Response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 in Northeast China

The objective of this study was to identify the response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 and grown extensively in Northeast China.Twenty-one hybrids were grown for 2 years in Northeast China at densities of 30,000,52,500,75,000,and 97,500 plants ha^(-1)and N application levels of 0,150,300,and 450 kg N ha^(-1).Irrespective of density or nitrogen application rate,grain yields both per plant and per unit area were significantly higher for newer than older hybrids.As plant density increased from 30,000 to 97,500 plant ha^(-1),yield per plant of 1970 s,1980 s,1990 s,and 2000 s hybrids decreased by 50%,45%,46%,and 52%,respectively.The response of grain yield per unit area to plant density was curvilinear.The estimated optimum plant densities were about 58,000,49,000,65,000,and 65,000 plants ha^(-1)for hybrids released in the 1970 s,1980s,1990 s,and 2000 s,respectively.The theoretical optimum densities for the hybrids released from the 1970 s to the 2000 s increased by 1750 plants ha^(-1)decade^(-1).Nitrogen fertilization significantly increased grain yields per plant and per unit area for all hybrids.The theoretical optimum N application rates for high yield for hybrids released in the 1970 s and 1980 s were about 280 and 360 kg ha^(-1),and the hybrids from the 1990 s and 2000 s showed highest yield at 330 kg ha^(-1)N.No significant difference in the grain yields of 2000 s hybrids between the N levels of 150 to 450 kg ha^(-1)was found.Significant yield gains per plant and per unit area were found,with average increases of 17.9 g plant^(-1)decade^(-1)and936 kg ha^(-1)decade^(-1)over the period 1970–2010,respectively.Yield gains were attributed mainly to increased yield per plant,contributed by increases in kernel number per ear and1000-kernel weight.The rates of lodging and barren plants of newer hybrids were significantly lower than those of older ones,especially at high plant density.

Synthesis of highly functional quinazolins via metal-free,visible-light-enabled radical cascade arylation/cyclization of fluorinated imidoyl isothiocyanates

A metal-free,efficient and easy-to-hand protocol for the synthesis of 2-perfluoroalkylquinazolins has been achieved by Eosin B catalyzed radical cascade arylation/cyclization reaction of fluorinated imidoyl isothiocyanates with aryldiazonium Salts.A variety of highly functionalized quinozaline derivatives bearing pharmaceutically important thiol and fluoroalkyl groups were efficiently assembled with broad substrate scope and good functional group tolerance.A series of mechanism experiments indicate that this reaction undergoes a radical cascade arylation/cyclization pathway.

Inclusion Complex of Podophyllotoxin with y-Cyclodextrin Preparation, Characterization, Anticancer Activity, Water-Solubility and Toxicity

An inclusion complex of podophyllotoxin （PPT） with 7-cyclodextrin （7-CD） was prepared. The behavior, char- acterization, and water solubility of the inclusion complex were carefully investigated via fluorescence spectroscopy, thermogravimetry, differential scanning calorimetry, X-ray diffraction analysis, and 1H and 2D nuclear magnetic resonance spectroscopy. Furthermore, antitumor activity to human cancer lines and toxicity in mice were studied. Results showed that the inclusion complex formed in a 1 ： 1 ratio with a considerable apparent stability constant Ks （4245.5 Lomol-l）. Water solubility was considerably improved. In addition, the anticancer activity of the inclusion complex was better than that of cis-platinum （DDP, positive control）. Most importantly, the toxicity of podophyl- lotoxin inclusion complex reduced and became more safety to mice which will be great valuable to research its ap- plications as a kind of antitumor drug to human in the further.