Boron Deficiency in Drug, Fumitory, and MasticaTORY Crops

In the field, boron deficiency is normally evident as stunted growth, following poor extension of the internodes; very few pods are formed. When the deficiency is more severe, growing points cease to grow and the upper leaves are small and spoon shaped. Stems are stiff and brittle, and flowers do not expand normally.

Boron deficiency causes dieback of the growing point, and the loss of apical dominance results in profuse lateral bud break and multiple, stubby shoot formation. The malformed leaves are often broad, very small, thick and twisted. Internodes are short. Boron deficiency causes profuse flowering, increases the flower size, and results in a preponderance of female flowers. Typically these female flowers do not set fruit and they fail to abscise. Fruit set is reduced and there is an increased incidence of parthenocarpic fruit.

In young poppy plants with boron deficiency, the leaves roll back along the midrib. The heart of the plant is stunted or deformed and soon rots, becoming dark violet in color. The midribs also show the same color. Death of plants is hastened by fungal and bacterial attack.

In other cases, the leaves may appear normal but the young seed heads turn blue while the capsules are deformed. In these capsules, seed set is poor. The stalks often show blisterlike swellings and later split.

The characteristic symptoms of boron deficiency are short internodes and dieback of the apical meristem. The first sign is the development of a basal chlorosis on the youngest leaves. When the whole leaf is not affected, the leaves subsequently expand but become distorted. The leaves are often one-sided and twisted. Likewise, the stem near the top of the plant is often twisted.

After the death of the apical growing point, suckers are likely to develop but these are also prone to dieback. The leaves become stiff and brittle as they mature and as a result, the midribs frequently break.

When the deficiency does not become acute until the flowering stage, many flowering buds are shed and very few seed pods set.