Calcium-Related Physiological Disorders of Plants

Abstract

Many ohhe physiological disorders,aftlicting both storage organs, such as fruits, certain vegetables, roots, and young, enclosed leafy structures are related to the Ca content of the respective tissues. Improving their Ca content normally diminishes the occurrence of the respective disease. Shear (157) has listed more than 30 Ca-deficiency disorders and this list probably will be extended as research. in this field proceeds. These disorders are believed to be due to an inefficient distribution of Ca rather than POOf. Ca uptake. This problem is illustrated by the observation that leaves contain considerably more Ca than storage organs or young enclosed tissues from the same plant ( 19,23, 126). Poor Ca distribution within the.plant can also explain both the frequent appearance of Ca-deficiency disorders leven on Ca-rich soils and the failure of Ca· fertilization, although often not done (123), to solve this problem. Ca has received considerable attention in recent years not only because of its relationship to physiological disorders but also because of other desir­ able effects, particularly in fruits where it can reduce respiration ( 13, 26), delay ripening ( 155), extend storage life ( 155), increase firmness ( 13, 40) and vitamin C content ( 12), and reduce storage rot ( 155). The continued in­ crease in interest in the effects of Ca on different physiological processes in plants as well as in its uptake and distribution within the plant is indicated by some international symposia on this subject. The reports of these sym­ posia, together with some comprehensive reviews, cover a great deal of the relevant literature (28, 3 1, 33, 49;, 52, 57, 70, 80, 108, IB, f57, 203).