|Crowley, David - UNIVERSITY OF CALIFORNIA|
Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 2, 1996
Publication Date: N/A
Interpretive Summary: Metal ion deficiencies in avocado cause severe losses in productivity and cultivation efficiency. Such deficiencies in avocado have traditionally been difficult to correct by conventional application methods. In this study, a rapid and reliable means of testing for iron deficiency in avocado trees is reported. This will aid growers and extension agents to: 1) rapidly identify iron deficiency in avocado trees, and 2) monitor the efficiency of new methods of iron applications. The changes that are reported in iron deficient avocado will add to the understanding the deliterious effects of inadequate iron in plant tissue.
Technical Abstract: Physiological responses to Fe-deficiency were characterized in the roots and leaves of avocado plants. These responses included sharply higher catecholase activity, but slightly lower peroxidase activity in leaves and roots of avocado seedlings grown in minus-Fe nutrient solutions, and in Fe-deficient leaves of field trees. Fe- deficiency in avocado seedlings resulted in much higher rates of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) reduction on the root surfaces. Similarly, the initial rates of FeHEDTA reduction were greater for roots of Fe-deficient avocado seedlings. In contrast, root respiration rates were relatively unaffected by Fe-deficiency. Large differences in the Mn and Zn concentrations in the leaves of the Fe-deficient and Fe-sufficient avocado seedlings suggested that the physiological responses that occurred in the roots during Fe-deficiency influenced the uptake of other metal micronutrients.