Evaluation of pasture legumes sown into a prepared seedbed at Tamworth, New South Wales. 2. Seed production and seed reserves

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.


1993 ◽  
Vol 33 (5) ◽  
pp. 581 ◽  
Author(s):  
BS Dear ◽  
PD Cregan ◽  
GM Murray

The density, productivity, flowering characteristics, and seed reserves of 14 lines (10 cultivars and 4 experimental lines) of subterranean clover were observed over 5 years (1983-87) on a red earth soil at Wagga Wagga, New South Wales. Plant density increased from 149-318 plants/m2 in 1983 to 1975-13925 plants/m'n 1987. Herbage yields of all cultivars during autumn-winter were similar in most years except in July 1985 when Seaton Park was superior. Cultivars in the midseason or later flowering groups were more productive in late spring and better able to utilise the extended growing seasons that occur periodically in this environment. The mean time from emergence to 5% flowering of all cultivars was 168 days with March germination in 1985 but decreased to 13.5 days with May germination in 1986. The number of days to flowering at Wagga Wagga was highly correlated with maturity ranking at Perth (r2 = 0.92 in 1985 and? = 0.93 in 1986). In the first year, average seed set was 295 kg seed/ha. but by summer of the fourth year the seed pool ranged from 124 kg/ha for Clare to 1190 kg/ha for Nungarin, the earliest flowering cultivar. The quantity of hard seed that carried over to the next year varied significantly between cultivars, with Enfield, Woogenellup, and Clare having the least, and Nungarin, Northam, Dalkeith, and Daliak the most. Seed set was related to maturity ranking only in 1984, although root disease probably affected seed yields in 1985-86. The proportion of hard seed that carried over was much higher than expected, particularly in soft-seeded cultivars. The newly released cultivar Junee was well adapted to the environment; it was later maturing than the recommended cultivar Seaton Park but was able to maintain high seed reserves. Karridale, another new cultivar, maintained higher seed reserves than the older Mount Barker.



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.



1998 ◽  
Vol 38 (6) ◽  
pp. 555 ◽  
Author(s):  
A. M. Bowman ◽  
D. M. Hebb ◽  
D. J. Munnich ◽  
J. Brockwell

Summary. Populations of Rhizobium meliloti in self-mulching clay soils (Vertisols) at 48 sites on 27 properties in north-western New South Wales were classified according to number and ability to fix nitrogen with several species of Medicago. Rhizobia were counted using serial dilution, nodulation frequency, plant infection tests. Abilities of the soil populations to fix nitrogen were determined in the laboratory with whole-soil inoculation of Medicago seedlings in test tubes with shoots exposed to the atmosphere and roots within the tubes under bacteriological control, and in the field using a technique based on the natural abundance of 15N in the soil. The majority of soils contained >1000 cells of R. meliloti per gram. The major component of those populations fixed nitrogen with lucerne (Medicago sativa) and some components of some soils also fixed nitrogen with M. polymorpha, M. scutellata, M. littoralis, M. tornata, M. laciniata and Trigonella suavissima. However, a number of soils were located which contained few if any rhizobia effective in nitrogen fixation with M. polymorpha. Overall, the effectiveness of nitrogen fixation of the naturally occurring populations of R. meliloti in association with M. polymorpha, M. scutellata, M. littoralis and M. tornata was only 46% of the effectiveness of standard strains. At one particular site, where 10 lines of annual Medicago spp. were growing experimentally, fixed nitrogen as a proportion of shoot nitrogen averaged only 28%. At that site, there were no effective rhizobia for M. scutellata and it was wholly dependent on the soil as the source of its nitrogen. The results are discussed in relation to the need for a substantial input of legume nitrogen for restoring the natural fertility of self-mulching clay soils in degraded wheat lands of north-western New South Wales. It is suggested that lucerne, or perhaps other perennial Medicago spp., might fill this role better than annual medics such as M. polymorpha and M. scutellata that are more dependent than lucerne on specific strains of R. meliloti to meet their requirements for symbiotic nitrogen fixation.



