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21.
The effect of phosphorus (P) concentration in barley seed on seedling growth has not been much investigated. Consequently,
two experiments were conducted in the greenhouse to determine the effect of P concentration in barley seed (Hordeum vulgare L., cv. Empress) on the seedlings grown in sand-filled boxes receiving a culture solution without P. Seeds were selected
with three P concentrations: high-P (113.0 mmol P kg−1), medium-P (80.7 mmol P kg−1) and low-P (54.9 mmol P kg−1). At 21 days after sowing, the shoot and root yield or shoot height was the least with seedlings from low-P seed. In the
other experiment, high-P and low-P seeds were wetted with distilled water or with a solution of 25.8 cmol L−1 of NaH2PO4 for 24 h, and then grown for 31 days. Solution P had been imbibed by seeds whether low or high in native P, but only the
imbibed P held by low native P seed benefited seedling dry matter accumulation and shoot elongation. The lack of benefit from
seed-imbibed P on seedlings grown from high-P barley seed was associated with low recovery of the imbibed P in those seedlings. 相似文献
22.
Örjan Totland 《American journal of botany》1996,83(4):452-458
Some plants in arctic and alpine habitats have heliotropic flowers that track the sun. This results in a heating of the flower's interior, which may improve the possibilities for insect pollination and seed production. Here, I examine whether flower heliotropism in an alpine population of the self-incompatible Ranunculus acris L. (Ranunculaceae) enhances pollinator visitation and seed production. Flowers of Ranunculus acris tracked the sun during the day. Tracking accuracy was greatest during the middle of the day. The temperature elevation in flowers was negatively correlated with the flower's angle of deviation from the sun. Despite the increased temperature, insects did not discriminate among flowers on the basis of their angle of deviation from the sun, or tend to stay longer in the flowers aligned closest towards the sun. A tethering experiment was conducted on three groups of plants flowering at different times in the 1993 season and on one group the following season. Manipulation plants were constrained not to track the sun, whereas control plants tracked the sun naturally. Solar tracking had no effect on seed:ovule ratio, seed mass, or abortion rate in any of the groups. There is probably a very narrow range of weather conditions (cold, sunny, and calm) where flower heliotropism may enhance visitation rate to flowers and their seed production. 相似文献
23.
Evolution of HCN from both rice ( Oryza sativa ) and cocklebur ( Xanthium pennsylvanicum ) seeds increased during a pre-germination period and preceded the evolution of (C2 H4 ). These two species were adopted as the representatives of starchy and fatty seeds, respectively. Ethylene promotes seed germination of many species. However, HCN evolution declined abruptly when the radicles emerged and before the peak in C2 H4 evolution. More-over, both rice and soybean ( Glycine max ) seeds showed some activity of β-cyanoalanine synthase (CAS, EC 4.4.1.9) even in the unimbibed dry state. The activities of CAS in the lower seed of cocklebur and in soybean seeds increased rapidly after emergence of the radicle. However, the CAS of rice seeds, with high activity in the dry state, exhibited a bimodal change, gradually decreasing until radicle emergence had occurred, but then increaing. It is thus likly that HCN evolution during initial imbibition may be derived from cyanogenic reserves and controlled by both pre-existing and subsequently-developing CAS. The exogenous application of C2 H4 stimulated the activities of CAS in both rice and upper cocklebur seeds and reduced their cyanogen contents. Therefore, the decline of HCN evolution after germination seems to be due to the increased activities of CAS by endogenously produced C2 H4 . 相似文献
24.
Abstract The study assessed the survival, during bushfires, of seedbanks of six serotinous Hakea species found in the Sydney region of southeastern Australia. The survival of seeds was examined when fruits were heated in a muffle furnace at ambient temperatures ranging from 200–800°C for 1 min. For each species, fruit weight and dimensions of fruit walls were measured to characterize insulation. A field experiment was performed to examine the survival of the serotinous seedbank of Hakea dactyloides in a bushfire. Ambient and internal fruit temperatures were recorded during the fire. The viability of seeds from fruits exposed to the fire was tested and compared with an unburnt sample. Viability of seeds within fruits exposed in the furnace varied according to species. Seeds of large fruited species such as Hakea constablei and Hakea propinqua survived, whereas those of the small fruited species Hakea teretifolia and H. dactyloides suffered significant mortality. The threshold temperature for death in four species was linearly related to the thickness of lower and lateral fruit walls, and to dry weight of fruits. Internal and external temperatures of fruits decreased with increasing height on experimental H. dactyloides plants in the field. High levels of mortality (relative to the unburnt control) corresponded with fire temperature maxima greater than 400°C (external) and greater than 60°C (internal). In general, these temperatures occur when shrub crowns burn. A high risk of death for H. dactyloides, H. teretifolia and H. sericea seeds will result because fruits of these species have thin walls. 相似文献
25.
