Factors affecting stress tolerance in recalcitrant embryonic axes from seeds of four Quercus (Fagaceae) species native to the USA or China

MethodsWater relations and survival of excised axes in response to water loss and cryo-exposure were compared for four Quercus species from subtropical China (Q. franchetii, Q. schottkyana) and temperate USA (Q. gambelii, Q. rubra).ConclusionsQuercus species adapted to arid and semi-humid climates still produce recalcitrant seeds. The ability to avoid freezing rather than drought may be a more important selection factor to increase desiccation tolerance. Cryopreservation of recalcitrant germplasm from temperate species is currently feasible, whilst additional protective treatments are needed for ex situ conservation of Quercus from tropical and subtropical areas.     

Pericarp development and fruit structure in borassoid palms (Arecaceae-Coryphoideae-Borasseae)

Background and Aims

The Borasseae form a highly supported monophyletic clade in the Arecaceae–Coryphoideae. The fruits of Coryphoideae are small, drupaceous with specialized anatomical structure of the pericarp and berries. The large fruits of borassoid palms contain massive pyrenes, which develop from the middle zone of the mesocarp. The pericarp structure and mode of its development in Borasseae are similar to those of Eugeissona and Nypa. A developmental carpological study of borassoid palms will allow us to describe the process of pericarp development and reveal the diagnostic fruit features of borassoid palms, determine the morphogenetic fruit type in Borasseae genera, and describe similarities in fruit structure and pericarp development with other groups of palms.

Methods

The pericarp anatomy was studied during development with light microscopy based on the anatomical sections of fruits of all eight Borasseae genera.

Key Results

The following general features of pericarp structure in Borasseae were revealed: (1) differentiation of the pericarp starts at early developmental stages; (2) the exocarp is represented by a specialized epidermis; (3) the mesocarp is extremely multilayered and is differentiated into several topographical zones – a peripheral parenchymatous zone(s) with scattered sclerenchymatous elements and vascular bundles, a middle zone (the stony pyrene comprising networks of elongated sclereids and vascular bundles) and an inner parenchymatous zone(s); (4) differentiation and growth of the pyrene tissue starts at early developmental stages and ends long before maturation of the seed; (5) the inner parenchymatous zone(s) of the mesocarp is dramatically compressed by the mature seed; (6) the endocarp (unspecialized epidermis) is not involved in pyrene formation; and (7) the spermoderm is multilayered in Hyphaeninae and obliterated in Lataniinae.

Conclusions

The fruits of Borasseae are pyrenaria of Latania-type. This type of pericarp differentiation is also found only in Eugeissona and Nypa. The fruits of other Coryphoideae dramatically differ from Borasseae by the pericarp anatomical structure and the mode of its development.     

cpDNA evidence of introgressions in Quercus L. (Fagaceae). The influence of the phytotopographic position

Genetic variability of species can appear due to different ecological factors, such as the position they occupy within vegetal communities. From an area in the southern Iberian Peninsula where a great number of species of the genus Quercus are found, we report the influence of winds on their chloroplast DNA (cpDNA) composition. Quercus faginea behaves as the genetic receiver of Q. canariensis, producing the hybrid Q. canariensis×Q. faginea, which is important in the landscape. Both species and the hybrid have a suitable altitudinal location for the pollen route, favoured by eastern winds. Quercus pyrenaica forests are protected from the eastern winds so they receive pollen from Q. lusitanica, favoured by western winds. The hybrids between Q. canariensis and Q. faginea are morphologically identifiable, while the introgressions between Q. lusitanica and Q. pyrenaica are not.     

Embryo Water Status and Survival in the Recalcitrant Species Quercus robur L: Evidence for a Critical Moisture Content

The responses of Q. robur L. fruits, seeds and embryonic axesto desiccation are characterized and discussed in relation tocurrent knowledge of recalcitrant seed behaviour. A relationshipbetween viability and seed moisture content is described. Thisrelationship was unaffected by rate of drying, year of harvestor presence of the pericarp. Desiccation sensitivity did notincrease with storage. Excised embryonic axes survived to lower moisture contents thanintact seeds. However, in the intact seed, loss of viabilityappeared to be determined by a critical moisture content inthe cotyledons. Consequently, the level of desiccation tolerancewithin the axis attached to cotyledons was not determined byaxis drying rate. A link is drawn between the difference in the desiccation toleranceof embryonic axes and of cotyledons, and estimates of theirdifferent levels of matrix-bound water. The results presentedare consistent with a critical moisture content for survivalwhich is determined by the loss of all free cellular water.This hypothesis takes account of the differential desiccationsensitivity of seed tissues and differences in desiccation tolerancebetween species.     

