High Germination Temperatures Research Articles

ウメ‘南高’の開花と花粉発芽の温度条件

The effects of temperature on flowering and pollen germination in Japanese apricot (Prunus mume Sieb. et Zucc.) cv. Nanko were investigated in a growth chamber where day and night temperatures were kept constant at 5°, 10°, 15° and 20 °C and under field conditions from mid-January to mid-April.1. At higher temperatures, anthesis was earlier and flowering period was shorter than they were at lower temperatures. Trees kept at 5 °C required more days to flower than did those in the field. All floral organs, including the ovary, were bigger at full bloom at lower than at higher temperatures.2. Pollen, collected from trees in all temperature treatments, germinated and grew within 4 hours at temperatures ranging from 0° to 30 °C when cultured on 1% ager and 20% sucrose. The germination rates at higher temperatures were more rapid than they were at 10 °C and below. Although some pollen germinated at 0 °C, the optimum range was between 20° to 25 °C in all treatments. Pollen tubes grew longer under higher germination temperatures up to 25 °C. Flowers kept at 15 °C had the longest tubes; those kept at 5 °C had the shortest.

The Influence of Temperature on Seed Germination in Cultivars of Common Bean

Common bean (Phaseolus vulgaris L.) is grown over a wide range of environments, including sites with low or high soil temperatures at sowing time. To describe the temperature responseof seed germination, 20 bean genotypes were evaluated using a rolled paper towel system with 11 constant temperatures ranging from 12 to 34 °C. Germination response was characterized by fitting cumulative counts using a maximum-likelihood analysis. Rate of germination increased from abase temperature (Tb) typically near 8 °C to an optimal development temperature (To) of 29 to 34 °C. Tb did not differ among common bean genotypes. Mesoamerican germplasm showed slightlyhigher To than Andean germplasm, but there was large variation in To within each of the two gene pools. The single accession of tepary bean (P. acutifolius) evaluated appeared to be the mosttolerant to high germination temperatures.

Improvement of High-temperature Germination of Spinach Seed with Acid Scarification and Priming with Polyethylene Glycol 6000.

Seed germination of spinach (Spinacia oleracea L. cv. Jiroumaru) was inhibited markedly at temperatures above 25°C. Exposure of the seeds to 36N sulfuric acid for 30 min or 18N for 60 and 120 min increased the final germination percentage at 25°C to 80-95%, compared to about 30% for the water-soaked control. In the de-coated seeds, the germina-tion percentage was increased to 90%; likewise, germination was also promoted by physi-cally cracking the pericarp. But at 30°C, the final germination percentage was 50% in the both acid-scarified and de-coated seed treatments.The acid scarification followed by priming with polyethylene glycol 6000 solution (-1.3 MPa, 1 week at 10°C) increased the germination percentage even at 30°C to more than 80% within 8 days after sowing for 6 cultivars including 'Jiroumaru'. Treatment with PEG alone was less effective in promoting germination.Scanning electron micrographs showed that the acid removed the pericarp cuticula, that the epidermal layer was pitted, and that some of pits had pores of 1-2μm in dia-meter on their bases.After acid scarification, the use of priming using PEG had beneficial effect on the ger-mination of spinach at 30°C, but very little is known about the physiological process of priming.

Germination Response of Subterranean, Berseem, and Rose Clovers to Alternating Temperatures

AbstractAnnual clover (Trifolium spp.) stands are sometimes poor because of low and slow germination due to unfavorable temperatures. The study was conducted to identify optimum temperature for germination of relatively new clover species to the U.S. Southeast to improve stand establishment. High temperature germination was also examined to estimate summer germination which usually results in seedling mortality and a decrease of the soil seed‐bank. Seed of 10 cultivars of T. alexandrinum L., T. brachycalycinum Katzn. and Morley, T. hirtum All., T. subterraneum L., and T. yanninicum Katzn. and Morley were subjected to alternating 12 h day/12 h night temperatures of 15/5, 20/10, 25/15, 30/20 and 35/25 °C. Germination counts were made at 3, 6, 9, and 12 d to determine percent germination and germination rate index (GRI). Germination was >80% for all entries at the three lowest temperature treatments except ‘Larisa’ subclover at 25/15 °. At 30/20 °C, germination of ‘Bigbee‘ berseem and T. brachycalycinum subclovers decreased to 54 to 66%, while the other species decreased to <35%. The 35/25 °C treatment suppressed germination to <25%. The optimum temperature for GRI was 25/15 followed by 20/10, 15/5, 30/20, and 35/25 °C. The optimum germination temperature of 25/15 °C occurs in October along the Texas‐Louisiana Gulf Coast. September plantings (30/20 °C) in this area should be limited to T. alexandrinum and T. brachycalycinum species. Cultivars that germinate at summer temperatures of 35/25 °C or higher should be avoided unless they have a high hard‐seed content.

