The following points highlight the three main theories regarding ascent of sap. The theories are: 1. Vital-Force Theory 2. Root-Pressure Theory 3. Physical-Force Theory. Theory # 1. Vital-Force Theory: These theories state that the vital capacity of the living cells is responsible for the ascent of sap. Living cells like xylem parenchyma and ray cells remain intimately associated with the [...]
In this article we will discuss about Phloem Transport. After reading this article you will learn about: 1. Mechanism of Phloem Transport 2. Factors Affecting Phloem Transport. Mechanism of Phloem Transport: The mechanism of long-distance transport through the sieve tube is soundly based on the internal organization of sieve tubes, without which it remains speculative. Phloem tissue is composed of [...]
After reading this article you will learn about: 1. Phloem Sap Composition 2. Movement in Phloem Sap. Phloem Sap Composition: The major phloem sap components are carbohydrates. Analyses of the phloem exudates from various plants have shown that sucrose is the major transportable form of carbohydrate. In some species of Cucurbitaceous, in addition to sucrose, certain oligosaccharides like raffinose, stachyose, [...]