Sympatric genome size variation and hybridization of four oak species as determined by flow cytometry genome size variation and hybridization

The Quercus species serve as a powerful model for studying introgression in relation to species boundaries and adaptive processes. Coexistence of distant relatives, or lack of coexistence of closely relative oak species, introgression may play a role. In the current study, four closely related oak species were found in Zijinshan, China. We generated a comprehensive genome size (GS) database for 120 individuals of four species using flow cytometry‐based approaches. We examined GS variability within and among the species and hybridization events among the four species. The mean GSs of Q. acutissima, Q. variabilis, Q. fabri, and Q. serrata var. brevipetiolata were estimated to be 1.87, 1.92, 1.97, and 1.97 pg, respectively. The intraspecific and interspecific variations of GS observed among the four oak species indicated adaptation to the environment. Hybridization occurred both within and between the sections. A hybrid offspring was produced from Q. fabri and Q. variabilis, which belonged to different sections. The GS evolutionary pattern for hybrid species was expansion. Hybridization between the sections may be affected by habitat disturbance. This study increases our understanding of the evolution of GS in Quercus and will help establish guidelines for the ecological protection of oak trees.     

Relationship between cell number,cell size and fruit size of seeded fruits of tomato (Lycopersicon esculentum Mill.), and those induced parthenocarpically by the application of plant growth regulators

Application of GA₃, IAA or 4-CPA to tomato ovaries induced the development of parthenocarpic fruit, which showed different growth rates. In the pericarp cell division and cell enlargement was affected differentially. GA₃-induced fruits had considerably less but larger cells than seeded control fruits, IAA treatment resulted in the same number of cells but these were smaller and 4-CPA treatment induced fruits with about 20% more cells. Reduction in cell number had a similar effect on final fruit size as diminution of cell size. A reduction in the number of cell division centres (area around vascular bundles) as well as changes in the degree of endoploidy are possible reasons for the observed reductions in cell numbers. Hormonal causes for the different number and size of pericarp cells after the various treatments are discussed.     

Pericarp ontogenesis in wild species of Arachis L. (Leguminosae; Papilionoideae)

The genus Arachis encompasses 80 validly described species and the most striking characteristics is the geocarpic fruit, which occurs in every species of the genus. Taking into consideration that much of the current knowledge about this subject is based on the anatomy and morphology of A. hypogaea, a cultivated species with fruits that were modified during domestication, the objective of this study was to learn more about the development of the geocarpic fruits of wild species of Arachis (A. paraguariensis, A. pintoi, A. stenosperma, and A. tuberosa), and to provide characters that can be used in future phylogenetic works about this group. Buds, flowers and fruits at different stages of development were collected and processed according to standard methods used for light field, interferential contrast, and scanning electron microscopy. Although the geocarpic fruits of the wild species share many adaptations, this study identified potentially diagnostic infrageneric characters, such as the type of trichomes on the pericarp, the presence of sclerenchyma caps in the bundles of the pericarp of the seed chamber of the fruit and isthmus, the presence of tracheoid cells in the pith of the isthmus, the location of crystalliferous cells, the presence of tannins in the cells of mesocarp outer layers, and the presence of projections in the sclerenchyma tissue. In addition, this article brings some inferences about functional characteristics of this peculiar geocarpic fruit.     

Ecological significance of seed desiccation sensitivity in Quercus ilex

Background and Aims

Several widespread tree species of temperate forests, such as species of the genus Quercus, produce recalcitrant (desiccation-sensitive) seeds. However, the ecological significance of seed desiccation sensitivity in temperate regions is largely unknown. Do seeds of such species suffer from drying during the period when they remain on the soil, between shedding in autumn and the return of conditions required for germination in spring?

Methods

To test this hypothesis, the Mediterranean holm oak (Quercus ilex) forest was used as a model system. The relationships between the climate in winter, the characteristics of microhabitats, acorn morphological traits, and the water status and viability of seeds after winter were then investigated in 42 woodlands sampled over the entire French distribution of the species.

