SOME BOTANICAL VARIATIONS IN THE NEEDLES OF TWO PINUS SPECIES AFFECTED BY AGE AND PARTS OF NEEDLE, SHADING AND POSITION OF THE NEEDLE ON THE TREE. | ||||
| Journal of Plant Production | ||||
| Article 11, Volume 29, Issue 12, December 2004, Page 6993-7010 PDF (4.87 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jpp.2004.238949 | ||||
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| Author | ||||
| R. A. Fouda, | ||||
| ·Agric. Botany Dept., Fac. of Agric., Mansoura Univ., Mansoura, Egypt. | ||||
| Abstract | ||||
| Some botanical variations in Pinus halepensis and Pinus canariensis were investigated during summer and autumn of growing season 2003 to compare some morphological characters and anatomical structure of the needles and to evaluate their systematic significance. The anatomical variations in the needles affected by needle age and needle parts, shading and position of the needle from the soil surface were also studied. The obtained results could be summarized as follows: 1- There are noticeable morphological differences between the two pine species. P. canariensis is characterized by great number of needles per dwarf stem, remarkable length of needle, large needle sheath and an extension of the female cone dimension as compared to P. halepensis. Another remarkable morphological difference between the two species is nature of the surface of the young branches. It is smooth without decurrent needle sheath in P. halepensis, while it is rough with decurrent needle sheath in P. canariensis. These morphological features are used for identifying the two species. 2- Anatomically, the needle of P. halep < /em>ensis is characterized by thicker epidermis and endodermal cell layer and wider mesophyll tissue and resin ducts, but thinner transfusion tissue compared with P. canariensis. The most striking anatomical differences between the two species occur, mainly in the hypodermal cell layers. endodermis as well as number and size of resin ducts. The hypodermis occurs in 1-3 cell layers in P. halep < /em>ensis. but in distinct patches in P. canariensis. The resin ducts also were wider in P. halepensis with more diposion of resin materials in the epithelial cell layer compared with P. canariensis. 3- Anatomical examination of dwarf stem and basal portion of the needle Indicated that there is correlation between the number of vascular bundles and cortical resin ducts in the dwarf stem and both are correlated with the number of needles per dwarf stem. 4- The needle dimension was increased with increasing the needle age. Two years- old needles have higher number and large size of resin ducts compared with one year-old-needle. 5- The middle portion of the needle is characterized by wider hypodermis and mesophyll tissue as well as presence and wider endodermis. It had also greater number and larger size of resin ducts in the two pine species compared with both basal and terminal portions of the needle. The results indicate that the anatomical changes which took place in the lower portion of the needle, are represented by lower degree of a sclerified fibrous hypodermis, thinner mesophyll tissue without developed internal ridges on the cell wall. The unicellular endodermis is still recognizable. 6- Needle structure is largely influenced by light conditions. The needle developing under shade conditions had weaker hypodermis, thinner and poorly developed mesophyll tissue as well as the resin ducts are lesser in number and smaller in size compared with sun-light grown needle. All the recorded anatomical characters of the needles increased with an increase in height from the soil surface. On the other hand. it was found a positive relation between the number and size of resin ducts in the neddle and their contents of total phenolic compounds. | ||||
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