Assessment of the potential of a range of microhabitats for use as seed production areas in moderately degraded rangelands in semiarid Australia

2017 ◽  
Vol 39 (1) ◽  
pp. 49
Author(s):  
Judith M. Bean ◽  
Gavin J. Melville ◽  
Ronald B. Hacker

Previous studies in mulga country with hard-setting red earth soils in north-west New South Wales, Australia, have demonstrated that small fenced seed production areas on local high points can contribute to regeneration of native perennial vegetation, and increases in the soil seedbank, on surrounding slopes. In this study the potential of seven microhabitats in this environment, each replicated twice, for use as seed production areas was assessed indirectly by a study of their functional characteristics and vegetation dynamics. Indices of landscape function (stability, infiltration and nutrient cycling) were determined for each of the 14 sites at the time of fencing and at the end of the study, over 2 years later, by determining the extent and surface characteristics of 53 surface types (in total) along three parallel transects within each site. Variation in establishment and survival of ground storey species among surface types was examined by co-ordination of all plants within belts centred on the line transects. At the start of the study landscape function indices for the ‘rocky ridge with rock outcrop’ microhabitat were not significantly higher than all, or some, other microhabitats. By the end of the study two of the three indices for this microhabitat were significantly higher than for all other microhabitats. This microhabitat also favoured the establishment and survival of the pastorally preferred species Monachather paradoxus Steud and Thyridolepis mitchelliana (Nees) S.T. Blake but did not favour establishment and survival of the pastorally unpreferred species Aristida jerichoensis (Domin) Henrad and Austrostipa variabilis (Hughes) S.W.L. Jacobs and J. Everett. This microhabitat was characterised by extensive areas of ‘water catchment’ surface types associated with in-situ rock outcrop, which facilitated the observed vegetation dynamics. This ‘rocky ridge with rock outcrop’ microhabitat occurs on local high points in the landscape and is readily recognised. It is therefore ideally suited for use as fenced seed production areas to assist rangeland regeneration.

2016 ◽  
Vol 38 (1) ◽  
pp. 47
Author(s):  
Judith M. Bean ◽  
Gavin J. Melville ◽  
Ronald B. Hacker ◽  
Sharon Anderson ◽  
Alicia Whittington ◽  
...  

Seed production areas containing populations of native grasses were fenced on topographically high areas at two study sites in the semiarid rangelands of north-west New South Wales, Australia. The surrounding slopes were initially almost bare of pastorally preferred grasses. Three restoration treatments (control, mechanical pitting, and contour-aligned branch piles) were established on these surrounding slopes and the size and composition of the native grass seedbanks determined. A positive influence of the seed production areas mostly occurred within 15 m of the fence and was probably insignificant beyond 33 m at both sites. On a hard-setting red earth site, the size of the native grass seedbank in all three treatments increased over 2 years with the greatest increase under the piles of branches and smaller increases in the pitting and control treatments. The piles of branches preferentially incorporated seed of the pastorally preferred species Monachather paradoxus Steud into the seedbank whereas pits preferentially incorporated seed of the pastorally unpreferred species Aristida jerichoensis (Domin) Henrad. Evidence generally pointed to incoming seed rain rather than the seedbank as the main source of new seedlings. On a medium-textured lithosol site neither the pits nor the branches treatment was effective in enhancing either the size or composition of the seedbank; in fact the piles of branches resulted in a decrease in its size.


1996 ◽  
Vol 36 (3) ◽  
pp. 299 ◽  
Author(s):  
TS Andrews ◽  
RDB Whalley ◽  
CE Jones

Inputs and losses from Giant Parramatta grass [GPG, Sporobolus indicus (L.) R. Br. var. major (Buse) Baaijens] soil seed banks were quantified on the North Coast of New South Wales. Monthly potential seed production and actual seed fall was estimated at Valla during 1991-92. Total potential production was >668 000 seeds/m2 for the season, while seed fall was >146000 seeds/m2. Seed fall >10000 seeds/m2.month was recorded from January until May, with further seed falls recorded in June and July. The impact of seed production on seed banks was assessed by estimating seed banks in the seed production quadrats before and after seed fall. Seed banks in 4 of the 6 sites decreased in year 2, although seed numbers at 1 damp site increased markedly. Defoliation from mid-December until February, April or June prevented seed production, reducing seed banks by 34% over 7 months. Seed banks in undefoliated plots increased by 3300 seeds/m2, although seed fall was estimated at >114 000 seeds/m2. Emergence of GPG seedlings from artificially established and naturally occurring, persistent seed banks was recorded for 3 years from bare and vegetated treatment plots. Sown seeds showed high levels of innate dormancy and only 4% of seeds emerged when sown immediately after collection. Longer storage of seeds after collection resulted in more seedlings emerging. Estimates of persistent seed banks ranged from 1650 to about 21260 seeds/m2. Most seedlings emerged in spring or autumn and this was correlated with rainfall but not with ambient temperatures. Rates of seed bank decline in both bare and vegetated treatment plots was estimated by fitting exponential decay curves to seed bank estimates. Assuming no further seed inputs, it was estimated that it would take about 3 and 5 years, respectively, for seed banks to decline to 150 seeds/m2 in bare and vegetated treatments.


