scholarly journals Physiolgical and Ecological Studies on Barnyard Grass (Echinocloa crus-galli Beauv. var. oryzicola Ohwi) : I. On the primary dormancy of the seed. (1) Relation of the seed covering to dormancy, and effects of temperature and oxygen on breaking dormancy.

1960 ◽  
Vol 29 (1) ◽  
pp. 130-132 ◽  
Author(s):  
Masao ARAI ◽  
Masuzi MIYAHARA
Keyword(s):  
Ecological Studies ◽  
Barnyard Grass ◽  
Primary Dormancy ◽  
Breaking Dormancy ◽  
Effects Of Temperature

Jojoba flower buds: temperature and photoperiod effects in breaking dormancy

1980 ◽  
Vol 31 (4) ◽  
pp. 727 ◽  
Author(s):  
RL Dunstone
Keyword(s):  
Seed Weight ◽  
Diurnal Temperature Range ◽  
Night Temperature ◽  
Flower Buds ◽  
Flower Bud ◽  
Desert Shrub ◽  
Breaking Dormancy ◽  
Controlled Environments ◽  
Effects Of Temperature ◽  
Lower Temperature

Jojoba (Simmondsia chinensis [Link] Schneid.) is a long-lived desert shrub, valued for the liquid wax which makes up 50% of the seed weight. As attempts are being made to domesticate the species, it is important to understand the environmental factors controlling the reproductive cycle and governing seed yield. The effects of temperature and photoperiod in breaking flower bud dormancy were studied on plants growing under well-watered conditions in controlled environments. Plants 42-48 months old produced only dormant flower buds when growing in 27/22� to 36/31�C day/night temperature. When the plants were moved to lower temperatures of 24/19� or 18/13�, every plant produced a flowering flush. In two experiments, clonal material was grown at either 30/25� or 36/3l�C, then moved to lower temperature treatments. Down to the lowest temperature used (18/13�), the greater the drop in temperature, the greater the number of flowers which opened. Flowering occurred under both short (8 h) or long (16 h) photoperiods. There was a critical temperature in the region of 27/22� to 30/25�, above which no flowering occurred. Flowering was not dependent on a large diurnal temperature range, but occurred only if the plants were subjected to a low temperature for at least 21 days.

Variation of Seed Dormancy and Germination Ecology of Cowcockle (Vaccaria hispanica)

Weed Science ◽  
2014 ◽  
Vol 62 (3) ◽  
pp. 483-492 ◽  
Author(s):  
Hema S. N. Duddu ◽  
Steven J. Shirtliffe
Keyword(s):  
Seed Dormancy ◽  
Great Plains ◽  
Northern Great Plains ◽  
Light Conditions ◽  
Primary Dormancy ◽  
Local Environments ◽  
Temperature Regimes ◽  
Effects Of Temperature ◽  
Two Temperature ◽  
Seed Dormancy And Germination

Cowcockle, an introduced summer annual weed of the Northern Great Plains, is being considered for domestication because of its high quality starch, cyclopeptides, and saponins. Loss of seed dormancy is one of the key desirable traits for domestication. To determine the potential for domestication of this species, an understanding of the seed dormancy and germination patterns is required. The objectives of this study were to evaluate seed dormancy in cowcockle ecotypes and determine how temperature and light affect seed dormancy. We evaluated 15 populations of cowcockle for primary dormancy by exposing them to five temperatures (5, 7.5, 10, 15, and 20 C) under two temperature regimes (constant and alternating) in both dark and light conditions. Freshly matured seeds of all the populations showed high levels of primary dormancy except ‘Mongolia’. Lower levels of dormancy at medium temperatures (10 and 15 C) and greater dormancy at low and high temperatures suggest conditional dormancy, a state at which seeds germinate over a narrower range of conditions compared to nondormant seeds. The effects of temperature regime, light, and their interaction was significant only at suboptimal (5 and 7.5 C) and supraoptimal (20 C) temperatures. Under these conditions, alternating temperatures were more effective in breaking the conditional dormancy, followed by light. The variation in optimum temperature, light, and their interactions among the cowcockle populations may be due to the plants evolving to adapt to their local environments. From a domestication perspective, the conditional dormancy in cowcockle can be observed as an evolutionary mechanism that prevents untimely germination following maturity and may not be a major obstacle for its domestication.

Temperature Paces Life

On Gaia ◽  
2013 ◽  
Author(s):  
Toby Tyrrell
Keyword(s):  
Primary Production ◽  
Temperature Effects ◽  
Metabolic Rates ◽  
Ecological Studies ◽  
Positive Correlation ◽  
Effects Of Temperature ◽  
Mechanistic Understanding ◽  
Living Organisms

This chapter addresses the question of optimal temperatures by looking at the evidence from physiological and ecological studies—evidence from studying living organisms. It summarizes what is known about the effects of temperature on growth, metabolic rates, primary production, biomass, and biodiversity. In each case, the overall tendency is a positive correlation with temperature—higher values at higher temperatures, lower values at lower temperatures. There are however plenty of exceptions, such as biomass and primary production in the sea and in deserts, and biodiversity in shallow versus deep seafloor muds. By building toward a mechanistic understanding of temperature effects, this study can overcome the habitat commitment obstacle.

Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover (T. subterraneum L.) I. Effects of temperature

1966 ◽  
Vol 17 (1) ◽  
pp. 29 ◽  
Author(s):  
RC Rossiter ◽  
AB Beck
Keyword(s):  
Total Concentration ◽  
Subterranean Clover ◽  
Maximum Growth ◽  
Biochanin A ◽  
Ecological Studies ◽  
Leaf Material ◽  
Long Day ◽  
Effects Of Temperature

Two strains of subterranean clover – Yarloop and Mt. Barker – were grown at controlled temperatures ranging from 36/31° to 9/4°C under long-day conditions. Leaf material was analysed for the three isoflavones formononetin, genistein, and biochanin A. In the Mt. Barker strain, the formononetin concentration was low (< 0.2% dry wt.) and varied little with temperature. Otherwise, isoflavone levels generally rose from very low values at 36/31° to a peak at 15/10°, and then decreased again to 9/4°. For both strains the total concentration of the three isoflavones and also the total amount of isoflavones per leaf were highest at 15/10°. This temperature was lower than that at which maximum growth occurred. The data are discussed in relation to evidence on the effects of temperature on the formation of flavonoid (especially anthocyanin) compounds. We conclude that temperature is unlikely to be a major factor in the incidence of "clover disease".

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