Protea Neriifolia Research Articles

LEAF BLACKENING IN PROTEA NERIIFOLIA R. BR.

Leaf blackening of Protea neriifolia is a common postharvest problem which renders flowers unsalable. Previous reports suggest that depletion of carbohydrates in source leaves caused by transfer of carbohydrates to the strong flower sink may be a major cause. Flowering stems of P. neriifolia were harvested in California under standard conditions and shipped to Baton Rouge, La. Upon arrival, the stems were re-cut (1 cm.), the number of leaves counted and the diameter and height of the flowers measured. Stems were transferred to 1 liter deionized distilled water containing 50 ppm hypochlorite, and 0.5% sucrose or no sucrose, and placed in a growth chamber (25°C) either with 12 hrs light (120 μmol/m2/s), or 24 hrs darkness. Number of leaves 10% black, flower diameter and height, and carbon exchange rates were measured every two days over a 16 day interval. Soluble and insoluble nonstructural carbohydrates were determined and assimilate export rate was estimated for each sampling day. Stems placed in the light maintained healthy foliage while those in the dark had 77-l00% of their leaves 10% black by day 8. Flower and leaf quality in the fight treatment were superior with addition of sucrose to the vase solution. Influence of treatments on carbohydrate metabolism in relation to leaf blackening and flower development will be discussed.

The influence of seed ageing on the plant on seed germination in Protea neriifolia (Proteaceae)

Protea neriifolia R. Br. retains its seeds in the canopy in persistent, woody inflorescences. The effects of ageing on the plant on percentage germination and germination rates of seeds were examined in a controlled (light, temperature) environment and in an open environment under cover. The seeds were classified into the following age classes: current years crop, previous years crop and all seeds remaining in inflorescences produced prior to this. The aims of this study were to determine whether the germination patterns of seeds were influenced by seed age and the conditions under which the seeds germinated. The percentage germination of seeds did not decline markedly with increasing seed age but the germination rate decreased significantly. Seeds that were planted 3 to 5 mm below the surface of sand in germination trays took longer to emerge and appeared less synchronously than seeds placed on the surface. Seedlings from seeds 3 or more years old will experience a greater risk of mortality during germination and establishment because they take longer to emerge and start growing. Successful germination and seedling establishment in the field may require 4 or more weeks of moist conditions, a condition which would generally restrict germination to the rainy season.

Neriifolin, an ester glucoside of benzene-1,2,4-triol

Neriifolin, a leaf metabolite of Protea neriifolia R. Br., is the 6-O-benzoyl-β-D-glucopyranoside of benzene-1,2,4-triol. The location of the benzoyloxy group on the sugar was directly confirmed by n.m.r. spectroscopy; the position of the glycosidic linkage to the benzenetriol was demonstrated by methylation and hydrolysis to 2,4-dimethoxyphenol (characterised by n.m.r. spectroscopy and by benzoylation).

Seasonality of shoot growth and flowering in the fynbos shrub Protea neriifolia cultivated in a summer rainfall area

The phenology of Protea neriifolia cultivated in the eastern Transvaal highlands (summer rainfall area) was studied. Shoot growth occurred from July to February and flowering extended from January to July. There were no seasonal patterns in litter production or decomposition. Shoot growth and flowering occurred several months earlier than in plants in their natural habitat in the south-western Cape. The results are discussed in terms of a current model describing the growth of mediterranean heathland plants on highly leached nutrient poor soils. Pruning procedures to maximize lateral shoot and flower production for commercial exploitation are recommended. Die fenologie van Protea neriifolia wat in die Oos-Transvaalse hoëveld (somerreënval-gebied) verbou word, is bestudeer. Lote het gegroei vanaf Julie tot Februarie, en die blomperiode het gestrek vanaf Januarie tot Julie. Daar was geen seisoenale patroon van afvalproduksie of ontbinding nie. Lootgroei en blom het etlike maande vroeër plaasgevind as in plante in hulle natuurlike habitat in die Suidwes-Kaap. Die resultate word bespreek in die lig van ’n kontemporêre model wat die groei van mediterreense heide-plantegroei op ’n hoogs-uitgeloogde substraat wat arm aan voedingstowwe is beskryf. Snoeimetodes vir maksimale produksie van laterale lote en kommersiële snyblomme word aanbeveel.