2021 ◽  
Vol 494 ◽  
pp. 119333
Author(s):  
Magda Paula dos Santos ◽  
Marcio José de Araujo ◽  
Paulo Henrique Müller da Silva

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 25-32
Author(s):  
P.S. Shindrova

SUMMARY Downy mildew caused by the fungus Plasmopara halstedii is the main disease on sunflower in Bulgaria. In recent years a number of authors have reported the occurrence of new more virulent races of the pathogen. According to other authors these races demonstrate resistance to the fungicides used up to now. This fact is rather alarming and imposes the necessity of annual researches with the aim of following the changes in the downy mildew race variability. In the period 1995-1997 downy mildew isolates were collected from the following locations: Bourgas, Boyanovo, Karnobat, Ognyanovo, Selanovtsi, Kroushari, Lovech, Koubrat, Brashlyan, Sitovo, Tervel, Targovishte, IWS “Dobroudja” and Dobrich. The samples were assessed for virulence on a set of sunflower differential - lines under greenhouse conditions. The obtained results do not reveal a great race variability of downy mildew population in Bulgaria. In the period of study two races of the pathogen were identified: race 1 which infects the differential lines without genes for resistance to the pathogen. It is distributed in all sunflower production areas of the country. The other one is race 2. It is of limited distribution and has been registered in individual fields of north-east and north-west Bulgaria. It attacks the differential lines carrying the resistance gene Pl-1.


1981 ◽  
Vol 21 (109) ◽  
pp. 236 ◽  
Author(s):  
IA Rose ◽  
WL Felton ◽  
LW Banks

The soybean varieties Lee, Forrest, Bragg and Dodds were studied in zinc fertilization experiments at three sites in central and north-west New South Wales. At each site foliar sprays of ZnSO47H2O were applied before flowering. At Narrabri one spray of 4 kg ha-1 gave a yield increase of 13%. At Trangie and Breeza, two sprays each of 4 kg ha-1 increased yield by 57% and 208%, respectively. Lee was the least responsive variety at each site and Dodds or Forrest the most responsive to applied zinc. Zinc fertilizer increased plant height, foliar zinc concentration, oil content (at two sites) but decreased leaf phosphorus content. Leaf concentrations of phosphorus in untreated plots were indicative of varietal sensitivity to zinc deficiency both within and between sites. The yield increases at Narrabri were obtained even though no visual symptoms were observed. Improvement of soybean yields with zinc fertilizer in seemingly healthy crops is worthy of further investigation.


1993 ◽  
Vol 33 (3) ◽  
pp. 299 ◽  
Author(s):  
GM Lodge

Plots sown in 1983 were used to examine the seed production and reserves (residual hardseeds) of 15 annual legumes over 5 years at Tamworth in northern New South Wales. Seed production characteristics were measured in 1983 for these annuals, and for 6 perennial legumes. After the annuals had set seed in 1983, an area of the plots was sprayed to prevent flowering in subsequent years, and the rates of decline in seed reserves were compared with those from areas that seeded annually. Seed yields of the perennials were often significantly lower than those of the annuals except Trifolium glomeratum. Seed yields of T. subterraneum var. subterraneum cvv. Seaton Park and Woogenellup were significantly higher than those of cv. Nungarin and T. subterrarzeum var. brachycalycinum cv. Clare. Seed numbers were lowest for Medicago scutellata cv. Sava among the annual medics, and for Nungarin among subterranean clovers. There was little relationship between the mean number of seeds produced from 1983-86 and maturity grading, and between seed numbers and relative dry matter yield. Seed reserves decreased over 5 years by more than 90% in the sprayed treatments of all species. This decrease was not continuous, with the largest declines occurring from December 1983 to August 1984. In the sprayed treatments of Seaton Park, Woogenellup, and Clare, and in both treatments of Astragalus hamosus cv. Ioman, Vicia dasycarpa var. villosa cv. Namoi, and T. hirtum cv. Hykon, none of the original 1983 seed was recovered in 1987. For the annual medics and Nungarin, the number of residual hardseeds in the sprayed treatments in 1987 was about 3-5% of the seed produced in 1983. From 1983 to 1987, seed numbers in the unsprayed treatments declined by 7040% for the annual medics and by 85-95% for Seaton Park, Woogenellup, and Clare. Long-term persistence of annual medics and Nungarin depended on seed production in most years and the maintenance of a high number of residual hardseeds in the soil. In contrast, the mid- and late-maturing subterranean clovers Woogenellup and Clare had low seed reserves and were dependent on seed production in most years for their continued regeneration.