Priming Improves High-temperature Germination of Pansy Seed

The optimum conditions for priming pansy (Viola × wittrockiana) seeds were in aerated osmotic solutions of polyethylene glycol 8000 (PEG 8000) at – 1.0 MPa for 7 days at 15C. Priming at – 0.8 MPa and 15C caused 8% to 26% of seeds to germinate during 4 to 13 days of priming. Increasing numbers of abnormal seedlings developed when priming was extended beyond 7 days. Final germination percentages were better in laboratory studies at 35C for primed (51%) than nonprimed (10%) seeds. Removal of the mucilage released by the seed with 240 g KOH or 170 g NaOH/liter for 15 or 30 seconds during priming did not affect total germination percentages, but did improve seed handling. Primed seed had higher, faster, and more uniform germination than nonprimed seeds after sowing in growing medium in plant growth chambers or greenhouses.

Mepiquat chloride seed treatment and germination temperature effects on cotton growth, nutrient partitioning, and water use efficiency

Cotton seed (Gossypium hirsutum L. cv. “Stoneville 825”), treated with 0, 0.2, 1.0, and 2.0 g active ingredient (a.i.) mepiquat chloride (MC) kg−1, was evaluated for the effect of MC on early plant growth. Emergence rate and total emergence of MC-treated seed and control were similar regardless of germination temperature. However, the number of leaves and squares and the dry weight of leaves, stems, and roots for hydroponically grown cotton plants were significantly lower at lower germination temperatures (15°C for 3 day/30°C for 1 day and 15°C for 4 days) than at higher germination temperatures (30°C for 4 days and 30°C for 3 days/15°C for 1 day). All MC treatments significantly decreased the number of nodes, leaves, and squares, as well as dry weight of leaves, stems, and roots, as compared to control plants at 28 days after emergence. MC seed treatments also significantly reduced plant height and total leaf area compared to controls. Water-use efficiency (WUE) was significantly lower for the 1.0 g a.i. MC treatment than for control plants. In general, the highest rate of MC seed treatment resulted in greater concentrations of calcium, phosphorus, and nitrogen in plant leaves and stems and also in greater concentrations of magnesium, phosphorus, and nitrogen in roots than in controls.

Effects of low temperature during seed development on the mother plant on subsequent bolting of chicory, lettuce and spinach

Low temperature exposure (5 and 10°C) during seed development on the mother plant increased bolting of chicory and lettuce in comparison to high temperature (15°C) exposure. Seed development in low temperature enhanced bolting of chicory even at high germination temperatures, and suggests that the crop vernalization requirement was already satisfied on the mother plant before seed harvesting. Bolting of spinach was not influenced by temperatures during seed development. Low temperatures during seed production decreased the emergence percentages of lettuce and spinach.

Malting of Finger Millet: Factors Influencing α-Amylase Activity and Wort Characteristics

