求翻译：茎中薯蓣皂素含量低且稳定，根状茎中薯蓣皂素含量总是高于叶片，峰值出现在7月初，而叶片中出现在6月初。是什么意思？

Stem diosgenin low and stable, rhizome in diosgenin content is always higher than the leaves, the peak in early July, while the leaves appear in early June.

elephant's foot stems in soap quality content is low and stable, the elephant's foot soap shaped stems in leaf is always higher quality content, a peak in early July in leaf, which appeared in early June.

In the stem the Chinese yam saponin content is low also is stable, in the rhizome the Chinese yam saponin content always is higher than the leaf blade, the peak value appears in the beginning of July, but in the leaf blade appears in the beginning of June.

Stem and diosgenin content in low and stable and that content of diosgenin in Rhizome is always higher than the leaf, peak at the beginning of July, and the leaves appear at the beginning of June.

Stem and diosgenin content in low and stable and that content of diosgenin in Rhizome is always higher than the leaf, peak at the beginning of July, and the leaves appear at the beginning of June.