Root segments and root-soil cores (6.5-cm diameter) from fields and nurseries of winter wheat and sorghum were tested for N2 fixation by using the acetylene reduction assay. Wheat samples (-1,200) from 109 sites generally had low or no activity (0 to 3.1 nmol of C2H4 produced per h per g [dry weight] of root segments), even after 24 h of incubation. However, a commercial field of Scout 66, located in western Nebraska, exhibited appreciable activity (290 nmol of C2H4 produced per h per g [dry weight] of root segments). Of 400 sorghum lines and crosses, grain sorghums (i.e., CK-60A, Wheatland A, B517, and NP-16) generally exhibited higher nitrogenase activity than forage sorghums or winter wheats. CK-60A, a male sterile grain sorghum, was sampled at four locations and had the most consistent activity of 24 to 1,100 nmol of C2H4 produced per h per core. The maximum rate extrapolated to 2.5 g of N per hectare per day. Numerous N2-fixing bacterial isolates were obtained from wheat and sorghum roots that exhibited high nitrogenase activity. Most isolates were members of the Enterobacteriacae, i.e., Klebsiella pneumoniae, Enterobacter cloacae, and Erwinia herbicola.

Pd(SC2NaH6)2]C12.1"5H20, Mr=440"64, monoclinic, P2/n, a = 9.401 (2), b = 13.540 (2), c = 12.172 (2) A, /3 = 101.15 (1) °, V= 1520.1 (5) A 3, Ox = 1.925 g cm-3, Z = 4, F(000) = 876, Mo Ka, )t = 0"7107 A, /z = 1"83 mm -1, room temperature, R = 0.065 for 2582 observed reflections. The structure analysis has shown that the Pd atom is cis-planar coordinated by two S and two N atoms from two 0108-2701/90/112065-04503.00

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Ciystals of N^-dimethylthiosalicylohydrazide are monoclinic, with Space group P2t and cell parameters a = 10.667(2), b = 9.155(2), c = 10.378(2) k,ß = 92.46(1)°, Z = 4 (two moleculcs in the asymmetric Unit), De = 1.286 gern"'. The crystal structure has been solved by Direct methods and Fourier syntheses. The least-squares refinement led to a final R value of 0.055 with 1792 observed reflections.The ligand may exist in (i) thiolo or in (ii) thiono form. IR spectrum of the ligand did not exhibit v(SH) at ca. 2600 cm~'. So it is assumed that the configuration (ii) is the preferred one. Structure analysis of the ligand has further supported this. There exists intramolecular hydrogen bonding between nitrogen in position 1 and oxygen, but no intennolecular hydrogen bonding is observed.