求助, 文章中的試驗設計圖(英文)

藍仔

我專題討論中,看不懂以下的試驗設計,請問有大大可以求助解答嗎??

A split plot design with 3 replications was used each year. 4 in row spacing (20, 25, 30 and 35 cm) were assigned to the main plots and 3 seed size (small, medium and large) were assigned to the sub plots.  Each sub-plots consisted of four rows having 5 m length and spaced 70 cm apart. Middle 2 rows in each plot were harvested by hand for determination of yield and yield components in 17 May 2006 and in 20 May 2007.

我跟著畫了以下的裂區設計,可是文章中紅字,我不懂以那2行收獲