Fig. 6
The protease and peptidase activity in boll wall under different planting densities in 2018. D1-D5: 15 000, 25 000, 45 000, 60 000, and 75 000 plants per hectare. The vertical bar represents S.E. of the mean (n = 3) when the value exceeds the size of the symbol. Lowercase letters indicate significance analysis among protease activity, and capital letters indicate significance analysis among peptidase activity. The same letter among treatments is not significantly different (P ≥ 0.05)