Extraction and activity of polyphenoloxidase and peroxidase from senescing leaves of Protea neriifoiia

In a study to determine the causes of post-harvest browning of foliage of protea neriifolia R. Br. inflorescences, proteins were extracted using 7% (w/v) polyethylene glycol 4 000 as a tannin adsorbing agent in the extraction medium. Acetone precipitation of the proteins after extraction gave higher enzyme activities and better resolution during electrophoresis. The polyphenoloxidase activity doubled during the first 14 days after harvesting, while the peroxidase activity increased five-fold during the Same period. Only a slight increase in total soluble protein content could be detected. After 14 days the polyphenoloxidase electrophoretic pattern was completely different from that found immediately after harvesting. The peroxidase pattern did not change, although the intensity of the electrophoretic bands differed. Activation processes caused by a water deficit in the cells may have been responsible for part of the observed increase in enzyme activity. However, the post-harvest incorporation of 14 C-L-alanine by six of the peroxidase isoenzymes indicates that at least some of the increase in activity may be due to de novo synthesis of the oxidizing enzymes. The increased activity of the oxidizing enzymes during the first 14 days after harvesting may have been responsible for the acceleration of post-harvest browning of P. neriifolia foliage. Hierdie studie is onderneem ten einde ’n moontlike verwantskap tussen fenoliese verbruining en polifenoloksidase- en peroksidase-aktiwiteit in loofblare van Protea neriifolia R. Br. na oes vas te stel. Gedurende die eerste 14 dae na pluk is ’n vyfvoudige toename in die peroksidase-aktiwiteit waargeneem, terwyl die polifenoloksidase-aktiwiteit verdubbel het. Gedurende dieselfde tydperk het die polifenoloksidase-isosiempatroon heelwat verander. Die peroksidasepatroon het egter geen verandering ondergaan nie. Aangesien die totale oplosbare proteïenkonsentrasie slegs ‘n geringe toename toon, kan die toename in ensiemaktiwiteit nie sonder meer aan ‘n de novo sintese van die ensieme toegeskryf word nie. Dit is egter moont1ik dat sekere aktiveringsprosesse, wat as gevolg van watertekorte in die selle ontstaan, vir die toename in ensiemaktiwiteit verantwoordelik mag wees. Die inkorporering van 14 C-L-alanien deur ses van die sewe peroksidase-isoënsieme toon egter dat ten minste ’n gedeelte van die toename in ensiemaktiwiteit aan de novo sintese van die oksiderende ensieme toegeskryf kan word. Dit blyk dus dat die toename in aktiwiteit van die oksiderende ensieme deur aktivering en/of sintese van die ensieme veroorsaak word. Die toename in aktiwiteit van die oksiderende ensieme is moontlik vir die vinniger naoesverbruining van P. neriifolia -loofblare verantwoordelik.

Promotive Effects of Auxin, Ethephon, and Daminozide on the Rooting of Protea neriifolia Cuttings1

Abstract Terminal cuttings of Protea neriifolia R. Br. gave earlier rooting and superior rooting index values when they received basal pretreatments of combinations of (2-chloroethyl)phosphonic acid (ethephon) at 300 ppm and indoleacetic acid (IAA) at 4000 ppm followed by a commercial rooting preparation composed of 1.0% indolebutyric acid (IBA) plus 0.5% NAA diluted 1:9 and combinations of 2500 or 4000 ppm butanedioic acid mono-(2, 2-dimethylhydrazide) (daminozide) with 4000 ppm of IBA or IAA. Treatment effects were evident after 3 and 4 months while the control required 5 to 6 months for similar rooting results.