College of Agricultural Sciences and Fisheries Technology

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Browsing College of Agricultural Sciences and Fisheries Technology by Author "Arap-Konuche, Paul Kipkoviv"

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    Root deformation in Pinus Patula: effects and possible causes at Turbo, Western Kenya
    (University of Dar es Salaam, 1977) Arap-Konuche, Paul Kipkoviv
    An evaluation of possible effects of root deformation on survival and growth of 9-year old Pinus petals was carried out. In 51 cluster plots, 391 trees were examined for root deformation, and 100 of the trees were excavated. Factors associated with root deformation were noted. The results showed that of the trees examined, 53.7 percent had deformed roots. However, only 0.77 percent had toppled over (wind damaged at root collar region). The damage was not, apparently, increasing with age. The trees with deformed roots did not appear liable to wind throw in the remaining 6 years before harvesting. There was a negative correlation between root deformation and survival. Trees with deformed roots had their mean height, d.b.h. and volume reduced by 4.3, 10.3 and 28.0 percent respectively. The reductions in d.b.h. and volume were significant. It was estimated that more than twice the mean annual increment in volume per tree at this age, had been lost because of root deformation. Root deformation was also significantly associated with leaning trees. The most likely causes of root deformation, acting singly or in combination, are polythene tube containers, poor nursery practices, and bad planting methods or practices. The basal stem snap or stem breakage at root collar is associated with some coiling roots and enlargements of root crown. The swollen root crown is possibly caused by the coiling roots impeding the flow of carbohydrates and growth hormones from the stem to the growing regions of roots. Pinus patina is susceptible to wind breakage at root collar when there is a weak connection between the stem base and the root crown. Among the suggestions made for minimising root deformation are: the use of smaller planting stock and the need to increase the size of planting holes.