Phenomenal progress has been made in our understanding of the several and diverse ways in which micronutrients alter or regulate the functioning of plants and produce a wide array of responses enabling quantitative and qualitative changes in plant yield. This book addresses biochemical and physiological roles of micronutrients in plants and the diverse ways in which they react to limitations in micronutrients supply, contributing to global constraints in crop production. The book is presented in two parts. Part I deals with roles of micronutrients and the changes induced in plants in response to their inadequate supply. Part II addresses the factors contributing to micronutrients deficiency, their diagnosis, evaluation and management through soil and plant based approaches.