scholarly journals Sorghum (Sorghum bicolour L.) Germination Dynamics at Extreme Temperatures

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 40
Author(s):  
Li ◽  
Eyre ◽  
Broad ◽  
Rodriguez
Keyword(s):  
Seed Germination ◽  
Cold Tolerance ◽  
Low Temperatures ◽  
Hybrid Seed ◽  
Seed Coating ◽  
Extreme Temperatures ◽  
Current Experiment ◽  
High Germination ◽  
North Eastern ◽  
Soil Temperatures

Water and heat stressors during flowering are predominant limitations of dryland sorghum yields across Australia’s north-eastern cropping zone. Crops sown early could flower before seasonal heatwaves, but the seed must uniformly germination and emerge at soil temperatures between approximately 10 to 15 °C. Furthermore, chemical coatings applied to commercial hybrid seed lots effectively protected the developing crop from pest, disease and herbicide damage but the combined influence of low temperatures and seed coatings on germination of hybrid sorghum seed batches is unknown. In this experiment, germination dynamics were modelled for 10 commercial sorghum hybrid-seed lots (with or without seed coating of a.i. thiamethoxam, oxabetrinil and thiram) incubated at continuous temperatures ranging from 9.4 to 46.1 °C. Results also show commercial seed treatments negatively affect final germination proportion especially at sub- and supra-optimal temperatures. Some hybrid-seed lots in current experiment were more sensitive to seed coatings at either sub- or supra-optimal temperatures regardless of seed germination capability (i.e., germination proportion at 25 °C). Seeds took 5 days to reach 50% germination (t50) at 9.4 °C but germinated within 24 h at constant temperatures between 20 and 40 °C. The spread of germination (time between 10 and 90% germination) increased from 0.5 days at 30 °C to 3.8 days at 9.4 °C. Therefore, some hybrid-seedlots are suited to early sowing because they can maintain high germination proportion (>90%) even at soil temperatures (9.4 °C) as long as the seedbed remains moist for a least 12 days. Research continues identify the basis of cold tolerance in some-hybrid seedlots.

scholarly journals Association mapping of germinability and seedling vigor in sorghum under controlled low-temperature conditions

Genome ◽  
2016 ◽  
Vol 59 (2) ◽  
pp. 137-145 ◽  
Author(s):  
Hari D. Upadhyaya ◽  
Yi-Hong Wang ◽  
Dintyala V.S.S.R. Sastry ◽  
Sangam L. Dwivedi ◽  
P.V. Vara Prasad ◽  
...  
Keyword(s):  
Seed Germination ◽  
Low Temperature ◽  
Cold Tolerance ◽  
Germination Rate ◽  
Strong Association ◽  
Marker Locus ◽  
Seedling Vigor ◽  
Mini Core Collection ◽  
Genome Wide ◽  
Soil Temperatures

Sorghum is one of the world’s most important food, feed, and fiber crops as well as a potential feedstock for lignocellulosic bioenergy. Early-season planting extends sorghum’s growing season and increases yield in temperate regions. However, sorghum’s sensitivity to low soil temperatures adversely impacts seed germination. In this study, we evaluated the 242 accessions of the ICRISAT sorghum mini core collection for seed germination and seedling vigor at 12 °C as a measure of cold tolerance. Genome-wide association analysis was performed with approximately 162 177 single nucleotide polymorphism markers. Only one marker locus (Locus 7-2) was significantly associated with low-temperature germination and none with vigor. The linkage of Locus 7-2 to low-temperature germination was supported by four lines of evidence: strong association in three independent experiments, co-localization with previously mapped cold tolerance quantitative trait loci (QTL) in sorghum, a candidate gene that increases cold tolerance and germination rate when its wheat homolog is overexpressed in tobacco, and its syntenic region in rice co-localized with two cold tolerance QTL in rice. This locus may be useful in developing tools for molecular breeding of sorghums with improved low-temperature germinability.

scholarly journals Near-infrared spectroscopy used to predict soybean seed germination and vigour

2018 ◽  
Vol 28 (3) ◽  
pp. 245-252 ◽  
Author(s):  
Maythem Al-Amery ◽  
Robert L. Geneve ◽  
Mauricio F. Sanches ◽  
Paul R. Armstrong ◽  
Elizabeth B. Maghirang ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Seed Germination ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Prediction Models ◽  
Soybean Seed ◽  
Seed Vigour ◽  
Near Infrared Spectra ◽  
High Germination ◽  
Qualitative Models

