Abstract
The eggs of the root knot nematode in the root gall develop in the form of egg-mass embedded in a protective jelly. The egg-masses cause damage to the crops next season. Under favorable conditions they hatch quickly and become free in the soil. The larvae which are the second stage in the development of the nematode move and infect host plants.
Studies were made in order to find out the environmental conditions which might hinder the hatching of eggs. Conditions such as high and low temperatures, desiccation, direct sunlight, ultra-violet rays, and hydrogen-ion concentration were tested.
In Meloidogyne incognita var. acrita, the hatching of eggs were hindered by the temperatures below 0°C while it was inhibited at -6°C for 20 days or -10°C for 5 days. In M. hapla the inhibition took place when exposed at -10°C for 20 days.
The resistance to high temperatures in the two varieties of nematodes was likewise similar: hinderance to hatching occurred at above 40°C, while at 42.5°C for 20 minutes or 45°C for 5 minutes inhibition took place.
The response of the nematodes to desiccation was more delicate. Between 85±2% and 70±2% air humidity the hinderance to hatching was remarkable, while at 70±2% for 2 hours or 60±1% for 1 hour the complete inhibition was observed.
Exposure to direct sunlight for 4 hours caused complete inhibition of the hatching of eggs.
Ultra-violet rays did not cause inhibition at an exposure of 5 hours. Within the limits of experiments performed, hydrogen-ion concentration had least effect upon the hatching of eggs of the nematodes.
The hatching process of eggs showed specific type when the eggs were exposed to desiccation and direct sunlight. The hatching process of them were normal for other conditions tested, except the ultra-violet rays which was intermediate.