Adaptive Variability in the Growth of Danthonia caespitosa Gaud. Populations at Different Temperatures

1976 ◽  
Vol 24 (3) ◽  
pp. 381 ◽  
Author(s):  
KC Hodgkinson ◽  
JA Quinn
Keyword(s):  
Growth Rates ◽  
Perennial Grass ◽  
Weight Ratio ◽  
Intraspecific Variability ◽  
Habitat Characteristics ◽  
Relative Growth Rates ◽  
The North ◽  
Eastern Australia ◽  
Different Temperatures ◽  
Net Assimilation

Five populations of the indigenous perennial grass Danthonia caespitosa Gaud. were selected from widely separated sites along a north-south transect in south-eastern Australia. The sites, spanning the latitudinal range (31° to 42° S.) for the species, extended from a hot semiarid environment in the north to a cool and moist temperate environment in the south. Two experiments, to assess the extent of intraspecific variability in response to different tempera- ture regimes, were conducted in naturally lit temperature-controlled glasshouses in the Ceres phyto- tron. All populations had a similar temperature optimum for growth of between 20.7 and 267°C (mean daily temperature), typical for temperate species. Rates of tillering, rates of leaf appearance, and leaf blade lengths and widths differed among populations and showed considerable phenotypic plasticity with respect to temperature. At all temperatures the growth rate of populations generally declined with increasing latitude of origin. A detailed analysis of growth rates showed that differences between populations in final weight could largely be accounted for by variability in mean relative growth rates. Northern populations in general had a higher net assimilation rate and leaf weight ratio than southern populations. The adaptive significance of these physiological and morphological differences between populations is discussed in relation to habitat characteristics and the distributional range of the species. It is concluded that along the latitudinal and climatic gradient there has been no significant change in temperature optima for growth but there has been natural selection resulting in higher growth rates of northern populations.

Studies on the sowing dates of cotton in the Sudan Gezira: I. The influence of date of sowing on plant growth and development

1967 ◽  
Vol 69 (3) ◽  
pp. 305-315 ◽  
Author(s):  
J. E. Jackson
Keyword(s):  
Growth Rates ◽  
Slow Growth ◽  
Seasonal Pattern ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Research Division ◽  
Sowing Dates ◽  
Net Assimilation ◽  
State Growth ◽  
Sudan Gezira

Growth analysis of cotton crops sown in the Sudan Gezira at monthly intervals between August and May revealed a marked seasonal pattern of growth. Irrespective of plant age and fruiting state growth of non-senescent plants was slowest during the cool winter months. Relative growth rates of young plants were highest in August, September and early October due to the high specific leaf areas and fairly high net assimilation rates found then. They were lowest when minimum temperatures were lowest. Net assimilation rates were also lowest in the coolest months, probably as a result of restricted growth. High temperatures in the spring reduced fruiting. It is concluded that low minimum temperatures and high evaporation rates are both associated with slow growth, and play a large part in determining the characteristic decline of growth rates of cotton sown at the usual date in August.I wish to thank the Chief of the Research Division, Ministry of Agriculture, Sudan, for permission to publish this paper and to record my gratitude to the team of field and laboratory assistants, especially Salih Saad and Hassan Osman, who helped in the work.

Effects of early drought and transplanting on the subsequent development of the tobacco plant

1968 ◽  
Vol 19 (1) ◽  
pp. 47 ◽  
Author(s):  
JM Hopkinson
Keyword(s):  
Growth Rates ◽  
Tobacco Plant ◽  
Subsequent Development ◽  
Leaf Expansion ◽  
Flower Initiation ◽  
Relative Growth Rates ◽  
Leaf Surfaces ◽  
Number Of Leaves ◽  
Net Assimilation ◽  
Short Time

Detailed studies were made of the growth of tobacco plants during and after the experimental imposition of water stresses similar to those of commercial hardening and transplanting. During water stress (due to root damage, drought, or both) all growth rates were depressed, but, a short time after the relief of stress, relative leaf expansion rates, net assimilation rates, and relative growth rates rose to higher values than were reached by untreated plants at comparable stages of development. As a result, all stressed plants rapidly recovered from their period of adverse conditions. The plants that had originally been subjected to the most severe treatments overhauled those that had suffered less and finally acquired the greatest total leaf areas and dry weights. The increase was due to: (1) a change in the distribution of leaf surfaces, which occurred when leaf initiation was retarded relative to leaf expansion and resulted in increased growth of the lower leaves; (2) a delay in flower initiation, which took place at a higher node, increased the number of leaves, and prolonged the period of vegetative growth.

COMPARISON OF SEEDLING GROWTH OF ROUGH FESCUE AND TALL FESCUE

1969 ◽  
Vol 49 (4) ◽  
pp. 465-470
Author(s):  
D. B. Wilson ◽  
A. Johnston
Keyword(s):  
Tall Fescue ◽  
Growth Rates ◽  
Festuca Arundinacea ◽  
Growth Analysis ◽  
Dry Weight ◽  
Native Grass ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Net Assimilation ◽  
Rough Fescue

Seedlings of a native grass, rough fescue, Festuca scabrella Torr., and of a tame grass, tall fescue, Festuca arundinacea Schreb., were grown in the greenhouse for 10 weeks. Each week 20 plants of each species were destructively harvested for growth analysis. Leaf and tiller numbers and leaf lengths were recorded for an additional 10 plants of each species. Mean net assimilation rates of rough fescue were similar to those of tall fescue, but leaf area ratios were significantly lower. Thus, mean relative growth rates of rough fescue were less than those of tall fescue. Tiller numbers were similar for both species but rough fescue produced fewer leaves. Dry weight of tops of the tame grass produced during the 10-week period was about 17 times that produced by the native grass.

