Summer drought survival and recovery in Microlaena stipoides

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

Australian Journal of Agricultural Research ◽

10.1071/ar05237 ◽

2006 ◽

Vol 57 (5) ◽

pp. 565 ◽

Cited By ~ 53

Author(s):

M. R. Norton ◽

F. Lelièvre ◽

F. Volaire

Keyword(s):

Soil Water ◽

Dactylis Glomerata ◽

Summer Drought ◽

Basal Cover ◽

Moisture Regimes ◽

Summer Dormancy ◽

Summer Storm ◽

Dactylis Glomerata L ◽

Reduced Activity ◽

Spring Sowing

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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Persistence and productivity of phalaris (Phalaris aquatica) germplasm in dry marginal rainfall environments of south-eastern Australia

Crop and Pasture Science ◽

10.1071/cp17203 ◽

2017 ◽

Vol 68 (8) ◽

pp. 781

Author(s):

R. A. Culvenor ◽

M. R. Norton ◽

J. De Faveri

Keyword(s):

Environmental Benefits ◽

Annual Rainfall ◽

Summer Drought ◽

Environment Interaction ◽

Phalaris Aquatica ◽

Mixed Farming ◽

Eastern Australia ◽

Summer Dormancy ◽

Average Annual Rainfall ◽

Establishment Phase

Perennial grasses have production and environmental benefits in areas of southern Australia typified by the mixed farming zone of southern New South Wales (NSW). The perennial grass phalaris (Phalaris aquatica L.) is widely used in southern Australia; however, it would find more use in the mixed farming zone if its persistence in marginal rainfall areas (450–500 mm average annual rainfall) were improved. We evaluated a range of germplasm (n = 29) including wild accessions, lines bred from these, and existing cultivars for persistence and production at three sites in a summer-dry area of southern NSW with 430–460-mm average annual rainfall. Two sites were used over 4 years and the third site over 5 years. Summer dormancy, maturity time and seedling growth were also assessed. Analysis of genotype × environment interaction employing factor analytic models and accounting for spatial and temporal correlations indicated that changes in persistence occurred mainly over time rather than between sites. Ranking changes occurred in the dry establishment phase of the experiment and during a severe final summer drought, with few changes occurring in the intervening high-rainfall years. Lines that survived the establishment phase best had vigorous seedlings and earlier maturity, whereas those surviving the final summer best were earlier maturing and higher in summer dormancy with high winter-growth activity. Some later maturing lines within the higher summer dormancy group were less persistent. Some accessions from North Africa were the most persistent; also, populations bred from these and other more persistent accessions generally persisted and produced better than cultivars used presently. However, present cultivars were capable of high yield in the higher rainfall years. We suggest that persistence of higher summer dormancy cultivars over very dry years could be improved by selecting for earlier maturity time.

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Rooting depth and plant water relations explain species distribution patterns within a sandplain landscape

Functional Plant Biology ◽

10.1071/fp03200 ◽

2004 ◽

Vol 31 (5) ◽

pp. 423 ◽

Cited By ~ 43

Author(s):

Philip K. Groom

Keyword(s):

Soil Moisture ◽

Soil Water ◽

Water Loss ◽

Rooting Depth ◽

Summer Drought ◽

Tissue Water ◽

Shrub Species ◽

Water Deficits ◽

Groundwater Levels ◽

Water Potentials

Tree and shrub species of the Banksia woodlands on the sandplains of northern Swan Coastal Plain, Western Australia possess a range of strategies to avoid or tolerate soil water deficits during the annual summer drought. Shallow-rooted shrub species (< 1 m rooting depth) inhabit a range of locations in the landscape, from top of dune crests to wetland embankments. These are the most drought-tolerant of all sandplain species, surviving extremely low summer soil water potentials (< –7 MPa) and tissue water deficits by significantly reducing their transpirational water loss (< 0.2 mmol m–2 s–1). This is in contrast to the few shallow-rooted species restricted to low-lying or seasonally waterlogged areas which are reliant on subsurface soil moisture or groundwater to maintain their relatively high summer water use. Recent studies of water source usage of selected Banksia tree species have shown that these deep-rooted species access groundwater up to a maximum depth of 9 m depth during the summer months, or soil moisture at depth when groundwater was greater than maximum rooting depths, depending on the species. Medium- and deep-rooted (1–2 m and > 2 m, respectively) shrub species cope with the summer soil drying phase and related decrease in groundwater levels by conserving leaf water loss and incurring predawn water potentials between –1 and –4 MPa, enabling them to occur over a range of topographic positions within the sandplain landscape.

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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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Water content of a red-brown earth subjected to a range of agronomic vegetation options in south-eastern Australia

Australian Journal of Agricultural Research ◽

10.1071/ar99169 ◽

2001 ◽

Vol 52 (5) ◽

pp. 587 ◽

Cited By ~ 6

Author(s):

