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Effect of pruning on the growth and development of Protea 'Pink Ice' (P. compacta R. Br. x P. susannae Phill.)
ENGLISH ABSTRACT: The main purpose of producing cut flowers is to earn a satisfactory income with the first endeavour normally to increase the total number of flowers produced. This has limits due to the number of flowers that can be produced per plant or per area planted. Another method is to ge...
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Stellenbosch : Stellenbosch University
2012
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| Summary: | ENGLISH ABSTRACT: The main purpose of producing cut flowers is to earn a satisfactory income with the
first endeavour normally to increase the total number of flowers produced. This has
limits due to the number of flowers that can be produced per plant or per area
planted. Another method is to get the bulk of the crop in the longest possible stem
length category to earn better prices. A third option is to target the seasons or times
of the year when prices are naturally higher due to a positive ratio between demands
and supply. Most of the protea cultivars grown commercially in South Africa flower
outside the period September to January when prices and demand for proteas on the
European markets are high. Previous work established that the flowering period of
some protea cultivars could be modified to more favourable marketing periods
through the timing of the pruning operation.
Plants of Protea ‘Pink Ice’ were pruned at monthly intervals from January to
December 1999. For the first crop after pruning the highest yield was achieved for
plants pruned in June. Flowers borne on an autumn flush needed 4 to 6 weeks
longer to complete their development than for spring flush borne flowers. However,
since flower initiation in autumn occurred earlier by more than 3 months than on the
spring flush, this difference in time accounted for the earlier flowering of the former in
spite of a longer period to complete the flower developmental process.
The effect of cropping this cultivar in a biennial system was tested against actual
prices to test the validity of the finding that the June treatment resulted in the highest
number of harvestable stems. It was found that the June treatment also gave the
best income and the phasing of production resulting from a June pruning in a biennial
cropping system fitted this cultivar the best. Orchards should be divided in two blocks
with one in the ‘on year’ and one in the ‘off year’.
The length of the shoot stub left after a shoot has been pruned determines the nature
of the regrowth. Four-year-old plants of Protea ‘Pink Ice’ were pruned to four different
bearer lengths in November 1999 or February 2000. Plants were pruned that either a
half, one, two or three flush length bearers were left on the plants. Plants with the two
longer categories of bearers took the shortest time to sprout buds from axillary positions on the bearers and also had the most buds developing into shoots. The
longer bearers produced more flowers per plant but the average length of the flowers
was shorter than the plants with shorter bearers. The average total income was more
in the instance of the longer bearers due to more flowers and the earlier harvest
resulting from buds sprouting earlier. |
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