Summer dormancy in Dactylis glomerata L.: the influence of season of sowing and a simulated mid-summer storm on two contrasting cultivars

A series of trials to increase understanding of the summer dormancy trait in Dactylis glomerata was conducted. Autumn-sown reproductive and younger, spring-sown plants of 2 drought-resistant cultivars, contrasting for summer dormancy, were established and then tested in summer 2002 under long drought, drought + mid-summer storm, or full irrigation. The autumn-sown reproductive plants of cv. Kasbah were summer dormant under all moisture regimes and exhibited the characteristic traits including growth cessation, rapid herbage senescence, and dehydration of surviving organs (–6.7 MPa). Cultivar Kasbah used 8% less soil water over the summer and also began to rehydrate its leaf bases from conserved soil water before the drought broke. The non-dormant cv. Medly grew for 10 days longer under drought and whenever moisture was applied; Medly also responded to the storm with a decline in dehydrin expression in leaf bases, whereas no decline occurred in Kasbah, presumably because it remained dormant and therefore much drier. The irrigated, younger, spring-sown swards of cv. Kasbah had restrained growth and produced only about 25% of the herbage of cv. Medly. Drought reduced activity and growth of young plants of both cultivars, but whereas Medly regrew in response to the storm, cv. Kasbah did not, indicating that dormancy, although only partially expressed after spring sowing, was reinforced by summer drought. A longer drought in 2003 caused a 22% loss of the basal cover in cv. Medly, whereas Kasbah fully maintained its sward and therefore produced a higher post-drought autumn yield. This work confirms summer dormancy as a powerful trait for improving persistence over long, dry summers.

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Summer drought survival and recovery in Microlaena stipoides

The Rangeland Journal ◽

10.1071/rj16005 ◽

2016 ◽

Vol 38 (5) ◽

pp. 501 ◽

Cited By ~ 2

Author(s):

M. L. Mitchell ◽

J. M. Virgona ◽

J. L. Jacobs ◽

D. R. Kemp

Keyword(s):

Soil Water ◽

Moisture Stress ◽

Pot Experiment ◽

Summer Drought ◽

Water Deficits ◽

North East ◽

Eastern Australia ◽

Summer Dormancy ◽

Microlaena Stipoides ◽

Summer Storm

Microlaena stipoides (microlaena) is an important perennial grass in over 7 million hectares of native pastures in southern Australia and can survive and persist despite severe soil water deficits during summer. Many other pasture species survive similar conditions by relying on summer dormancy, which raises the possibility that microlaena may behave similarly. A field experiment using rainout shelters was conducted on an existing microlaena pasture in north-east Victoria. The experiment was a split-plot design with two watering treatments (‘summer storm’ or ‘summer dry’) as main plots and three defoliation treatments (nil, intense defoliation, strategic defoliation) as subplots. The ‘summer storm’ treatment resulted in the formation of new buds and tillers and increased basal cover from 1% in February to 18% in March. A glasshouse pot experiment examined the recovery of microlaena after different periods of drought and subsequent rewatering. In the pot experiment, microlaena withstood relatively short (up to 30 days) dry periods and then recovered when rewatered. Thus, it appears that microlaena is a persistent, perennial pasture plant that, although it survives very dry summers in Mediterranean areas, is not summer dormant. Microlaena does not exhibit summer dormancy in response to moisture stress and enter a quiescent stage, because normal growth is prevented by the lack of water, but it quickly recommences growth when soil water becomes available. The ability of microlaena to withstand summer soil water deficits and to recruit from seedlings make it a valuable pasture species across drought-prone environments, and this undoubtedly partly explains its very broad adaptation across eastern Australia.

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Evaluation of populations of Dactylis glomerata L. native to Mediterranean environments

Crop and Pasture Science ◽

10.1071/cp12276 ◽

2012 ◽

Vol 63 (12) ◽

pp. 1124 ◽

Cited By ~ 6

Author(s):

V. Copani ◽

G. Testa ◽

A. Lombardo ◽

S. L. Cosentino

Keyword(s):

Genetic Diversity ◽

Biomass Yield ◽

Agronomic Traits ◽

Dactylis Glomerata ◽

Leaf Length ◽

Mediterranean Environment ◽

Summer Dormancy ◽

Low Levels ◽

Dactylis Glomerata L ◽

Different Levels

Several morphological and agronomic traits and the genetic diversity of nine Dactylis glomerata L. populations collected throughout Sicily (semi-arid Mediterranean environment) were evaluated for two successive years. Significant differences were recorded for morphological traits (plant height, leaf length, leaf width). In relation to the measurement of summer dormancy, the results suggest the expression of different levels of dormancy (completely dormant, semi-dormant, and non-dormant). For biomass yield, some Sicilian populations (SD63 and SD56) characterised by low levels of summer dormancy show production levels similar to the summer-active control varieties (Medly and Porto). However, SD46, with a much higher level of dormancy, gave biomass yield higher than the summer-dormant control variety (Kasbah). The genetic diversity evaluated by fAFLP analysis confirms the observed morphological and agronomic variability.

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Summer dormancy in Festuca arundinacea Schreb.; the influence of season of sowing and a simulated mid-summer storm on two contrasting cultivars

Australian Journal of Agricultural Research ◽

10.1071/ar06082 ◽

2006 ◽

Vol 57 (12) ◽

pp. 1267 ◽

Cited By ~ 72

Author(s):

M. R. Norton ◽

F. Volaire ◽

F. Lelièvre

Keyword(s):

Festuca Arundinacea ◽

Water Status ◽

Severe Drought ◽

Summer Drought ◽

Full Irrigation ◽

Leaf Elongation ◽

Aerial Growth ◽

Summer Dormancy ◽

Summer Storm ◽

Moisture Conditions

Due to the shortage of information on summer dormancy in tall fescue (Festuca arundinacea, syn. Lolium arundinaceum), we tested the response of 2 cultivars of differing dormancy expression and growth stage to a range of summer moisture conditions, including full irrigation, drought, and a simulated mid-summer storm and analysed whether traits associated with summer dormancy conferred better survival under severe field drought. Autumn-sown reproductive and younger, spring-sown plants of 2 cultivars, claimed to exhibit contrasting summer dormancy, were established and then tested in summer 2002 under either long drought, drought + simulated mid-summer storm, or full irrigation. The autumn-sown reproductive plants of cv. Flecha exhibited traits that can be associated with partial summer dormancy since under summer irrigation they reduced aerial growth significantly and exhibited earlier herbage senescence. Moreover, cv. Flecha used 35% less soil water over the first summer. However, the water status of leaf bases of young vegetative tillers of both cultivars was similar under irrigation and also throughout most of the drought (leaf potential and water content maintained over –4 MPa and at approx. 1 g H2O/g DM, respectively). The summer-active cv. Demeter did not stop leaf elongation even in drought and produced twice as much biomass as Flecha under irrigation. Cultivar Demeter responded to the simulated storm with a decline in dehydrin expression in leaf bases, whereas no decline occurred in Flecha, presumably because it remained partially dormant. The younger, spring-sown swards of both cultivars had similar biomass production under summer irrigation but whereas Demeter regrew in response to the simulated storm, cv. Flecha did not, indicating that dormancy, although only partially expressed, was reinforced by summer drought. In all trials, cv. Flecha out-yielded Demeter in autumn regrowth. In particular, the severe drought in 2003 caused a 25% loss of the basal cover in cv. Demeter, whereas Flecha fully maintained its sward allowing it to produce a higher post-drought autumn yield. This work links summer dormancy with higher persistence over long, dry summers.

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