Optimal Germination Conditions Research Articles

Germination responses of Salicornia rubra to temperature and salinity

Salicornia rubra Nels. is one of the most salt tolerant species in the western half of the United States and Canada. Salicornia rubra seeds were collected from Goshen, Utah. Seeds were germinated at five temperature regimes and six salinities to determine optimal conditions for germination and recovery from saline conditions. A temperature regime of 25°C night and 35°C day yielded maximum germination. The lower temperature regime 5–15°C significantly inhibited seed germination. Rate of germination decreased with increase in salinity. Final recovery germination percentages in high salt treatments were significantly higher indicating that exposure to high concentration of NaCl did not permanently inhibit germination.

595 Computer Root Image Analysis of Citrus Rootstock Seedlings

Florida citrus has had an average annual on-tree-value of ≈1 billion dollars during the past decade in Florida. Nearly all of the 845,260 acres of citrus in Florida is produced on grafted trees consisting of a commercial scion cultivar and a rootstock selected specifically for local soil, environment, and pest pressures. With vastly different root-zone environments, ranging from deep sands to drained and cleared pine Flatwoods, a large number of different rootstocks are utilized. These rootstocks are started from seed at more than 100 commercial nurseries statewide, which currently produce an estimated 6 million trees a year. Although the optimum germination conditions, basic physiological performance, and adaptability of many rootstocks are known, there has been minimal investigation on early root development in seedling trays at the nursery. Four hundred seedlings of `Swingle' citrumelo (Citrus paradisi Macf. `Dunacn' × Poncirus trifoliata), `Smooth Flat Seville', `Volkamer' lemon (Citrus volkameriana), and `Sun Chu Sha' mandarin were seeded in a randomized block experimental design and grown at a commercial nursery. Seedling root systems (100/rootstock) were analyzed for a number of variables using the Rhizo (Regent Instruments, Inc.) software package and a dual light source scanner. Using the SAS general linear model procedure, hypothesis testing revealed rootstock selection had a significant effect on total root length, total root surface area, total root volume, number of root tips, number of root forks, root dry weight, and stem diameter. For most characteristics, rootstock genotype accounted for a greater portion of variability than samples (plant to plant variability).

Analysis of the effects of maturation treatments on the probabilities of somatic embryo germination and plantlet regeneration in pistachio using a linear logistic method

Embryogenic masses (EMSes) of pistachio (Pistacia vera L.) were proliferated in liquid Murashige and Skoog (MS) medium without growth regulators. To determine the effects of benzylaminopurine (BAP), racemic (±) abscisic acid (ABA) and sucrose treatments during maturation on the subsequent germination and plantlet regeneration, clusters of mature somatic embryos were transferred from maturation medium onto the surface of 0.7% agar-solidified Murashige and Skoog medium. Neither germination nor plantlet development medium contained BAP or ABA. Germination studies were carried out using 80 somatic embryos at every combination of four sucrose concentrations, three maturation periods and either five concentrations of BAP or four of ABA, and the numbers germinating were recorded after four durations of culture. A similar experimental plan was used to study plantlet regeneration. The number of germinated somatic embryos increased markedly with duration of the culture on germination medium, and was influenced by the concentrations of BAP or ABA in the maturation medium; the concentration of sucrose in this medium had little influence. Plantlet regeneration also increased with culture duration and was reduced at the highest levels of BAP or ABA; with ABA, the probability of plantlet regeneration was lower for longer maturation periods. ABA and BAP have similar effects on somatic embryo germination (except at the highest levels used), but BAP is superior to ABA for promoting subsequent plantlet regeneration. Linear logistic models were used to investigate the significance of the treatments, and to estimate the optimum conditions for germination and plantlet regeneration.