The effect of germination temperature and duration and application of gibberellic acid on α-amylase activity and some wort characteristics of finger millet malt was studied. Two samples of finger millet were steeped to 33% moisture and germinated at 20, 25, 30, and 35° C for 48 and 96 hr with and without gibberellic acid (0.1 mg/kg). α-Amylase of the malts increased in response to higher germination temperatures (30-35° C). The α-amylase activity showed substantial decrease at the maximum mashing temperature of 70° C. The extract yield varied from 42.7 to 73.5% depending on malting conditions. The worts were light in color, low in soluble nitrogen, and filtered slowly. Reducing sugars were higher in the worts prepared from malts germinated at 30-35° C than those germinated at lower temperatures (20-25° C). Desirable free α-amino nitrogen levels (120-150 mg/L) in the worts were obtained from the malts germinated at higher temperatures for 48-96 hr. Malts treated with gibberellic acid and germinated at 30-35° C for 48 hr produced worts comparable to those of control malts germinated for 96 hr. Response to exogenous gibberellic acid was higher in the malts germinated at 30-35° C than in those germinated at 20-25° C

Germination depth vs. temperature requirements in naturally dispersed seeds of Leucospermum cordifolium and L. cuneiforme (Proteaceae)

Myrmecochory (ant dispersal) and the requirement for both low and high diurnal soil temperatures during seed germination after fire, are important ecological determinants in the seedling recruitment phase of Leucospermum R. Br. species. A crucial unknown parameter linking these two factors is the effective burial depth (i.e. germination depth) of seeds stored in the subterranean seed bank. The germination depth of seedlings was effectively determined in a nursery trial by measuring the length of the hypocotyl between the radicle end and ground level. Using this method the germination depth of Leucospermum cordifolium (Salisb. ex Knight) Fourcade and L. cuneiforme (Burm. f.) Rourke seedlings emerging during winter, after summer burns in three localities was estimated. Average estimated germination depths varied between 30 and 45 mm. Daily minimum and maximum temperatures were measured at various soil depths during winter in burnt and unburnt mesic mountain fynbos. Temperatures measured at 10, 20 and 40 mm depths during winter were close to the known optimum daily low and high germination temperatures in L. cordifolium , in burnt fynbos, but not in unburnt fynbos. These temperatures in burnt fynbos prevailed especially during early winter. It was concluded that a high proportion of the Leucospermum cordifolium seed bank will germinate only during the first early winter following a fire. Other aspects of natural seed dispersal were studied. These included seedling dispersal numbers and patterns around burnt mother plants. Evidence for seed dispersal and burial by ants was found.

Effects of Seed Coating and Osmotic Priming on the Germination of Lettuce Seeds

Abstract Lettuce (Lactuca sativa L. ‘Empire’) seeds (achenes) were primed in aerated solutions of polyethylene glycol 8000 (−1.56 MPa) for 24 hr at 18°C and dried to 6% water content. Control (untreated) and primed seeds then were commercially coated in a clay-based material (Royal Sluis Splitkote). Priming prevented the occurrence of thermodormancy in seeds imbibed at temperatures between 32° and 37° and accelerated the rate of germination at all temperatures tested. Coating delayed germination slightly and reduced the maximum germination temperature of control seeds. Primed seeds exhibited thermodormancy when tested immediately after coating, but they soon regained their capacity for high-temperature germination. When tested after 5 months of storage at 5°, primed seeds germinated at temperatures up to 37° regardless of coating. Osmotically primed seeds retained the capacity for germination at high temperature after seed coating and storage, providing an effective means of improving stand establishment of direct-seeded lettuce in hot weather.

Alleviation of Thermodormancy in Coated Lettuce Seeds by Seed Priming

Abstract Lettuce (Lactuca sativa L. ‘Empire’) seeds (achenes) were given an osmotic priming treatment (24 hr in aerated —1.5 MPa polyethylene glycol (PEG 8000) solution at 18°C in the light) which alleviated thermodormancy in laboratory tests. The seeds then were coated commercially for precision planting. Additional seeds also received a proprietary treatment for enhancing high temperature germination (Royal Sluis Split-kote D). In field trials in the Imperial Valley of California, where the soil temperature exceeded 35°C for the first 11 hr of imbibition under sprinkler irrigation, total emergence of untreated seeds after 6 days was between 18% and 21%, whereas that of primed and Splitkote D seeds ranged from 46% to 69%. Uniformity and rate of emergence were also greater for the primed seeds, with 91 % of the final emergence occurring by the 3rd day, as compared to only 70% for the control. Seed priming prior to coating can be an effective method of improving lettuce stand establishment under high temperature conditions.

