Structure Development of Cassva Tuberous Root in Field-grown and in vitro

Manihot esculenta Crantz cv.South China 8 was used as the experimental material.The method of tissue culture was applied to obtain the micro-tuber.The development and morphological structure of cassava in micro-tuber and tuber was studied by the method of anatomical technology.The conclusions of the analysis are as follows: 1) In vitro,there was no secondary tissue formed in the whole procession of micro-tuber induction.The expansion of micro-tuber was the results of the enlargement of cortical parenchyma cell volume and intercellular space.Not like micro-tuber,the tuber in field-grown formed secondary tissue and a large number of starch grains stored in xylem parenchyma cells.2) There was a time and space difference in starch accumulation between micro-tuber root and tuber.There was no starch grains in micro-tuber until five to ten days cultured.A small amount of starch grains occurred in the cortical parenchyma cells.The starch in field-grown cassava roots was produced in the primary root after secondary structure beginning to accumulate.Starch mainly accumulated in the secondary xylem parenchyma cells.A small number of distribution in the cortex and phloem.