Embryology and systematic relationships of Kiggelaria (Flacourtiaceae)

Bothalia ◽  
2003 ◽  
Vol 33 (2) ◽  
pp. 199-206 ◽  
Author(s):  
E. M. A. Steyn ◽  
A. E. Van Wyk ◽  
G. F. Smith
Keyword(s):  
Seed Germination ◽  
Molecular Genetics ◽  
Seed Coat ◽  
Seed Structure ◽  
Systematic Relationships ◽  
Host Parasite ◽  
Outer Epidermis

Kiggelaria L. is endemic to Africa and the only representative of tribe Pangieae (Flacourtiaceae) on the continent. Molecular genetics, phytochemistry and host-parasite relationships have indicated a relationship between this woody, pantropical tribe of Flacourtiaceae and a small, trigeneric family of herbaceous, southern African endemics, the Achariaceae. In the present study, ovule and seed structure in Kiggelaria were investigated and compared with relevant data recently reported for Achariaceae. Support for an alliance with Achariaceae were found in the presence of anatropous, bitegmic. sessile ovules with zigzag micropyles. deep-lying embryo sacs covered by an epistase in the ovule and seed, endotestal-exotegmic seed coat layers, suspensorless embryos and sarcotestal seed with a prominent, plate-like hypostase. Unlike Achariaceae.  Kiggelaria seeds do not have chalazal seed lids, pronounced raphal ridges, a fringe layer, or stomata in the outer epidermis of the sarcotesta. Structural dissimilarities in seeds of omithochorous  Kiggelaria and myrmeco- chorous Achariaceae were regarded as adaptations linked to adifferent strategies for seed germination and dispersal.

scholarly journals Asymbiotic germination of Vanilla planifolia in relation to the timing of seed collection and seed pretreatments

2021 ◽  
Vol 62 (1) ◽  
Author(s):  
Chih-Hsin Yeh ◽  
Kai-Yi Chen ◽  
Yung-I. Lee
Keyword(s):  
Seed Germination ◽  
Seed Development ◽  
Seed Coat ◽  
Germination Percentage ◽  
Vanilla Planifolia ◽  
Outermost Layer ◽  
Seed Collection ◽  
Seed Pretreatment ◽  
Immature Seeds ◽  
Mature Seeds

Abstract Background Vanilla planifolia is an important tropical orchid for production of natural vanilla flavor. Traditionally, V. planifolia is propagated by stem cuttings, which produces identical genotype that are sensitive to virulent pathogens. However, propagation with seed germination of V. planifolia is intricate and unstable because the seed coat is extremely hard with strong hydrophobic nature. A better understanding of seed development, especially the formation of impermeable seed coat would provide insights into seed propagation and conservation of genetic resources of Vanilla. Results We found that soaking mature seeds in 4% sodium hypochlorite solution from 75 to 90 min significantly increased germination. For the culture of immature seeds, the seed collection at 45 days after pollination (DAP) had the highest germination percentage. We then investigated the anatomical features during seed development that associated with the effect of seed pretreatment on raising seed germination percentage. The 45-DAP immature seeds have developed globular embryos and the thickened non-lignified cell wall at the outermost layer of the outer seed coat. Seeds at 60 DAP and subsequent stages germinated poorly. As the seed approached maturity, the cell wall of the outermost layer of the outer seed coat became lignified and finally compressed into a thick envelope at maturity. On toluidine blue O staining, the wall of outer seed coat stained greenish blue, indicating the presence of phenolic compounds. As well, on Nile red staining, a cuticular substance was detected in the surface wall of the embryo proper and the innermost wall of the inner seed coat. Conclusion We report a reliable protocol for seed pretreatment of mature seeds and for immature seeds culture based on a defined time schedule of V. plantifolia seed development. The window for successful germination of culturing immature seed was short. The quick accumulation of lignin, phenolics and/or phytomelanins in the seed coat may seriously inhibit seed germination after 45 DAP. As seeds matured, the thickened and lignified seed coat formed an impermeable envelope surrounding the embryo, which may play an important role in inducing dormancy. Further studies covering different maturity of green capsules are required to understand the optimal seed maturity and germination of seeds.

scholarly journals Scarification with sulphuric acid of Schizolobium amazonicum Huber ex Ducke seeds - FABACEAE