344 Dormancy Breaking and Germination of Liriope spicata Lour.

There are many ground covers native to Korea. Liriope spicata is very promising for landscaping purposes due to its waxy and dark-green foliage fragrant and pink flowers, as well as fruit. However, seeds harvested during late fall do not germinate at all if they are sown in spring. Thus, series of experiments were conducted to undestand the physiological mechanism of dormancy breaking and germination of Liriope spicata Lour. seeds and to determine the effective methods for enhancing seed germination. Fruit were harvested in October through December. Depulped seeds germinated rapidly, indicating that one or more inhibitors may be present in the pulps of fruit and/or seeds. GA3, NaOCl, NaOH, and H2SO4 treatments and dry cold treatment had no effect on germination, whereas wet, cold seed treatment for at least 30 days promoted germination up to 75% within 15 days. Optimum conditions for germination was continuous dark and 25/20 °C alternate temperature conditions. Extracts from pulps and seeds showed a strong inhibition effects on the germination of lettuce seeds, indicating that germination inhibitors are present in pulp and seeds. Since extracts from naked seeds did not show inhibition, inhibitory substances are thought to be present in pulp and seedcoat. Pulp and seeds were extracted with water and methanol and autoclaved at 115 °C, followed by bioassay experiments. Germination inhibitors were found water soluble and heat stable by series of bioassay experiments. Diluted extracts 4 to 8 times still maintained inhibitory effects. Optimum seed harvesting time was from 22 Nov. to 1 Dec., where seed germination was high without additional seed treatments. Total phenolic compounds and ABA contents of pulp and seeds decreased by wet cold seed treatment. Changes in total phenolic compounds and ABA in from October through December were correlated with germination during the seed development. When contents of total phenolic compounds and ABA were high, seeds did not germinate at all, while low contents resulted in good seed germination.

332 Effects of Heat Stress on Spinach Seed Germination

Seed germination of spinach (Spinacia oleracea L.) is partially inhibited by a high germination temperature (35 °C). Tolerance of high germination temperatures varies widely depending on the variety used. We ascertained that seed germination of these spinach varieties was thermoinhibited at 35 °C and secondary dormancy was not induced as seeds germinated when transferred to optimum germination conditions (20 °C). Treatment with 99% oxygen and 10 ppm kinetin significantly increased germination of thermoinhibited varieties at 35 °C. During heat stress, all organisms produce heat shock proteins (HSPs), which may function as molecular chaperons, are possibly required for the development of thermotolerance, and may be crucial for cell survival during heat stress. Western blotting of SDS-PAGE gels using antibodies to various heat shock proteins indicated that spinach varieties with the highest degree of thermotolerance have higher levels of HSP expression than varieties with the lowest degree of thermotolerance during germination. These results suggest that thermotolerance could be further improved, either through a breeding program or possibly by genetic engineering.

Main Physiological Factors Affecting the Germination of Annona muricata L. Seeds

Dormancy and latency factors such as moisture content, temperature, growth regulators, and seed-coat affecting germination of the Annona muricata L., a tropical fruit, were studied. Three types of fruits were used with presence of stylar residues (medium and big size) and absent of stylar residues. The fruits were taken from 4-year-old trees, which were naturally pollinated. A complete randomized design was used for the study, with 50 seeds per experimental unit and four replications per treatment. The variables measured were days and percent of germination, and average germination velocity. The seed germination was affected by the moisture and oxygen content, because the structure of the seed and their high content of the lipid in there. The length of the germination period was determinated by the concentration of the exogen hormones applied, the temperature range, the kind of scarification used, the substrate utilized and the moisture content present during the assays. Highly significant differences were found among treatments. The optimal conditions for germination (97.5%) were: 30 °C of temperature, no scarification, sand as substrate, and 750 ppm of gibberellic acid. The average of days to germination was 24.5 days. No significant differences were found for the different kind of fruits used in this assay. The results showed that this species presented characteristics of recalcitrant seeds.

