Plant Growth and Crop Production

Abstract

Higher plants have specialized organs characterized by specific metabolic processes. For growth and crop production one may distinguish between organs in which primary organic molecules are produced and organs in which organic matter is stored or consumed. In Crop Physiology the former are called physiological sources and the latter physiological sinks. Most important sources are green photosynthetic plant tissues in which chloroplasts import inorganic constituents to synthesize primary organic molecules such as sugars and amino acids (see page 149 and 174). Physiological sinks are meristematic tissues which use the primary molecules for growth and storage tissues such as fruits, seeds, stems, tubers and roots. The flow from the source to the sink is almost exclusively mediated by phloem transport. Partitioning of these primary molecules, the photosynthate, and their long distance transport from source to sink are essential processes for growth and crop production which is considered in the following sections.