recovery in aged wheat aleurone layers
Authors: Livesley M.A. , Bray C. M. 
Published: September 2008

AbstractAgeing of wheat seeds (Triticum aestivum cv. Galahad, 1986 harvest) during storage is accompanied by an increase in the proportion of abnormal seedlings produced when aged seed lots germinate. The response of aleurone layers from normally and abnormally germinated seeds to heat shock has been investigated. [14C]-amino acid incorporation into aleurone layers from 3-d normally and abnormally germinated seeds diminished after 4 h at 42°C but the aleurone layers were able to recover significantly during a 5-h period at 20°C following heat shock. [35S]-methionine pulse-labelling of aleurone proteins showed that α-amylase isoenzyme synthesis was abolished upon heat shock in aleurone layers for both normally and abnormally germinated seeds and that only aleurone layers from normally germinated seeds were capable of recommencing substantial α-amylase synthesis during the recovery period. Heat shock caused aleurone layers from abnormally germinated seeds to synthesize polypeptides not synthesized by aleurone layers from normally germinated seeds under the same conditions. The synthesis of certain polypeptides by aleurone layers from abnormally germinated seeds was enhanced at 20°C, 42°C and during recovery compared with normally germinated seeds. These results are discussed in terms of the control of gene expression during heat shock and recovery during seed ageing.