2003 ◽  
Vol 54 (6) ◽  
pp. 621 ◽  
Author(s):  
M. R. Gardener ◽  
R. D. B. Whalley ◽  
B. M. Sindel

This is the second in a series of papers investigating the ecology of Nassella neesiana (Trin. & Rupr.) Barkworth (Chilean needle grass) in pastures on the Northern Tablelands of New South Wales. The reasons for its success as a pasture weed are discussed. Nassella neesiana has a large and persistent soil seedbank. After 3 years without seed input, the seedbank declined from 4676 to 1323 seeds/m2. When an exponential decay curve was fitted to the data it was predicted that the seedbank would reach 10 seeds/m2 after 12.4 years. When seed production was large in 1996, 41.6% of seeds produced were incorporated into the seedbank, whereas in 1995 and 1997 the smaller seed production was only sufficient to maintain seedbank numbers. Furthermore, it is likely that the seedbank numbers were underestimated because they did not include basal cleistogenes. In a separate experiment, basal cleistogenes were found to contribute a further 20% to the seedbank.A small proportion of the viable seeds in a natural seedbank emerged from bare ground over 2 years. Seedling survival was high, with 78% of those germinating from bare ground surviving for at least 20 months. Several experiments were designed to investigate the mechanisms of this germination and survival. It appears that the seeds of N. neesiana have an after-ripening requirement of between 3 months and 1 year for maximum germination. Lemma removal from seeds stored for 8 months increased germination from 49 to 82%. The rate of germination and the total percentage of seeds germinating also increased with time of burial in the ground. Of seeds that had been buried for 2 years, 90% germinated after laboratory incubation compared with 48% of seeds stored in the laboratory as controls. Depth of seed burial appears to affect seedling emergence and survival. A smaller number of seedlings emerged from 0–10 mm and they had lower survival than those from seed buried at 10–20 mm.



1996 ◽  
Vol 47 (4) ◽  
pp. 559 ◽  
Author(s):  
GM Lodge

Seedling emergence and survival of 15 annual pasture legumes was studied in the field at Tamworth, northern New South Wales. Emergence was measured in permanent quadrats (0.09 m2) in covered and uncovered areas approximately every 15 days from 30 November 1983 to 30 November 1984. Survival of seedlings was estimated from 15 December 1983 to 31 August 1984, before plants senesced. Emergence was generally highest in summer and autumn following seed set and lowest in winter and spring. Two legumes, Medicago scutellata cv. Sava and Trifolium subterraneum cv. Seaton Park, had high emergence in winter (mid July). Total seedling emergence was highest ( P < 0.05) in covered areas of cv. Seaton Park and uncovered areas of T. hirtum cv. Hykon. All T. subterraneum cultivars, M. minima, Astragalus hamosus cv. Ioman, Vicia villosa cv. Namoi, and M. truncatula cv. Paraggio had higher total emergence in covered compared with uncovered areas. In contrast, total emergence of M. aculeata, M. truncatula cv. Jemalong, Sava, and Hykon was lowest in covered areas. Cover had little effect on the total emergence of M. truncatula cv. Sephi and T. glomeratum. Of the 7700 individual seedlings marked from November 1983 to August 1984, a mean of only 31% (covered) and 41% (uncovered) survived until 31 August 1984. For each emergence time, highest ( P < 0.05) survival rate coincided with the highest (P < 0.05) number of emerged seedlings in 4 of the legumes in covered areas (cv. Namoi, 31 January; cv. Ioman, 31 March; cv. Hykon, 15 April; cv. Sava, 15 July; Table 4) and 9 in uncovered areas (cvv. Nungarin, Seaton Park, and Namoi, 31 January; M. aculeata and cv. Sephi, 28 February; cvv. Jemalong and Ioman, 31 March; T. glomeratum, 15 April; cv. Sava, 15 July). In all other legumes there was no optimum time for emergence, since the highest (P < 0.05) survival rates were associated with seedling survivals <50%. Generally, survival curves with a mortality constant rather than a mortality rate were a better fit ( P < 0.05) for most legumes and times. This implied that these survival curves were determined at the time of recruitment, and declined at a constant rate, despite below-average post-emergence rainfall in May-June. Low rates of survival at times of highest ( P < 0.05) emergence indicated that there may have been some density-dependent regulation in some of the legumes.



