W1-2-60-1-6
JOMO KENYATTA UNIVERSITY OF AGRICULTURE AND TECHNOLOGY
UNIVERSITY EXAMINATIONS 2016/2017
YEAR I SEMESTER I EXAMINATION FOR THE DEGREE OF MASTER OF SCIENCE IN HORTICULTURE
AHS 3103: PLANT NUTRITION
DATE: DECEMBER, 2016 TIME: 3 HOURS
INSTRUCTIONS: Answer Any FOUR Questions.
Question One
Describe the current theories of ion uptake across root cell membranes while highlighting their strengths and weaknesses. [20 marks]
Question Two
a) Discuss the processes that hinder the solute movement across the root to the xylem. [6 marks]
b) Explain with examples four factors that influence the rate of ion absorption by the roots. [8 marks]
c) Ion uptake by roots has a consequence on the chemistry of rhizosphere. Discuss giving practical examples. [6 marks]
Question Three
a) Describe the processes of ion transport in the xylem and in the phloem while highlighting factors that retard their movement in these vascular vessels. [15 marks]
b) Describe the process of phonem unloading to sink sites. [5 marks]
Question Four
a) Discuss with examples of particular plant nutrients, how the latter influence root morphology. [10 marks]
b) Explain the parameter shoot/root ratio and how it is influenced by plant nutrition. [4 marks]
c) Using nitrogen as an example, explain how it influences sink formation in plants. [6 marks]
Question Five
a) Differentiate between disease tolerance and resistance. [2 marks]
b) Discuss the mechanisms in which plant nutrition may impart disease tolerance in plants. [12 marks]
c) Explain how potassium imparts disease tolerance in plants. [6 marks]
Question Six
a) Discuss four mechanisms of alumininum tolerance in plants. [12 marks]
b) To apply ammonium nitrogen or nitrate nitrogen depends on various factors related to plant and media. Discuss. [8 marks]
