The Influence of Day Length on Plant and Nodule Development of Fababeans (Vicia faba L.) and Grasspeas (Lathyrus sativus L.)

The valuation of the influence of different day length (DL) on plant and especially nodule development of fababeans ( Vicia faba L.) and grasspeas ( Lathyrus sativus L.) was the aim of these experiments. For that, experiments in growth chambers (Exp. 1) with DL of 10, 13, 16 and 19 hours and an experiment in vegetation boxes (Exp. 2) with DL of 7, 10, 13 hours and natural DL as control (CON) were conducted. The development of plants was studied by 6 and 7 harvests (HA) respectively beginning at 27 and 31 days after emergence (DAE) respectively, as well as consecutive determinations of leaf area, dry matter (DM) of the different plant organs and nodule number.
Total- and pod-DM of both species increased with higher DL (19 h, CON). Nodule-DM was positive influenced by longer assimilation duration and bigger leaf areas of the higher DL treatments. With onset of pod ripening, which occurred early under higher DL, lower nodule-DM was determined due to the beginning of nodule senescence. Under 19 h DL the fababeans established highest nodule-DM, 1,100 mg/plant, whereas the grasspea 410 mg only. Nodules under shorter DL (7 h, 10 h) showed less intensive red tissue and less nodules > 6 mm diameter. The grasspea established more bigger nodules than the fababeans. Total nodule number was not unequivocal affected by DL, however, it increased with the course of vegetation. Senescence of nodules was most evident at time of highest growth rates of the pod-DM.