Effect of alternating day/night temperatures and light regimes on seed germination of turnip weed seeds from Gatton (RRG) and St George (RRS) incubated at 15/5, 20/10, 25/15 and 30/20°C light/dark and dark in a 12-h photo-period for 21 days.

<p>Error bars are LSD (p≤0.05, n = 6).</p

Effect of buffered pH solutions on the germination of two populations of turnip weed from St George (RRS) and Gatton (RRG) incubated at 25/15°C day/night temperatures in a 12-h photoperiod for 21 days.

<p>Error bars are LSD (p≤0.05, n = 6).</p

Effect of sodium chloride (NaCl) on the emergence of two populations of turnip weed from St George (RRS) and Gatton (RRG) incubated at 25/15°C day/night temperatures in a 12-h photoperiod for 21 days.

<p>Lines represent the functional three-parameter sigmoid model fitted to the data. Error bars are standard error of mean (n = 6).</p

Germination ecology of turnip weed (<i>Rapistrum rugosum</i> (L.) All.) in the northern regions of Australia

<div><p>In Australia, turnip weed has been rapidly emerging as one of the major weeds in conservation agricultural systems. Germination and emergence of turnip weed were examined for two populations collected from Gatton and St George regions of Australia; two locations with high and low rainfall, respectively. The seeds of turnip weed germinated at all the tested temperatures, but germination was the lowest at 15/5°C, intermediate at 20/10°C and highest at 25/15°C and 30/20°C. The results indicated a high adaptability of turnip weed to warm environmental conditions, although it is a major problem in the winter season. Germination was higher in dark than light/dark regimes except at 30/20°C. Three was a concomitant reduction in germination as the osmotic potential values decreased from 0 to -1.0 MPa. There was 2 and 4% germination at -0.8 MPa for Gatton and St George populations, respectively, and no germination occurred at an osmotic potential of -1.0 MPa. There was a reduction in germination when the sodium chloride (NaCl) concentration was increased from 0 to 150 mM, and no germination was observed at 200 and 250 mM of NaCl. Turnip weed germinated over a broad range of pH (4 to 10). Seedling emergence was higher at 1 cm depth compared to 0.5 cm or at the soil surface. There was 28 and 33% emergence at the surface for the Gatton and St George populations, respectively, compared to 48 and 56% emergence from 1 cm depth for the Gatton and St George populations, respectively and no emergence was observed from 6 cm depth. The results indicated that tillage leading to shallow burial would promote the emergence of turnip weed; on the contrary, tillage that could bury seeds deep into the soil profile might minimise the emergence. Under ideal conditions and lack of integrated weed management programmes, this weed will emerge, set seeds and enrich the soil seed bank and thereby continue to be a problem in the northern grain region of Australia.</p></div

Les manuscrits des écrivains / sous la dir. de Louis Hay

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Effect of environmental factors on the germination and emergence of <i>Salvia verbenaca</i> L. cultivars (<i>verbenaca</i> and <i>vernalis</i>): An invasive species in semi-arid and arid rangeland regions - Fig 1

<p><b>Effect of temperature and photoperiod on germination of <i>S</i>. <i>verbenaca</i> varieties (a) <i>verbenaca</i> and (b) <i>vernalis</i>.</b> Nails on the vertical bars represent standard error of the means.</p

Effect of temperature with photoperiod, osmotic potential, NaCl concentration, pH and seeding depth on germination or emergence parameters of <i>S</i>. <i>verbenaca</i> var. <i>verbenaca</i>.

<p>Effect of temperature with photoperiod, osmotic potential, NaCl concentration, pH and seeding depth on germination or emergence parameters of <i>S</i>. <i>verbenaca</i> var. <i>verbenaca</i>.</p

Effect of temperature with photoperiod, osmotic potential, NaCl concentration, pH and seeding depth on germination or emergence parameters of <i>S</i>. <i>verbenaca</i> var. <i>vernalis</i>.

<p>Effect of temperature with photoperiod, osmotic potential, NaCl concentration, pH and seeding depth on germination or emergence parameters of <i>S</i>. <i>verbenaca</i> var. <i>vernalis</i>.</p

Effect of environmental factors on the germination and emergence of <i>Salvia verbenaca</i> L. cultivars (<i>verbenaca</i> and <i>vernalis</i>): An invasive species in semi-arid and arid rangeland regions - Fig 3

<p><b>Effect of NaCl concentration on seed germination of <i>S</i>. <i>verbenaca</i> varieties (a) <i>verbenaca</i> and (b) <i>vernalis</i>.</b> Bold line represents a three-parameter logistic model fitted to the data. Vertical dash line represents X-axis value at 50% of the maximum germination. Vertical bars represent ± standard error of the mean.</p

Effect of environmental factors on the germination and emergence of <i>Salvia verbenaca</i> L. cultivars (<i>verbenaca</i> and <i>vernalis</i>): An invasive species in semi-arid and arid rangeland regions

<div><p><i>Salvia verbenaca</i> (wild sage) is a commonly cultivated herbal medicine plant, which is native to the Mediterranean climate regions of Europe, Africa, Asia and the Middle East. However, it has become an invasive species in semi-arid and arid regions of southern Australia. Two varieties are present in this region, var. <i>verbenaca</i> and var. <i>vernalis</i>, each of which can be distinguished by differences in morphology and flowering period. Following trials to determine the optimum temperate regime for germination and response to light and dark, seeds of both varieties were tested for their response to variations in pH, moisture stress, salinity, and burial depth. The temperature and light trial was carried out using three different temperature regimes; 30/20°C, 25/15°C and 20/12°C, and two light regimes; 12 hours light/12 hours dark and 24 hours dark, with var. <i>vernalis</i> responding to relatively higher temperatures than var. <i>verbenaca</i>. The germination rate of neither species was significantly inhibited by complete darkness when compared to rates under periodic light exposure. Both varieties germinated at near optimum rates strongly to very strongly in all pH buffer solutions, from pH 5 to pH 10, but they responded most strongly at neutral pH. Var. <i>vernalis</i> showed slightly more tolerance to reduced moisture availability, moderate to strong salinity, and burial depth, compared to var. <i>verbenaca</i>. However, even a fairly shallow burial depth of 2 cm completely inhibited germination of both varieties. Thus, in circumstances where both varieties are present in a soil seedbank, var. <i>vernalis</i> could be expected to establish in more challenging conditions, where moisture is limited and salinity is ‘moderate to high’, implying that it is a more serious threat for invasive weed in conditions where crop plants are already challenged.</p></div