Influence of soil temperature on the development of pea root rot

Abstract

Pisum sativum vars. Early June, Early Sweet, and Sweet were grown in five root-rot soils and a sterilized control soil maintained at 28°, 26°, 24°, 22°, 18°, 16°, 14°, and 10 °C. Light intensity, day length, and soil moisture were kept constant. Data were recorded from seeding to mature plant development on loss of seed weight, gain in plant weight and height, losses due to preemergence killing and postemergence wilting, lesioning on the subterranean part of the epicotyls, and the fungi and nematodes found associated with the diseased tissues. Results showed that soil temperature generally, with distinct exceptions, had a definite influence on the growth of the peas, according to varieties, in the root rot soils. One fungus predominated as the causal agent of root rot for each variety: Fusarium spp. for var. Early June, which was highly tolerant to root rot soil, and Rhizoctonia solani for Early Sweet and Sweet, which were later maturing varieties. Pythium spp. was also involved in the root rot. The number of seedlings lost as a result of preemergence killing showed greater variation in relation to pea variety and root-rot soil than soil temperature, but postemergence wilting was correlated more closely with soil temperature. The variety Early Sweet was so susceptible to root rot over a wide range of soil temperatures as to preclude its general use in pea-growing areas.