1851 ◽  
Vol 2 ◽  
pp. 239-240
Author(s):  
Thomas Anderson

About thirty years ago a species of manna, obtained from the Eucalyptus Mannifera, was brought from New South Wales, and was examined by Dr Thomas Thomson, and afterwards by Professor Johnston, both of whom ascertained it to contain a new species of sugar, different from the mannite which exists in ordinary manna. The author had, through the kindness of Mr Sheriff Cay, an opportunity of examining a very different species of manna, remarkable both from its chemical constitution, and from its possessing a definitely organised structure. This substance was discovered by Mr Robert Cay in 1844, in the interior of Australia Felix, to the north and north-west of Melbourne, where it occurs at certain seasons on the leaves of the Mallee plant, Eucalyptus Dumosa, and is known to the natives by the name of Lerp.


Archaeologia ◽  
1838 ◽  
Vol 27 ◽  
pp. 96-108
Author(s):  
Henry Brandreth

Having, at various times, amused myself with tracing the Roman roads Watling street and Ikening street, more especially as connected with the station Magiovintum, perhaps the result of some of my personal observations relative thereto, may add something, however little, to the stock of antiquarian knowledge in reference to Britannia Romana. The roads, to which I have alluded, are too well known to warrant my offering any lengthened remarks. They are considered to have been British trackways many centuries before the island was traversed by Roman roads, and that while the latter run from Venta Icenorum, Caister near Norwich, to Durnovaria, Dorchester in Dorsetshire; the former, commencing at Rutupium, Richborough in Kent, proceeded north-west to Mona, Anglesea, in North Wales. Both these roads had many vicinal branches, of which I will only name four of the Ikening. One seems to have branched off westward to Venta Silurum, Caerwent, in South Wales; another southward to Venta Belgarum, Winchester; a third, I suspect, run along to Camulodunum, Maldon, in Essex; whilst another took a northerly direction to Durobrivae, now Dorenford or Dornford, in Huntingdonshire.


Plant Disease ◽  
2014 ◽  
Vol 98 (3) ◽  
pp. 421-421 ◽  
Author(s):  
L. Ménard ◽  
P. E. Brandeis ◽  
P. Simoneau ◽  
P. Poupard ◽  
I. Sérandat ◽  
...  

In 2011, carrot (Daucus carota L.) seed production occurred on 2,900 ha, which accounts for approximately 25% of the area devoted to the production of vegetable fine seeds. Since 2007, symptoms of umbel browning have been regularly observed in carrot production areas located in the central region. Initially, triangular necrotic lesions appeared on carrot umbels that later spread to the entire umbels and often progressed to the stems. Diseased umbels became dried prematurely, compromising seed development. The loss in seed production was estimated at approximately 8% of the harvested carrot umbels during the cropping seasons of spring and summer 2007 and 2008 in France. In collaboration with seed companies, diseased carrot stems were collected from seven fields of seed production (eight plants per field) and a fungus was isolated from the tissue. The cultures were grown on malt (2%) agar (1.5%) medium and incubated for 2 weeks at 22°C in darkness. Young fungal colonies were white and a brownish green pigmentation developed when the colonies became older. The same color was observed from the top and on the reverse of the colonies. To induce sporulation, isolates were grown on water agar (1.5%) medium in the presence of carrot stem fragments for 1 week at 22°C in darkness, followed by 1 week at 22°C in white light under a 16-h photoperiod. Pycnidia were produced on stem fragments and contained alpha and beta conidia typical of the genus Diaporthe (2). Alternatively, pycnidia were also obtained on malt agar medium after 2 weeks of culture at 25°C in white light under a 12-h photoperiod. The size of alpha and beta conidia was 6.3 ± 0.5 × 2.3 ± 0.4 μm and 23.3 ± 1.8 × 0.9 ± 0.2 μm, respectively (n = 170). In order to confirm the identification at the genus level and determine the species, DNA was extracted from the mycelium of three representative isolates and the ITS regions of the ribosomal DNA were amplified using universal primers (1). The sequences of the amplified products (GenBank Accession Nos. KF240772 to KF240774) were 100% identical with the ITS sequence of a Diaporthe angelicae isolate deposited in the NCBI database (CBS 111592 isolate, KC343027). To confirm pathogenicity, the three isolates of D. angelicae were inoculated on carrot umbels in the greenhouse. A total of nine plants were inoculated (three plants per isolate). Using a micropipette, 10 μl of a conidial suspension containing alpha and beta conidia (105 conidia mL–1) were deposited at the base of the primary umbel and two secondary umbels, which were wounded before inoculation using a scalpel blade. Seven inoculated plants developed triangular, necrotic lesions that were typical umbel browning. D. angelicae was re-isolated on malt agar medium from the inoculated diseased carrot umbels. To our knowledge, this is the first report of D. angelicae in carrot cultivated for seed production in France. The disease resembles the lesions described in the Netherlands in 1951 on carrot inflorescence caused by Phomopsis dauci (3). In future experiments, it would be crucial to precisely determine if D. angelicae could be transmitted to the seeds. References: (1) M. A. Innis et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990. (2) J. M. Santos and A. J. L. Philips. Fungal Divers. 34:111, 2009. (3) J. A. von Arx. Eur. J. Plant Pathol. 57:44, 1951.


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