Morphology and Germination of Yellow and Brown Caryopses of Aegilops Geniculata Roth (Gramineae) Population from Italy

Abstract

The germination percentage of Aegilops geniculata Roth caryopses was studied on four Italian populations (Pisa, Manfredonia, Catania and Simbirizzi). Observation of the germination trend was carried out at constant temperatures of 10°, 20° and 30°C, from maturation up to 60 days after harvesting. Spike, spikelet and caryopsis phenotypic characteristics were also studied. The populations of Pisa, Manfredonia and Simbirizzi presented two different types of caryopses: yellow caryopses - larger, heavier and composing roughly 60% of total—and brown caryopses—smaller and lighter in weight. The Catania population formed an exception in that brown caryopses were virtually absent (5%). This Sicilian accession also showed the largest spikelet size.

Yellow caryopses germinated more rapidly than the dark ones, which were shown to be endowed with longer relative dormancy, above all at 10° and 30° C. Such a phenomenon allows the two types of caryopses to have a different germination ecology, thus providing A. geniculata with a broader choice of germination opportunities and consequently favouring spread and survival of the species.     

Changes in Respiratory Potential of Dormant and Non-dormant Galium aparine L. (cleavers) Seeds during Dry Storage

Hilton, J. R. and Thomas, J. A. 1987. Changes in respiratorypotential of dormant and non-dormant Galium aparine L. (cleavers)seeds during dry storage.—J. exp. Bot. 38: 1484–1490. Pre-germinative rates of O₂ uptake of two collections of Galiumaparine L. seed were compared throughout a 9 month period ofdry storage at 4 °C, 23 °C and at ambient (frost-protected)temperatures. Uptake of O₂ by the dormant seeds was generallyhigher than that of the less dormant seeds except when freshly-harvested.Moreover, changes in the O₂ consumption of seeds stored at ambienttemperatures could be associated with periods of germinationand seedling emergence in the field. The results are discussedin relation to changes in respiratory metabolism during dormancybreakage.     

Effects of Cutting Phenology (Non-dormant Versus Dormant) on Early Growth Performance of Three Willow Clones Grown Under Different Weed Treatments and Planting Dates

To assess the effects of cutting phenology on early growth performance of three willow clones grown under different weed treatments and planting dates, freshly harvested (non-dormant) and cold-stored (dormant) cuttings from willow clone Tora, Jorr, and Olof were planted in bucket experiment outdoors in central Sweden on five planting dates (May–June 2013) with or without a model weed (spring barley). Non-dormant cuttings sprouted faster than dormant cuttings when planted early in the season. For cuttings planted later in the season, bud sprouting was affected only by willow clone. Aboveground biomass production was affected by cutting phenology, planting date, clone, and weed treatment. When planted on May 3 and May 10, biomass produced from non-dormant and dormant cuttings did not differ, while willows grown from dormant cuttings produced 59% more aboveground biomass than willows grown from non-dormant cuttings when planted on May 24–June 16. Tora produced on average 12% more biomass than Jorr and Olof, and weed competition reduced aboveground biomass production on average with 36%. The ability of willow to suppress weeds (WSA) was 26 (non-dormant cuttings) and 12% (dormant cuttings) higher for willows planted on May 3 compared with WSA of willows grown from cuttings planted later in the season. The ability to tolerate competition from weeds (WT) was 51 and 52% lower for willows grown from non-dormant and dormant cuttings planted late in the season compared with WT of willows planted earlier in the season. We conclude that planting with long-term cold storage of willow cuttings can be replaced with planting freshly harvested cuttings when planting is performed in early season, and that weed competition strongly reduces biomass production. Weed control during the establishment phase is crucial in order to maximize willow biomass production.     

The Effects of Aluminium on the Seed Germination and Seedling Growth in Hibiscus moscheutos (Malvaceae) and Wheat (Triticum aestivaum,Gramineae)

The effects of AlCl₃ on Hibisucs moscheutos seed germination and growth were investigated to evaluate its hardiness to Aluminum (Al), in compassion with Carazinho, a wheat genotype tolerant to Al, and Egret, agenotype sensitiveto Al . For H. moscheutos and two wheat genotypes, our results indicated that germination was insensitive to AlCl₃ until at 500μmol/L. AlCl₃ of 50μmol/L inhibited the elongation of primary and lateral roots significantly, but had less effect on the number of lateral roots. There was no difference of root elongation between the H. moscheutos and wheat, but the lateral roots of H. moscheutos were more tolerant to Al than that of wheat genotypes. Under AlCl₃ of 50μmol/L, the reduction of root biomass was significant in wheat genotypes, but not in H. moscheutos, comparing to their control, suggesting that H. moscheutos is more tolerant to Al than the two wheat genotypes, and that Al has different effects on the growth of primary and lateral roots in both H. moscheutos and wheat .     