AbstractRapid, non-destructive methods for measuring seed germination and vigour are valuable. Standard germination and seed vigour were determined using 81 soybean seed lots. From these data, seed lots were separated into high and low germinating seed lots as well as high, medium and low vigour seed lots. Near-infrared spectra (950–1650 nm) were collected for training and validation samples for each seed category and used to create partial least squares (PLS) prediction models. For both germination and vigour, qualitative models provided better discrimination of high and low performing seed lots compared with quantitative models. The qualitative germination prediction models correctly identified low and high germination seed lots with an accuracy between 85.7 and 89.7%. For seed vigour, qualitative predictions for the 3-category (low, medium and high vigour) models could not adequately separate high and medium vigour seeds. However, the 2-category (low, medium plus high vigour) prediction models could correctly identify low vigour seed lots between 80 and 100% and the medium plus high vigour seed lots between 96.3 and 96.6%. To our knowledge, the current study is the first to provide near-infrared spectroscopy (NIRS)-based predictive models using agronomically meaningful cut-offs for standard germination and vigour on a commercial scale using over 80 seed lots.

scholarly journals Seed Germination in Cistus ladanifer: Heat Shock, Physical Dormancy, Soil Temperatures and Significance to Natural Regeneration

Plants ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 63 ◽  
Author(s):  
Luís Silva Dias ◽  
Isabel Pires Pereira ◽  
Alexandra Soveral Dias
Keyword(s):  
Heat Shock ◽  
Seed Germination ◽  
Natural Regeneration ◽  
Heat Load ◽  
Fire Effects ◽  
Ground Vegetation ◽  
Cistus Ladanifer ◽  
Physical Dormancy ◽  
Soil Temperatures ◽  
Heat Loads

Seeds of Cistus ladanifer experience bursts of germination following fires. The effects of heat shock from 10 °C to 150 °C on seed germination were investigated by final germination plus the number of days required for germination to start and finish, and symmetry of cumulative germination. The occurrence of physical dormancy in C. ladanifer seeds was investigated by a variety of methods, including imbibition, scanning electron microscopy (SEM) and light microscopy, and use of dyes. The significance of responses of C. ladanifer seeds to fires was investigated essentially by abstracting existing literature and by using fire effects models and simulations. Parameters of germination were variously affected by heat treatments—positively in the range 80–100 °C, negatively above 130 °C. Non-dormancy was consistently found in about 30% of seeds but no evidence was obtained to support the existence of physical dormancy in the dormant fraction of C. ladanifer seeds. Two complementary processes seem to be in place in seeds response to fire. A direct fire-driven increase in germination of virtually all seeds in response to the appropriate heat load produced by fire or, in the absence of such heat loads, the germination of the non-dormant fraction provided that above-ground vegetation burns.

Enhancement by Low Temperatures of the Anaerobic Induction of Cocklebur Seed Germination

1977 ◽  
Vol 4 (6) ◽  
pp. 849 ◽  
Author(s):  
Y Esashi ◽  
Y Ohhara
Keyword(s):  
Seed Germination ◽  
Low Temperature ◽  
Gibberellic Acid ◽  
Low Temperatures ◽  
Anaerobic Treatment ◽  
Maximal Response ◽  
Benzyl Adenine ◽  
Anaerobic Induction ◽  
Time Period ◽  
Proportional Increase

Non-dormant, upper cocklebur (Xanthium pensylvanicum Wallr.) seeds, incapable of germinating under ordinary conditions, can germinate when previously subjected to anaerobiosis; this has been termed the anaerobic induction of seed germination. Aerobic presoaking of the seeds was also required for successful anaerobic induction, and exerted two counter-acting effects on seed germination. When the time period of aerobic presoaking was sufficiently prolonged, the increasing duration of an anaerobic treatment resulted in proportional increase of germination potential but, when it was short, the effect of the anaerobiosis was saturated in a few days. Prolonging the aerobic presoaking period caused less response of the seed to the anaerobic induction, suggesting the development of some germination-inhibiting system during the aerobic presoaking period. This system could not develop in the absence of O2 or at low temperature. Thus, low temperature during prolonged presoaking produced a maximal response to anaerobic induction. Various germination stimulants, CO2, ethylene, gibberellic acid and benzyl adenine, did not significantly alter the effects of the presoaking.

