Conditions For Seed Germination Research Articles

Germination of six native perennial grasses that can be used as potential soil cover crops in drip-irrigated vineyards in semiarid environs of Argentina

Native desert plants have structural adaptations that maximize photosynthesis rates and minimize water loss. They can be successfully utilized as soil cover crops in drip-irrigated vineyards where water availability is low. The objective of this paper is to study seed germination conditions and to recommend which best species is most apt as soil cover crop in drip-irrigated vineyards. Seed weight (the higher the seed weight, the greater the success of mechanical seeding) and germination tests (at 15, 20, 25, 30, and 35 °C in light and dark conditions) were carried out for six species native to Mendoza, Argentina. Germination percentage (GP) and mean time germination (MTG) were calculated. Digitaria californica (C4) had the highest GP (97% in light condition), which is recommended as a cover crop because of its seed germination potential. Pappophorum phillippianum (C4) had a 70% GP in light conditions (regardless of temperature) and a high seed weight. Leptochloa dubia (C4) and Sporobolus cryptandrus (C4) reached the highest GP at the highest temperature, although S. cryptandrus had the lowest seed weight. Nassella tenuis (C3) averaged 54% GP at 25 °C in light conditions. The GP of Setaria leucopila (C4) was not affected by temperature (26% in light, and 16% in darkness). Based on the GP results, S. leucopila was the worst choice of the six species. Hence, during seeding, soil temperature should be high (>20 °C) to ensure a rapid plant establishment of all species.

Germination of recalcitrant Baccaurea ramiflora seeds

Tolerance to desiccation in recalcitrant seeds depends on the genetic background and the developmental conditions of the seeds, both of which are relevant to harvest and storage for conservation purposes. The tropical south and south-east Asian species, Baccaurea ramiflora Lour., has recalcitrant seeds and is a locally important resource. We measured germination success and desiccation tolerance of B. ramiflora at different temperatures and light conditions for 76, 86, 96, and 106 days after anthesis to describe seed germination requirements and the relationship between seed development and desiccation tolerance of seeds for storage. We found that light is not an important factor in B. ramiflora seed germination, and that optimal seed germination conditions occur at 30/20 °C. During their development from 76-106 days after anthesis, seeds and their embryonic axes undergo changes in morphological characteristics, germination ability, moisture content, and desiccation tolerance. The best time for collection of B. ramiflora seeds for storage is around 96 days after anthesis, when desiccation tolerance is maximal.

Allelopathy of the invasive plant Bidens frondosa on the seed germination of Geum japonicum var. chinense.

Five gradient concentrations (0.02, 0.04, 0.06, 0.08, and 0.10 g/mL) of leaching liquors from the roots, stems, and leaves of the invasive plant Bidens frondosa were used as conditioning fluid to examine its influence on seed germination conditions of the native plant Geum japonicum var. chinense in Huangshan. All leaching liquors of organs suppressed the seed germination of Geum japonicum var. chinense and reduced the final germination percentage and rate, and increased the germination inhibition rate, with a bimodal dependence on concentration. The leaching liquor inhibited the seed germination significantly at the concentration of 0.02 g/mL respectively. The seed germination was also inhibited as the concentration reached to 0.04 g/mL and beyond. Hence the allelopathic effects of the organs were significantly enhanced respectively. This phenomenon represented the presence of allelopathy substances in the root, stem and leaf of Bidens frondosa.

