72679 - Environmental Stress Disorders

Learning outcomes

At the end of the course, the student will acquire skills to identify the main disorders and  alterations of plants and of their products caused by climate, weather and/or edaphic  stressing conditions. He will be able to identify the physiological and morphological modification induced by water, temperature, nutrient, light and pollution stresses that precede the appearance of the disorders.

Course contents

Course contents

A)     Prerequisites

Courses student need to have taken before: physics, plant biology, plant pathology, agricultural chemist and general agronomy. These basic and applied courses are provided in year 1 and 2 of the degree.

B)     Teaching units

1. Introduction  to the course (TUs  2 h)

Syllabus presentation and discussion – lectures, demonstrations, study visits, class material, contacts, final exam. Objectives and importance of the course within the degree and the profession of agricultural technician, with a particular emphasis on climate changes effects. Students suggestions and requests will discussed.

 

1. Brief information about stress physiology (TUs 2 h)

Skills acquired in TU 2:

• Effects of environmental conditions on plants
• Main strategies of the plants to adapt  to the various environments and to their changes
• Main diagnostic methods of the stress disorders   

1. Water stress disorders (TUs  6 ore)

Water deficit  general aspects, effects on plants , resistance to drought, main disorders and alterations

Water saturation and flooding (lack of O2) General aspects, effects on plants, resistance to flooding, disorders

Skills acquired in TU 3:

• Mechanisms of drought tolerance in plants
• Main disorders and alterations induced by water deficit
• Influence of drought stress on plant susceptibility to diseases
• Effects of  low relative humidity on postharvest life of  fresh plant products
• Influence  water saturation of the soil  on plants anoxia stress
• Main disorders and alterations of roots in water saturated soils
• Tolerance to flooding  of the main crops   

1. Temperature stress disorders (TUs  7 h)

Heat stress General aspects, effects on plants, resistance to heat, main disorders and alterations.

Chilling stress- General aspects, effects on plants, resistance to low temperatures, main disorders and alterations

 

Freezing stress - General aspects, effects on plants, resistance to negative temperatures, main disorders and alterations

Skills acquired in TU 4:

• Influence of high temperatures on alteration of plant physiological processes
•  Main adaptation strategies of the plants to high temperatures
• Disorders induced by high temperatures
• Plants susceptibility to chilling disorders depending on plant climate zones, cell membrane composition and ROS control.
• Disorders induced by chilling and freezing in field and in  storage conditions
• Susceptibility of plants to freezing disorders
• Plants acclimatation strategies  to frost
• Passive and active methods to prevent frost damage 

5. Light stress disorders  (TUs  3 h)

Photoperiodism, short day, long day and day neutral plants; abnormal day length effects on some plants (bloom, growth, productivity). Effects of light deficiency: etiolation, whitening (blanching) and shading. Effects of light intensity and wavelength. Effects of UV C on plant disease resistance.  Greening of root crops and potatoes  and  build up of toxic glycoalkaloids. 

Skills acquired in TU 5:

• Influence of photoperiod  on life and productivity of plants
• Main disorders and alterations induced by light deficiency and abnormal wavelength 

6. Nutritional stress disorders ( TUs 5 h)

Brief information about mineral nutrition definition of nutrients and their activity, healthy condition, nutrient  mineral elements, macro and micro nutrients. Definition of nutrient deficiency, Liebig’s law, root absorption, mineral interaction, chronic and acute deficiency. Diagnosis of nutrient deficiency, symptoms,

tissue and soil analysis. Main disorders caused by N, P, K, Ca, Fe deficiency. Influence of mineral elements on diseases. Management of plant nutrition.

Skills acquired in TU 6:

• Importance and influence of mineral nutrition on growth and plant health
• Main methods and technics for the diagnosis of  mineral deficiency in plants
• Main disorders induced by nutrients deficiency
• Effects of mineral deficiency on susceptibility to biotic diseases

7. Allelochemicals  induced disorders ( TUs 3 h)

Definition of allelochemicals and allelopathies, mechanisms of production and release of allelochemicals, types of allelopatic interactions, effects of allelopathic substances. Examples of releasing plants, allelopathic control of weeds. 

Skills acquired in TU 7:

• Main allelopathic substances that induce disorders in plants
• Allelopathic substances for weed control.

    8. Exercises and study visits (TUs 12 h)

The exercises and study visits aim at deepening, from a practical point of view, the concepts presented during lectures. Specific emphasis will be devoted to the  technics  for the diagnosis and to the  symptoms induced by the various stress agents, on the main crops. For  this purpose power point presentations visualizing diagrams, figures, outlooks,  and  images of the disorders  are shown together with collected fresh specimens.

A study tour to research centres e bio-monitoring stations is  organized to help students to understand,  through “case studies†of  applied diagnostic technics and control methods and how disorders impact real world.

Readings/Bibliography

Readings/Bibliography

Taiz. L, Zeiger E. (Translated by Maffei M.) Fisiologia Vegetale. Piccin Nuova Libraria SpA. Padova, 2006. Only chapters: 5 - La nutrizione minerale  e  26 - Fisiologia dello stress. (also at  Biblioteca centralizzata G. Goidanich).

Additional  readings:

Shurtleff C.M., Averre W.C. The plant disease clinic and field diagnosis of abiotic diseases. APS press, St. Paul, Minnesota, 1997

Teaching methods

The course is divided into two teaching modules:

1)       Class room  lectures with power point presentations visualizing diagrams, figures, outlooks. Students’  discussion, curiosity, and critical thinking on plant stress and the causing agents is stimulated. T heir progresses and hurdles  will be informally assessed through the talks.

2)       Exercises and study visit, see 8

Assessment methods

The knowledge acquired in this course  is assessed via a written examination lasting 40 minutes. It consists of 31 quizzes and  open-ended questions, referring to the entire course program. Each question/quiz is marked with a maximum of 1 point (31 responses, evaluated with the maximum score, allow to achieve a final score of 30 cum laude). Students are assessed on at least 4 teaching units. The exam will last 40 minutes. The aim of the evaluation is to assess the overall capacity of the student to address problems areas in the field of environmental disorders and their control and to recognize the symptoms on the main crops. 

Teaching tools

PC, video-projector and plant parts damaged by environmental stress

Office hours

See the website of Paolo Bertolini