Technical annual report 2000-01
Dept. of Regional Development, Primary Industry, Fisheries and Resources technical annual report; Department of Regional Development, Primary Industry, Fisheries and Resources technical and annual report; Reports; PublicationNT; Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295
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Agriculture -- Northern Territory -- Periodicals; Fisheries -- Northern Territory -- Periodicals
Dept. of Primary Industry and Fisheries
Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295
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Department of Primary Industry and Fisheries 126 1. Identification of outstanding hybrids and their comparison. 2. Inheritance studies including an assessment of relative expression of different characteristics for determining dominance. 3. Comparison of parents to identify preferred donor cultivars for selected traits. Preliminary Analysis of Inheritance of Characters General Comments: Assessment was carried out on the limited hybrid lines that produced fruit in the 1999/2000 season. In most cases the numbers of hybrids in any one parental combination were small, limiting our analysis of many characteristics at this stage. However some of the early trends are discussed below. Many are based on hybrids of Irwin and Kensington Pride that were well represented (39 hybrids) in the cropping trees Blush Colour (orange, pink, red, and burgundy) Scoring was generally consistent, although there was not always a clear distinction between categories 3 (red) and 4 (burgundy). One line of Irwin x KP was scored separately as 1 (orange) and 3 (red). Of the 39 Irwin x KP hybrids assessed, 28 (72%) were scored as having red or burgundy blush colour. In this combination, therefore, red blush colour can be considered an incompletely dominant character. Embryo Type (polyembryonic, monoembryonic) The hybrids between Irwin and KP gave 19 mono to 16 poly. Other combinations involving monoembryonic female parents and KP as pollen donor indicated 1:1segregation for this character. A similar pattern was seen when polyembryonic Nam Dok Mai was used as a pollen parent, suggesting that Kensington Pride and Nam Dok Mai are both heterozygous for gene(s) conditioning polyembryony. The 1:1 segregation is consistent with polyembyony being controlled by a single dominant gene, as suggested by Aron et al. (1998) but in contrast to earlier studies. Flavour (unacceptable, Floridian, Indian, Kensington, and South East Asian) Scoring was consistent, given the inherent difficulties in categorising fruit flavour, as well as possible variation according to fruit maturity. In the combination Irwin x KP, 23 of the hybrids (58%) were scored as having KP flavour, suggesting incomplete dominance of this character, or alternatively heterozygous for genes controlling production of the unique flavour compounds in KP. Fruit Weight There was really very good consistency in this character between different samples of a given line. There was a wide distribution of fruit. Thus, although most of the Irwin x KP hybrids (74%) fell in the range 300 600 g, there were five lines with fruit below 300 g, and two with fruit greater than 1,000 g. This suggests transgressive segregation of genes controlling fruit size in mango, since many lines are producing smaller or larger fruit than the parents Irwin (262 g, previously) and KP (414 g, previously). Pulp Texture (Common, Tommy Atkins, R 2 E2, Kensington and Nam Doc Mai) There was remarkable consistency in scoring of this character. In the Irwin x KP hybrids, pulp texture category 4 predominates with 22 (or 56%) scored as KP-type.