Narrative
WAR 8.
LUCERNE
Medicago sativa
`Aquarius' syn `Y408'
Application No: 1993/237 Accepted: 3 Nov 1993.
Applicant: NSW Agriculture, Orange, NSW.
Agent: South Australian Seedgrowers Co-operative Ltd, Hilton, SA.
Description - see table of comparisons and figure
`Aquarius' is a highly winter-active lucerne with high resistance to phytophthora root rot. Mean plant height two weeks after the equinox and four weeks after cutting in the first year was 36.1cm (range 18-53). Plant height in spring averaged 28.8cm (range 21-48). Plants were generally semi-erect in growth habit with dark green foliage. Flowering was early with a high frequency of plants possessing dark blue-violet flowers (45%). There were no plants with variegated, cream, white, or yellow flowers. Stems were medium to long at flowering with a mean of 92.0 cm (range 59-122). The percentage of seedlings resistant to phytophthora root rot (Phytophthora medicaginis) and to spotted alfalfa aphids (Therioaphis trifolii f. maculata) was assessed using standard tests as published by the North American Alfalfa Improvement Conference. `Aquarius' showed higher resistance to phytophthora root rot (85.8% survivors) than comparators. Resistance to spotted aphid was similar to other resistant varieties (34.2% survivors).
Origin
`Aquarius' was bred by the NSW Lucerne Improvement Program at Yanco by D.B. Waterhouse and R.W. Williams. `Aquarius' originated from a controlled cross between a breeding line selected from the highly winter-active variety, `CUF-101' with elite clones from line `NAPB 0310'. Plants from `CUF-101' were initially selected in the field in 1979 at Windsor, NSW, for resistance to stem nematode (Ditylenchus dispsaci) and to various leaf diseases including stemphylium leaf spot (Stemphylium botryosum) and pepper spot (Leptosphaerulina trifolii). These selections were polycrossed by hand and the progeny screened for resistance to leaf disease in the field at Nowra, NSW, and for resistance to blue-green aphid (Acyrthosiphon kondoi) and colletotrichum crown rot (Colletotrichum trifolii) in the greenhouse at Yanco. Plants form this second cycle of selection were hand-crossed using pollen from clones of NAPB 0310 selected for major resistance genes to phytophthora root rot. Progeny from this cross were further screened for resistance to blue-green aphid and to spotted aphid in the greenhouse, then polycrossed to form Aquarius. Selection for resistance in each of the last two generations was practised within and among half-sib families. `Aquarius' is a synthetic variety based on seed from 97 plants in the final generation of crossing. Propagation is by seed.
Comparative Trial
Comparators: `CUF-101', `Sceptre', `Quadrella', `Aurora'. Location: Yanco, NSW Dec 1993 to Apr 1995. Conditions: red-brown earth, irrigated, no obvious disease or nutrient disorders. Trial design: randomised complete block with four replicates, 30cm within and between row spacings, with separate row plots arranged in two replicates for flower colour measurements. Measurements: 80 plants per variety.
Prior Applications and Sales Nil.
Description: R.W. Williams, NSW Agriculture, Yanco, NSW.
Comparison of Lucerne varieties
`Genesis' `Aquarius' *`CUF-101' *`Sceptre' *`Quadrella' *`Aurora'
PLANT HEIGHT (cm) 7/10/94 (natural height at spring time) LSD(P0.01) = 2.6)
mean 29.0bc 28.8bc 33.3a 27.5c 30.5ab 28.1bc
std deviation 5.4 6.1 6.5 5.9 4.8 7.0
PLANT HEIGHT (cm) 11/1/95 (height at flowering after 1st cut) LSD(P0.01) = 2.5)
mean 52.7a 56.7c 54.5abc 53.5bc 53.2c 55.9ab
std deviation 4.9 6.0 7.4 4.8 6.5 6.1
PLANT HEIGHT (cm) 2/3/95 (height at flowering after 3rd cut) LSD(P0.01) = 3.5)
mean 43.9c 48.4b 54.9a 47.8b 48.1b 48.9b
std deviation 8.7 7.8 9.9 7.9 7.6 9.1
PLANT HEIGHT (cm) 4/4/95 (4 wks regrowth, cut 2 wks after equinox in 2nd year) LSD(P0.01) = 2.7)
mean 29.4c 32.3b 37.5a 32.6b 32.8b 30.9bc
std deviation 6.3 6.5 6.5 6.5 6.3 7.5
PLANT GROWTH HABIT
semi-erect medium erect erect semi-erect medium
PLANT FOLIAGE GREEN COLOUR
dark medium light medium medium medium
RESISTANCE TO PHYTOPHTHORA ROOT ROT (% seedling survivors) LSD(P0.01) = 18.6)
mean 61.2b 85.8a 64.6b 49.1b 52.3b 65.9b
std deviation 6.2 9.3 15.9 15.6 15.2 5.1
RESISTANCE TO SPOTTED ALFALFA APHID (% seedling survivors) LSD(P0.01) = 18.0)
mean 28.0c 34.2bc 48.8ab 40.5abc 23.5c 57.0a
std deviation 6.8 8.0 18.0 15.6 10.8 10.3
Means followed by the same letter are not significantly different at P0.01.