The role of free, membrane-bound and tightly-bound polysomes in precocious germination of triticale caryopses

During the development and ripening of triticale caryopses cv. Grado, a gradual increase in the precocious germination ability of the grain was observed. After 48 hrs of incubation (at 22 °C under optimal moisture conditions for germination in darkness) of the freshly-collected caryopses of different ripeness, the percentage of polysomes in the ribosomal fraction isolated from embryonic tissue in buffer A + PTE (to yield released FP + MBP) was about 15 % in the sample of grains gathered at the milk-ripeness stage, over 27 % at the wax-ripeness stage and over 63 % at the full-ripeness stage. Percentages of polysomes solubilized in the pellets in buffer U (TBP, putative cytoskeleton-bound polysomes), were always higher and amounted to about 36 % at the milk-ripeness stage, 58 % at the wax-stage and 68 % at the full-ripeness stage. The incorporation of 3H-uridine into polysomal RNA (mRNA+rRNA) of triticale embryos increased during the development and maturation of the caryopses subjected to germination from about 19 and 33 Bq/mg RNA at the milk-ripeness in the FP+MBP and the TBP to 220 and 312 Bq·mg−1 RNA at the full-ripeness stage, respectively. The effect of the pericarp and other tissues surrounding the embryo was also investigated. Removal of the outer pericarp strongly stimulated germination of unripe caryopses in the middle period of development e.g. 32 and 39 DAF. The strongest stimulatory effect on transcription was found in the embryo during germination, in all samples of caryopses of various degrees of ripeness, by isolating it completely from the pericarp, testa and endosperm. The high percentage of polysomes in the TBP and the high incorporation 3H-uridine into RNA in that fraction during precocious germination suggests an important role for this sub-population of polysome (and the proteins synthesised by them) in initiation of precocious germination processes.

Genetic and non‐genetic factors affecting germination and vitality in spring barley seed

AbstractGermination of eight spring barley varieties, grown in two years at eight different locations in State varietal trials in the Czech republic, was analysed. All the combinations were tested under optimal conditions for germination as recommended by ISTA and also at low temperatures (5 and 10°C), and underwater stress (‐ 2 and ‐ 4 bar). Germination under low temperature and water stress was considered as a character of seed vitality.Varieties in nearly all experiments were a significant source of variation and their relative contribution to the total variation was higher for vitality (5.7–38.7%) than for germination (2.0–4.3%). However, the percentage of germination were not related to the percentage of vitality.The location in nearly all the experiments caused the greatest variation and the impact was greater for germination than for vitality. Provenance effects were different for germination and for vitality; grains harvested in the lowland had the highest germination values, but not the highest vitality values.The results should encourage breeding for seed vitality and some reconsideration of provenance effects on seed vitality.

Optimization of germination process of cowpea by response surface methodology

The effect of soaking time, germination time and temperature on the nutrient content, oligosaccharides and trypsin inhibitor activity in cowpea was evaluated by response surface methodology. All the three processing variables affected nutrient content, oligosaccharides and trypsin inhibitor activity. Optimization was based on conditions that maximized reduction in oligosaccharides and trypsin inhibitor activity and minimized total solids losses. Optimum conditions for germination of cowpea were: soaking time = 8 h, germination time = 52 h and germination temperature = 25 °C and under these conditions the predicted values using a polynominal equation for total solids loss, protein, fat and ash contents were 7.71, 23.30, 1.48 and 2.29 (% dry basis), respectively. The trypsin inhibitor level was 4.28 mg/g dry solids. The values for raffinose, stachyose and sucrose were 0.90, 1.96 and 3.61 (% dry basis), respectively. Good agreement was found between experimental values obtained at optimum process conditions and predicted values.

Optimisation of Germination Conditions by Response Surface Methodology of a High Amylose Rice (Oryza sativa) Cultivar

Germination conditions for a high amylose rice cultivar were optimised using response surface methodology. Germination time and temperature significantly affected the amylase activity and thiamin content of the subsequent flour. All germination conditions investigated significantly affected the malting loss while the change in cold paste viscosity was significantly influenced by steeping time, germination time and temperature. The yield or recovery was significantly affected by germination time only. Protein content was not altered significantly by the germination conditions investigated. Optimum germination conditions for high amylose rice were: steeping time 24 h at 25 °C or 16 h at 35 °C, germination time 3 d, germination temperature 30 °C. Values predicted at optimum conditions by the response surface model for malt loss, viscosity, amylase activity, yield and thiamin content were experimentally tested and close agreement between experimental and predicted values was observed.

