Physiology of Crop Productivity in Cold Climate

Abstract

The goal of the present chapter is to give the reader a clearer sense of some of the many processes that involve mineral nutrients and ranges of rates at which those processes occur. Mineral nutrition of plants involves the acquisition of elements from the environment, and the organization and functioning of essential plant nutrients are a consequence of the interaction of deoxyribonucleic acid (DNA) of the plant with the environment. Because of the great complexity of plants, processes involving essential nutrient elements vary from relatively slow to relatively fast. Plants require 17 essential nutrients, and several other elements, such as cobalt, sodium, and silicon, have been found to stimulate the growth of some plants (Epstein and Bloom, 2005). Green plants obtain carbon from the air, whereas nonphotosynthetic plants such as fungi obtain carbon as saprophytes, breaking down organic materials of living or dead organisms. Unicellular and multicellular, photosynthetic, nonvascular plants such as algae obtain carbon and other essential elements with little transport from the environment to the site of photosynthesis, and the products of photosynthesis are transported relatively short distances to become new living tissue or to be expelled from the plant to the environment. Vascular plants, on the other hand, have evolved to move essential plant nutrients within the xylem and the phloem over distance far greater than the dimensions of the uncharged atoms, molecules, or ions containing the essential plant nutrients. The anatomy of vascular plants as well as nonvascular plants can be understood to include sources and sinks, between which mineral nutrients move. In addition, the plant itself can be viewed as a sink, which, as a result of the organizing force of DNA, is the recipient of essential nutrients of the plant that originate from the environment, which can be considered a source. Several means of measuring rates of transport of mineral nutrients in plants, other than velocity, include volume transfer (cm3 h−1), mass transfer (g h−1), and specific mass transfer (g cm−2 h−1) (Canny, 1960). CONTENTS