6: Graves et al 1989

Question 1

what measurements can be used to form a carbon balance model?

Answer 1

growth and gas exchange

Question 2

what does striga reduce and maintain?

Answer 2

reduce: growth + grain and stem weight
maintain: leaf and root biomass

Question 3

how may sorghum host plant productivity be lost?

Answer 3

C export to parasite striga hermonthica and parasite reductions in host photosynthesis

Question 4

what proportion of total parasite C requirement does host derived C account for?

Answer 4

1/3

Question 5

why is striga dependent on host C export?

Answer 5

because it has low photosynthesis and high respiration rates

Question 6

when do most reductions in host photosynthesis occur?

Answer 6

before emergence above ground

Question 7

what type of root system does striga hermonthica have?

Answer 7

vestigial- maintains vascular continuity with host

Question 8

what was the dry weight of infected sorghum like compared to uninfected?

Answer 8

over 40% less

Question 9

what happened to grain yield of infected hosts?

Answer 9

reduced to negligible levels

Question 10

what happened to the stems of the infected?

Answer 10

shorter with reduced internodal distance

Question 11

what is the main factor for reduced growth in infected sorghum?

Answer 11

reduced photosynthesis and transfer of C from host to parasite

Question 12

before and after emergence how did striga reliability on host plant change?

Answer 12

before- entirely dependent

adult- less so

Question 13

what % of host production reduction was due to

• diversion of C to parasite
• lower rates of C fixation by host

Answer 13

20%

80%

Question 14

what may alleviate the effects of parasite on crop productivity?

Answer 14

use of cultivators to maintain photosynthetic capacity during infection