INFLUENCE OF NATIVE ENDOMYCORRHIZA, SOIL FLOODING AND NURSE PLANT ON MYCORRHIZAL STATUS AND GROWTH OF PURPLE NUTSEDGE (CYPERUS-ROTUNDUS L)

A study was made to investigate the effects of native endomycorrhizal fungi, soil flooding and nurse plant (onion) on the mycorrhizal status , growth and phosphorus (P) uptake of purple nutsedge (Cyperus rotundu s L.). Above ground (AG) and below ground (BG) dry weight of mycorrhiz al purple nutsedge plants were significantly lower than the non-mycorr hizal plants, but ratios of BG:AG dry weight were the same except when grown with onion. Mycorrhizal infection was characterized by vesicles and hyphae, both intraradical and extramatrical, but lacked arbuscule s. Percentage root colonization of purple nutsedge and onion was signi ficantly higher when the two grew together, but plants growing alone h ad less infection. Flooding of soil inhibited mycorrhizal formation in purple nutsedge, and mycorrhizal infected plants produced smaller tub ers than uninfected plants. AG tissue P concentration was lower in myc orrhizal purple nutsedge but BG P concentration had no significant var iations between infected and uninfected plants. P utilization efficien cy (PUE) was similar for mycorrhizal and non-mycorrhizal purple nutsed ge. Plants in flooded soil had the maximum AG and BG dry weights, tube r dry weight and P content, but had lower AG:BG dry weight ratio and P UE.