Mineral nutrition of cultivated South African proteaceace
Date
2006-03
Authors
Matlhoahela, Patience Tshegohatso
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
Protea, Leucadendron and Leucospermum belong to the Proteaceae family. These
three genera form an important part of the floriculture industry in South Africa and
are commonly used as fresh cut flowers or dried flowers for both the local and
international market. The distribution of macro and micro - nutrients was
investigated in Protea ‘Cardinal’ using rooted cuttings grown from October 2001 to
March 2002. The plants were divided into 1st flush leaf and stem, 2nd flush leaf and
stem, basal leaf and basal stem, roots and the flower bud. These tissues were
analysed to determine N, P, K, Ca, Mg, Fe, S, Na, B and Mn concentration.
Results indicated that N decreased over time in all tissues and accumulated more in
leaves than in stems. P in leaves and stems increased with time, while K increased in
leaf tissues and remained stable in stem tissue. Ca did not change in young leaves
but was high in old leaves. Mg in leaves increased but in basal stem, 1st flush stem
and roots Mg decreased over time. Fe in leaves and roots increased with time and not
a less significant change occurred in stems. In most tissues, B and Na decreased with
time. S increased in leaves and decreased in stems with time. Mn was relatively
stable in most tissues except in basal leaves where it increased. Nutrient
concentration in tissues, especially in leaves, showed no distinct pattern in the
distribution of nutrients.
Eleven cultivars from the three genera, namely Protea, Leucadendron and
Leucospermum, were used to develop deficiency symptoms of macro - nutrients by
using different nutrient compositions. The plants were grown in 20cm pots from December 2002 to September 2003. The eleven cultivars were chosen because of
their high market value. Visual symptoms were recorded in two stages with a five -
month interval for each stage. The first stage was recorded from December 2002 to
April 2003 and the second stage was recorded from May 2003 to September 2003.
Observed symptoms indicated significant differences between the control and
treatments in which specific nutrients were withheld. Some cultivars exhibited some
symptoms that are commonly noticed under field conditions, e.g. in the N deficiency
treatment the upper leaves of Protea ‘Sylvia’ were reddish and the lower leaves were
chlorotic especially at the later stage. Protea ‘Red Rex’ in the P deficiency treatment
had random red tints around the leaf including the petiole, these symptoms are also
commonly noticed in Protea ‘Red ‘Rex’ in field conditions. Leucadendron ‘Rosette’
also showed some uncommon symptoms of accumulating “sugar” on leaf tips in Ca
deficiency treatment that was not observed in any other cultivar. In some cultivars
the symptoms were systematic e.g. Leucadendron ‘Chameleon’ while in other
cultivars the deficiency affected a certain leaf age e.g. Leucospermum ‘High Gold’ in
the Ca deficiency treatment. The buds in 'High Gold' died prematurely in the Ca
deficiency treatment.
Protea ‘Cardinal’ was used to determine the optimal N and P source and
concentrations for optimal growth. Protea ‘Cardinal’ was grown in a temperaturecontrolled
glasshouse for seven months using silica sand as growth medium.
Different levels and sources of N and P were applied. The N was applied in a
complete nutrient solution as NH4
+, NO3
-, NH4
+: NO3
- (1: 1, 1: 4 and 4: 1 ratios) and
Urea, at different concentration levels: 5 mM, 1 mM and 0.1 mM. P was applied at 1 mM, 0.1 mM and 0.01 mM. The plants were fertigated manually with 1L nutrient
solution on every second day of the week.
P at 0.01 mM and 0.1 mM resulted in optimal plant growth. The 1 mM P resulted in
marginal leaf scorching or dryness. When N was applied at 5 mM plant growth was
more optimal than when N was applied at 1 mM and 0.1 mM. More dry weight was
accumulated at 5 mM than at 1 mM or 0.1 mM N. The dry weight of leaves, stem
and roots tissues at 5 mM were higher in the NO3
- treatment.
Description
Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2006.
Keywords
Dissertations -- Horticulture, Theses -- Horticulture, Dissertations -- Agriculture, Theses -- Agriculture, Proteaceae -- Nutrition, Plants -- Assimilation, Minerals, Plant nutrients