1995 ◽  
Vol 35 (1) ◽  
pp. 97 ◽  
Author(s):  
H Marcellos ◽  
KJ Moore ◽  
A Nikandrow

The effects of 5 foliar-applied fungicides on seed yield of faba bean (Vicia faba) cv. Fiord were studied over 3 years at Tamworth in northern New South Wales. In 2 seasons when the diseases chocolate spot (Botrytis fabae) and rust (Uromyces viciae-fabae) were significant, 5 applications of foliar fungicides after flowering increased yield, by up to 1.6 t/ha in 1990 and nearly 0.9 t/ha in 1992, compared with the unsprayed treatment.Mancozeb, dichlofluanid, and tebuconazole were the most effective fungicides for preventing yield reduction, and vinclozolin and procymidone had little or no effect. Mancozeb and tebuconazole were effective in reducing the severity of both diseases, whereas procymidone was only active against chocolate spot. Differences between the most effective fungicides when applied 5 times or twice (at early and mid flowering) were seldom significant. Seed yields following 2 applications of tebuconazole were significantly higher than from 1 application, but for mancozeb, 2 applications were better than 1 in 1992 only. It was estimated that rust accounted for most of the yield loss in 1990 and 1992, and did so mainly by reducing seed size. Application of mancozeb early and during late flowering provided an effective and economical increase in grain yield in 1990 and 1992.



2008 ◽  
Vol 48 (4) ◽  
pp. 553 ◽  
Author(s):  
S. P. Boschma ◽  
G. M. Lodge ◽  
S. Harden

Two adjacent sites (a naturalised pasture and a previously cropped area) with differing potentials for salinity/sodicity and waterlogging near Tamworth, New South Wales were sown with temperate perennial grasses and legumes, temperate annual legumes and tropical perennial grasses to assess their herbage mass and persistence from 2003 to 2006. Plots were either grazed or mown seasonally. Days to flower in the establishment year and seedling regeneration were assessed each year for the annual legumes. In May 2003, salinity levels at soil depths >0.6 m were as high as 8 and 12 dS/m at the naturalised pasture and previously cropped sites, respectively, but generally were >5 and >3 dS/m at a soil depth of 0–0.10 m for these sites in 2004–05. With below average rainfall, no waterlogging was observed at the previously cropped site and only short-term waterlogging of a few days duration occurred at the naturalised pasture site. Under these conditions Puccinellia ciliata cv. Menemen did not establish or perform well, but Thinopyrum ponticum (cvv. Dundas and Tyrrell) was productive and persistent compared with Phalaris aquatica. At both sites, Digitaria eriantha cv. Premier and Chloris gayana cv. Katambora were the best tropical grasses, while the performance of Bothriochloa bladhii subsp. glabra cv. Swann was good at the previously cropped site and Panicum coloratum subsp. makarikariense cv. Bambatsi was best at the naturalised pasture site. At both sites, Medicago sativa had the highest herbage mass and persistence, with cv. Aquarius being superior to cv. Salado after 3 years. Compared with M. sativa, the herbage mass and persistence of Trifolium fragiferum was low. Of the annual legumes, M. polymorpha cv. Scimitar and Melilotus sulcatus had the highest herbage mass.



2003 ◽  
Vol 54 (6) ◽  
pp. 613 ◽  
Author(s):  
M. R. Gardener ◽  
R. D. B. Whalley ◽  
B. M. Sindel

Nassella neesiana (Trin. & Rupr.) Barkworth (Chilean needle grass) originated in South America and is now a widespread weed in pastures in south-eastern Australia. To date, little research on the biology of N.�neesiana has been undertaken in Australia. This study investigated several aspects of the biology of N. neesiana in pastures on the Northern Tablelands of New South Wales. The main flowering period for N. neesiana in Australia was shown to extend from November to February and is similar to that in South America. Potential for production of panicle seeds was large and varied from 1584 seeds/m2 in 1995 to 22 203 seeds/m2 in 1996 as a result of changes in the density of flowering tillers per unit area. Nassella neesiana produced a further 7.2 cleistogenes (hidden seeds in the flower stem) on average per tiller. Hence, total potential seed production (panicle seeds and cleistogenes) was 28 282 and 8036 seeds/m2 in 1996 and 1997, with the cleistogenes accounting for 21.5 and 26.1% of the total respectively. Furthermore, the production of cleistogenes was not affected by clipping flowering tillers at 3 different heights. Three possible dispersal mechanisms of N. neesiana seeds were investigated. Adherence of seeds to the wool appeared to be the most effective. Twenty-five per cent of seeds that were picked up naturally in the wool of sheep after grazing in a paddock of N. neesiana, remained after 5 months. Shearing just before seed set reduced the number of seeds adhering to the wool. An average of 1.7% of panicle seeds and 5.3% of cleistogenes fed to Angus steers passed through the animal intact within 4 days, but <50% of these seeds were viable. The majority of seeds recovered from a wind dispersal experiment were within 1 m of the parent plant and the furthermost seed was 2.8 m away. The implications of these results for management are discussed.



