7: Khan et al 2002

Question 1

what were desmodium uncinatum and desmodium intortum found to do?

Answer 1

reduce infestation of maize by parasitic witchweed striga hermonthica

Question 2

what happened when an aqueous solution was taken from D.uncinatum pots to irrigate maize with high s.hermonthica levels?

Answer 2

parasite growth almost completely suppressed and infestation reduced

Question 3

what can the desmodium species be used as and why?

Answer 3

intercrops as have high value and reduce witchweed infestation

Question 4

which of the species had the most effect on reducing s.hermonthica infestation?

Answer 4

D.intortum

Question 5

when exposed to D.uncinatum root exudates what can be observed?

Answer 5

inhibition of primary haustoria

Question 6

in what ways can parasitic witchweed be controlled?

Answer 6

• increase available N in soil
• shading
• allelopathic effect from chemicals produced by desmodium roots

Question 7

what may be a downside to the allelopathic effect?

Answer 7

depletion of viable seeds in the soil and may reduce farmers productivity

Question 8

how may shading help prevent emerging witchweed?

Answer 8

reduce temp and raise humidity so reduces transpiration and supply of nutrition from host

Question 9

what was the level of suppression observed greater than?

Answer 9

than would be expected through effects of shading and N addition

Question 10

which combination had the largest effect?

Answer 10

maize + desmodium + N

Question 11

what does the allelochemical effect do?

Answer 11

• less growth of striga when exposed to desmodium
• suicidal germination
• increased maize performance