2007 ◽  
Vol 64 (3) ◽  
pp. 308-313 ◽  
Author(s):  
Eniel David Cruz ◽  
José Edmar Urano de Carvalho ◽  
Rafaela Josemara Barbosa Queiroz
Keyword(s):  
Statistical Analysis ◽  
Experimental Design ◽  
Seed Germination ◽  
Sulphuric Acid ◽  
Seed Coat ◽  
Immersion Time ◽  
Germination Index ◽  
Efficient Treatment ◽  
Tukey Test

Seed coat impermeability to water occurs in many species, including Schizolobium amazonicum Huber ex Ducke. To promote germination in seeds with coat impermeability the use of sulphuric acid (H2SO4) is recommended. The objective of this study was to identify a better time for the scarification with sulphuric acid for S. amazonicum seeds. The effect of scarification with sulphuric acid for 20, 40 and 60 min on germination and speed germination was studied for seeds that were either sowed immediately after scarification or after a 24-hour period of immersion in water. Seeds were sown on a mix of sand and sawdust (1:1). The experimental design was completely randomized with four replications of 50 seeds. The statistical analysis of germination was carried out at six, nine, 12, 15, 18, 21 and 24 days after sowing, in a factorial scheme. For speed germination the means were compared by the Tukey test. There was an interaction between treatments to overcome dormancy and immersion time after scarification in most evaluations. Immersion in water accelerated the beginning of germination. All treatments to overcome dormancy promoted seed germination. However, scarification for 60 min, showed better germination, 92% when immediately sown and 86.5% when sown after 24 hours. Speed germination index was highest for scarified seeds for 60 min followed by immersion in water. Scarification for 60 min was the most efficient treatment to promote germination in S. amazonicum seeds.

scholarly journals Activation of rape (Brassica napus L.) embryo during seed germination. V. The first zones of ultrastructural changes and their expansion

2014 ◽  
Vol 56 (1) ◽  
pp. 77-91 ◽  
Author(s):  
Mieczysław Karaś
Keyword(s):  
Brassica Napus ◽  
Seed Germination ◽  
Seed Coat ◽  
Basal Part ◽  
Ultrastructural Changes ◽  
Embryo Axis ◽  
Brassica Napus L ◽  
Root Cells ◽  
Basal Zone

In the germinating rape embryo the columella and basal part of hypocotyl undergo earliest activation. Its first ultrastructural symptom is the appearance of numerous ER vesicles after 3-6 h of seed swelling. Their number is the highest in the external layers of the columella and decreases in basipetal direction. Dermatogen cells in the basal zone of the hypocotyl contain the greatest amount of ER structures, whereas decreasing amounts are found in both directions along the embryo axis and centripetally. Further changes in the ER spread in a similar order. The vesicles merge and form a tubular and plate-like ER. Then, they disappear and are replaced by tubular and vesicular forms. The changes in the ER are gradually followed by ultrastructural symptoms of activation of mitochondria, plastids and dictyosomes. The highest number of ER structures and other organelles accumulate in root cells shortly before piercing of the seed coat. After germination their amount decreases and remains almost stable.

scholarly journals Asymbiotic Germination of Mature Seeds and the Seed Development of Vanilla Planifolia

2021 ◽  
Author(s):  
Chih-Hsin Yeh ◽  
Kai-Yi Chen ◽  
Yung-I Lee
Keyword(s):  
Cell Wall ◽  
Seed Germination ◽  
Seed Development ◽  
Seed Coat ◽  
Germination Percentage ◽  
Vanilla Planifolia ◽  
Outermost Layer ◽  
Seed Pretreatment ◽  
Immature Seeds ◽  
Mature Seeds

