Effects of Light and Temperature on the Association between Zea mays and Spirillum lipoferum

Zea mays was grown on a low N nutrient solution under 16 conditions of light and temperature in a crossed-gradient room in an attempt to determine whether or not variation in climatic conditions influences N(2) fixation by the association between maize and Spirillum lipoferum. Temperatures were 28, 32, 36, and 40 C and 10 C lower at night; light intensities were 500, 1,250, 2,400, and 3,000 ft-c. Plants harvested after 94 days showed no significant benefit from association with S. lipoferum either in dry weight production or in total N content; variations in temperature and light had only a small influence on N(2) fixation under the conditions tested. Measurements of total N, together with designated assumptions, indicated that less than the equivalent of 0.5 kilogram of N was fixed/hectare during the entire growing period by the maize-S. lipoferum association. Rates of C(2)H(2) reduction by replicate root samples generally were low and variable and did not correlate with the measurements of total N.