Abstract:
Moist filter papers are widely usedfor seed gennination tests but their water confent and matric suction
are not usually controlled. A technique for controlling filter paper matric suction is described and
usedfor germination studies involving fresh and aged sorghum seed (Sorghummcolor (L) Moench).
Filter papers wetted to matric suctions of 0.1 ,land 10 kPa were used to study germination, root and
shoot growth rate offour cultivars (M35-1, ICSV-1l2, CSH-9 & CSH-ll) of sorghum at 25°C. Time
to germination, root and shoot growth were all affected by the increase in matric suction from either
0.1 to 1, or 1 to 10 kPa. Root and shoot emergence ratefrom seeds, decreased with increasing matrie
suction. The increase in matric suction resulted in significant reductions (P= O. 05) in final root and
shoot length. Final germination percentage was not affected by variation§ in matric suction. Ageing
delayed shoot emergence. Seedlings with emetged shoots were significantly fewer at 10 kPa as
compared to 1 kPa only for aged seed, and for all cultivars except Icsv-i 12. A link between matrie
suction, seed-liquid contact area and the rate of water uptake by seed is demonstrated. We conclude
from this study: that changes in the matric suction on filter paper even at the wet end will cause
variations in gennination rate and therefore ought to be controlled during germination tests. Seed
tests separated in time and space can not be compared iffilter paper matric suction is not controlled.
