弱小

Many animals display maternal instincts only while their offspring are young and helpless.

许多动物在其幼崽弱无法自助时都显出了母性的本能。

Results showed that germination percentage of urediospore, uredium number and sporulation of challenge inoculation race were reduced after inoculation with weak virulent race.

试验结果表明，弱导接可以降低挑接菌系的子萌、子堆数量、产量。