Effects of the Environment on the Symptom Pattern of Nickel Toxicity in the Oat Plant

Under conditions of nickel toxicity in oats (Avena byzantina),a predisposing condition for the development of chlorosis isinduced in areas of the leaf before emergence from the coleoptileor the enclosing leaf sheath. These areas give rise to chloroticbands which develop on the emerged leaf a little over 24 h afteremergence of the tissue. Alternating light and dark are essentialfor the development of chlorotic bands. The evidence indicatesthat the potentially green tissue is that which is developingunder the coleoptile during the day and emerges later in theday or early in the night, while the potentially chlorotic tissueis that which develops under the coleoptile during the nightand emerges from the top of the coleoptile later in the nightor during the following daylight hours before midday. Plants containing high levels of nickel contain higher levelsof protochlorophyll and lower levels of of chlorophyll thancontrol plants. The visual symptom of nickel toxicity is influenced by the lengthof the light and dark periods. The nature of these effects isdiscussed. Avena byzantina, oat, nickel toxicity symptoms, chlorosis