Tests of the seed inoculation with Rhizobium on some species of genus Acacia. (Preliminary report)

Sterile seedlings of seventeen species of Acacia and three other legumes, Samanea saman Merr., Delonix regia Raf. and Casia siamea Lam. were used for a test of finding their position among cross inoculation groups. The test was also aimed to find non-nodule-forming species of the legumes. Four mixed inoculated section were disposed for the test. Each section consisted of as followings; Section A; Alfalfa, Clover, Pea, Bean, Lupine, and Soybean. Section B; Alfalfa, Clover, Pea, Bean, Lupine, Soy-bean, and Cowpea. Section C; Acacia mollissima, A. dealbata, A. melanoxylon, Lespedeza bicolor, Cytisus scoparius, Albizzia julibrissin, Cowpea, Phaseolus angularis, Arachis hypogaea, Pueraria thunbergiana. Section D; Robinia pseudoacacia, Amorpha fruticosa. A mixture of strains of rhizobia from each host in a section was made in 500 cc of sterile water. Thus four mixtures were made from four sections. Nodulation was inspected by inoculating the four mixtures respectively to the sterile seedlings grown in 9 cm pots in diameter which contained 200 g of sterile soil, and 3 g of fertilizer mixed in the ratio of 1 part of N, 4 parts of P_2O_5 and 2 parts of K_2O. Nitrogen sulphate is used for N, Calcium superphosphate for P_2O_5, and potassium sulphate for K_2O. For the supplementary test, 18 kinds of strain inoculated in the sections A, B, C and D were inoculated to the seedlings raised in 18 cm pots in diameter containing 1.5 kg of unsterile soil and 7.25 g of mixed fertilizer of which ratio of the ingredients was same as used in 9 cm pot test. Conclusion was as follows: 1. It was seemed that such species as Acacia acuminata Benth., A. albida Del., A. cultriformis Cunn., A. dealbata Link., A. longifolia Willd., A. melanoxylon R. Br., A. mollissima Willd., A. pravissima F. v. M., A. prominens, A. pycnantha Benth., A. sieberiana. DC., A. decurrens Willd. belong to the 7th cross inoculation group. 2. Acacia farnesiana Willd. was recognized as a non-nodule-forming species. 3. Acacia baileyana F. v. M., which was reported as non-nodule-forming species, showed nodulation in this experiment. The nodule bacteria of the species seemed to belong to the 7th group. 4. It was not able to clear which group of cross inoculation Acacia confusa Merr., A. podalyriaefolia Cunn. and Samanea saman Merr. should belong to. 5. Acacia arabica Willd. was not identified whether it is non-nodule-forming species or it belongs to inoculation group other than the 1st through the 7th one. Detailed test would be necessary to bring it into light. 6. Delonix regia Raf. seemed to be non-nodule-forming species as being reported. 7. Various nodule bacteria from different inoculation groups were mixed and inoculated to the seedlings. However, the proper nodule bacteria to the host were not interrupted forming nodulation by mixing the proper nodule bacteria with together improper ones