The Effect of Sodium Hypochlorite on Germination of Lettuce Seed at High Temperature

Investigations into the effects of treatment with sodium hypochlorite solution on high-temperature germination of lettuce seed are described. A 2 h treatment in a solution with 10% available chlorine enabled up to c. 70% of seeds to germinate at 35 °C, without impairing germination and normal seedling development at 20 °C. A 10 min rinse in 0-01 N HC1 following such treatment enhanced its effect and treated seeds retained their ability to germinate at high temperature for at least 18 months. Seedling development at 20 °C following treatment was influenced by treatment temperature and batch of hypochlorite solution. Emergence from compost in a cycling (30/15 °C) temperature regime was improved in three out of five cultivars tested, and there were indications that hypochlorite treatment enabled one of the other cultivars to escape induced thermodormancy.

Variation in seed germination inhibition of Chenopodium bonus-henricus in relation to altitude of plant growth

Chenopodium bonus-henricus achenes have poor germination whatever the temperature; this phenomenon is reinforced with increasing elevation of seed harvest. Since the excised embryo is never dormant, germination of intact seeds is prevented by the seed coat. The seed coat thickens and contains more polyphenols with increasing elevation. This process appears to be responsible for the reduced permeability of the seed coat. High germination temperatures reduce the gas solubility in water and, at the same time, increase polyphenol oxidation in the seed coat. The embryos of seeds collected at low elevation thus receive a reduced O2 flux. When high temperature is applied to seeds from high elevation, the O2 flux is drastically reduced because of the thicker seed coat and increased levels of oxidizable polyphenols.There is a high correlation between germination and the mean of the average daily temperature for the 30 days preceding harvest, high temperature prior to harvest being correlated with high germination.Progenies of plants transferred from high to low elevation (and the inverse) show the direct influence of the new environment on the seed coat inhibition of germination.

The Effects of Temperature Upon Seed Germination in Festuca pratensis var. Apennina

SUMMARY (1) The effects of temperature upon seed dormancy and germination were studied in eleven populations of tetraploid Festuca pratensis var. apennina from the Italian Alps and Apennines. (2) Three populations from the Apennines had a smaller cold requirement to break dormancy. There was no correlation between cold requirement to break dormancy and the altitude from which the population was collected. (3) Populations from the Apennines germinated over a wider range of temperature than those from the Alps. Populations from lower altitudes had a lower optimum temperature for germination than those from high altitudes. (4) The seeds of all populations had a high optimum germination temperature (c. 27 0C), when given only a short period of cold treatment. As the period of exposure to low temperatures was increased, the range at which germination occurred extended to lower temperatures. The relationship between optimum germination temperature and the period of exposure to low temperatures may provide an adaptive mechanism which ensures survival at high altitudes.

The effect of temperature on the germination and endogenous cytokinin and gibberellin levels of pecan nuts

Summary Incubation of pecan embryos at 30 °C resulted in an increase in the level of endogenous cytokinins and gibberellins and also gave optimum germination. A much slower rate of hormone production occurred with incubation at 20 °C and this is possibly correlated with the poor germination obtained at this temperature. Incubation at 4 °C partly substituted for the high temperature germination requirement and resulted in hormonal changes very similar to those recorded at 30 °C. Kinetin and gibberellin acid were also found to substitute partially for the high temperature requirement. These results suggest that endogenous hormones may play an important role in the mobilization of lipid food reserves to supply the energy required for germination.

DIMETHYL SULPHIDE FORMATION IN MALT-EFFECT OF MALTING CONDITIONS

The dimethyl sulphide (DMS) content of kilned malt, and, presumably, the level of precursor in green malt, is significantly affected by malting conditions. Increasing proteolysis favours increased DMS formation in the malt, particularly when induced by higher germination temperatures. The additives gibberellic acid and potassium bromate have opposing effects, some increase being caused by the former and significant reduction being achieved by the latter.