Abstract Background: Vanilla planifolia is an important tropical orchid for production of natural vanilla flavor. Traditionally, V. planifolia is propagated by stem cuttings, which produces identical genotype that are sensitive to virulent pathogens. However, sexual propagation with seed germination of V. planifolia is intricate and unstable because of the extremely hard seed coat. A better understanding of seed development, especially the formation of impermeable seed coat would provide insights into seed propagation and conservation of genetic resources of Vanilla.Results: We found that soaking mature seeds in 4 % sodium hypochlorite solution from 75 to 90 min significantly increased germination and that immature seeds collected at 45 days after pollination (DAP) had the highest germination percentage. We then investigated the anatomical features during seed development that associated with the effect of seed pretreatment on raising seed germination percentage. The 45-DAP immature seeds have developed globular embryos and the thickened non-lignified cell wall at the outermost layer of the outer seed coat. After 60 DAP, the cell wall of the outermost layer of the outer seed coat became lignified and finally compressed into a thick envelope. These features matches the significant decreases of immature seed germination percentage after 60 DAP. Conclusion: We report a reliable protocol for seed pretreatment of mature seeds and for immature seeds culture based on a defined time schedule of V. plantifolia seed development. The thickened and lignified seed coat formed an impermeable envelope surrounding the embryo, and might play an important role in seed dormancy of V. plantifolia.

Ovule and seed structure in Scolopia zeyheri (Scolopieae), with notes on the embryology of Salicaceae

Bothalia ◽  
2005 ◽  
Vol 35 (2) ◽  
pp. 175-183 ◽  
Author(s):  
E. M. A. Steyn ◽  
A. E. Van Wyk ◽  
G. F. Smith
Keyword(s):  
Microscopic Study ◽  
Seed Coat ◽  
Embryo Sac ◽  
Single Layer ◽  
Relevant Information ◽  
Seed Structure ◽  
Globular Embryo ◽  
Polygonum Type ◽  
Old World ◽  
Seed Characters

Scolopia zeyheri (Nees) Harv. is a widespread African tree and a member of the largest genus of the tropical Old World tribe Scolopieae (Salicaceae sensu lato). This light microscopic study is the first report on ovule and seed structure in the genus and the tribe. Ovules vary from four to six per ovary, are anatropous. crassinucellate. bitegmic and occur in an epitropous (rarely pleurotropous). median-parietal position in the unilocular, usually bicarpellate ovary. A very extensive nucellus cap. comprising nucellus epidermal derivatives and parietal tissue, characterizes the young ovule during mega- sporogenesis and megagametogenesis, but the chalazal nucellus is poorly developed. During meiosis. the micropvlar dyad cell degenerates early. The functional dyad cell forms two megaspores of which the chalazal one usually develops into a Polygonum-type embryo sac. At maturity, the micropylar end of the embryo sac is covered by the remnants of the nucellus epidermis, the parietal tissue having degenerated. The globular embryo has a short suspensor and lies in nuclear endosperm becoming cellular. The seed coat develops from both integuments, is tannimferous. has a glabrous surface with stomata and a single layer of exotegmic, longitudinal fibres.Results are compared with relevant information previously reported for genera in the tribes Flacourtieae. Samvdeae. Saliceae, Scyphostegiae and for Oncoha Forssk. (Salicaceae sensu lato). Embryologically Scolopia shows a number of ple- siomorphic features compared to other Salicaceae. For example, it lacks an extranucellar embryo sac. an apomorphic fea­ture in many Salicaceae. A summary of ovule and seed characters in Salicaceae sensu lato is given and contrasted with data available for Achariaceae  sensu lato. Embryological data broadly supports the reclassification of genera, traditionally referred to Flacourtiaceae. amongst Salicaceae sensu lato and Achariaceae sensu lato.

scholarly journals Effect of Osmotic and Matric Potentials on the Availability of Water for Seed Germination

1971 ◽  
Vol 24 (3) ◽  
pp. 423 ◽  
Author(s):  
JR Mcwilliam ◽  
PJ Phlllips
Keyword(s):  
Soil Moisture ◽  
Seed Germination ◽  
Osmotic Stress ◽  
Soil Water ◽  
Seed Coat ◽  
Moisture Diffusivity ◽  
Matric Potential ◽  
Water Potentials ◽  
Germination Behaviour ◽  
Dry Soil

Under special conditions where soil-moisture diffusivity and seed-soil contact are non-limiting, the osmotic and matric potentials of the substrate were found to be equivalent in their effect on the germination of seeds of ryegrass and dehulled phalaris over a range of water potentials from 0 to -15 bars. However, with intact phalaris seeds it appears that the seed coat constitutes a large resistance to the absorption of soil water, and under these conditions the equivalence between osmotic and matric potential no longer holds, and results of germination under osmotic stress must be used with caution in predicting the germination behaviour of seeds in dry soil.

