000 02282nam a2200313Ia 4500
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100 _aThomas V
245 0 _aSeasonal activity of cambium and changes in bark structure of hevea brasiliensis
260 _bIndian Journal of Natural Rubber Research
_c2002
300 _a55-65
520 _aSeasonal activity of vascular cambium and bark anatomical parameters related to latex yield such as thickness of soft bark, latex vessel rows, height and width of ray cells in Hevea brasiliensis were studied for two consecutive annual cycles. Climatic variations have significant influence on cambial rhythm. With the onset of rain in April-May, the cambium started to divide periclinally to produce daughter cells, which differentiated into secondary vascular tissues. Mean maximum thickness for the cambial zone was the highest during monsoon (June-September) and least during summer (February-May). Bark thickness was high during July to October and low during February to May. The number of latex vessels rows in the soft bark was higher during the monsoon season and declined gradually in the succeeding months to a considerably lower number during the summer. While ray height showed significant variation between seasons, width did not. Starch grains varied considerably both in size and distribution in bark, cambium and wood width seasonal fluctuations and were not located in the soft bark during January to March. Calcium oxalate crystals were found throughout the year in the bark with abundance in the month of June, November and February. Depletion of crystals was noticed in August, January and May. The role of reserve metabolities and especially that of crystals in plant metabolism is discussed.
650 _aCalcium oxalate crystals
650 _aCalcium oxalate crystals
650 _aHevea brasiliensis
650 _aHevea brasiliensis
650 _aLatex vessels
650 _aLatex vessels
650 _aSeasonal cambial activity
650 _aSeasonal cambial activity
650 _aStarch
650 _aStarch
650 _aVascular ray
650 _aVascular ray
700 _aNair R B
700 _aSailajadevi T
700 _aSaraswathyamma C K
700 _aShankar S
942 _cAR
999 _c47086
_d47086