Physiological Diseases

Abstract

Physiological disorders can be caused by several abiotic factors such as frost (Fig. 8.1), high temperatures, low soil pH, phytotoxicity caused by agricultural chemicals (Fig. 8.2), “melanosis” (Fig. 8.3), as well as nutritional imbalance. The gene Sr2 conferring resistance (slow rusting) to stem rust, is known to be linked with pseudoblack chaff expression in glumes and near nodes of the stems, also called “melanosis”. Soil acidity and low pH caused stunting of the plants which remain sterile and the phenomenon is referred to as “crestamento” in Latin-America. For details, the reader may refer to some specific publications (Snoball and Robson 1991; Mcfadden 1939; Sanderwirth and Roelfs 1980).