Effect of pruning on economic biomass production of Protea cv. Carnival

[摘要] ENGLISH ABSTRACT:Many Proreaceae species indigenous to South Africa have potential as cutflowercrops. Commercial production of proteas for expurt, mainly to Europe, mustemphasise quality of flowers and time of production. Good export quality flowers havestems longer than 50cm and unblemished flowers. Cut-flower proteas are in greaterdemand and command better prices during the European winter (September to May,Southern hemisphere), when competition from flowers grown in Europe is less. Bothquality and time of harvest can be manipulated by pruning techniques.Protea cv. Carnival (a natural hybrid, possibly between P. neriifolia and P.compacta) produces flowers in late summer, from February through to May. Pickingflowers or pruning shoots of Proteo cv. Carnival entails removing the terminal portionof shoots with heading cuts to leave on the plant short stumps, known as bearers.Lateral shoots arising from axillary buds on bearers elongate by successive growthflushes until flowers are initiated terminally. The characteristics of the shoot determinewhether or not flower initiation will take place, and will affect the quality of theresulting flower. Plants were pruned to produce bearers of different length anddiameter. The characteristics of shoots arising from different bearers were recordea.Thick bearers of length 20-25cm produced the most shoots, and the longest shoots.Plants producing flowers biennially, rather than ann'Jally, produced thicker bearers,which, in turn, lead to production of better quality shoots arising from the bearers inthe following season.Changing the time of pruning changed both the flowering cycle and the biomassallocation of Prorea cv. Carnival. Plants of Profea cv. Carnival were pruned on sixdifferent dates in 1991. Pruning in March, April or May, 1991, resulted in an annualflowering cycle. Less than 40% of the fresh mass produced in 1993 was reproductive,of which approximately 5% had stems long enough for export. The 1994 annualharvest was of s:milar size and quality as the 1993 annual harvest. Pruning in July,August or September, 1991, resulted in a biennial cycle of flowering. No flowers wereproduced in 1992, and a large crop was harvested in 1993. In 1993 lip to 70% of the fresh mass produced was reproductive, of which approximately 80% had stems longenough for export. Plants were pruned shortly after flowering in 1993, and thebiennial cycle was replaced by an alternate flowering cycle, with a large crop beingfollowed by a smaller crop. The large harvest in 1993 was significantly earlier thannormal, but the small crop produced in 1994 was later. The harvest in 1994 fromplants with an alternate flowering cycle was similar in size to the 1994 harvest fromplants floweting annually, but flower stems were longer.

[发布机构] Stellenbosch University