1. USDA‐ARS, Agronomy Department, Agronomy Physiology Laboratory, IFAS Building No.350, University of Florida, PO Box 110965, Gainesville, FL 32611–0965, USA,
2. Laboratoire de Physiologie Végétale, Département de Biologie, Faculté des Sciences‐Semlalia, BP S 15 Marrakech, Morocco and
3. Department of Crop, Soil, and Environmental Sciences, Altheimer Laboratory, University of Arkansas, Fayetteville, AR 72703, USA