Key Results

The percentages of germination and normal seedling development were tightly linked to the water content of seeds after the winter period, revealing that in situ desiccation is a major cause of mortality. The homogeneity of seed response to drying suggests that neither intraspecific genetic variation nor environmental conditions had a significant impact on the level of desiccation sensitivity of seeds. In contrast, the water and viability status of seeds at the time of collection were dramatically influenced by cumulative rainfall and maximum temperatures during winter. A significant effect of shade and of the type of soil cover was also evidenced.

Conclusions

The findings establish that seed desiccation sensitivity is a key functional trait which may influence the success of recruitment in temperate recalcitrant seed species. Considering that most models of climate change predict changes in rainfall and temperature in the Mediterranean basin, the present work could help foresee changes in the distribution of Q. ilex and other oak species, and hence plant community alterations.     

Development and Characterization of Genomic and Gene-Based Microsatellite Markers in North American Red Oak Species

Oaks (Quercus: Fagaceae) are ecological and economic keystones of many forested ecosystems but effective genetic management strategies are hindered by high levels of phenotypic plasticity within species and frequent hybridization among them. These same features, however, make oak communities suited for the study of speciation, hybridization, and genetic adaptation. Efforts to develop new and to adapt existing genomic resources to less-studied members of this genus should not only improve oak conservation and management but also aid the study of fundamental evolutionary processes. Here, we present a suite of 27 highly polymorphic simple sequence repeat (SSR) markers tested in four North American red oak (Quercus section Lobatae) species: Q. rubra, Q. ellipsoidalis, Q. coccinea, and Q. velutina. Five markers are genomic SSRs (gSSRs) — four novel and one previously transferred from Q. petraea — and 22 are gene-based SSRs derived from Q. robur and Q. petraea expressed sequence tags (EST-SSRs). Overall, levels of polymorphism detected with these primer pairs were high, with gene diversity (H _e) averaging 0.66 across all loci in natural populations. In addition, we show that EST-SSR markers may have the potential to detect divergent selection at stress-resistance candidate genes among closely related oak species.     

Ecological dynamics of Quercus dominated woodlands in California and southern Spain: a state-transition model

There are many similarities between Spanish and Californian Quercus woodlands and savanna. Both are located in Mediterranean climate zones, and are used predominantly for livestock grazing. The Californian overstory is dominated by one or a combination of five Quercus species and their hybrids: Quercus douglasii H.&A., Q. agrifolia Nee., Q. wislizenii A.DC., Q. lobata Nee., and Q. englemennii Greene (blue, coast live, interior live, valley, and Englemann oaks). In southern Spain and Portugal, Quercus woodland overstory is predominantly one or a combination of two Quercus species, Quercus ilex L. (holm oak) and Quercus suber L. (cork oak). The underlying natural and semi-natural ecological dynamics of the Quercus woodlands of Spain and California are different, and it follows that the management practices employed also differ. The greatest point of contrast between California and Spain is in the intensity and diversity of management goals and practices. A state-transition model for comparing the ecological dynamics of Quercus woodlands and savanna in California and southern Spain is developed and examined. The highly simplified model is an analytic tool of use in organizing research and developing management practices. States are reached and maintained in different ways in Spain and California, but their appearance and their function in each landscape are quite similar.     

Post-dispersal seed removal in four Mediterranean oaks: species and microhabitat selection differ depending on large herbivore activity

Quercus forest regeneration is limited by different factors, post-dispersal predation being one of the most critical stages. We analysed seed removal of four coexisting Quercus species (Q. ilex, Q. suber, Q. faginea and Q. pyrenaica) in a Mediterranean forest located in Southern Spain. Marked and weighed acorns from each of the species were placed in experimental units with or without exclusion of large herbivores and in two microhabitat types (Q. ilex shade or open). Acorn removal was monitored for 120?days in order to test the effect of exclusion of large herbivore and microhabitat type on seed removal rates and species selection. Interestingly, the results of microhabitat and species selection differed depending on the presence of large herbivores. Removal was faster in sites without exclusion, where most seeds (??85%) disappeared during the first 9?days. In these sites, no differences in seed removal were found between different microhabitats, but seeds of two species, those with higher seed mass (Q. suber and Q. pyrenaica) were most preferred. However, under exclusion of large herbivores, seed removal was affected by the microhabitat, this being greater in Q. ilex shaded microhabitats, which showed a higher structural diversity. Also, species selection was completely different under exclusion of large herbivores, and seeds of Q. ilex and Q. faginea were removed faster. These results highlight the importance of large herbivore activity on seed removal and its effect on microhabitat and species selection. Therefore, specific selection by seed consumers may modify seedling recruitment and may have an important influence on the relative abundance of coexisting Quercus species.     

