Longidorus Elongatus and Tylenchorhynchus Dubius On Lolium Perenne

Abstract

The growth of Lolium perenne plants at about 20° C until eight weeks after sowing and their final leaf weight was not or hardly affected by population densities of Longidorus elongatus between 0 and 10 nematodes per g soil at the beginning of the experiment, multiplying to five times the initial density in eight weeks, with a maximum of 5 nematodes/g soil. However, water consumption and final root weight at the highest initial nematode density were reduced to about a quarter of that at 0 to 0.4 nematodes/g soil. Water consumption during the last three days of the experiment was proportional to root weight. Contrary to L. elongatus, Tylenchorhynchus dubius hardly affected the shoot weight to root weight ratio of L. perenne at the end of the experiment. Apparently attack by L. elongatus puts the regulation of the shoot weight to root weight ratio out of action, whereas attack by T. dubius did not. As, apparently, L. perenne could grow at the normal rate with a much smaller root mass than present normally, T. dubius attack did not reduce growth by reduction of the quantity of water and plant nutrients available to the plants.