Microstructural Study On The Organs Of Macadamia

In this trial, we studied the micro structures and feature of new growth of root, stem, leaf, flower and fruit of Macadamia(Macadamia integrifolia Maiden& Betche) Cultivar ’SSCRI-2’ via conventional paraffin method. The results were as follows. 1. The new growth of root hairs of the macadamia cultivar was dense. The size of the cortex cells of primary roots was large with thin wall; Primary xylem of primary roots belongs to the typical exarch development pattern. The root caps developed very well, and cells were loosely arranged, with mucus-bearing outer walls and pectin substances internal.2. The cortex and the parenchyma of stele in the stem Internodes of macadamia cultivar contain mainly idioblasts with tannin. There was no lenticel differentiation in the epidermis cells and most of parenchyma cells in cortex contain chloroplast. Vascular bundles in the internodes were developed in a typical endafch pattern, and the number of vascular bundles in the nodes was significantly more than that at the internodes, whose cells were dense and small.3. The mesophyll cells in Leaf of macadamia cultivar were few and loosely arranged, and palisade tissue and spongy parenchyma were poor development. Lateral veins in Leaf were vigorous and there were few stomas per unit leaf area. As indexes for cold resistant, the cell tense ratio(CTR)was 0.18, the cell spongy ratio (SR)was only 0.45, and vein protuberant degree (VPD) was only 1.61.4. Flowers of macadamia cultivar were epigynous, with a single carpel and ventricle, 1-2 endogenous ovules, double integument and a thick nucellus. In general, the characteristics of inflorescence and ovary were in accordance with the traits of the Proteaceae family. The anther development was earlier than the stigma’s, and stigma elongation occurs during the flower opening. It was observed that the floral receptacle, calyx, ovary wall, stigma and filament cells contained large amounts of tannin. Pollen was 3-colporate, and one of them was for germination.5. Fruits of macadamia cultivar developed rapidly after fertilization. Fruit development could be divided into three stages based on microscopic morphology:1) un-distinguish development stage,2) distinguish development stage and 3) fully forming stage, which showed an "S" curved shape development. Endosperm developed from a transparent liquid to a translucent paste, and to a milky white paste and finally into a milky white kernel. Shell origins from the development of integument cells which eventually form a thick hard shell through the thicken cell wall and the differentiated sclereids. Peel, containing tannins, developed from the ovary wall by cell wall strongly thickening from the early parenchyma cells. The secreting glands occured in endocarp during the medium-term development, whose secreting cells died in the later period of peel development and the cell wall got into fibrosis and form a small cluster granulous structure.