Nodulation of lime pelleted lupins and serradella when inoculated with peat and agar cultures

Abstract

Lime coating yellow lupin (Lupinus luteus L.) seed, when inoculated with bacteria from agar slopes, reduced nodulation substantially. By contrast, when peat cultures were used there was no adverse effect of lime coating on nodulation, even when inoculated seeds were stored for 61 days at 75¦F, before planting. In two experiments the nodulation of unhulled serradella (Omithopus comljressus L.) was generally unaffected by lime coating when either agar or peat cultures were used. In a third experiment nodulation was significantly reduced with both agar and peat cultures on unhulled and hulled seed. This adverse effect was greater with agar cultures than with peat cultures. It is concluded that peat, and possibly the serradella seed pod, protects the bacteria from the effects of lime. The practice of lime coating lupin and serradella seed, when inoculated with peat cultures, is a useful technique, particularly when the seed is sown in contact with acid superphosphate. On the other hand, some adverse effects of lime on the nodulation of serradella when a peat culture was used suggest that other workers should test the suitability of the lime pelleting method under their own conditions. Rock phosphate and bentonite were also investigated as pelleting agents, but neither seemed to offer any advantages over lime.