Analysis on Absorption,Utilization and Transfer Efficiency of Nitrogen in High-yield Wheat Cultivars at Different Sowing Dates

This study aimed to analyze the absorption, utilization and transfer char- acteristics of nitrogen in high-yield winter wheat （Triticum aestivum） cultivars at dif- ferent sowing dates, so as to determine the optimum sowing dates for different high-yield wheat cultivars. A field experiment was conducted in the Shajiang black soil of Anhui Province with Jimai 22, Wanrnai 52 and Zhoumai 22, and the effects of early sowing （October 3）, optimum sowing （October 12） and late sowing （October 30） on wheat plant N content and accumulation, pre-and post-anthesis N accumula- tion （NA） of total plant, nitrogen remobUization to grain （NR）, N remobilization effi- ciency （NRE）, contribution of N remobilized to grain （NRC）, grain yield, N use effi- ciency （NUE） and N harvest index （NHI） of different wheat cultivar were investigat- ed. The results showed that sowing date had an impact on N content, absorption and utilization in wheat plants at various growth stages. The NA, NR and NRC of aboveground vegetative organs of wheat before anthesis were higher than those af- ter anthesis. Under the condition of late sowing, the grain N accumulation mainly depended on the N absorption by vegetative organs before anthesis. Under the conditions of optimum and early sowing, the absorbed N after anthesis accounted for a large proportion in grain N accumulation. The N uptake intensity and relative cumulative rate differed greatly among different growth stages and different-genotype wheat cultivars, and the pre-anthesis NA, pre-anthesis NR, pre-anthesis NRE, post- anthesis N assimilation amount and post-anthesis NRC showed significant differ- ences among different wheat cultivars. The grain yields of different wheat cultivars under the early and optimum sowing were all higher than those under the late sowing. The NHI and grain N accumulation were highest under the optimum sow- ing, and the latter significantly decreased with the delay of sowing dates. In con- trast, the NUE was highest under the late sowing, reaching 35.95%-41.32%. It indi- cated that under the condition of late sowing, most of the nitrogen was not ab- sorbed by wheat, but the use efficiency of the absorbed nitrogen significantly in- creased. In overall, the three high-yield wheat cultivars were all suitable for early and optimum sowing. Under the condition of late sowing, the yield of Zhoumai 22 showed the smallest differences with those under early and optimum sowing, and its NUE was significantly improved. Therefore, among the three high-yield wheat culti- vars, Zhoumai 22 was most suitable for late sowing.

Synthesis and Structure of L-Aspartato- nickel(II) Complex with Benzimidazole

The title complex Ni(C4H5NO4)(C7H6N2)31.75(H2O) (C25H26.5N7NiO5.75, Mr = 575.74) has been prepared and its crystal structure was determined by X-ray diffraction method. The crystal of this chiral complex belongs to monoclinic, space group P21 with a = 13.208(1), b = 10.741(1), c = 19.398(1) ? b = 104.39(1)o, V = 2665.8(4) 3, Z = 4, Dc = 1.435 g/cm3, m(MoKa) = 0.780 mm-1 and F(000) = 1198. The final R = 0.0504 and wR = 0.1267 for 9159 observed reflections (I > 2s(I)), and R = 0.065 and wR = 0.1299 for 11006 independent reflections. The complex assumes a distorted octa- hedral coordinate geometry formed by one aspartate dianion and three benzimidazole ligands. The aspartate chelates to the Ni atom as a tridentate ligand. The lattice water molecules are hydrogen- bonded to the Ni complex molecule.