Hydraulic conductance and vulnerability to cavitation in corn (Zea mays L.) hybrids of differing drought resistance

Water transport through the xylem is essential for replacing water loss during transpiration, thus preventing desiccation and permitting photosynthesis. The occurrence of cavitation and embolism due to drought impairs transport to the transpiring leaves. Most research in this discipline has been conducted on woody plants. Less attention has been given to cavitation of crops and its physiological significance for understanding crop water relations. In this paper, hydraulic conductance and vulnerability of xylem to cavitation were studied in corn hybrids with different drought resistances. The results indicated that stems of drought-resistant ‘Pioneer 3902’ not only had a higher conductivity on both a stem area and leaf area basis but also had a greater resistance to cavitation. The estimated xylem pressure at 63.2% loss of conductivity (Weibull fitting parameter b) and at 50% loss of conductivity (P₅₀) in ‘Pioneer 3902’ were about 0.2 MPa lower than in ‘Pride 5’. Higher conductivity in ‘Pioneer 3902’ was mainly attributed to more vascular bundles per stem area rather than greater vessel diameter. The central bundles and peripheral vascular bundles showed the same degree of cavitation although the vessels of central bundles were generally larger than in peripheral bundles.     

Osmotic stress responses of individual white oak (Quercus section, Quercus subgenus) genotypes cultured in vitro

White oaks (Quercus section, Quercus subgenus) are widely distributed in Europe. Quercus petraea (sessile oak), an economically important species is predicted to be affected by climate change. Q. pubescens (pubescent oak) and Q. virgiliana (Italian pubescent oak) are economically less important, drought tolerant species. Frequent hybridization of white oaks was observed and currently the introgression of Q. pubescens and Q. virgiliana in non-mediterranean regions of Europe has been reported. Our goal was to use tissue cultures established from individual trees of the above taxa and their putative hybrids, all present in the forest stand of Síkf?kút LTER Research Area (NE Hungary) as simple experimental model systems for studying drought/osmotic stress tolerance. Tissue cultures are more suitable models for such studies, than seedlings, because they are genetically identical to the parent plants. Polyethylene glycol (PEG6000) treatments were used for this purpose. The identification of taxa was based on leaf morphological traits and microsatellite analysis and showed that Q. petraea is genetically distinct to all other taxa examined. We established six callus lines of Quercus. As expected, in Q. petraea cultures PEG6000 induced severe loss of fresh weight and the ability to recover after removal of the osmoticum, which was not characteristic for Q. pubescens and Q. virgiliana. Putative hybrids exhibited an intermediate response to osmotic stress. Activity gels showed the increase of single-strand preferring (SSP) nuclease and no significant change of guaiacol-peroxidase activities in drought-sensitive genotypes/cultures and no significant increase of SSP nuclease activities accompanied with increases of guaiacol-peroxidase activities in drought-tolerant ones. This indicates that drought/osmotic stress tolerance is associated to increased capacity of scavenging reactive oxygen species and hence less susceptibility to DNA damage. Our results confirm that tissue cultures of oak are suitable model systems for studying drought/osmotic stress responses.     

Cloning and Expression Analysis of Litchi (Litchi Chinensis Sonn.) Polyphenol Oxidase Gene and Relationship with Postharvest Pericarp Browning

