Improving the tolerance of Phalaris aquatica L. to soil acidity by introgression of genes from P. arundinacea L

1990 ◽  
Vol 41 (4) ◽  
pp. 657 ◽  
Author(s):  
RN Oram ◽  
AM Ridley ◽  
MJ Hill ◽  
J Hunter ◽  
DA Hedges ◽  
...  

A comparison was made of the growth on acid and non-acid soils near Canberra of 66 lines in Phalaris aquatica, in seven other Phalaris species which can be crossed with P. aquatica and in seven allopolyploid or backcross hybrids involving P. aquatica. The yield of tops by mid-spring on the strongly acid site was only 20% of that on the mildly acid site. Some variation was apparent among the 38 P. aquatica accessions and cultivars, but some P. arundinacea accessions and hybrids were less inhibited by acidity than any P. aquatica line. Fifty plants from the first or second backcross of four P. aquatica X P. arundinacea hybrids to P. aquatica were selected for their capability of producing a large root system in a nutrient solution containing 10 mg aluminium per L at pH 4.1. On acid soils near Bendigo, Seymour, Benalla and Canberra, offsets of seven of these backcross plants were rated as growing significantly larger at the end of the first growing season than plants of Sirosa, Sirolan and Uneta phalaris, Porto and Currie cocksfoot, Demeter and Melik tall fescue and of Victorian and Brumby perennial ryegrass. However, two of the backcross genotypes appeared to be significantly smaller than the phalaris and cocksfoot controls. Thus, factors in addition to excess aluminium appear to affect the growth of phalaris in these soils, but some backcross genotypes tolerate these adverse conditions. Four of the productive, acid-tolerant genotypes survived the first summer, regenerated vigorously in the following autumn, were palatable to sheep in test grazings over two summers at Armidale, N.S.W., and also were fertile and retained some of the ripe seed in their panicles. Therefore, it seems probable that phalaris cultivars for acid soils in south-eastern Australia can be selected from later generations of the backcross population.

2004 ◽  
Vol 55 (6) ◽  
pp. 681 ◽  
Author(s):  
R. A. Culvenor ◽  
J. T. Wood ◽  
A. L. Avery ◽  
W. Dempsey ◽  
S. E. McDonald ◽  
...  

Half-sib families in the AT98 Phalaris aquatica × P. arundinacea × P. aquatica backcross population bred for acid soil tolerance were compared for establishment, persistence, and yield with phalaris (P. aquatica L.) controls and cocksfoot (Dactylis glomerata L. cv. Porto) at 4 sites in south-eastern Australia with the aim of selecting the parents of a new cultivar. The sites had strongly acid soils but differed in parent material, pH profile, soil fertility, and suitability for phalaris. Establishment by AT98 was clearly superior to all phalaris controls and similar to cocksfoot in an acid soil high in Al to depth at Chiltern, north-eastern Victoria, after sowing in early spring 2000. It was considered likely that better establishment by AT98 was due to its higher Al tolerance. In contrast, little variation in establishment was observed at 3 other sites sown in late autumn 1999, possibly due to a longer period free of moisture stress compared with the later sown Chiltern site. Once established, the control cultivars of phalaris at the autumn-sown sites in general persisted and yielded similarly to the mean of the AT98 families. Significant family variation was observed and predicted heritability on a family mean basis was high for persistence measured as basal frequency and moderately high for yield in the third year. Family by site interaction was relatively low for both attributes. A cultivar based on the best families should give more reliable establishment on acid soils high in Al under conditions where rapid root growth to depth is needed for survival, and give more flexibility of sowing date on these soils. Its best performance relative to cv. Landmaster in terms of third-year yield was predicted to occur on granite-derived soils in north-eastern Victoria.


