Intraspecific variability in Schizaphis graminum （Rondani） was studied in 2002-2005. Aphid clones were sampled from sorghum field at the Kuban Experimental Station （Krasnodar region, Northern Caucasus, Russia） in ...Intraspecific variability in Schizaphis graminum （Rondani） was studied in 2002-2005. Aphid clones were sampled from sorghum field at the Kuban Experimental Station （Krasnodar region, Northern Caucasus, Russia） in June （active greenbug migration to the field）, July （high rate of the population increasing）, and August （greenbug abundance decreasing） and at the end of September or in the beginning of October （appearance of sexual males and females）. Damage rating was estimated for two plant sets composed of three sorghum differentials. Set A contains Deer （gene for resistance Sgr4）, Sarvasi （Sgrl ＋ Sgr2） and Capbam （Sgrl2）. Set B contains Shallu （Sgr3）, Sorgogradskoe （Sgr5） and Durra Belaya （Sgr5 ＋ Sgr6）. To estimate variability in greenbug subpopulations criteria proposed by Zhivotovsky （1982） were used. Frequencies of greenbug clones with virulence to sorghum accessions essentially differed. Very high overall and seasonal polymorphism of the insect for virulence was revealed. Among 517 aphid clones tested 33 phenotypes for virulence were identified. The aphid subpopulations collected from the same field at different periods of sorghum vegetation varied significantly in share of rare phenotypes. Criteria of similarities varied from 0.268 to 0.739; according to criterion of identity significant differences between 44 summer subpopulations from 66 studied were found.展开更多
In this note,the Payne's conjecture from convex domains to concave domains is generalized.It is shown that the nodal line N of the second eigenfunction of the Laplacian over some simply connected concave domain Ω...In this note,the Payne's conjecture from convex domains to concave domains is generalized.It is shown that the nodal line N of the second eigenfunction of the Laplacian over some simply connected concave domain Ω in R^2 must intersect the boundary ■Ω at exactly two points.展开更多
文摘Intraspecific variability in Schizaphis graminum （Rondani） was studied in 2002-2005. Aphid clones were sampled from sorghum field at the Kuban Experimental Station （Krasnodar region, Northern Caucasus, Russia） in June （active greenbug migration to the field）, July （high rate of the population increasing）, and August （greenbug abundance decreasing） and at the end of September or in the beginning of October （appearance of sexual males and females）. Damage rating was estimated for two plant sets composed of three sorghum differentials. Set A contains Deer （gene for resistance Sgr4）, Sarvasi （Sgrl ＋ Sgr2） and Capbam （Sgrl2）. Set B contains Shallu （Sgr3）, Sorgogradskoe （Sgr5） and Durra Belaya （Sgr5 ＋ Sgr6）. To estimate variability in greenbug subpopulations criteria proposed by Zhivotovsky （1982） were used. Frequencies of greenbug clones with virulence to sorghum accessions essentially differed. Very high overall and seasonal polymorphism of the insect for virulence was revealed. Among 517 aphid clones tested 33 phenotypes for virulence were identified. The aphid subpopulations collected from the same field at different periods of sorghum vegetation varied significantly in share of rare phenotypes. Criteria of similarities varied from 0.268 to 0.739; according to criterion of identity significant differences between 44 summer subpopulations from 66 studied were found.
基金supported by the National Natural Science Foundation of Chinathe National Basic Research Program of China under Grant No.2011CB808002the National Research Foundation of South Africa
文摘In this note,the Payne's conjecture from convex domains to concave domains is generalized.It is shown that the nodal line N of the second eigenfunction of the Laplacian over some simply connected concave domain Ω in R^2 must intersect the boundary ■Ω at exactly two points.
