EFFECTS OF LIGHT, MAGNESIUM AND SUCROSE ON LEAF ANATOMY, PHOTOSYNTHESIS, STARCH AND TOTAL SUGAR ACCUMULATION, IN KIWIFRUIT CULTURED IN-VITRO

Shootlets of kiwifruit plants (Actinidia deliciosa) were cultured in v itro. Combinations of light intensity, Mg and sucrose in the cultures showed that an increase of light intensity resulted in a corresponding increase of the relative size of the leaf mesophyll cells and in a de crease of the numbers of chloroplasts and contained starch grains. The addition of sucrose to the substrate media negatively affected the si ze of the mesophyll cells under normal Mg concentration (35 mg l(-1)), and positively under high Mg concentration (105 mg l(-1)). Sucrose fu rther resulted in an increase in the numbers of chloroplasts and conta ined starch grains. The photosynthetic capacity of leaves greatly incr eased when Mg concentration was enhanced and sucrose was excluded from the nutrient substrate. Total sugar accumulation in all treatments wa s favoured by normal light intensity and addition of sucrose.