The Ih and lh
i alleles have been shown previously to reduce the level of endogenous gibberellin A1 (GA1) in shoots of pea (Pisum sativum L.), resulting in a dwarf phenotype compared with the wild type, cv. Torsdag (Lh). In addition, plants homozygous for the lh
i allele have reduced seed yield compared with Lh (tall, wild type) and lh (dwarf) plants. In this paper we show that the lh
i mutation is expressed in developing seeds and pods. Comparison of GA levels in young shoots and developing seeds of genotypes lh and lh
i demonstrates that the relative severity of the two mutations varies in different tissues. Homozygous h
i seeds have reduced GA levels, weigh less, and are less likely to develop to maturity when compared with Lh seeds. However, fertilization of lh
i plants with Lh pollen increases seed GA levels, seed weight and seed survival, indicating that an increase in seed GA levels due to the presence of the Lh allele can restore normal seed growth. Pods developing on self-pollinated lh
i plants are shorter than pods on Lh (wild type) plants, although this may be an indirect effect of the increased seed abortion of lh
i plants. Based on these results we suggest that endogenous GAs play an important role in the development of seeds of P. sativum L.Abbreviations GA(n)
gibberellin An
We wish to thank Katherine McPherson, Peter Newman, Leigh Johnson and Peter Bobbi for technical assistance, Professor L. Mander (ANU, Canberra) and Professor B.O. Phinney (UCLA, USA) for labelled GA standards, and the Australian Research Council for financial support. 相似文献
26.
Wajirou Suzuki 《Ecological Research》1993,8(1):107-110
Seeds of twoRubus species,R. palmatus var.coptophyllus andR. microphyllus, buried for 7.5 years in soil were subjected to germination tests to investigate their germinability and germination traits.
Most of the retrieved seeds were viable, and germinated at the alternating temperatures of 20/30°C in both light and dark.
The twoRubus species showed similar responses of germination to temperature and light, although the final percentages of germination were
slightly higher inR. palmatus var.coptophyllus. These characteristics of seed dormancy and germination would be involved in the species' utilization of ephemeral habitats
created by unpredictable and infrequent disturbances. 相似文献
27.
E. H. ROBERTS 《Biological journal of the Linnean Society. Linnean Society of London》1991,43(1):23-29
The safest and most economical and convenient way of preserving the genetic resources of the majority of crop plants is by long-term seed storage. The technology is well developed, but recent research resulting from a greater understanding of behaviour at very low water potentials is leading to further improvements 相似文献
28.
29.
Professor M Goodfellow R Davenport F M Stainsby T P Curtis 《Journal of industrial microbiology & biotechnology》1996,17(3-4):268-280
Large numbers of mycolic acid-containing actinomycetes were isolated from foam and scum samples taken from three activated-sludge sewage-treatment plants using several selective isolation media. Organisms presumptively identified as gordonae formed the dominant population in all of the samples. A representative set of these strains have chemical properties consistent with their classification in the genusGordona. Forty-eight of theGordona strains were compared through 165 unit characters with the type strains of validly described species ofGordona. The resultant data were examined using the Jaccard and simple matching coefficients and clustering achieved using the unweighted pair group method with arithmetic averages algorithm. The numerical classification was only marginally affected by the statistics used or by test error, estimated as 3.92%. The isolates were assigned to five multi-membered and 28 single-membered clusters defined by the simple matching coefficient at the 89% similarity level. With few exceptions, the isolates were sharply separated from theGordona marker strains. Essentially the same classification was obtained when the test strains were examined using a Curie-point pyrolysis mass spectrometric procedure. It can be concluded that the gordonae form a heterogeneous taxonomic group, the members of which can be distinguished from representatives of validly described species ofGordona. 相似文献
30.