Hypogenetic plant, lower photosynthetic rates and enzyme activities decrease self-resistance of the cucumber plant to disease.These form the internal-causes of cucumber disease outbreak.

• 黄瓜植株生长发育不良，黄瓜的光合速率及抗性酶活性降低，植株自身抗病性下降，是引起黄瓜病害发生加重的内因；