Polyphenol oxidase (PPO) plays a key role in the postharvest pericarp browning of litchi fruit, but its underlying mechanism remains unclear. In this study, we cloned the litchi PPO gene (LcPPO, {"type":"entrez-nucleotide","attrs":{"text":"JF926153","term_id":"350601663","term_text":"JF926153"}}JF926153), and described its expression patterns. The LcPPO cDNA sequence was 2120 bps in length with an open reading frame (ORF) of 1800 bps. The ORF encoded a polypeptide with 599 amino acid residues, sharing high similarities with other plant PPO. The DNA sequence of the ORF contained a 215-bp intron. After carrying out quantitative RT-PCR, we proved that the LcPPO expression was tissue-specific, exhibiting the highest level in the flower and leaf. In the pericarp of newly-harvested litchi fruits, the LcPPO expression level was relatively high compared with developing fruits. Regardless of the litchi cultivar and treatment conditions, the LcPPO expression level and the PPO activity in pericarp of postharvest fruits exhibited the similar variations. When the fruits were stored at room temperature without packaging, all the pericarp browning index, PPO activity and the LcPPO expression level of litchi pericarps were reaching the highest in Nandaowuhe (the most rapid browning cultivar), but the lowest in Ziniangxi (the slowest browning cultivar) within 2 d postharvest. Preserving the fruits of Feizixiao in 0.2-μm plastic bag at room temperature would decrease the rate of pericarp water loss, delay the pericarp browning, and also cause the reduction of the pericarp PPO activity and LcPPO expression level within 3 d postharvest. In addition, postharvest storage of Feizixiao fruit stored at 4°C delayed the pericarp browning while decreasing the pericarp PPO activity and LcPPO expression level within 2 d after harvest. Thus, we concluded that the up-regulation of LcPPO expression in pericarp at early stage of postharvest storage likely enhanced the PPO activity and further accelerated the postharvest pericarp browning of litchi fruit.     

The root-tuber anatomy of Asphodelus aestivus

The root tubers of Asphodelus aestivus consist mostly of enlarged fleshy storage tissue. They are bounded by a multiple-layered velamen, responsible for rapid water uptake, water loss reduction, osmotic and mechanical protection. In the cortex area, thin-walled idioblasts contain numerous raphides of calcium oxalate in their large vacuole with a distinctive tonoplast. Wide morphological variations are observed among the raphide cross sections. Electron-dense compounds penetrate the raphide surface and raphide groove. Raphides seem to be vital for the protection of the root tuber parenchyma from herbivores. The cells of uniseriate endodermis are heavily thickened possessing a few plasmodesmata. The vascular cylinder is 20–28-arch and the root xylem consists of vessels in short radial rows, alternating with clusters of phloem cells. The presence of cells, which contain soluble polysaccharides in their large vacuole, is conspicuous after employing the Schiff's reagent. Exodermis cells and all cell walls, especially the thick ones of the endodermis, are also stained. Numerous parenchyma cells, especially those around vascular bundles are stained intensely, when exposed to Sudan Black B. These cells occurring as solitary idioblasts abundantly accumulate oil. Electron-dense remnants are evident within the vacuoles of the storage cells especially near the vascular tissue. The morphological features of A. aestivus root tubers and the major part of the total plant biomass are responsible for the species’ occurrence and frequent dominance in a wide array of arid environments. A. aestivus possessing root tubers is proved to be very efficient in storing water during the long summer drought, less susceptible to climatic stress and well synchronized with the climatic fluctuations of the Mediterranean environment.     

A systematic histological study of palm fruits. VI. Subtribe Linospadicinae (Arecaceae)

The pericarp structure of representative species of the four genera of the subtribe Linospadicinae is described and compared. Tissues found in the pericarp of this group are similar to those found in other subtribes of the Areceae, with no characters unique to the subtribe and nothing to suggest its closest affinities. The four genera, as well as each species examined, do show distinctive pericarp features, however.Laccospadix andLinospadix are similar, both with a single series of fibrous, bundles and an outer series of prominent raphide-bearing cells dominating the pericarp. In bothHowea andCalyptrocalyx, a complex exocarp forms from a series of fibrous bundles and brachysclereids, but each genus has other distinctive characters.Howea has vascular bundles in the exocarp zone, an outer series of raphide-bearing cells, and a conspicuously thickened locular epidermis. Based on a limited sample of four species, raphide-bearing cells appear to be always interior to the exocarp inCalyptrocalyx, and the locular epidermis is thin.     

Pericarp histogenesis and histochemistry during fruit development in Butia capitata (Arecaceae)