RAPID GERMINATION OF WHITE PINE SEED

1959 ◽  
Vol 35 (3) ◽  
pp. 203-211 ◽  
Author(s):  
D. P. Fowler
Keyword(s):  
Seed Germination ◽  
Seed Coat ◽  
White Pine ◽  
Fresh Seed ◽  
Work Done ◽  
Better Than

This paper reports the results of some work done to develop a rapid germination technique suitable for small quantities of valuable white pine seed.It was found that by removing the seed coat from fresh seed, germination was more rapid and yielded a higher per cent germination than seed stratified for 20 days at 40 °F. Three types of soaking (aerated water, changed water, and unchanged water) and three durations of soaking (3, 7 and 10 days) were tested. Soaking seed in aerated water for three, seven or ten days was almost as good as 20 days stratification. Aerated water was superior for soaking treatments than water which had been changed twice daily, which in turn was better than water which was not changed. Seed germination decreased as the length of soaking period increased except for seeds which had been soaked in aerated water.Attempts to germinate seed directly from cones which had not been allowed to dry were not successful. Apparently embryos in these seeds were not fully developed.The implications of the results are discussed briefly.

scholarly journals Seed Germination of selected Taxa from Kachchh Desert, India

2010 ◽  
Vol 2 (2) ◽  
pp. 41-45 ◽  
Author(s):  
Vinay Madhukar RAOLE ◽  
Aruna Girish JOSHI ◽  
Sandhya Kiran GARGE ◽  
Rinku Jitendrakumar DESAI
Keyword(s):  
Seed Germination ◽  
Growth Regulators ◽  
Seed Coat ◽  
Native Species ◽  
Arid Regions ◽  
Conservation Status ◽  
Storage Period ◽  
The Other ◽  
Viable Seeds ◽  
Semi Arid

The district of Kachchh contains many culturally important plants. However, their conservation status is little known due to direct and indirect human activities. This study was undertaken with the aim of contributing to the conservation of the native species of these semi-arid regions through germination trials under laboratory conditions. Mature fruits of ten selected species were collected randomly from the known habitats to obtain viable seeds. These seeds were pre-treated with growth regulators singly or in combination after acid scarification or without scarification. Seeds were found to be dormant due to presence of thick seed coat or due to low level of endogenous hormonal level. Most of these seeds required different storage period to mature. Only seeds of Capparis cartilaginea germinated without treatment while the other species required treatments. Addition of growth regulators has enhanced seed germination in few taxa singly and in some plant cases in combination.

The effect of sodium hypochlorite, gibberellic acid, and light on seed dormancy and germination of wild buckwheat (Polygonum convolvulus) and cow cockle (Saponaria vaccaria)

1979 ◽  
Vol 57 (16) ◽  
pp. 1735-1739 ◽  
Author(s):  
A. I. Hsiao
Keyword(s):  
Seed Germination ◽  
Gibberellic Acid ◽  
Sodium Hypochlorite ◽  
Seed Coat ◽  
Inhibitory Effect ◽  
Promoting Effect ◽  
Wild Buckwheat ◽  
Polygonum Convolvulus ◽  
Effect Of Light ◽  
Main Factor

Seed germination of wild buckwheat (Polygonum convolvulus L.) and cow cockle (Saponaria vaccaria L.) increased with increasing time of immersion in 6% sodium hypochlorite (NaOCl). Maximum germination was obtained at 6 to 8 h for wild buckwheat and at 2 h for cow cockle. The effect of NaOCl treatment of wild buckwheat seeds mimics the effect of acid scarification. Wild buckwheat germination was not influenced by light and (or) gibberellic acid (GA3). To induce 50% germination (t½) of cow cockle NaOCl treatments of 0.5 and 1 h were required for seeds incubating in the dark and light, respectively. Once the seed coat was made more permeable by NaOCl, both the promoting effect of GA3 and the inhibitory effect of light were increased. When the optimum effect of NaOCl occurred, all the seeds germinated. However, prolonged NaOCl treatment resulted in either poor germination or seed disintegration.The hard coat seems to be the main factor in regulating wild buckwheat seed germination. Cow cockle, however, is regulated by at least two other factors, light and hormones, in addition to seed coat.

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