Water relations of some annual weeds
1992
Kazinczi, G. (Pannonian Univ. of Agriculture Sciences, Keszthely (Hungary). Inst. for Plant Protection) | Hunyadi, K.
We have examined the water relations of weeds of different growth form (Digitaria sanguinals (L.) Scop., Matricaria inodora L., Alopecurus myosuroides Huds., Apera spica-venti (L.) P. Beauv., Papaver rhoeas L.). We have studied the change of actual water saturation deficits (WSD) of the leaves during the vegetation period. The weeds were compared on the basis of their sublethal WSD, relative drought index and specific survival time. All of the experimental plants have an unstable water balance because the values of the actual WSD changed considerably during the growing season and seemed to be in connection with the rainfall. The actual WSD was the highest in case of Matricaria inodora L. and Apera spica-venti (L.) P. Beauv. (40-42 per cent). The index of sublethal WSD is considerable only in case of Digitaria sanguinalis (L.) Scop. (71 per cent), it means that water-saturated leaves can lose even 71 per cent of their water content without irreversible injuries. The relative drought index never reached 100 per cent, Matricaria inodora L. had the highest value (85.2 per cent). Water losses of isolated leaves at the beginning are significant, leaves already lose the water equal with their sublethal WSD in half an hour. The specific survival time is the highest at Digitaria sanguinalis (L.) Scop. (2.47 hours), followed by Papaver rhoeas L. over Matricaria inodora L. over Apera spica-venti(L.) P. Beauv. over Alopecurus myosuroides Huds. The conclusion is that among the experimental weeds only Digitaria sanguinalis (L.) Scop. has considerable drought-resistance due to its high sublethal WSD and comparatively reduced cuticular transpiration
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