Palm fruits show great structural complexity, and in-depth studies of their development are still scarce. This work aimed to define the developmental stages of the fruit of the neotropical palm Butia capitata and to characterize the ontogenesis of its pericarp. Biometric, anatomical, and histochemical evaluations were performed on pistillate flowers and developing fruits. The whole fruit develops in three phases: (I) histogenesis (up to 42 days after anthesis – DAA), when the topographic regions of the pericarp are defined; (II) pyrene maturation (42 to 70 DAA), when the sclerified zone of the pericarp is established; and (III) mesocarp maturation (70 to 84 DAA), when reserve deposition is completed. During pericarp ontogenesis (i) the outer epidermis and the outer mesophyll of the ovary give origin to the exocarp (secretory epidermis, collenchyma, parenchyma, sclerenchyma, and vascular bundles); (ii) the median ovarian mesophyll develops into the mesocarp, with two distinct topographical regions; (iii) the inner ovarian epidermis originates the endocarp; and in the micropylar region, it differentiates into the germination pore plate, a structure that protects the embryo and controls germination. (iv) Most of the inner region of the mesocarp fuses with the endocarp and, both lignified, give rise to the stony pyrene; (v) in the other regions of the mesocarp, carbohydrates and lipids are accumulated in a parenchyma permeated with fiber and vascular bundles. The development of the B. capitata pericarp presents high complexity and a pattern not yet reported for Arecaceae, which supports the adoption of the Butia-type pyrenarium fruit class.

     

Sexual reproduction in the cork oak (Quercus suber L). II. Crossing intra- and interspecific barriers

Intraspecific barriers promote outcrossing while interspecific mechanisms may contribute to the isolation of species; both control the exchange of genes between plants. In this paper we establish that post-pollination mechanisms promote outcross and act at different temporal and spatial levels to control seed set and quality in Quercus species. Controlled pollinations were performed to investigate intraspecific crossing barriers in Q. suber and pollen-pistil interactions following interspecific pollinations with some simpatric Quercus species. Cytological data of intraspecific crosses in Q. suber and Q. ilex have shown different kinetics on pollen tube growth after self and outcross pollination, but pollen tubes were able to reach the base of the styles in both species and seed set was successful. Although some pre-zygotic interaction is occurring at the style, the most important interaction takes place at ovary. The cross between Q. ilex and Q. suber is possible only in one direction, revealing a case of unilateral incongruity. We show that the lack of seed set observed in the cross Q. suber×Q. ilex is due to the inability of pollen tubes to penetrate the transmitting tissue after germination. With Q. suber mainly as female parent, pollinations with other simpatric Quercus species have shown different levels of constraint on pollen tube progression at stigma and style levels. Eventual hybridisation between Quercus species will depend on the compatibility of pollen-pistil interactions, on the competitive ability of pollen genotypes, and, most important, on the overlapping of geographical, phenological and ecological factors. Differences in seed set and seed allocation was evident in all crosses, and was particularly outstanding in interspecific and in self intraspecific crosses, determining the ultimate level of seed production and quality in Quercus species. Received: 4 April 2001 / Accepted: 8 May 2001     

Effect of Water Stress on Pigment Formation in Quercus Species

The effect of water stress in three Quercus species belongingto different habitats is investigated. Chlorophyll concentrationdecreased in all Quercus species with the greatest decreaseoccurring in Quercus robur. An increase of total carotenoidcontent was observed in Quercus coccifera and Quercus ilex,while in Q. robur water stress effected a carotenoid contentreduction. Anthocyanins increased with decreasing relative watercontent in the three Quercus species, the largest increase occurringin Q. coccifera. A correlation between xerophytic characterand pigment concentration is discussed.     

栎属7种植物种子的发芽抑制物质研究

运用系统溶剂法和生物测定法,以栎属7种植物种子为材料,研究了其种皮、胚(胚及周围部分子叶)和子叶(远离胚端2/3子叶)1.0 g/mL和0.5 g/mL浓度甲醇等浸提液以及各有机相对白菜种子萌发的影响。结果表明:栓皮栎、锐齿栎、蒙古栎、沼生栎和麻栎甲醇浸提液均能显著降低白菜种子发芽率、根长和苗高,且对发芽率的抑制作用逐渐降低;夏栎和房山栎甲醇浸提液对白菜种子发芽率没有显著影响,但对根长和苗高有一定的抑制作用;种子不同部位甲醇浸提液的抑制作用表现为胚>子叶>种皮,且甲醇高浓度浸提液的抑制作用大于低浓度的抑制作用;甲醇相对白菜种子发芽率、苗高或根长的抑制作用最强,其次是乙酸乙酯相,其它溶剂相萃取液的抑制作用不明显。栎属种子甲醇浸提液及各有机相对白菜种子苗高和根长的抑制作用强于对发芽率的影响,说明栎属种子中所含抑制物质主要是限制自身根和芽的生长,可能是造成延迟萌发和出苗不整齐的原因。