English

A plant regeneration system was established from cotyledon explants of chieh-qua (Benincasa hispida Cogn. var. Chieh-qua How). To obtain optimal conditions of adventitious shoot induction, the cotyledon explants were excised from seedlings of different genotypes as well as seed germination conditions, and then cultured on media containing different concentrations of 6-benzylaminopurine (6-BA)/1-naphthaleneactic acid (NAA). Among the eight genotypes, the highest rate of shoot regeneration was obtained from the cotyledons of inbred line A39. The adaxial portion of cotyledons of seedlings cultured for 3 days in darkness and 1 day in light was the appropriate explants for adventitious shoot organogenesis. The highest frequency of adventitious shoot organogenesis (52.2%) and mean number of shoots per explant (4.2) were achieved on Murashige and Skoog (MS) medium supplemented with 6 mg l-1 6-BA and 0.2 mg l-1 NAA. Adventitious shoots were observed to regenerate directly from cotyledons rather than from calli. A medium supplemented with AgNO3 was not beneficial for shoot induction. Adventitious shoots were elongated in MS medium supplemented with 3 mg l-1 6-BA and 0.2 mg l-1 NAA. Elongated shoots were rooted in ½ MS medium with 0.5 mg l-1 indole-3-acetic acid (IAA). Regenerated plantlets were transferred to a greenhouse for about 1 month, and subsequently transplanted into an open field. Key words: Benincasa hispida, chieh-qua, adventitious shoot, genotypes, plant regeneration.

Morphology, germination, and storage behaviour in seeds of Tuscan populations of Fritillaria montana (Liliaceae), a rare perennial geophyte in Italy

Fritillaria montana Hoppe ex W.D.J.Koch (Liliaceae) is a rare perennial geophyte growing in south-eastern Europe. Although it occurs in most of the Italian territory, it is very rare and is included in the Red List of threatened plant species of most of the regions in which it grows; in Tuscany (central Italy), it is listed as Critically Endangered. The aim of our study was to investigate the seed size, weight, and morphology; the seed moisture and oil contents; the seed germination conditions; and the effect of different storage treatments on final germination success in F. montana. Seeds were collected from the only Tuscan population that set fruit in 2008, and they were then subjected to morphometric, moisture, and oil content measurements; germination tests; and different storage conditions. Morphometric measurements and shape index evidenced the flat and drop-like shape of the seeds, which have a moisture content of 14.62% and an oil content of 1.09%. They need a period of cold stratification to break dormancy and germinate, with a final percentage of 77.5%. The germination percentage after storage at 5 °C was 70%, while after storage in a drying room it was 55.2%. The differences between the final germination percentage of fresh seeds and treated seeds were only weakly significant. In the short time allotted for the trial, seeds of F. montana showed a good tolerance to drying and a potential predisposition to ex situ conservation techniques.

Reproductive biology of Abies cephalonica Loudon in Mount Aenos National Park, Cephalonia, Greece

The reproductive biology of the endemic to Greece Abies cephalonica Loudon, including the phenology of the reproductive life cycle, cone production in relation to plant age and the required seed germination conditions, was studied. All individuals growing within 20 permanent plots of 100 m2 each established in 11 different locations covering the entire strictly protected area of Mount Aenos National Park (Cephalonia) were monitored over a period of 4 years. The cones are formed on the upper part of the previous year’s branches, mostly at the upper crown half of the reproductive individuals (over 53 years old). Female flowers are pollinated in spring and cone maturation lasts until the beginning of autumn, when seed dispersal occurs. The annual production of cones per individual varied significantly, revealing masting behavior for this tree. This behavior was also expressed in the number of trees producing cones, as well as the percentage of sound seeds per cone. A significant difference in the mass and the length of the cones between the years of low and high cone production was observed, being higher in the years of massive cone production. Similar germination percentages were observed in full darkness or under “canopy light” and “sun light”, provided that the seeds were previously stratified for 6 weeks. It is concluded that A. cephalonica exhibits plasticity expressed in its reproductive behavior for alternating years of high to low cone production and in its seed germination for an array of habitat light conditions.

Symbiotic seed germination and evidence for in vitro mycobiont specificity in Spiranthes brevilabris (Orchidaceae) and its implications for species-level conservation

Orchid–mycobiont specificity in the Orchidaceae was considered controversial and not well understood for many years. Differences in mycobiont specificity during germination in vitro vs in situ have lead some to consider orchid–mycobiont specificity as being generally low; however, others have suggested that specificity, especially in vitro, is surprisingly high. Mycobiont specificity may be genus or species specific. An in vitro symbiotic seed germination experiment was designed to examine mycobiont specificity of the endangered Florida terrestrial orchid Spiranthes brevilabris using mycobionts isolated from both the study species and the endemic congener Spiranthes floridana. In a screen of mycobionts, isolates Sflo-305 (99.5%), Sflo-306 (99.5%), and Sflo-308 (89.9%) (originating from S. floridana) supported higher initial (stage 1) seed germination than isolate Sbrev-266 (32.4%) (originating from S. brevilabris) after 3 wk culture. However, only isolate Sbrev-266 supported advanced germination and protocorm development to stage 5 (53.1%) after 12 wk culture. These findings suggest that S. brevilabris maintains a high degree of mycobiont specificity under in vitro symbiotic seed germination conditions. High orchid–mycobiont specificity in S. brevilabris may be indicative of the rare status of this orchid in Florida.

