Changes in the Surface Characteristics of Capsules of Papaver somniferum L. During Maturation

Abstract

Changes in the surface characteristics of capsules of P. somniferum and their effects on contact angle and water penetrability were monitored in a commercial crop during the 1978-79 season. The wax crystals on the surface of very immature capsules, and of mature capsules in which interplant abrasion was prevented by secure staking, were typically rod-shaped, at least 3 µm long and about 0.5 µm thick. However, under normal field conditions, damage to the wax structure and loss of wax from the capsule surface occurred. By week 11 after full bloom, approximately 80% of the capsule surface showed signs of damage, while at week 13 deep cavities had appeared which, coupled with fungal activity, resulted in severe damage to the external pericarp wall.

Associated with these changes, the contact angles of water droplets on the surface of the pericarp decreased and the apparent ability of water to penetrate the capsule increased as the capsule matured.

The disappearance of alkaloids from capsules is discussed in relation to wax damage, water penetration through the capsule wall and stigmatic rays, and fungal activity.