Abstract：This experiment measured peel hardness of 2 seed-used Cucurbita pepo sister lines by shore
hardness tester，and carried out slice observation and grain plumpness measurement．The correlation between
peel hardness and grain plumpness was also analyzed．The results showed that there were extremely significant
differences in pericarp hardness of Cucurbita pepo sister lines．The peel hardness of Q212-6-3-1 with hard
peel was 30.3 HD．The width of epidermis 10 columnar cells was 3 526.7 μm．The epicarp thickness was
3 792.6 μm．The thickness of mid mesocarp was 27 700.0 μm．Its difference with soft peel Q212-6-3-2 was
significant or extremely significant．The hundred-grain weight of hard peel fruit was extremely significant
higher than that of the soft peel fruit．Pericarp hardness and hundred-grain weight presented extremely
significant positive correlation．The harder of the peel，the bigger of the hundred-grain weight，the more
plump of the grain．Therefore，hard pericarp could be taken as a major target trait for seed-used Cucurbita
pepo breeding．