scholarly journals Gene Characterization and Enzymatic Activities Related to Trehalose Metabolism of In Vitro Reared Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) under Sustained Cold Stress

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 767
Author(s):  
Xin Lü ◽  
Shi-chou Han ◽  
Zhi-gang Li ◽  
Li-ying Li ◽  
Jun Li
Keyword(s):  
Cold Tolerance ◽  
Enzyme Activities ◽  
Low Temperatures ◽  
Insect Pests ◽  
Egg Parasitoid ◽  
Threshold Temperature ◽  
Gene Expressions ◽  
Gene Characterization ◽  
Trichogramma Dendrolimi

Trichogramma spp. is an important egg parasitoid wasp for biocontrol of agriculture and forestry insect pests. Trehalose serves as an energy source or stress protectant for insects. To study the potential role of trehalose in cold resistance on an egg parasitoid, cDNA for trehalose-6-phosphate synthase (TPS) and soluble trehalase (TRE) from Trichogramma dendrolimi were cloned and characterized. Gene expressions and enzyme activities of TdTPS and TdTRE were determined in larvae, prepupae, pupae, and adults at sustained low temperatures, 13 °C and 16 °C. TdTPS and TdTRE expressions had similar patterns with higher levels in prepupae at 13 °C and 16 °C. TdTPS enzyme activities increased with a decrease of temperature, and TdTRE activity in prepupae decreased sharply at these two low temperatures. In vitro reared T. dendrolimi could complete entire development above 13 °C, and the development period was prolonged without cold injury. Results indicated trehalose might regulate growth and the metabolic process of cold tolerance. Moreover, 13 °C is the cold tolerance threshold temperature and the prepupal stage is a critical developmental period for in vitro reared T. dendrolimi. These findings identify a low cost, prolonged development rearing method, and the cold tolerance for T. dendrolimi, which will facilitate improved mass rearing methods for biocontrol.

scholarly journals Thermally induced torpor in fullterm lizard embryos synchronizes hatching with ambient conditions

2006 ◽  
Vol 2 (3) ◽  
pp. 415-416 ◽  
Author(s):  
Rajkumar Radder ◽  
Richard Shine
Keyword(s):  
Environmental Conditions ◽  
Low Temperatures ◽  
Access To Information ◽  
Ambient Conditions ◽  
Thermally Induced ◽  
Ambient Temperatures ◽  
Ground Conditions ◽  
Soil Temperatures ◽  
Bassiana Duperreyi ◽  
Do So

Eggs inside an underground nest have limited access to information about above-ground conditions that might affect the survival of emerging hatchlings. Our measurements of heart rates of embryos inside the intact eggs of montane lizards ( Bassiana duperreyi , Scincidae) show that low temperatures induce torpor in fullterm embryos, but do not do so during earlier embryogenesis or later, post-hatching. Because above-ground conditions affect soil temperatures, this stage-dependent torpor effectively restricts hatching to periods of high ambient temperatures above ground. Torpor thus can function not only to synchronize activity with suitable environmental conditions during post-hatching life (as reported for many species), but also can occur in embryos, to synchronize hatching with above-ground conditions that facilitate successful emergence from the nest.

Parasites and low temperatures

Parasitology ◽  
1999 ◽  
Vol 119 (S1) ◽  
pp. S7-S17 ◽  
Author(s):  
D. A. Wharton
Keyword(s):  
Life Cycle ◽  
Cold Tolerance ◽  
Low Temperatures ◽  
Cold Hardiness ◽  
Free Living ◽  
Rate Of Growth ◽  
Subzero Temperatures ◽  
Growth Development ◽  
Epidemiological Significance

SUMMARYLow temperatures affect the rate of growth, development and metabolism of parasites and when temperatures fall below 0°C may expose the parasite to the potentially lethal risk of freezing. Some parasites have mechanisms, such as diapause, which synchronise their life cycle with favourable seasons and the availability of hosts. Parasites of endothermic hosts are protected from low temperatures by the thermoregulatory abilities of their host. Free-living and off-host stages, however, may be exposed to subzero temperatures and both freezing-tolerant and freeze-avoiding strategies of cold hardiness are found. Parasites of ectothermic hosts may be exposed to subzero temperatures within their hosts. They can rely on the cold tolerance adaptations of their host or they may develop their own mechanisms. Exposure to low temperatures may occur within the carcass of the host and this may be of epidemiological significance if the parasite can be transmitted via the consumption of the carcass.