Germination Characteristics of Shingle Beach Species, Effects of Seed Ageing and their Implications for Vegetation Restoration

1. Restoration of coastal-shingle vegetation at Sizewell, Suffolk, UK, after construction of a power station, was underpinned by an investigation into the germination ecology of six key species: Crambe maritima, Eryngium maritimum, Glaucium flavum, Honckenya peploides, Lathyrus japonicus and Rumex crispus. The use of indigenous seed, collected from the site before the 6-year construction project, necessitated long-term storage. The effects of seed ageing on viability and germination responses to temperature, light and salinity were examined to determine how any reduction in germination might be mitigated. 2. Innate seed dormancy was important in all species, except R. crispus. C. maritima and L. japonicus showed hard-seed dormancy. Stratification of E. maritimum, G. flavum and H. peploides effectively softened the pericarp or testa, and satisfied their varying requirements for low temperature to overcome physiological dormancy. 3. All species germinated well in diurnally alternating temperature regimes. Germination of H. peploides was promoted by light, but the other species were insensitive to light. Increasing salinity progressively reduced germination rate relative to that in distilled water, and sea water at concentrations of 50% or more completely inhibited germination. 4. Seed storage at low temperature and humidity for 7 years did not affect innate dormancy, except in H. peploides, where the requirement for stratification was lost. Storage reduced germination rate in all species, except R. crispus. Ageing resulted in considerably less germination at higher temperatures in some species. Salinity-enforced dormancy was significantly greater in aged seed for four of the species. The promotion of germination by light in H. peploides disappeared with age. These changes represented a narrowing of the environmental conditions that allow germination, even when viability only declined slightly. 5. Innate dormancy among shingle species and the use of stored seed, with high viability, but stringent germination requirements, are likely to result in poor and erratic germination. The use of appropriate pretreatments to overcome dormancy and optimal conditions for germination should allow the efficient use of seed for plant production in restoration projects.

Spore Germinability of Bacillus coagulans and Acidophile Bacillus spp. Isolated from PET-bottled Tea and Juices.

We examined the optimal conditions for germination of the spores of Bacillus coagulans and an acidophile Bacillus spp isolated from PET-bottled drinks on the market containing Japanese tea or orange or apple juice. Among the spores of B. coagulans BUB strains, isolated from Japanese tea, BUB46 germinated effectively at an acidic pH in a mixture of D-glucose plus KNO3 (G+K), and in a mixture of L-asparagine, D-glucose, D-fructose and KCI (AGFK) at 45 or 53°C, but not by L-alanine. The spores of BUB130 germinated in a mixture containing G+K, AGFK or L-alanine, and BUB44 spores also germinated most effectively in an acidic solution of AGFK. Pretreatment of the BUB44 spores with 1/16N NaOH stimulated germination, but that with 1% sodium dodecyl sulfate plus 5 mM dithiothreitol did not. The spores of an acidophile Bacillus spp. isolated from fruit juice germinated at pH 3.0 in a mixture containing G + K, AGFK, L-alanine or potato dextrose.

Inhibition of barley grain germination by light

Intact grains of barley (Hordeum distichum cv. Triumph) germinated rapidly in the dark or when exposed to brief daily light breaks in the temperature range 15-25°C, although germination proceeded less rapidly at low temperatures. Prolonged illumination (16 h/day) or continuous light inhibited germination of grains most effectively when conditions were less than optimal for germination, i.e. under low temperatures, restricted water, and low water potential induced by mannitol. Embryos isolated from grains responded in a similar way to light applied when the amount of water was restricted; water stress did not affect germination percentages in the dark or after one brief tight break (3 min) but appreciably reduced the rate of germination. While light was only slightly inhibitory to embryos under optimal germination conditions, its inhibitory effect was intensified when other factors tending to delay germination were present. Water restriction also caused ABA contents in embryos to rise. Under conditions of water stress (water restriction or low osmotic potential), CaCl2 enhanced the inhibitory effect of light; however, addition of LaCl3 reversed this effect. The nature of light-induced inhibition of germination is discussed.

