under ground portion meaning in Chinese

地下部分

Results dry matter accumulation of aerial part and under ground part of a . dahurica showed " s " curve , dry matter of aerial part gradually increased from the end of july to the early october and got to the peak in mid - october , then gradually decreased ; dry matter of under ground portion increased slowly in earlier stage and became rapidly from the end of august to the end of september , then reduced
结果白芷地上和地下部分干物质积累呈“ s ”型曲线，地上部分干物质在7月底至10月初逐渐增加， 10月中旬达到高峰，随后降低；地下部分干物质前期增加较慢， 8月底至9月底为快速增长期，随后增加稍有减慢。