Root development of P. patula

[摘要] ENGLISH ABSTRACT:Pinus patula is one of the most important softwood species planted in South Africafor fibre and timber production and also the main species to be planted in the NorthEastern Cape managed by Mondi Forests. Pinus patula is an exotic species to SouthAfrica and therefore only commercially exists in man made plantations. Transplantsare being grown in containerised nurseries and flowing from this regime are rootalterations with potential root deformity risks. Current difficulties include poor rootdevelopment and instability. The so-called old land syndrome also occurs in oldagricultural soils.In this study my objective was to investigate the extent of this problem and whetherthe problem could be solved by better silvicultural practises. Literature indicated thatbad root development occurs within the period in which transplants are kept in thenursery. Old land soils have numerous possible variables that could be investigatedand tested. Trials were conducted where different dimensions of transplants, cuttingsand seed were planted under different soil, climate and chemical conditions. Rootdevelopment, root weight, root growth potential, shoot growth and survival weremeasured in order to establish the ideal containerised seedling dimension for optimumsurvival and growth. Ideal growth conditions for optimal transplant and later treedevelopment in old land soils were also determined.It was evident that smaller seedlings had better chances of survival and growth. Theeffects of container volume and dimension on root development were unfortunatelynot 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 horizontalcircular direction, as it will cause an altered root development.Old lands do not have a single individual factor causing bad survival and growth butrather a combination of factors. Weed competition weakens the transplants and otherdetrimental factors such as pathogens, soil structure deterioration, sub standardtransplants, toxins and soil nematodes aggravate matters.

[发布机构] Stellenbosch University