1970 ◽  
Vol 21 (3) ◽  
pp. 427 ◽  
Author(s):  
AD Robson ◽  
JF Loneragan

On a moderately acid soil (pH 4.6 in 115 suspension of soil in 0.01M calcium chloride), nodulation of Medicago truncatula cv. Cyprus responded markedly to increasing applications of calcium carbonate, which increased soil pH. Since the effect of increasing soil pH on the percentage nodulation could be replaced to a large extent by increasing the inoculation level, it appeared that nodulation was restricted by the inability of Rhizobium meliloti to survive or multiply in the acid soil. The growth of R, meliloti appeared more sensitive to soil acidity than growth of the host plant of annual Medicago species. It is suggested that more acid-tolerant strains of R. meliloti would permit annual Medicago species to be grown successfully on moderately acid soils, thus extending the range of soils suitable for the growth of these species.


1983 ◽  
Vol 100 (3) ◽  
pp. 607-611 ◽  
Author(s):  
R. Rai ◽  
V. Prasad

SUMMARYNitrosoguanidine-induced acid-tolerant mutants S1 and M1 of Lens esculenta Rhizobium leguminosarum were used for nodulation and symbiotic N2-fixation in acid soils having different pH and associated factors of acidity. The range of soil pH and associated acidity factors in which nodulation and N2-fixation responded varied, depending on mutant strains. However, strain M1 was more responsive and effective than S1. Antagonistic effect of Mn to Fe was found when the active Fe2+ and total Mn were determined in fresh nodules.


2014 ◽  
Vol 65 (11) ◽  
pp. 1165 ◽  
Author(s):  
R. A. Culvenor ◽  
R. J. Simpson

Persistence is consistently claimed by Australian farmers as a high priority for perennial grasses in long-term pastures. Phalaris (Phalaris aquatica L.) is a productive perennial grass with proven persistence in south-eastern Australia. Nevertheless, factors that determine the persistence of pasture species in southern Australia related to climate (drought), soil (acidity), grazing pressure, and, importantly, their interaction can reduce persistence of phalaris and other species in various situations. These factors and their interactions are discussed in this review, and strategies to improve persistence with emphasis on plant breeding approaches are considered, with the most durable outcomes achieved when breeding and management options are employed concurrently. Two examples of breeding to improve persistence traits in phalaris are described. A program to improve acid-soil tolerance resulted first in the release of cv. Landmaster, and recently Advanced AT, which is the most aluminium (Al)-tolerant cultivar of phalaris to date. It was bred by recurrent selection on acid soils in a population containing genes from a related, more Al-tolerant species, P. arundinacea. The higher Al tolerance of cv. Advanced AT is of most benefit in more assured establishment on acid soils under variable moisture conditions and confers improved flexibility of sowing date. Cultivar Holdfast GT was bred to address complaints of poor persistence under heavy grazing by cultivars of the highly productive, winter-active type, since high grazing tolerance is needed to achieve profitable returns from developed pastureland. Evidence of good persistence under grazing for cv. Holdfast GT and possible tradeoffs with productivity are discussed. Maintaining high productivity under a predicted higher incidence of drought stress (climate change) and increasing areas of acid soils presents ongoing challenges for persistence in pastures.


2020 ◽  
Vol 71 (9) ◽  
pp. 850
Author(s):  
Richard A. Culvenor ◽  
Stuart Kemp ◽  
Kevin F. M. Reed

Germplasm of the perennial pasture grass Phalaris aquatica L., from Sardinia, Italy, is a potentially valuable source for grass breeders owing to climatic similarities to regions where P. aquatica is used, a relatively high incidence of acidic soils, and exposure to prolonged grazing pressure. At field sites in south-eastern Australia, Sardinian accessions were compared as spaced plants and drill-rows with accessions from southern Europe and north-western Africa and with commercial cultivars. They were also evaluated in grazed swards at three sites over 4 years under conditions that challenge persistence, including heavy grazing pressure, acid soils and drought. Morphologically, the accessions were comparatively dense, fine and short, with similarities to southern European accessions and cultivars of the cv. Australian type. However, they were earlier heading and more summer-dormant, particularly those from southern Sardinia. In drill-rows, Sardinian accessions were later heading and less productive in winter than accessions from Morocco. In swards, Sardinian accessions had lower seedling vigour and winter growth potential than modern winter-active cultivars. However, they were dense and persistent under high grazing pressure, and some accessions survived better than all cultivars on an acid, low-fertility soil. Developing cultivars that are superior to the cv. Australian type with acceptable seed production and alkaloid levels presents a challenge to breeders. However Sardinian germplasm offers a range of maturity times combined with higher levels of summer dormancy and a grazing-tolerant morphology, attributes that may expand the area of adaptation of the species into the hotter and more drought-prone margin.