铝对秋葵、小麦种子萌发和幼苗生长的影响

以不同抗铝小麦（Triticum aestivum L．）基因型：Carazinho（抗铝型）和Egret（铝敏感型）为参比,研究了铝胁迫对秋葵（Hibiscus moscheutos L．）种子萌发和幼苗生长的影响。结果表明：秋葵和小麦种子的萌发对铝胁迫不敏感;高浓度的AlCl3（50μmol／L）显著抑制主根和侧根伸长,但对侧根数目的影响较小;两种植物的主根伸长对铝胁迫的差异不显著,而秋葵侧根对铝毒的抗性比两个供试的小麦基因型强;50μmol／L的AlCl3显著降低两个小麦基因型的根系生物量,但秋葵的根系生物量与对照比变化不大。表明秋葵幼苗的抗铝性强于两个小麦品种,铝对秋葵、小麦侧根和主根的生长影响不同。     

Effect of Salt Stress on Seed Germination and EmbryoGrowth of Spartina alterniflora (Gramineae)

In this paper , the effect of NaCl concentration ( 1× 104 - 6× 104 mg/L) on the seed germination of smooth cordgrass ( Spartina alterniflora) was investigated using 1/2 Hoagland as the basic culture solution. The results indicated that the coleoptile and embryonal axis grew before the radicle and plumule in the stage of germination . Salinity level had no influence on the seed germination percentage when the salt concentration didn′t exceed 3×104 mg/L. The optimal salinity level for seed germination and embryo growth was 1×104 mg/L . The inhibit effect of salt concentration on the growth of embryo′s different part was different, and the length of radicle and plumule decreased significantly with the increase of salt concentration. However , the lesser inhibition on the embryonal axis and coleoptile was observed under the higher salt concentration, and thus the seedlings out of soil were ensured and the species was quickly adapted to the environment of inter- tidal zone .     

New Structures in Binding Designs of Freshwater Ectoprocta Dormant Bodies (Statoblasts)

With the critical point drying method a scanning electron microscopic study of freshwater Ectoproct dormant structures was made. The suture zones of major phylactolaemate genera were described suggesting methods of their classification. The new structures revealed, throw light on the binding mechanism and early kinetics of germination of these dormant bodies. Median ribs and lateral ribs were described in the suture zones of Plumatella fruticosa, P. casmiana and Pectinatella magnifica. Dormant bodies of Fredericella sultana lack a medial or lateral rib in their suture zone. The fine structure of the polymorphic statoblasts of P. casmiana revealed different binding mechanisms as suited to different seasons. During germination, the internal pressure increases within the statoblast and the well cemented medial rib unfolds, letting its two valves separate. The mechanics of valve separations and subsequent germination were related to their respective environmental conditions favouring their domination.     

盐胁迫对互花米草种子萌发及胚生长的影响

以1/2Hoagland溶液为基础培养液,研究了1×104-6×104mg/L NaCl对互花米草(Spartina alterniflora)种子萌发的影响.结果表明,互花米草种子在萌发阶段胚芽鞘和胚轴生长先于胚根和胚芽;当盐浓度不超过3×104mg/L时,互花米草种子的萌发率未受到影响,种子萌发及胚生长的适宜盐浓度为1 x104mg/L,盐浓度对胚的不同部位生长的抑制程度不同,随着盐浓度的升高,胚根、胚芽的长度旱明显下降趋势,但盐浓度对胚轴、胚芽鞘生长的抑制作用较小,有利于已萌发的互花米草幼苗快速出土,迅速适应多变的潮间带环境.     

ATP Synthesis during Water Imbibition in Caryopses of Genetically Dormant and Non-dormant Lines of Wild Oat (Avena fatua L.)

Levels of ATP in dry caryopses of wild oats (Avena fatua L.)were much lower than in imbibed seeds of the seven geneticallypure lines surveyed. The ATP content of the lines with highgenetic dormancy was consistently lower than the ATP contentof genetically non-dormant lines, but no significant correlationwith depth of dormancy was found apart from this. Massive increasesin ATP content occurred within 30 min of water uptake by caryopsesof both dormant and non-dormant lines. The synthetic pathwaystudied utilized inorganic phosphate with great avidity to formATP. The ability to form ATP upon imbibition was present inboth embryo and de-embryonated caryopsis. The ATP levels attainedin imbibing caryopses appeared sufficient to support considerablesynthetic activity, and this reduced the possibility that adeficiency in ATP was responsible for the maintenance of dormancyin such imbibed seeds. The low levels of inorganic phosphatein the embryos of genetically dormant lines of wild oat couldrepresent a limiting factor, if the active formation of ATPupon water imbibition resulted in a scarcity of phosphate forother reactions essential to germination. Key words: Avena fatua, ATP synthesis, Inorganic phosphorus, Seed dormancy, Germination, Water uptake     

Abscisic Acid-like Inhibitors and Cytokinins during After-ripening of Dormant Peanut Seeds (Arachis hypogaea)

Changes in abscisic acid-like inhibitors and cytokinins were studied during dry storage after ripening of dormant peanut seeds. Decrease in ABA-like inhibitors and increase in cytokinin levels was found as the seeds lose their dormancy. Dormancy of peanut seeds is associated with presence of a high level of ABA-like inhibitors and a low level of cytokinins.     

