The influence of temperature on growth and nodulation of White Clover infected with Bean yellow mosaic virus.

important factors in loss of stand of white clover (Trifolium refocus L.). Kreitlow et al. (5) showed that bean yellow mosaic virus reduced clover yields 23 to 55% in the field. Houston and Oswald (2) isolated several viruses from white clover and related all of them either to bean yeiIow mosaic or to alfalfa mosaic. Various other factors have been shown to be involved in the control of plant growth responses. Jones and Tisdale (3) demonstrated the influence of temperature on nodulation and growth of soybeans and other leguminous crops many years ago. They showed that growth and yield increased with increasing temperature to a point then decreased as the temperature was increased. More recently Kasannis (4) showed the influence of temperature on virus multiplication in plants. He found that some viruses would multiply at temperatures as high as 97° F. while others would not. Baxter (1) found that virus-infected white clover plants could be grown at 50° F. and cuttings from the new tissue were free from the virus which infected the older tissue. These reports show some of the results of research on individual factors as they influence plant responses. This research combines several factors for simultaneous observation and was set up to determine the effect of temperature on healthy and virus-infected white clover in the presence or absence of rhizobia inoculation under controlled environment.