NODULATION CAPACITY AND NITRATE REDUCTASE ACTIVITY OF BIRDSFOOT TREFOIL, SAINFOIN AND WHITE CLOVER IN GRASS-LEGUME MIXTURES

摘要

Nodulation capacity of birdsfoot trefoil (Lotus corniculatus L.) variety "Targovishte 1", sainfoin (Onobrychis Adans.) breeding N 26 and white clover (Trifolium repens L.) variety "Milka" alone and in grass-legume mixtures (1:1) was studied in the conditions of a pot trial. Crested wheatgrass (Agropyron cristatum L) local population was used as a grass component. It was found that the nodulation capacity of birdsfoot trefoil and sainfoin was greater in mixtures than in pure crops. Birdsfoot trefoil formed the greatest nodule number in mixture with white clover and the increase was 25-27% as against the pure crop. Sainfoin had the best nodulation capacity in mixture with crested wheatgrass-139%. Crested wheatgrass suppressed the noduiation of birdsfoot trefoil and white clover to a greater extent in the second year of development. White clover nodulated better as a pure crop than in mixture. The highest nitrate reductase activity was found in the white clover leaves- 2.57mumol/g fr.w. It increased in the mixtures with crested wheatgrass participation. The values of nitrate reductase activity in white clover mixed with legumes were lower than in its pure cultivation. Total content of plastid pigments increased in the mixture of birdsfoot trefoil andcrested wheatgrass. In the mixtures of legume crops, the plastid pigment content did not change in birdsfoot trefoil, decreased in sainfoin and increased in white clover.