Browsing by Author "Foale, M.A."

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    Fruit component analysis of south Pacific coconut palm populations
    (1997) Ashburner, G.R.; Thompson, W.K.; Halloran, G.M.; Foale, M.A.
    The south Pacific region contains a large genetic resource for the genetic improvement of coconut palms (Cocos nucifera L.). A study of the diversity in the species was made during 1992/3 using fruit component analysis on a representative sample from 29 distinct south Pacific populations in order to characterise the germplasm present in the region. A large diversity in fruit morphology was found that ranged from populations exhibiting wild-type characters in central Pacific to populations displaying domesticated characteristics in Rennell Island, the Sikaiana Islands, the Marquesas Islands, and in Papua NewGuinea. Many populations exhibited fruit characteristics intermediate between the two, which were thought to have arisen due to introgressive hybridisation between the wild and domesticated populations. Continuous variation in fruit morphology was found in these populations, and cluster analysis arbitrarily divided the continuum into discrete groups which were consistent with geographic affinities. Groups were defined in Melanesia, Western Polynesia and Eastern Polynesia. The continuum displayed clinal variation from populations with small fruit and low husk content in the west to large fruit and more husk in the east of the region. The wild and domesticated populations were found in disjunct pockets throughout the area, and did not form part of the clines. Most populations consisted of a wide range of fruit morphology, from individuals expressing wild-type characters to those with domestic-type characters. The occurrence of both wild and domesticated populations within the clinal variation indicates that further exploration should be made to determine the presence of other potentially useful populations.While this activity is proceeding, collection and conservation can proceed using the classification already defined.
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    The growth of the young coconut palm (Cocos nucifera L.). I. The role of the seed and of photosynthesis in seedling growth upto 17 months of age.
    (1968) Foale, M.A.
    The growth of coconut seedlings and the changes occurring within the seed were studied over a period of 17 months from the germination of the coconuts. Removal of the husk prior to germination made possible an estimate of the endosperm content of each seed and also permitted the exact date of germination to be observed. Seedlings were grown with a non-limiting supply of water and nutrients; 63 seedlings were harvested on each of 10 occasions to enable a growth analysis to be made. A high initial relative growth rate, arising through contributions by the endosperm, fell at 4 months to a level which remained roughly constant to 17 months. By 4 months the haustorium had reached its full size, but thereafter the relative contribution from the endosperm via the haustorium was much diminished. Between 4 and 15 months a gradual change over to full dependence on photosynthesis took place. By 17 months less than 10% of the endosperm remained in the nut. The rate of leaf production was constant with time, but the leaf area increased almost exponentially. There was some indication of a positive relationship between net assimilation rate and solar radiation. Some conclusions are drawn concerning cultural methods with young coconuts
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    The growth of the young coconut palm (Cocos nucifera L.). II. The influence of nut size on seedling growth in three cultivars
    (1968) Foale, M.A.
    The growth of three coconut cultivars of the tall type from germination up to 17 months of age was compared by growth analysis. These cultivars differ considerably in mean nut size. Within each cultivar a comparison was also made between the growth of seedlings from small, medium, and large nuts. There were considerable differences between cultivars in seedling growth up to 2 months but these differences did not persist. Similarly differences due to nut size within cultivars were recorded at early harvests but had disappeared by 6 months. Thus neither genotype nor nut size had any sustained effect on the plant size. Consumption of endosperm depended on seed size: evidently a lower, compensating net assimilation rate occurred in plants with large nuts to give a similar total supply of assimilate. This suggests that the potential supply of assimilate was not limiting the growth rate. Large nuts transfer dry matter from the endosperm more rapidly than do smaller nuts; hence under unfavourable conditions for photosynthesis, larger nuts may produce larger seedlings. It is suggested that any seedling selection should be done in a favourable nursery environment so that emphasis is placed on differences in seedling vigour due to genetic variation