1992 ◽  
Vol 43 (3) ◽  
pp. 765 ◽  
Author(s):  
JG Howieson ◽  
AD Robson ◽  
LK Abbott

The growth of Rhizobium meliloti is sensitive to soil acidity, and its poor growth and survival limits the production from Medicago spp. on acid soils. In the selection of acid tolerant rhizobia for medics, growth in acidified laboratory media has been poorly related to persistence in acid soils. However, the Ca concentration in laboratory media may have been inadequate for growth of some rhizobial strains at low pH. Therefore, acid-tolerant and acid-sensitive strains of R. meliloti were grown in a buffered, defined medium at a range of Ca and P concentrations, and at several pH values. Growth rate was increased by increasing the Ca concentration from 200 to 2000 8M at low (5-70) and moderate (6.50) pH, but not at pH 7.30. Thus, the Ca requirement for the growth of R. meliloti under acid conditions is much higher than previously thought.


1977 ◽  
Vol 57 (2) ◽  
pp. 197-203 ◽  
Author(s):  
W. A. RICE ◽  
D. C. PENNEY ◽  
M. NYBORG

The effects of soil acidity on nitrogen fixation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were investigated in field experiments at 28 locations, and in greenhouse experiments using soils from these locations. The pH of the soils (limed and unlimed) varied from 4.5 to 7.2. Rhizobia populations in the soil, nodulation, and relative forage yields (yield without N/yield with N) were measured in both the field and greenhouse experiments. Rhizobium meliloti numbers, nodulation scores, and relative yields of alfalfa decreased sharply as the pH of the soils decreased below 6.0. For soils with pH 6.0 or greater, there was very little effect of pH on any of the above factors for alfalfa. Soil pH in the range studied had no effect on nodulation scores and relative yields of red clover. However, R. trifolii numbers were reduced when the pH of the soil was less than 4.9. These results demonstrate that hydrogen ion concentration is an important factor limiting alfalfa growth on acid soils of Alberta and northeastern British Columbia, but it is less important for red clover. This supports the continued use of measurements of soil pH, as well as plant-available Al and Mn for predicting crop response to lime.


1977 ◽  
Vol 57 (2) ◽  
pp. 157-164 ◽  
Author(s):  
D. C. PENNEY ◽  
M. NYBORG ◽  
P. B. HOYT ◽  
W. A. RICE ◽  
B. SIEMENS ◽  
...  

The amount of cultivated acid soil in Alberta and northeastern British Columbia was estimated from pH values of farm samples analyzed by the Alberta Soil Testing Laboratory, and the effect of soil acidity on crops was assessed from field experiments on 28 typical acid soils. The field experiments consisted of two cultivars of barley (Hordeum vulgare L.) and one cultivar each of rapeseed (Brassica campestris L.), red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) grown with and without lime for 2 yr. There are about 30,000 ha of soils with a pH of 5.0 or less where soil acidity seriously restricts yields of all four crop species. There are approximately 300,000 ha with a soil pH of 5.1–5.5 where liming will on the average increase yields of alfalfa by 100%, yields of barley by 10–15%, and yields of rapeseed and red clover by 5–10%. There are a further 1,600,000 ha where soil pH ranges from 5.6 to 6.0 and liming will increase yields of alfalfa by approximately 50% and yields of barley, rapeseed and red clover by at least 4–5%.


2017 ◽  
Vol 68 (8) ◽  
pp. 781
Author(s):  
R. A. Culvenor ◽  
M. R. Norton ◽  
J. De Faveri

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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