Root development of P. patula

Terblanche, A. L.( Andries Louis) (2000-12)

Thesis (MSc.)--Stellenbosch University, 2000.

Thesis

ENGLISH ABSTRACT: Pinus patula is one of the most important softwood species planted in South Africa for fibre and timber production and also the main species to be planted in the North Eastern Cape managed by Mondi Forests. Pinus patula is an exotic species to South Africa and therefore only commercially exists in man made plantations. Transplants are being grown in containerised nurseries and flowing from this regime are root alterations with potential root deformity risks. Current difficulties include poor root development and instability. The so-called old land syndrome also occurs in old agricultural soils. In this study my objective was to investigate the extent of this problem and whether the problem could be solved by better silvicultural practises. Literature indicated that bad root development occurs within the period in which transplants are kept in the nursery. Old land soils have numerous possible variables that could be investigated and tested. Trials were conducted where different dimensions of transplants, cuttings and seed were planted under different soil, climate and chemical conditions. Root development, root weight, root growth potential, shoot growth and survival were measured in order to establish the ideal containerised seedling dimension for optimum survival and growth. Ideal growth conditions for optimal transplant and later tree development in old land soils were also determined. It was evident that smaller seedlings had better chances of survival and growth. The effects of container volume and dimension on root development were unfortunately not tested. My results indicated it a very important factor in root development. Taproots should not be pruned and the laterals should not start to grow in a horizontal circular direction, as it will cause an altered root development. Old lands do not have a single individual factor causing bad survival and growth but rather a combination of factors. Weed competition weakens the transplants and other detrimental factors such as pathogens, soil structure deterioration, sub standard transplants, toxins and soil nematodes aggravate matters.

AFRIKAANSE OPSOMMING: Pinus patula is van die mees belangrike sagtehout spesies tans aangeplant in Suid Afrika vir vesel en saaghout doeleindes. Genoemde spesie is die hoofspesie geplant in die studie area naamlik die Noord Oos Kaap bestuur deur Mondi forests. Pinus patula is ‘n uitheemse spesie en kom kommersieel slegs in plantasievorm voor. Saailinge word in houer kwekerye gekweek en wortel misvorming kan hieruit voortvloei. Swak wortel ontwikkeling en onstabiliteit is twee van die hoofprobleme wat met laasgenoemde ondervind kan word. Die sogenaamde oulandsindroom word in ‘n erge graad in die studie area ondervind My studie poog om die omvang van genoemde probleme te ondersoek en of die probleme opgelos kan word deur verbeterde boskultuurpraktyke al dan nie. Literatuur dui daarop dat die wortelmisvormingsprobleem hoofsaaklik spruit uit die tydperk waar die saailing in die kwekery deurbring. Die oorsaak van mortaliteit in oulande is ook ondersoek. Eksperimente is uitgele waar verskillende dimensies van saailinge, steggies en saad geplant en getoets is in verskillende grond, en klimaats toestande. Wortel ontwikkeling, wortel gewig, wortel groeipotensiaal, lootgroei en oorlewing is gemeet ten einde die ideale saailing dimensie en groeitoestande vir optimum oorlewing en groei vas te stel. Saailinge met ‘n kleiner dimensie het ‘n groter kans tot normale oorlewing en groei. Houerdimensie en volume is nie in hierdie studie getoets nie. Hierdie studie dui daarop dat houerdimensie en volume ‘n belangrike faktor is in die ontwikkeling van wortels. Die studie dui ook daarop dat dit belangrik is om nie in ‘n praktyk te verval waar die penwortel gesnoei word en laterale wortels horisontaal sirkelvormig begin groei nie. Genoemde sal wortel vervorming tot gevolg he. Geen enkel faktor kon vir die swak groei en hoe mortaliteit in oulande verantwoordelik gehou word nie maar wel ‘n kombinasie van kompeteerders. Onkruid kompetisie het wel die saailinge onderdruk en gevoelig gemaak vir ander ouland beperkings soos patogene, grondstruktuurverval, lae standaard saailinge, toksiene en grondnematode.

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