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Twenty fungal genera, including 14 Fusarium species, were examined for ice nucleation activity at-5.0°C, and this activity was found only in Fusarium acuminatum and Fusarium avenaceum. This characteristic is unique to these two species. Ice nucleation activity of F. avenaceum was compared with ice nucleation activity of a Pseudomonas sp. strain. Cumulative nucleus spectra are similar for both microorganisms, while the maximum temperatures of ice nucleation were-2.5°C for F. avenaceum and-1.0°C for the bacteria. Ice nucleation activity of F. avenaceum was stable at pH levels from 1 to 13 and tolerated temperature treatments * Corresponding author.

Bradyrhizobia and rhizobia are symbiotic bacterial partners forming nitrogen fixing nodules on legumes. These bacteria share characteristics with plant growth promoting rhizobacteria (PGPR). Nodule inducing bacteria, like other PGPR, are capable of colonizing the roots of non-legumes and produce phytohormones, siderophores and HeN. They also exhibit antagonistic effects towards many plant pathogenic fungi. The potential of nodule inducing bacteria to function as PGPR, was examined by using radish as a model plant. Three percent of the 266 strains tested were found to be cyanogens, while a majority (83%) produced siderophores. Fifty eight percent of the strains produced indole 3-acetic acid (IAA) and 54% solubilized phosphorus. Some of the bacterial species examined were found to have a deleterious effect while others were neutral or displayed a stimulatory effect on radishes. Bradyrizobium japonicum strain Soy 213 was found to have the highest stimulatory effect (60%), and an arctic strain (N44) was the most deleterious, causing a 44% reduction in radish dry matter yield. A second plant inoculation test, performed in growth cabinets, revealed that only strain Tal 629 of B. japonicum significantly increased (15%) the dry matter yield of radish. This indicates that specific bradyrhizobia have the potential to be used as PGPR on non-legumes.