O3A

Apple

Variety Description

Variety used for comparison: 'O3'

Summary: 'O3A' is an apple rootstock variety which produces more basal shoots in a stool bed than variety 'O3'. The leaves of 'O3A' are larger than those of 'O3'. The fruit of 'O3A' has more prominent ribbing than that of 'O3'. The fruit of 'O3A' has russet around the eye basin and not on the cheeks, whereas 'O3' has russet on the cheeks and not around the eye basin.

Description:

TREE: end use as clonal rootstock, intermediate vigour, moderate number of basal shoots, straight to wavy growth of basal shoot, low tendency to produce suckers, poor root anchorage, dwarfing to very dwarfing effect

DORMANT ONE-YEAR OLD SHOOT: moderate pubescence on upper half, moderate shine of bark, weak flexibility,
many mid-size lenticels, predominantly reddish brown on sunny side
LATERAL BUD: small to medium in size, pointed tip, adpressed position relative to axis of shoot, small to medium size support
GROWING TIP: red

SHOOT TIP LEAVES: straight to slightly convex in cross section, very sparse to sparse pubescence on upper side, green on lower side, secondary colour on main vein
LEAF: no lobes, large to very large, outwards to downwards, length/width ratio of 1.5, cuspidate apex, serrate margin, weak glossiness on upper side, sparse pubescence on lower side, weak anthocyanin colouration of veins, medium green upper side, absent to very weak anthocyanin colouration on upper side, large stipule

FLOWER BUD: medium pink at full balloon stage
FLOWER: single type, green pedicel
PETAL: ranging from almost circular to oblong, overlapping margins, white on upper side, white with a slight blush (RHS 58A) on lower side

FRUIT: very small, globose to oblong in shape, symmetric in side view, strong ribbing, moderate crowning at distal
end, large eye with half open aperture, persistent calyx in mature fruit, long sepals overlapping at base, very shallow to shallow moderately wide eye basin, very thin and very long stalk, deep and broad stalk cavity
FRUIT SURFACE: smooth, weak to moderate bloom, moderate waxiness of skin, yellow ground colour (RHS 8C), low to medium amount (20-60%) of bright reddish pink (RHS 47A-B) over colour, washed out to blush over colour, absent to low amount of russet positioned around stalk cavity and eye basin, small to medium sized lenticels, intermediately prominent lenticels on over colour and not prominent to very slightly prominent on ground colour
FRUIT IN CROSS-SECTION: cream-coloured flesh, absent or very weak core line, closed locules

SEED: mainly brown at maturity, ranging from globose to conical in shape

Origin & Breeding History: 'O3A' is an apple rootstock variety derived from a mutation of 'O3', and evaluated since 1975 in a stool bed at the Agriculture and Agri-Food Canada Horticulture Research and Development Centre in Saint-Jean-sur-Richelieu, Quebec, for characteristics such as vigour, winter hardiness, disease resistance, dwarfing effect, and effect on tree branch structure. 'O3A' has better precocity, higher yield and wider branch angle compared to 'O3'. 'O3A' was selected in 1984 and planted in 1997 in replicated trials in several plots at the Agriculture and Agri-Food Canada substation in Frelighsburg, as well as at two grower sites.

Tests & Trials: Trials for variety 'O3A' were conducted at the Agriculture and Agri-Food Canada substation of L'Acadie, Quebec. Trees were planted in a randomized block design in four replicates, in 3 m rows with trees 40 cm apart. Additional data was collected from stool beds grown at L'Acadie, and plots at the Agri-Food Canada substation in Frelighsburg. All colour characteristics were determined using the 2001 Royal Horticultural Society (RHS) colour chart and measured characteristics were based on ten measurements.

Comparison tables for 'O3A' with reference variety 'O3'

Width of leaf (cm)

Colour of petal (RHS)

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Apple: 'O3A' (bottom) with reference variety 'O3' (top)

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Apple: 'O3A' (right) with reference variety 'O3' (left)