2010 ◽  
Vol 61 (6) ◽  
pp. 435 ◽  
Author(s):  
B. S. Dear ◽  
M. B. Peoples ◽  
R. C. Hayes ◽  
A. D. Swan ◽  
K. Y. Chan ◽  
...  

Changes in pasture yield and botanical composition due to gypsum application were examined on Vertosols at two locations of differing soil sodicity, Grogan and Morangarell, in southern New South Wales. Two pasture treatments were examined. One was an annual pasture comprised of 3 annual legumes (2 subterranean clover Trifolium subterraneum L. cultivars, Clare and Riverina, and balansa clover T. michelianum Savi cv. Paradana), while the second treatment consisted of lucerne (Medicago sativa L.) cv. Aquarius sown in a mixture with the same annual legumes. Gypsum had no effect on the establishment or persistence of lucerne at either site. Gypsum increased the number of subterranean clover seedlings present in autumn in annual swards at the more sodic Grogan site in each of the 4 years, but provided no difference when the clover was in a mixture with lucerne. Annual legume seed yields in annual-only swards increased with gypsum by up to 58% at Grogan and 38% at Morangarell. Seed yields of both cultivars of subterranean clover declined as a proportion of the total annual legume seed bank when lucerne was included in the mixture, in contrast to balansa clover (at Grogan) and the naturalised annual legumes, burr medic (M. polymorpha L.) and woolly clover (T. tomentosum L.), which all increased in relative seed yield in the presence of lucerne. Total pasture production at the Grogan site increased with gypsum by up to 15% per annum in annual swards and 36% in lucerne swards depending on the season. Yield responses to gypsum by the lucerne component were observed in 10 of the 13 seasonal yield measurements taken at Grogan. However, total pasture yield and seasonal yields were unaffected by both gypsum and pasture type at the less sodic Morangarell site. It was concluded that sowing a diverse mixture of annual legumes or polycultures was conducive to maintaining productive pastures on these spatially variable soils. Lucerne dried the soil profile (0.15–1.15 m) more than annual pastures at both sites. The combination of gypsum and lucerne enhanced water extraction at depth (0.6–1.15 m) at the Grogan site increasing the size of the dry soil buffer whereas gypsum increased soil water at depth (>0.6 m) under annual swards.



2002 ◽  
Vol 42 (1) ◽  
pp. 15 ◽  
Author(s):  
D. R. Kemp ◽  
D. L. Michalk ◽  
M. Goodacre

Seven experiments were established across a range of environments (latitude 33°S) in central New South Wales to evaluate 52 legume cultivars and lines against currently recommended cultivars. Plots were grazed by either sheep or cattle after each harvest. Criteria for inclusion were that lines were either commercially available or in the process of being registered. Three experiments also included chicory. Sites had from 600 to 900 mm annual rainfall and were at altitudes of 440–1000 m. The 4-year program included the dry summer of 1990–91. White clover and subterranean clover were the most productive species over time. Among subterranean clovers, the subspecies subterraneum cultivars were more productive than the yanninicum or brachycalycinum subspecies. Other species such as balansa, Persian, strawberry, red and crimson clovers, lotus major and murex medic were more variable in production. These legumes often grew well in the establishment year, but failed to persist. Lucerne was in general, not as productive as white or subterranean clover. Caucasian clover and yellow serradella should be evaluated further as conclusive judgements could not be formed. Chicory was often the most productive species in the experiments, especially over the warmer 6 months of the year. It persisted under a 6-week harvest regime and during the drought year. The newer subterranean clover cultivars, Leura, Goulburn and Denmark all exceeded the production from the previously recommended cultivars, Woogenellup and Karridale, even though no major disease was evident in the later group. The lines 89820D and 89841E were sufficiently productive to warrant further evaluation and possible development as cultivars. In contrast, while Huia, Tahora, Bonadino and Tamar were often as productive as the recommended white clover cultivar Haifa, they were not consistently better. Where summer rainfall occurs and the annual rainfall exceeds 650 mm, the greater potential yield of white clover compared with subterranean clover justifies its use. However, no white clover cultivars survived the summer drought in 1990–91 as intact plants. Further work is needed to develop more drought-tolerant cultivars.



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