GROWTH-RESPONSE OF BOLBOSCHOENUS-MARITIMUS SSP MARITIMUS AND BOLBOSCHOENUS-MARITIMUS SSP COMPACTUS TO DIFFERENT TROPHIC CONDITIONS

Bolboschoenus maritimus (L.) Palla (= Scirpus maritimus L.) forms exte nsive stands in the littoral zone of small fishponds and as a weed in rice and maize fields. Within the species, two subspecies are distingu ished: Bolboschoenus maritimus subsp. maritimus, B. maritimus subsp. c ompactus. They differ in ecology, especially in their relationships wi th trophic conditions and salinity of habitats. To determine growth re sponse of these two types to different nutrient levels, we compared th eir seasonal development under experimental cultivation at four contro lled nutrient levels. Some differences between the subspecies were fou nd to be stable, regardless of nutrient level, namely greater amount o f smaller underground tubers and more extensive rhizome system in subs p. compactus compared to less numerous larger tubers and simpler rhizo me system in subsp. maritimus. In response to trophic conditions, the plants of subsp. compactus were more resistant to the conditions of th e highest trophic level than those of subsp. maritimus, which were str essed. This demonstrates better adaptability and spreading ability of B. maritimus subsp. compactus at high trophic levels.