A Systematic and Evolutionary Study of Zizania L. (Gramineae) Pollen Morphology

This paper deals with pollen morphology of Zizania L. and its relatives. A total of 7 genera, 13 species, 3 varieties and 1 form were examined under light microscope and scanning electron microscope. The results are as follows: 1. The genus Zizania belongs to tribe Oryzeae as shown by pollen characters, i, e. subspheroidal to ovoid in shape, monoporate, exine two-layered, with minute granules under LM. 2. The evolutionary trend of these taxa seems to be from minute granules free (Zizania latifolia, Z. texana, Zizaniopsis milicea and Oryza sativa) to minute granules aggregated in a group of 2-4 (many) (Zizania aquatica, Z. palustris, Leersia hexandra etc.). The genus Zizania may be derived from the ancient stock which has also given rise to the genus Oryza, and therefore parallel evolution may have taken place in Oryzeae, i. e. from perennial species to annual species in Zizania in one line, and from the genus Oryza to Leersia, Chikusichloa etc. in the other. 3. The characters of pollen morphology under LM and SEM support the division of the genus, Zizania into 4 species, 2 subspecies in the world, i. e. Z. latifolia (Griseb.) Turcz. ex Stapf, Z. texana Hitchc., Z. aquatica subsp. aquatica, Z. aquatica subsp. brevis (Fassett) S. L.Chen, Z. palustris subsp. palustris, and Z. palustris subsp. interior (Fassett) S. L. Chen.     

极度濒危植物-云南蓝果树的种子形态和不同处理条件对种子萌发的影响

观察了云南蓝果树(Nyssa yunnanensis)种子的形态,并初步研究了萌发基质、光照、人工破坏内果皮和pH梯度碱液处理对云南蓝果树种子萌发的影响。结果表明:云南蓝果树种子(带内果皮)平均大小为0.94cm×0.52cm×0.17cm(长×宽×厚),千粒重约234.3g,有萌发瓣;红土/腐殖土/泥炭土(v/v/v,1∶1∶1)为云南蓝果树种子萌发的适宜基质;种子在光、暗条件下都能萌发;人工破坏内果皮能明显地提高种子的萌发率;碱液处理对云南蓝果树种子的萌发有抑制作用,但对中国蓝果树(N.sinensis)种子的萌发有促进作用。本文还对云南蓝果树的致濒原因进行了讨论。     

Weedy adaptation in Setaria spp. V. Effects of gaseous environment on giant foxtail (Setaria faberii) (Poaceae) seed germination

The effects that naturally occurring gases (oxygen, nitrogen, carbon monoxide) may cause in dormant giant foxtail (Setaria faberii) seed germination under favorable temperature and moisture conditions were investigated. The germination responses to gas mixtures supported the hypothesis that S. faberii germination behavior is regulated by the amount of oxygen taken into hydrated seed over time. Setaria faberii seed germination was markedly affected by O(2) concentration (in N(2)) above and below that of air (20% O(2)): the largest increase in germination (from 37 to 60%) occurred between 20-25% O(2); between 0-10% O(2), germination increased from 0-30%; and surprisingly germination at 10 and 20% O(2) was similar. These observations reveal an asymmetrical response to incremental changes in O(2) above and below that typically found in agricultural soils. Carbon monoxide had opposite effects on S. faberii germination in air depending on concentration, stimulation, and inhibition: germination increased from 37 to 56% with the addition of 1% CO, but decreased from 37 to 14% with 75% added CO. An explanation may be that there are two separate effects of CO, each occurring in different physiological systems of dormant seeds at the same time. At high concentrations (75%) in air CO inhibited seed germination, probably by inhibiting mitochondrial respiration. But low CO concentrations (0.1 or 1%) in air stimulated seed germination. It was not apparent which physiological system(s) CO and O(2) affected. It seems unlikely that CO-stimulated germination arises from effects on the respiratory apparatus, but may be a consequence of CO interactions with an as yet unknown physiological factor in the seed. We provide a model of Setaria spp. dormancy consistent with its seed morphology, the gas-germination data, and the hypothesized second physiological factor that may be involved in CO stimulated germination.     

The flavonoids in leaves of diploidTriticum species (Gramineae)

Leaf flavonoids have been identified in seven species ofTriticum, all of which have been considered at one time as putative parents of the cultivated tetraploid and hexaploid wheats. The major constituents are apigenin- and luteolin-based glycosylflavones, some of which contain various O-glycosidic attachments at the 6-position. Four tricin glycosides are present in minor amount, as is free tricin. The flavonoid patterns link togetherT. searsii, T. speltoides andT. squarrosa, on the one hand, andT. monococcum, T. boeoticum, T. thaoudar andT. urartu, on the other. These results indicate that the first three taxa are more likely to be diploid ancestors to the hexaploidT. aestivum than the latter four species.