White ascospore mutants in Ascobolus immersus: lack of the secondary spore wall, and allelism-testing

Ascospore pigmentation mutants have been very important in studies of gene conversion and crossing-over in such fungi as Neurospora, Sordaria and Ascobolus. Most such mutants are autonomous, with each haploid ascospore's genotype controlling its phenotype. In the Pasadena strains of Ascobolus immersus, where wild-type (+) ascospores are red/brown, we have autonomous white (w) mutants at several different loci. The white spores are completely unpigmented in + x w crosses, even though the apothecia and hyphae are a mixture of + and w genotypes. The developing w ascospores are surrounded by the same ascal sap as the + spores, yet do not develop pigment even if in contact with a + spore. Possible explanations for the non-pigmentation of white ascospores are: (i) they are structurally the same as red/brown + spores but cannot make the pigment even if some precursors are present in the ascus; (ii) the mutant ascospores could make the pigment but lack some suitable structure for it to form on - a parallel would be white-eyed Drosophila of w,w;Cn,Cn;Bn,Bn genotype, which have no eye pigment because they lack the pigment-attachment protein from W, although they can make pterins and ommochrome pigments from Cn,Bn. In case (ii), the lack of a structural feature in white ascospores might change other properties, such as optimum germination conditions.

Influence of Temperature on Germination of Japanese Brome Seed

Japanese brome (Bromus japonicus Thunb.), an introduced annual grass, is now common in some northern mixed-prairie communities. This species has the potential to alter both the seasonality of standing crop and forage quality. We sought to gain a greater understanding of Japanese brome seed germination by subjecting seed to a series of 55 constant or alternating temperature regimes following 3 to 9 months of dry laboratory storage. Cold and moderate temperature regimes provided optimum germination conditions (defined as not lower than the maximum observed minus one-half its confidence interval at the 0.05 level of probability). Extremely cold or warm temperatures suppressed germination. Germination of afterripened seed over a wide range of temperature combinations, many of which occur during fall in the Northern Great Plains, should enhance establishment and perpetuation of Japanese brome on rangelands.

Plant regeneration via somatic embryogenesis in many cultivars of cotton (Gossypium hirsutum L.)

Embryogenic callus was formed from several cultivars of cotton (Gossypium hirsutum L.) when sections of hypocotyl and cotyledon were cultured on medium supplemented with 5 mg/liter 6-(γ, γ-dimethylallyl-amino)-purine (2iP) and 0.1 mg/liter α-naphthaleneacetic acid (NAA) for callus initiation and proliferation, and subcultured on medium supplemented with 5 mg/liter NAA and 0.1 to 1 mg/liter 2iP for embryogenic callus induction. It seems that a high 2iP:auxin ratio is preferred for callus initiation and proliferation, but should be exchanged with a higher NAA:cytokinin ratio before differentiation will occur. Embryogenic calluses were recovered at a frequency of 2 to 85% depending on the cultivar used. Coker cultivars produced embryogenic callus faster and at higher frequencies than other cultivars. Embryogenic callus produced somatic embryos on phytohormone-free medium. This medium was used to maintain and proliferate embryogenic callus for a perid of 18 to 24 mo. Somatic embryos were converted to plants on a lower ionic strength medium supplemented with 0.1 mg/liter gibberellic acid (GA3) and 0.01 mg/liter NAA. Glucose was the only carbohydrate used through all phases of tissue culture and was much better than sucrose, on which phenolic production was very high. High temperature (30° C) and low light intensity (9 µE · m−2 · s−1) were optimal conditions for callus initiation, embryogenic callus induction, and maintenance, whereas lower temperature (25° C) and high light intensity (90 µE · m−2 s−1) were the optimal conditions for somatic embryo maturation, germination, and plantlet development. Plants could be regenerated within 10 to 12 wk in Cokers or 7 to 8 mo. in others.