Cold Stratification Improves Germination of Katsura Tree

Katsura tree (Cercidiphyllum japonicum Sieb. & Zucc.), an ornamental tree native to Japan and China, is valued for its broad pyramidal form and apricot-yellow fall leaf color. Another species, Cercidiphyllum magnificum (Nakai) Nakai, exists, but is rarely encountered outside of wild populations, except in a pendulous form. Propagation of katsura is by seed germination and softwood cuttings, although little information exists in the scientific literature regarding either method of propagation. To determine conditions for optimal seed germination, we subjected C. japonicum seed to a factorial combination of moist stratification and exposure to light. Two seed lots were obtained from the Arnold Arboretum of Harvard Univ., accessions 1150-67 and 882. Half of the seeds in each lot were moist stratified in petri dishes on filter paper for 8 days at 3.5°C. All seeds then were germinated at 25°C with either a daily photoperiod of 15 hr or complete darkness. Those samples not exposed to light were placed in a light-tight container. Germination was defined as the average percentage of seeds per treatment combination that showed the emergence of a radicle. Unstratified seeds germinated at 44.7% over both seed lots. Moist stratification increased germination to 92.0% and 56.7% for 1150-67 and 882, respectively. Light did not affect germination for either seed lot. Optimal seed germination conditions for C. magnificum will be determined in future studies. We have shown that moist stratification of katsura seeds improves germination and recommend this method as a means of promoting seed germination.

Multiplication of Four Penstemon Species in Vitro

Table 1. Summary of in vitro growth response of four Penstemon spp. to five concentrations of BA.z Penstemon (beard tongue) is a native genus of U.S. wildflower that is used for landscape plants (Lindgren, 1984a, 1984b, 1990), for cut flowers (Lindgren, 1986), and for ecological studies (Stubbendieck et al., 1982). Tissue culture techniques could be useful for propagating cultivars and species in this genus as some do not breed true from seed, require special seed germination conditions, or are difficult to propagate using other vegetative methods (Lindgren, 1984b, 1990; Stubbendieck et al., 1982). Penstemon haydenii is also the only listed endangered plant species in Nebraska. The Penstemon spp. P. digitalis Nutt. ‘Husker Red’ (Lindgren, 1984b); P. grandiflorus Nutt. ‘Prairie Snow’ (Lindgren, 1990); P. barbatus (Cav.) Roth ‘Schooley’s Yellow’ (Lindgren, 1984a), and P. haydenii S. Wats (Stubbendieck et al., 1982) were evaluated for their growth response to five levels of N(phenylmethyl)-1H purine-6-amine (BA). Lateral buds from greenhouse-grown plants of each of the four species were surface sterilized by sequential immersion in 75% ethanol for 1 min and 0.53% NaOCl for 15 min, followed by rinsing three times in sterile water. Explants were then placed in 120-m] baby food jars with polypropylene closures that contained 30 ml Woody Plant Medium (Lloyd and McCown, 1980) with 0.1% (w/v) Gelrite, 0.3% (w/v) Sigma agar, 2% (w/v) sucrose, 6 mM calcium gluconate, and 0.4 μM BA. Shoots were grown on this medium for 8 weeks, then transferred to Murashige and Skoog (MS) basal medium (Murashige and Skoog, 1962) without BA and grown for 6 weeks. Shoot sections with one node each were then transferred to 30 ml MS medium, placed vertically, and supplemented with either 0, 0.01, 0.1, 1.0, or 10.0 μM BA. At the end of 4 weeks, shoot tips (1 cm) were transferred to fresh MS me-