Growth of seedlings of prairie grass and tall fescue in small swards of kikuyu at different temperatures

1985 ◽  
Vol 36 (2) ◽  
pp. 213 ◽  
Author(s):  
MJ Hill ◽  
CJ Pearson ◽  
LC Campbell
Keyword(s):  
Tall Fescue ◽  
Growth Rates ◽  
Festuca Arundinacea ◽  
Perennial Grasses ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Temperature Regimes ◽  
Prairie Grass ◽  
Different Temperatures ◽  
Grass Sward

Seeds of prairie grass (Bromus catharticus Vahl) and tall fescue (Festuca arundinacea Schreb.) were planted in established small swards of kikuyu (Pennisetum clandestinum Hochst ex Chiov.). Growth of the temperate seedlings and the subtropical grass sward was measured over a period of 59 days under four temperature regimes from 14/6 to 23/20�C (12/12 h). The capacity of the seedlings of the oversown temperate perennial grasses to establish in the sward of the subtropical kikuyu depended on temperature. At low temperature (mean daily temperature < 1l�C) the seedlings grew faster than the kikuyu and became successfully established. At moderate temperatures (11-19�C) the relative growth rates of seedlings were comparable with the relative growth rates of kikuyu tillers, but the latter dominated due to a greater absolute growth rate. Stature was an important component in the inter-species competition, and the taller prairie grass grew much better in competition with kikuyu than did fescue. Temperatures above 20�C exceeded the optimum of the seedlings of the temperate species but not that of kikuyu, so that the sown species were at a disadvantage and kikuyu dominated the mixture. It is concluded that prairie grass and tall fescue can be established successfully only in swards of kikuyu when day temperatures are below 21 and 15�C respectively, unless kikuyu is suppressed for a long period. A herbicide may be an economical means of doing this.

Physiological responses of semiarid grasses. III.* Growth in relation to temperature and soil water deficit

1975 ◽  
Vol 26 (3) ◽  
pp. 447 ◽  
Author(s):  
EK Christie
Keyword(s):  
Soil Water ◽  
Growth Rates ◽  
Soil Water Potential ◽  
Dry Weight ◽  
Phosphorus Concentration ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Ample Supply ◽  
Net Assimilation ◽  
Tissue Phosphorus

The optimum temperature for vegetative growth of mulga grass was about 25°C, and for Mitchell and buffel grasses 30°. Buffel grass had the highest yield at all temperatures, partly because of its higher growth rate which in turn can be ascribed to both a higher net assimilation rate and the diversion of a greater proportion of dry weight into leaf area. Seedlings with an ample supply of phosphate had higher relative growth rates than phosphorus-deficient seedlings at the commencement of the soil drying cycle, but their growth rates declined more rapidly as the soil water potential fell. This decline was associated with a reduction in the rate of phosphate absorption as well as a decrease in the tissue phosphorus concentration. *Part II, Aust. J. Agric. Res., 26: 437 (1975).

Germination and seedling growth of prairie grass, tall fescue and Italian ryegrass at different temperatures

1985 ◽  
Vol 36 (1) ◽  
pp. 13 ◽  
Author(s):  
MJ Hill ◽  
CJ Pearson ◽  
AC Kirby
Keyword(s):  
Tall Fescue ◽  
Growth Rates ◽  
Festuca Arundinacea ◽  
Lolium Multiflorum ◽  
Italian Ryegrass ◽  
Relative Growth Rates ◽  
Prairie Grass ◽  
Radicle Emergence ◽  
Different Temperatures ◽  
Field Emergence

We measured the effects of temperature on the germination, emergence and growth during early tillering of Italian ryegrass (Lolium multiflorum), prairie grass (Bromus catharticus) and tall fescue (Festuca arundinacea). Radicle emergence (the percentage of seeds with emerged radicles) and 'field' emergence (the percentage of seeds with shoots > 1 cm long) were reduced at 35�C (constant, all lines), or 30/25�C (12/12 h, prairie grass and Tama Italian ryegrass only). All lines took longer to germinate at 15 and 10�C (constant) than at higher temperatures, and final percentage germination of tall fescue lines was lower at 10�C (constant) than at other temperatures. Italian ryegrass had the fastest shoot extension, and consequently the fastest 'field' emergence. Seed respiration rates were higher in fescue than in the other lines at 4 days from imbibition, and rates rose in all lines at 8 days. Over the first 20 days after sowing, growth rates were closely related (r = 0.87-0.99) to weights of seed and caryopses, when account was taken of perenniality (which was associated with relatively slow growth) and polyploidy (which was associated with growth faster than might be expected from seed size alone), and a multivariate relationship including temperature was developed (R2 = 0.88). Growth rates of shoots at 20 days after sowing were ranked Tama Italian ryegrass > prairie grass > Ucivex Italian ryegrass > tall fescue, and 24/19 > 21/16 > 18/13 > 30/25 > 15/10�C. Growth during tillering, up to 42 days after emergence, was ranked Italian ryegrass > prairie > tall fescue and 21/16 = 18/13 > 24/19 = 15/1O�C. Relative growth rates and relative rates of tillering were independent of temperature in Italian ryegrass, but were lower at 15/10 and 24/19 than at 21/16 and 18/13�C in prairie grass and tall fescue. Prairie grass had higher yield per tiller but lower tiller numbers than Italian ryegrass; tall fescue had both lower yield per tiller and lower tiller number. Italian ryegrass was therefore the species best adapted to variations in environment and competition at sowing.

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