Emergence and Seedling Survival of Calden in the Semiarid Region of Argentina

Calden (Prosopis caldenia Burk.) is one of the woody species that is increasing in abundance due to poor grazing management in the semiarid region of central Argentina. The objectives of this work were to evaluate emergence and seedling survival of calden under grazed-low herbaceous foliar cover, and ungrazed-intermediate and ungrazed-high herbaceous foliar cover. Seedling emergence was recorded weekly after 3 planting dates: October 1987, September 1988, and October 1989. Seedling survival was recorded every 2 weeks until all seedlings died. Precipitation, soil water potential, and soil temperature were monitored during the study period. Since calden only reproduces from seeds, optimal conditions for germination under different controlled photoperiod and temperature regimes were also studied. In the laboratory, greatest germination of freshly harvested unscarified seeds occurred at a diurnally alternating temperature regime of 15 and 30 degrees C with light provided for 9 hours. Lead germination occurred at 15 degrees C and continuous darkness. Acid scarification significantly increased germination percentage and germination rate. Unscarified seeds incubated in light exhibited a lower rate of germination than scarified seeds under all temperatures. In the field, soil water availability was usually similar among the 3 experimental conditions. Soil temperature was only occasionally higher in the grazed-low herbaceous cover site. Only for 1987 data, emergence was greater on the grazed area with relatively low herbaceous foliar cover and similar within the ungrazed area. Treatment effect was very little on seedling survival, being lower in the grazed area for only 2 evaluation dates in 1989. Regardless of treatment the emerged seedlings survived 40 days on the average. The highest calden seedling mortality was always coincident with higher soil temperature and lower soil water availability.

Role of Microsclerotia as Primary Inoculum ofMicrodochium panattonianum,Incitant of Lettuce Anthracnose

Microdochium panattonianum, incitant of lettuce anthracnose, was soilborne. Lettuce planted in soil collected from fields 1-4yr after an epidemic, or in soil artificially contaminated with residue infected with M. panattonianum, developed anthracnose. The pathogen was eliminated from soil, however, by fumigation with methyl bromide. Microsclerotia were observed in cells of lettuce tissues infected by M. panattonianum. Microsclerotia also were produced in vitro on a basal salts agar medium, germinated, infected, and incited anthracnose on inoculated lettuce; optimum conditions for germination and infection were 6 hr of continuous leaf wetness at 20-22 C (.)

GERMINATION RESPONSE OF TWO ALPINE GRASSES FROM THE ROCKY MOUNTAINS OF ALBERTA

Germination studies on alpine bluegress (Poa alpina L.) and broad-glumed wheatgrass (Agropyron latiglume Scribn. and Smith [Rydb.]) were undertaken to determine optimum germination conditions, the presence of seed dormancy and the extent of variability among populations for rapid germination. Poa alpina seeds germinated best under darkness and 16/8 h cycles of 22/15 °C temperature, while A. latiglume needed a 29/22 °C regime and darkness for best germination. Rapid germination in both species occurred within a narrow range of temperature conditions. Light and suboptimal temperatures appeared to have an inhibitory effect on seed germination during the initial period of imbibition. Germination inhibition through external factors (secondary dormancy) and the presence of primary dormancy in the nursery-grown seeds may be a genetic adaptation to stressful alpine environments. This and the differences among populations for seed germination in both species are encouraging for our breeding program which is developing genotypes for alpine and subalpine reclamation.Key words: Alpine bluegrass, broad-glumed wheat grass, temperature effect, light, population, seed germination.

Germination and establishment of Sahelian rangeland species : I. Seed properties.

In the context of a study on the dynamics of Sahelian rangelands, seed characteristics of about 30 species have been described, with particular attention to germination characteristics. Data on both form and weight of the seeds are presented. Germination was studied under controlled conditions in a climate room. Optimum conditions for germination were established, and the species were characterized by induction time, slope of germination vs. time curve and final germination percentage. The results obtained under climate room conditions appear to be correlated satisfactorily with the behaviour of the different species in the field.