Sanctions are triggered continuously with nitrogen fixation.

<p>Linear regression of the natural log of estimated rhizobia per nodule (counting CFUs of serially diluted extracts of crushed nodules) against the shoot biomass of the host(dry weight) Hosts were singly inoculated with near-isogenic <i>M</i>. <i>loti</i>: MAFF (pink diamond), STM30 (yellow square) and STM6 (green triangle). Each symbol represents one nodule. (<b>A)</b> Hosts harvested at 6wpi; F_1,38 = 8.197. (<b>B)</b> Hosts harvested at 8wpi; F_1,46 = 13.1525.