The Effect of extreme Temperatures on different Stages of Aëdes aegypti (L.)

1957 ◽  
Vol 48 (3) ◽  
pp. 593-599 ◽  
Author(s):  
Micha Bar-Zeev
Keyword(s):  
Aedes Aegypti ◽  
High Temperatures ◽  
Low Temperatures ◽  
Extreme Temperatures ◽  
Fourth Stage ◽  
Wetting And Drying ◽  
The Third ◽  
Adult Females ◽  
Cent Mortality

Earlier investigations of the effects of extreme temperatures on different stages of Aëdes aegypti (L.) were supplemented by studies of eggs, larvae and pupae in water, and of eggs and adult females in air at various relative humidities.Larvae of the same stage, young pupae (defined as those less than half-an-hour old) and old pupae (at least 36 hours old), in groups of 100, 25 and 25, respectively, were kept for various periods at low temperatures in incubators, or, at high temperatures in glass cylinders closed at their lower ends by cloth filters and inserted into water baths, and then transferred to water at 28°C. and the mortality determined from the numbers surviving 24 hr. later (in the case of larvae) or becoming adult (in the case of pupae). Eggs in batches of 1,000 were similarly treated, except that periods of 24 hr. in water at 28°C. with yeast as food added were alternated with 24-hr. periods of drying, and mortality determined on the number that hatched and survived to the third or fourth stage. Adult females (four days old) were exposed in groups of 50 for various periods in jars over appropriate solutions giving a complete range of relative humidities and kept at low, medium and high temperatures. Eggs in batches of 1,000 were subjected to the same treatments. The adults were kept at 28°C. and 60 per cent. R.H. before treatment and for 24 hr. afterwards and mortality then determined. Mortality of eggs was determined after alternate 24-hr. periods of wetting and drying at 28°C., as in the case of eggs treated in water. The results of all the experiments were expressed as the exposure-times required to give 50 per cent. mortality (T50), calculated from the observed data.

The Influence of Date of Oviposition and Climatic Conditions on Hatching of Camnula pellucida (Scudder) (Orthoptera: Acrididae)

1966 ◽  
Vol 98 (11) ◽  
pp. 1145-1159 ◽  
Author(s):  
R. Pickford
Keyword(s):  
Embryonic Development ◽  
Snow Cover ◽  
Temperature Regime ◽  
Low Temperatures ◽  
Extended Period ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Soil Conditions ◽  
Soil Temperatures ◽  
Dry Soil

AbstractField and laboratory hatching experiments were conducted from 1960 through 1963 with eggs of Camnula pellucida (Scudder) laid in field cages and collected at fortnightly intervals. Before freeze-up, embryonic development usually reached prediapause level in all eggs laid before the middle of August; these eggs were the first to hatch when incubated in the laboratory or when left in the soil outdoors. Eggs laid later than mid-August showed progressively less embryonic development and consequently hatched later. Viability was highest in eggs laid during the latter half of August; those laid early in the season often suffered from desiccation because of their long exposure to dry soil conditions; those laid towards the end of the season showed declining viability caused, apparently, by low temperatures. The percentage hatch was relatively high in eggs laid before the end of August but declined progressively thereafter; those laid in October rarely hatched. Seasonal hatching patterns were largely dependent upon weather conditions; such patterns were rapidly completed when an extended period of hot, dry weather continued through the hatching period, but often extended intermittently over a month or more when weather was unsettled. The typical diurnal hatching pattern, which also closely followed the temperature regime, commenced in the morning at 0900–1000 hours as soil temperatures exceeded 65°F., rising to a peak about 1100–1200 hours when temperatures reached 85°F., and then generally declined during the afternoon. However, during rapidly changing weather conditions hatching frequently started and stopped as skies cleared and again clouded over. Winter kill occasionally may be an important factor in reducing populations, especially when snow cover is removed by a mid-winter thaw and sub-zero temperatures follow.

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