(N/A) The five main deficiency symptoms observed in plants are:
$1$. Chlorosis: This is the loss of chlorophyll leading to the yellowing of leaves. It is caused by the deficiency of $N, K, Mg, S, Fe, Mn, Zn,$ and $Mo$.
$2$. Necrosis: This refers to the death of plant tissues,particularly leaves. It is caused by the deficiency of $Ca, Mg, Cu,$ and $K$.
$3$. Inhibition of cell division: This leads to reduced growth and is caused by the deficiency of $N, K, S,$ and $Mo$.
$4$. Delayed flowering: This occurs when the concentration of essential nutrients is low,specifically due to the deficiency of $N, S,$ and $Mo$.
$5$. Stunted plant growth: This is a general symptom of poor development caused by the deficiency of $Cu$ and $S$.