Yellow lupin (Lupinus luteus) tolerates waterlogging better than narrow-leafed lupin (L-angustifolius) - II. Leaf gas exchange, plant water status, and nitrogen accumulation

Yellow lupin (Lupinus luteus) may have potential as a legume crop in waterl ogging-prone areas of Western Australia. To elucidate the physiological res ponse of yellow lupin and the widely grown narrow-leafed lupin (L. angustif olius) to transient waterlogging we conducted experiments in controlled env ironments. Narrow-leafed lupin and yellow lupin were grown in pots and wate rlogged for 14 days from 28 to 42, or 56 to 70 days after sowing, each bein g followed by a 14-day recovery period. Root and shoot growth responses, le af gas exchange, water relations, and N accumulation were assessed. During the period of waterlogging, net nitrogen accumulation ceased in both species at both ages. During recovery, yellow lupin accumulated more nitro gen than narrow-leafed lupin. Waterlogging reduced leaf gas exchange more w ith older plants than with younger plants, and more so with narrow-leafed l upin than yellow lupin. Some components of leaf gas exchange, particularly leaf conductance, were reduced by up to 80%. Waterlogging had no effect on leaf water potential of yellow lupin but reduced it in narrow-leafed lupin, from about -450 to -1100 kPa, especially during the recovery period. Yellow lupin was more adapted to transient waterlogging than narrow-leafed lupin because it maintained its leaf water status, it accumulated more nitr ogen during recovery, and its photosynthetic activity recovered quickly aft er removal of waterlogging.