THE EFFECT OF PLANT ROOTS ON THE NEMATODE POPULATION OF THE SOIL

Abstract

The number of nematodes in the rhizosphere of wheat, barley, oats, soybeans, and peas is greater than in the adjacent root-free soil. Pratylenchus sp. is present in the rhizosphere of grains in greater numbers than in the rhizosphere of legumes; Paratylenchus sp. on the other hand showed a preference for legumes. Other genera identified were more abundant in the rhizosphere than in root-free soil, but were not as numerous as Pratylenchus or Paratylenchus, nor did they show a preference for any of the plants tested. One nematode species (Tylenchorhynchus) was present in small numbers and was equally abundant in the rhizosphere and in root-free soil. The consistent distribution pattern of nematodes in the rhizosphere of wheat and of soybeans, observed at high levels of illumination (1200 foot-candles), was not maintained when the illumination was reduced to 300 ft-c or less.