The early vegetative growth of two annual pasture grasses (Hordeum leporinum Link and Lolium rigidum Gaud.)

1973 ◽  
Vol 24 (1) ◽  
pp. 11 ◽  
Author(s):  
PS Cocks ◽  
CM Donald
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Vegetative Growth ◽  
Root Weight ◽  
Lolium Rigidum ◽  
Pasture Production ◽  
Relative Growth ◽  
Pasture Grasses ◽  
Seedling Growth Rate ◽  
Hordeum Leporinum

The early vegetative growth of Houdeum Iepouinum and Lolium rigidum was studied at three temperatures in a controlled environment cabinet. The seedling growth rate in each species was much more rapid during the period of endosperm availability than after cndospcrm exhaustion. At the temperatures tested (10, 17, and 24�C) the relative growth rate of Lolium was greater than that of Houdeum, with a relatively slight difference at 10 and 24�, but with a considerable difference at 17�. In spite of the superior relative growth rate of Lolium, seedlings of Houdeum were, for a considerable period following emergence, larger in terms of total weight, leaf area, root weight, root depth, and plant height because of the greater seed size. The length of this period of greater size depended on the temperature, being least (c. 26 days) at 17�C, when the advantage of Lolium was greatest. The implications of these findings in pasture production in southern Australia, and especially in the competitive relationships of Hordeum and Lolium, are described.

Transpiration, Intracellular Carbon Dioxide Concentration and Carbon-Isotope Discrimination of 24 Wild Species Differing in Relative Growth Rate

1994 ◽  
Vol 21 (4) ◽  
pp. 507 ◽  
Author(s):  
H Poorter ◽  
GD Farquhar
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Carbon Isotope Discrimination ◽  
Growth Parameters ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Root Weight ◽  
Relative Growth ◽  
Unit Leaf ◽  
Intercellular Co2

Various aspects of the water economy were investigated for a range of herbaceous species varying in relative growth rate. Plants were grown in a growth chamber with a non-limiting supply of water and nutrients, and the rate of transpiration, short-term intercellular CO2 concentration and long-term carbon isotope discrimination (Δ) in the leaves were determined. No correlation was found between the relative growth rate of these species, and the transpiration rate per unit leaf area, the intercellular CO2 concentration and the 13C-discrimination. There was a positive correlation, however, with the rate of water uptake per unit root weight. From these observations we infer that the previously observed differences in photosynthetic nitrogen-use efficiency, the rate of photosynthesis per unit leaf nitrogen, can not be explained by variation in intercellular CO2 concentration. These data were also used to analyse correlations between Δ and both growth parameters and chemical composition. Apart from parameters related to the water economy, Δ only correlated (positively) with the fractional biomass allocation to the roots (root weight ratio) and the specific root length (root length divided by root weight), and not with any other investigated growth parameters.

scholarly journals Seed mass effects on germination and growth of diverse European Scots pine populations

1994 ◽  
Vol 24 (2) ◽  
pp. 306-320 ◽  
Author(s):  
P.B. Reich ◽  
J. Oleksyn ◽  
M.G. Tjoelker
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Scots Pine ◽  
Field Experiments ◽  
Seed Mass ◽  
Growing Season ◽  
Turkish Population ◽  
Dry Mass ◽  
Relative Growth ◽  
Mass Effects

Seedlings of 24 European Scots pine (Pinussylvestris L.) populations were grown in controlled environment chambers under simulated photoperiodic conditions of 50 and 60°N latitude to evaluate the effect of seed mass on germination and seedling growth characteristics. Seeds of each population were classified into 1-mg mass classes, and the four classes per population with the highest frequencies were used. Photoperiod had minimal influence on seed mass effects. Overall, seed mass was positively related to the number of cotyledons and hypocotyl height. Populations differed significantly in seed mass effect on biomass. In northern populations (55–61°N), dry mass at the end of the first growing season was little affected by seed mass. However, dry mass in 9 of 15 central populations (54–48°N) and all southern (<45°N) populations correlated positively with seed mass. Relative growth rate was not related to seed mass within or across populations, and thus early growth is largely determined by seed mass. Relative growth rate also did not differ among populations, except for a geographically isolated Turkish population with the highest seed mass and lowest relative growth rate. After one growing season, height was positively correlated (r2 > 0.6) with seed mass in 15 populations. To check the duration of seed mass effects, height growth of 1- to 7-year-old field experiments established with the same seed lots were compared. Seed mass effects on height were strongest for 1-year-old seedlings and declined or disappeared by the age of 5–7 years among central and southern populations, but remained stable over that time in northern populations.

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