Abstract
Ladino clover and orchard grass were grown in 1/2000 a pots at the sowing ratios of 10:0, 8:2, 5:5, 2:8 and 0:10 (ladino clover: orchard grass) in order to investigate the variation of growth and symbiotic N fixation capacity of ladino clover in mixed swards. In addition, ladino clovers were grown in 1/10, 000 a pots at the different shading levels (100%, 71%, 45% and 23% of full sun light) to elucidate the effect of mutual shading in mixture swards in a separate experiment. The effect of NO_3-N concentration on the symbiotic N fixation capacity of ladino clover was also investigated in a water culture. Results obtained are as follows. 1. The growth of ladino clover was markedly decreased in both top and root by association with orchard grass, and it was more critical at high N treatment than at the low N treatment whereas the top growth of orchard grass did not reveal the large differences among the different sowing ratios in any N treatment. The root growth of orchard grass, however, showed a gradual increase with the increment of sowing ratins. 2. The legume ratios calculated from the yield of both forages were higher at the low N treatment than at the high N treatment. At both low and high N treatments, the legume ratios were reduced rapidly with the decrease of sowing rations of ladino clover from 10:0 to 8:2, but no significant differences were present among the sowing ratio treatments of 8:2, 5:5 and 2:8. The simmilar tendency was observed on root. 3. Symbiotic N fixation capacity/pot was reduced drastically with the decrease of sowing rations of ladino clover at high N treatment whereas they revealed the almost same values as that of ladino clover pure culture at low N treatment until the sowing ratios of ladino clover decrease to about 50%. 4. A shading imposed on ladino clover (about 70% of full sunlight) resulted in a remarkable decrease of yield and symbiotic N fixation capacity/pot. Nodule formation/plant was not affected by shading to the 45% of full sunlight. 5. In a water culture of ladino clover, symbiotic N fixation capacity was reduced with the increase of N0_3-N concentration in the culture solution, and the N fixation capacity was recovered by the removal of N0_3-N from the media. 6. The symbiotic N fixation capacity of ladino clover grown in 10 ppm N0_3-N culture solution was higher in the without renewal plot of culture solution than that in the renewal plot with weekly intervals and the different values between the two plots were supposed to be resulted from the different concentrations of N0_3-N in the media of both plots.