D. M. Whitfield

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Deficit ◽

Soil Water Deficit ◽

Water Deficits ◽

South Eastern ◽

Eastern Australia ◽

Ground Water Recharge ◽

South Eastern Australia

The management of ground water recharge in south-eastern Australia relies on the formulation of agricultural practices that utilise rainfall before it moves below the root-zone. Annual cycles of soil water content were therefore measured in a red-brown earth subjected to 5 fallow-free crop sequences, to 2 crop sequences that included fallow, and to 3 pastures. Changes in soil water content induced by wheat, barley, lupin, pea, safflower, canola, and fallow were compared with those of annual pasture and 2 monocultures of the deep-rooted perennials phalaris and lucerne in 3 years of study. Mean minimum soil water content (0–1.6 m) seen in December and May was approximately 355 mm in lucerne and phalaris, 410 mm in annuals (crops and pasture), and 475 mm in fallow. Corresponding soil water deficits appropriate to lucerne, annuals, and fallow were 185, 135, and 65 mm, respectively. Lucerne and annuals both removed approximately 85 mm water from the upper 0.6 m of the soil profile. Differences arose in the subsoil below 0.6 m, where lucerne, annuals, and fallow produced soil water deficits of approximately 100, 50, and 25 mm, respectively. The difference in soil water deficit of deep-rooted perennials and annuals was therefore caused by the extra 50 mm of water extracted by lucerne and phalaris below 0.6 m in the period September–December. The dry subsoil endured through summer to promote the storage, by soil, of rainfall in winter. The data suggest that the spatial utility of an agronomic recharge control option in south-eastern Australia depends on the magnitude of the soil water deficit associated with the vegetation. The soil water deficit, relative to winter (May–August) rainfall, discriminates between areas where annuals suffice for recharge control, where lucerne and phalaris are required for recharge control, and where agronomic annuals and perennials are both conducive to high rates of drainage.

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The nature of the perennial response in Mediterranean grasses. II. Senescence, summer dormancy, and survival in Phalaris

Australian Journal of Agricultural Research ◽

10.1071/ar9680397 ◽

1968 ◽

Vol 19 (3) ◽

pp. 397 ◽

Cited By ~ 35

Author(s):

JR McWilliam

Keyword(s):

Carbon Assimilation ◽

Moisture Stress ◽

Grass Species ◽

Summer Drought ◽

Summer Dormancy ◽

Summer Stress ◽

The Difference ◽

Major Factors ◽

And Function ◽

Lower Stem

Adaptation to summer drought has been one of the major factors influencing the life cycle of the Mediterranean grasses. The nature of this adaptation has been studied by comparing the behaviour of a typical perennial, Phalaris tuberosa, with a closely related annual species P. minor, under simulated summer drought conditions. One of the most important factors controlling the plant survival of these two species is the difference in the rate and pattern of senescence after flowering under the influence of moisture stress. In the annual, senescence is rapid and complete, but in the perennial it is retarded, and function is retained in certain organs, including the lower stem and root system, throughout the summer stress. This permits survival of dormant buds which contain the meristems vital for regrowth in the autumn. Another feature which may be important in the perennial is the limited carbon assimilation by the dormant culms during the summer which contributes a source of energy for the maintenance of root activity, and for the regeneration of dormant buds. The evidence suggests that these factors may be of general significance, and could well form the basis of the perennial response in other Mediterranean grass species.

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MODELLING THE INFLUENCE OF IRRIGATION ON THE POTENTIAL YIELD OF TEA (CAMELLIA SINENSIS) IN NORTH-EAST INDIA

Experimental Agriculture ◽

10.1017/s0014479702001151 ◽

2003 ◽

Vol 39 (2) ◽

pp. 181-198 ◽

Cited By ~ 9

Author(s):

R. K. PANDA ◽

W. STEPHENS ◽

R. MATTHEWS

Keyword(s):

Soil Water ◽

Yield Response ◽

Potential Yield ◽

Water Deficits ◽

Water Capacity ◽

North East India ◽

Available Water ◽

North East ◽

Daily Weather Data ◽

Available Water Capacity

This study reports the results of model simulations of the potential yield of tea in north-east India. The CUPPA-Tea model, developed using data from a high-altitude site close to the equator in East Africa, was validated against the yield data from irrigation experiments conducted on contrasting soil types at Siliguri and Tezpur in the tea growing region of north-east India. The close correspondence between observed and predicted yield and yield distribution suggests that the model is applicable in north-east India. The model was used to simulate the yield response of tea to drought and irrigation using daily weather data for seven years (1983–89) at Siliguri and 14 years (1974–85) at Tezpur. On a clay loam soil at Siliguri, with an available water capacity of about 200 mm m−1, the predicted mean reduction in yield was 1.5 kg ha−1 for each 1 mm reduction in evapotranspiration. However, there appeared to be no reduction in evapotranspiration until the soil water deficit reached about 240 mm. By contrast, at Tezpur on loamy sand, with an available water capacity of about 100 mm m−1, evapotranspiration was reduced once soil water deficits exceeded about 85 mm. There was then a mean reduction in yield of 2.2 kg ha−1 for each 1 mm reduction in evapotranspiration. At both sites, even when soil water deficits were not limiting, the predicted year-to-year variation in yields was about 500 kg ha−1. The results highlight the soil-related differences in response to irrigation and the benefits of using process-based simulation models to investigate the potential yields over long periods.

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Environmental and agronomic constraints in dryland pasture and choice of species

NZGA: Research and Practice Series ◽

10.33584/rps.3.1985.3316 ◽

1985 ◽

Vol 3 ◽

pp. 39-43

Author(s):

J.H. Hoglund ◽

J.G.H. White

Keyword(s):

Soil Water ◽

Slow Growth ◽

Moisture Stress ◽

Summer Drought ◽

Hill Country ◽

The North ◽

Winter Temperatures ◽

Choice Of Species ◽

Wilting Point

Hawkes Bay in the north down to North Otago, the duration and intensity of summer drought is unpredictab!e and variable. Within this region, winter temperatures are generally high enough to allow slow growth of pasture but summer drought can completely halt growth in most years, particularly on the commonly found shallow free draining soils. On these soils, moisture stress can develop very quickly because of the limited available soil water. Nearer the foothills, rainfall is greater and severe moisture stress less common. On sunny aspects in hill country however soils are commonly below wilting point for over six months of the year.

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