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3.4 DISCUSSION Soil sampling and analysis R. culumnae grows in soils that are richer in nutrients and less saline compared to the soils in which R. monadelpha and R. sabulosa grows. The concentrations of nitrogen, phosphorous and potassium was higher in soil sampled from the natural habitat of R. culumnae in Turkey (KÖK et al., 2007). The soil of the habitat of R. culumnae had a smaller N:P:K ratio (1.000:6.897:1.069) and a lower salinity. The pH of the soils from the Namaqualand and Turkey is however similar. R. culumnae also occurs in a loamy clay soil, which is essentially a combination between the clay soil (sample 1) and a sandy loam soil (sample 2) in which R. monadelpha and R. sabulosa occurs, except for the slightly higher sand content that such a combination would have. Elements that are in abundance or that are lacking or low in the natural environment may have an effect on germination and growth in some species (BASKIN & BASKIN, 1998). In soil sample 1 and 2 calcium is abundant. Although the percentage Fe content was not tested, the red colour of the clay indicates that the soils are rich in Fe. 3.5 SUMMARY • The pH and soil texture of soils in which R. sabulosa and R. monadelpha, and R. culumnae occur is similar. • Soils in which R. sabulosa and R. monadelpha are found is more saline and has a much lower percentage nitrogen, phosphorous and potassium than soil in which R. culumnae is found. 97
4 Germination physiology 4.1 INTRODUCTION Species in the Iridaceae may exhibit morphological and/or morphophysiological dormancy. These mechanisms of delaying germination is due to the underdeveloped embryo of species in this family (TILLICH, 2003). The only literature published so far in relation to the germination of Romulea species is that of DENO (1993) and EDDY & SMITH (1975). These studies indicates that species of this genus requires a low temperature of 10°C for germination and temperatures between 16.5°C and 20°C may have an inhibitory effect on germination. EDDY & SMITH (1975) showed that application of KNO3 and pre-chilling for 5 days at 2°C did not increase germination of R. rosea. Seeds of this species are effectively dispersed by sheep and showed only 38% germination in its faecal pad compared to the normal germination of 96% (EDDY & SMITH, (1975). This finding suggests that scarification is not an ideal treatment to break the dormancy of these seeds. R. rosea is an invasive species on other continents and some islands. This is the only Romulea species which shows high germination under natural environmental conditions. On the other hand, there are several other important potential horticultural species that are not easily germinated and their seed biology remains unknown. The aim of this Chapter was to understand the physiological mechanism behind dormancy and germination and to improve percentage germination of some important Romulea species with economic potential. Additionally, to test the germination mechanism of R. rosea in more detail, which can help in eradicating/controlling this species in countries where it is invasive. 4.2 MATERIALS AND METHODS In South Africa, collection of many Romulea species is legally restricted due to the limited existence of natural populations. For this study, seeds were obtained from Silverhills Nursery, Kenilworth and African Bulbs, Napier. Both are South African 98
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Propagation of Romulea species Pier
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Contents 2.7 GERMINATION PHYSIOLOGY
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Contents 5.3.1 Explants from seedli
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Abstract The suitability of various
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Declarations I Pierre André Swart,
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Declarations DETAILS OF CONTRIBUTIO
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Publications from this thesis ASCOU
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List of Figures Figure 2.13: Suther
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was significantly different from th
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List of Tables Table 2.1: Names of
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List of Abbreviations 2,4-D 2,4-Dic
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Die vlakhaas spits sy oor hy het di
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As die mens dan ook so sy dankbaarh
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Introduction where a great number o
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Introduction The subgenera Romulea
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2 Literature review Leef van daad e
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Literature review Figure 2.2: Life
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Literature review Figure 2.4: Life
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Literature review The plants are sh
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Literature review flowers (DE VOS,
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Literature review often found on cl
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Literature review flowers of R. lei
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Literature review flattened upper s
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2.2.16 Romulea tabularis Literature
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Literature review extinct, R. papyr
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Literature review R. leipoldtii occ
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Literature review Figure 2.8: Calvi
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Literature review Figure 2.14: Fras
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Figure 2.20: Nieuwoudtville weather
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Literature review Figure 2.26: Grah
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Literature review Figure 2.29: Diag
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Literature review Figure 2.30: A te
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Literature review Macronutrients ca
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Literature review The soils of the
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Literature review The embryo is the
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Page 95 and 96: Literature review The essential fun
Page 97 and 98: 2.9.3.4 Abscisic acid Literature re
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Page 103 and 104: Literature review and the addition
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Page 107 and 108: Literature review environmental str
Page 109 and 110: 2.11 IN VITRO FLOWERING Literature
Page 111 and 112: Literature review higher regenerati
Page 113 and 114: Subfamily Ixioideae (continued) Tri
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Page 121: Soil sampling and analysis Table 3.
Page 125 and 126: 4.2.2 Water content and imbibition
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Page 135 and 136: Germination (%) 100 80 60 40 20 0 c
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Page 141 and 142: 5.2 MATERIALS AND METHODS In vitro
Page 143 and 144: In vitro culture initiation and mul
Page 145 and 146: 5.2.3 Explant comparison In vitro c
Page 159 and 160: 5.4 DISCUSSION In vitro culture ini
Page 163 and 164: 6 In vitro corm formation and flowe
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Page 167 and 168: 6.3 RESULTS 6.3.1 Corm formation In
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In vitro corm formation and floweri
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In vitro corm formation and floweri
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Commercialization potential of Romu
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Commercialization potential of Romu
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BASKIN, C. C., and BASKIN, J. M. (1
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Literature cited DOWLING, P. M., CL
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Literature cited HILTON-TAYLOR, C.
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Literature cited KUMAR, A., SOOD, A
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Literature cited PIERIK, R. L. M. (
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Literature cited STEINITZ, B., COHE
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