Fruit Ripening in the Oil-palm Elaeis guineensis

Some gross morphological, biochemical, and quantitative sizechanges of the fruit which occur during the 150 or 80 days fromfertilization to ripeness for this species are described. Threemain phases of development are discernible. For the first 15days little activity may be noted. This is followed by a differentiationperiod of 60 to 70 days during which the fruit develops to almostmaximum size and the embryo, endosperm, mesocarp, and epicarpare virtually completely differentiated. The last period ofripening is considered a maturation period during which timethe embryo becomes viable, the tissues become consolidated intofinal forms, and oil formation in the endosperm and mesocarptakes place. These processes are described quantitatively withgrowth curves.     

Phyllotaxis in the Oil Palm: Applications in Selection of Interspecific Hybrids

The main purpose of the investigation was to determine whethermeasures associated with or dependent on the differences inphyllotaxis organization of the stem, fronds, and inflorescencesof three families of oil palms which differ considerably ingrowth habit and genetic background could be associated with,or allow prediction of their yield differences. Two of the familiesused are interspecific crosses between Elaeis guineensis andE. melanococca and these hybrids yield almost double that ofthe third ‘family’ (a group of E. guineensis selections)and have about twice the individual frond areas, inflorescencevolume, and surface area and about half the rate of verticalgrowth; they have, however, a slightly slower rate of frondand inflorescence production. One of the views expressed isthat the phyllotaxis organization which determines the measuredreduction of stem volume in the interspecific crosses is associatedwith the greater development of more productive reproductiveelements. Further, it is suggested that measurements of frond(even in the juvenile stage) and both male and female inflorescenceorganization could be used in yield prediction for these familiesand possibly other genetic groups-and thus increase the speedand efficiency of genetic selection.     

Phylogeographic structure in mitochondrial DNA of a South-east Asian freshwater fish, Hemibagrus nemurus (Siluroidei; Bagridae) and Pleistocene sea-level changes on the Sunda shelf

We postulated that the biogeographical history of South-east Asia contributed to extensive admixture during Pleistocene low sea levels of genetic groups of an obligate freshwater fish (the river catfish, Hemibagrus nemurus) isolated during periods of high sea levels. During Pleistocene glacial maxima, the sea level was lower than at present and the islands of the Sunda shelf (Sumatra, Borneo and Java) and the Asian mainland were connected by lowlands traversed by rivers. Restriction fragment length polymorphisms in mitochondrial DNA were documented for 140 putative H. nemurus analysed from 13 sampling sites resulting in the definition of 35 haplotypes. The high level of haplotype differentiation (mean P × 100 = 2.22, SD = 1.33) indicates that the subdivision of the ancestral H. netnurus group was extensive and probably occurred early in the Pleistocene. The occurrence of some genetically divergent groups of the H. netnurus complex occurring in sympatry in widely separated locations supports the proposition that low sea levels aided the dispersion and mingling of genetic groups. Based on both genetic and morphological evidence, the main H. nemurus line gave rise to three regional groups: (1) a morphologically distinct ‘Indochinese’ group composed of two mtDNA clades overlapping in east peninsular Malaysia; (2) a ‘Sundaic’ group composed of various lineages of differing morphology and genetic identity; (3) a genetically distinct ‘Sarawak’ group in west Borneo, similar in morphology to the ‘Sundaic’ and ‘Indochinese’ groups, but including a small, golden colour morph as a distinct dade. The morphologically similar Sundaic forms from west Java, Sumatra and west Borneo show some degree of genetic divergence, but their phylogenetic relationships are poorly resolved. The most genetically and morphologically distinct Sundaic dade, assigned to H. hoevenii, colonized the Kapuas river (west Borneo), east Sumatra and south peninsular Malaysia. Contrary to our original hypothesis and present biogeographical theory, little exchange of genetic groups has apparently occurred between the mainland and the Sunda Islands during recent glaciations.