Da. Dawoud et J. Sauerborn, IMPACT OF DROUGHT STRESS AND TEMPERATURE ON THE PARASITIC WEEDS STRIGA-HERMONTHICA AND ALECTRA-VOGELII IN THEIR EARLY GROWTH-STAGES, Experimental Agriculture, 30(2), 1994, pp. 249-257
The effect of simulated drought on the germination of Striga hermonthi
ca and Alectra vogelii was studied in growth cabinets. Drought stress
was applied either during the preconditioning of the seeds or at the t
ime of application of the germination stimulant. The response of these
weeds to a range of alternating day/night temperatures during germina
tion and their attachment to the host plant was also investigated usin
g root chambers. During the preconditioning period S. hermonthica was
not sensitive to variation in osmotic potential between 0 and -1.5 MPa
but A. vogelii required longer preconditioning periods at -1.2 and -1
.5 MPa. The germination of both parasites was significantly reduced by
increasing the osmotic potential of the stimulant. Optimum day/night
temperatures for germination and attachment of S. hermonthica were 30/
20-degrees and 35/25-degrees-C, and of A. vogelii 25/15-degrees and 30
/20-degrees-C. Deviation in temperature from the optimum significantly
reduced the germination and attachment of both parasites. The results
show that S. hermonthica is more adaptive to adverse climatic conditi
ons of increased osmotic potential and extreme temperatures than A. vo
gelii.