通过本章的学习,使学生掌 握果蔬贮运期间侵染性病害病原菌侵染 的规律、影响发病的因素及综合防治措 施、生理性病害发生的原因及控制措施; 了解部分果蔬贮运中主要侵染性病害和 生理性病害的发生特点和防治措施;了 解果蔬贮运中主要害虫的种类及其危害, 掌握防治贮运害虫的措施

Aims of this lecture Summarize properties of the rhizosphere, especially Gradients in Nutrient concentration Redox potential Exudates Microbial activity Non-infecting rhizosphere microorganisms Infecting rhizosphere microorganisms that are relevant to plant mineral nutrition red from H Marschner:

Scope of this lecture Root functions: for plant, soil and ecosystem Root structure and pathways for uptake of nutrients the symplast and apoplast Root architecture(结构) and morphology(形态) Responses of roots and root systems to environmental stress Root hairs and their functions Introduction to combined strategies for efficient

THE CELL WALL Before traversing the plasma membrane(p. m., ions must first cross the cell wall and contact the p. m the bulk flow of soil solution coul theoretically carry inorganic ions into the cell wall and through the apoplastic pathway. The thickness of a cell wall is in the range of 500 to 1000 nm. It is porous

Concept of plant nutrition Plant nutrition is a term that takes into account the interrelationships of mineral elements in the growth medium as well as their role in plant growth

Acknowledge I expresses thanks to Assoc. Prof. rob Reid of Adelaide university of Australia, Dr Jeff Gale, foreign teacher of northwest A&F University of China, and Prof. Zhang Fusuo, Prof. Li Xiaolin of China Agriculture University, Prof Liu Yuanyin of Northeast agriculture Unversity and other authors who provide materials for me, or whose materials, such as photographs and figures etc, I used in the lectures

Phosphorus in plant physiology P content of plants Approximately 0.2% of plant dry weight is P Plants require a relatively large amount of P. The phosphate concentration in the cytosol is maintained at fairly constant concentrations in the 5 to 8 mol/m3 regardless of the external phosphate concentration except under severe P deficiency. By contrast is the vacuolar phosphate concentration

Plant nitrogen 1.1 Uptake of N 1. N is required by plants in large amounts Most plant material contains 2-4%N and 40%C. 2. N is usually the limiting nutrient in unfertilized systems 3. Most n is taken up from the soil in the form of nht or no a small amount of NH3 can be absorbed through the leaves N2 can be used by legume plant via biological nitrogen fiXation

The principles of application fertilizers Law of the Minimum: the crop's yield is restricted by the lack of one element, even Mg- al Zn S though there may be sufficient quantities of all the

Soil fertil Soil fertility is the characteristics of soil that enables it to Provide nutrients in adequate amounts in adequate time In appropriate balance for growth of particular plant(s)