Effect of Temparature and Dormancy on Germination of Tall Fescue1

The effects of alternation and duration of temperature levels on the germination of dormant and nondormant seed of tall fescue (Festuca arundinacea Schreb ‘Fawn’) were evaluated. Dormancy induction and temperature preconditioning of dormant seed were also studied.Dormancy was greater in seed matured at 15 C compared to that matured at 26.6 C. The expression of dormancy was also more pronounced at a higher germination temperature (26.6 C).Temperature preconditioning of dorma nt fescue seed was important in relieving dormancy; germination response was essentially confined to imbibing temperatures of ≥ 15 C. Preconditioning time was important and 48 days at 1 C, 24 or 48 days at 5 C, and 24 days at 10 C gave near maximum germination response.Germination of dormant and nondormant seed was influenced differentially by level and alternation of temperature and by the amplitude of temperature fluctuation. For nondormant seed, constant temperature at 20 to 25 C was optimum. For dormant seed, alternating temperatures were more favorable, and the optimum regime was 8 hours at 20 to 25 C and 16 hours at 10 to 15 C with the range of response to temperature being more restricted than for nondormant seed. Germination response of dormant seed diminished as the time period at the higher temperature increased.The germination responses of dormant seed observed in this study indicate that at least two physiological phenomena may be involved. The thennogradient response could be a combination of the effects of temperature on the germination processes, per se, and on the metabolic and/or physical processes involved in dormancy. In nondormant seed, only the rate and extent of germination was affected by the temperature regime.

Seed and Embryo Germination in Syringa vulgaris and S. reflexa as Affected by Temperature during Seed Development

AbstractEffects of controlled temperature conditions during seed development on seed and embryo germination of Syringa vulgaris were studied using vegetatively propagated mother plants. Seeds from mother plants grown at 18–24°C were partially dormant at low (15°C) but not at high (21°C) germination temperature, while seeds from outdoors or from plants grown at 12°C were not dormant at all. Seed dormancy at low temperatures was induced as well when branches from outdoor plants were kept at 18–24°C for the last two‐three weeks before harvesting. The dormancy induced by 24°C during seed development was not broken by keeping branches at 12°C for the last two‐three weeks. In most cases the induced seed dormancy was broken completely by gibberellic acid.Embryo germination at 24 or 15°C was not affected by mother plant temperature. Part of the embryos from plants grown at 24°C were, however, dormant at 9°C. The ability of embryos to germinate in osmoticum was only slightly affected by mother plant temperature.The mechanical resistance of the endosperm was significantly higher in the seeds from plants grown at 24°C than in seeds from 12°C.Both the embryos and the seeds of S. reflexa were dormant at the time of termination of embryo elongation. Experiments with three seed‐propagated mother plants indicated that the water potential of embryos may be reduced by high mother plant temperature.

Germination regulating mechanism in arid-zone plants: High temperature stimulus and germination ofRhynchosia seeds

Constant high temperature pretreatment given to the seeds ofRhynchosia minima D.C. andRhynchosia arenaria Blatt. and Hall., beside breaking hard seedcoat dormancy, tends to stimulate germination as well as seedling growth.

THE DEVELOPMENT OF DORMANCY IN SEEDS OF COCKLEBUR (XANTHIUM)

In a previous paper (2) it was shown that dormancy may be induced in the after-ripened embryos of ragweed (Ambrosia trifida L.) by means of high temperature germination in connection with restricted oxygen supply to the embryos due to the fruit and seed membranes that envelop them. These embryos, however, were dormant at maturity and the induced secondary dormancy was evidently merely a reversal of the essential changes through which the embryos had gone in the after-ripening process or the removal of the original or primary dormancy. The embryos of seeds of Xanlhium canadense and X. commune have at no time during periods of dry storage of seeds in the burs exhibited any tendency to dormancy when placed under germinating conditions. No doubt this is also true of other species of Xanthium. Shull (4) compared the germination of embryos of seeds of X. glabratum, when quite green, with those of fully ripened seeds and of seeds one year old and was able to detect no perceptible after-ripening in passing from the unripe to the ripe and year-old conditions. The so-called dormancy or delay in the germination of these seeds at certain temperatures is due, as pointed out first by Crocker (i), to the restriction of the oxygen supply to the embryos by the seed coats for when the seed coats are removed and the naked embryos are placed under suitable conditions, germination usually takes place within 24 to 48 hours.