In three-dimensional quantum electrodynamics (QED3) with a massive gauge boson, we investigate the coupled Dyson-Schwinger equations for the fermion and photon propagators in the rainbow approximation, and obtain the ...In three-dimensional quantum electrodynamics (QED3) with a massive gauge boson, we investigate the coupled Dyson-Schwinger equations for the fermion and photon propagators in the rainbow approximation, and obtain the critical gauge boson mass for various numbers of the fermion flavors. A comparision with the previous results is presented.展开更多
Two allelopathic rice accessions, PI312777 and Allelopathy1, significantly suppressedthe growth of associated weeds in the field. Moreover, their weed-suppressing effectswere correlated with the cultivation patterns. ...Two allelopathic rice accessions, PI312777 and Allelopathy1, significantly suppressedthe growth of associated weeds in the field. Moreover, their weed-suppressing effectswere correlated with the cultivation patterns. The weed-suppressing effects of throwingand transplanting were more effective than that of direct seeding. Furthermore, theamounts of allelochemicals (resorcinols, flavones and hydroxamic acids) produced andreleased from two allelopathic rice accessions were much higher than that from a non-allelopathic rice variety Hua-Jing-Xian1, and reached the maximum concentration at the6th leaf stage. Differences in the weed-suppressing effects of rice accessions appear toresult from the accessions producing and releasing different amounts of allelochemicalsin the field. Further research confirmed that in PI312777 plants, allelochemicals weresynthesized by the above-ground parts, and then secreted through the root tissues. Roottissues of PI312777 plants never produced the allelochemicals. Root exudates fromPI312777 could significantly inhibit the growth of E. crus-galli surrounding rice plantsin water culture. However, when activated carbon was added to the culture solution, whichcould absorb allelochemicals from root exudates, the growth of E. crus-galli was nolonger significantly inhibited. Weed-suppressing effects of rice accessions depended onallelopathy, cultivation patterns and other factors in rice fields, while allelopathywas one of important factors. Interestingly, the amounts of allelochemicals produced andreleased from allelopathic rice plants may be induced by the presence of E. crus-galli.This suggests that there is a possible chemical recognition between rice and E. crus-galli.展开更多
When beetle Aulacophora femoralis chinensis Weise fed on cucumber seedlings, it first chewed a circular trench on their leaves and then nibbled the leaf tissues iso-lated by the trench, but when it was fed with the de...When beetle Aulacophora femoralis chinensis Weise fed on cucumber seedlings, it first chewed a circular trench on their leaves and then nibbled the leaf tissues iso-lated by the trench, but when it was fed with the detached fresh cotyledons of cucumber, such an interesting trenching behavior did not occur, which indicated that the feeding be-havior of the beetle was obviously correlated with the chemical response of the cucumber to the herbivory. Within 60 min after feeding, the level of cucurbitacin C in fed coty-ledons of the cucumber seedling increased 10 fold or more. Cucurbitacin I was also detected 15 min after feeding, which reached 75 mg/g within 60 min. The high levels of cucurbi-tacins C and Ⅰ in fed cotyledons could be maintained for at least 24 h. A. femoralis chinensis was strongly stimulated to take food by cucurbitacin C at a concentration between 10 and 250 mg/g, and the feeding deterrent activity was observed at >250 mg/g, while the feeding deterrent threshold of A. femoralis chinensis to cucurbitacin I was 50 mg/g. The mix-ture of cucurbitacins C and Ⅰ had a much stronger feeding deterrent activity than single cucurbitacin I. The results suggested that cucumber could elicit chemical response to the beetle herbivory, its leaf being induced to produce more kinds of cucurbitacins and make them reach the levels of feeding deterrent activity on the beetle, while the trenching behavior of A. femoralis chinensis was its strategy to answer the chemical response of cucumber. The trenching behavior of the beetle not only stopped the cucurbitacins biosynthesis in cucumber leaf tissues, but also blocked the translocation of cucurbitacins to the feeding sites. The trenching behavior of the beetle and the chemical response of host cucumber were the mutual adaptive strategies for protecting the host plant and the beetle themselves.展开更多
文摘In three-dimensional quantum electrodynamics (QED3) with a massive gauge boson, we investigate the coupled Dyson-Schwinger equations for the fermion and photon propagators in the rainbow approximation, and obtain the critical gauge boson mass for various numbers of the fermion flavors. A comparision with the previous results is presented.
基金supported by the National Natural Science Foundation of China(30070130)the Natural Science Foundation of Guangdong Province,China(021045)+1 种基金National Key Technologies R&D Program in the Tenth Five-Year of China(2001BA509B07)the Scientific Fund for Scholars Returning Overseas of Ministry of Education,China(2001-498).
文摘Two allelopathic rice accessions, PI312777 and Allelopathy1, significantly suppressedthe growth of associated weeds in the field. Moreover, their weed-suppressing effectswere correlated with the cultivation patterns. The weed-suppressing effects of throwingand transplanting were more effective than that of direct seeding. Furthermore, theamounts of allelochemicals (resorcinols, flavones and hydroxamic acids) produced andreleased from two allelopathic rice accessions were much higher than that from a non-allelopathic rice variety Hua-Jing-Xian1, and reached the maximum concentration at the6th leaf stage. Differences in the weed-suppressing effects of rice accessions appear toresult from the accessions producing and releasing different amounts of allelochemicalsin the field. Further research confirmed that in PI312777 plants, allelochemicals weresynthesized by the above-ground parts, and then secreted through the root tissues. Roottissues of PI312777 plants never produced the allelochemicals. Root exudates fromPI312777 could significantly inhibit the growth of E. crus-galli surrounding rice plantsin water culture. However, when activated carbon was added to the culture solution, whichcould absorb allelochemicals from root exudates, the growth of E. crus-galli was nolonger significantly inhibited. Weed-suppressing effects of rice accessions depended onallelopathy, cultivation patterns and other factors in rice fields, while allelopathywas one of important factors. Interestingly, the amounts of allelochemicals produced andreleased from allelopathic rice plants may be induced by the presence of E. crus-galli.This suggests that there is a possible chemical recognition between rice and E. crus-galli.
文摘When beetle Aulacophora femoralis chinensis Weise fed on cucumber seedlings, it first chewed a circular trench on their leaves and then nibbled the leaf tissues iso-lated by the trench, but when it was fed with the detached fresh cotyledons of cucumber, such an interesting trenching behavior did not occur, which indicated that the feeding be-havior of the beetle was obviously correlated with the chemical response of the cucumber to the herbivory. Within 60 min after feeding, the level of cucurbitacin C in fed coty-ledons of the cucumber seedling increased 10 fold or more. Cucurbitacin I was also detected 15 min after feeding, which reached 75 mg/g within 60 min. The high levels of cucurbi-tacins C and Ⅰ in fed cotyledons could be maintained for at least 24 h. A. femoralis chinensis was strongly stimulated to take food by cucurbitacin C at a concentration between 10 and 250 mg/g, and the feeding deterrent activity was observed at >250 mg/g, while the feeding deterrent threshold of A. femoralis chinensis to cucurbitacin I was 50 mg/g. The mix-ture of cucurbitacins C and Ⅰ had a much stronger feeding deterrent activity than single cucurbitacin I. The results suggested that cucumber could elicit chemical response to the beetle herbivory, its leaf being induced to produce more kinds of cucurbitacins and make them reach the levels of feeding deterrent activity on the beetle, while the trenching behavior of A. femoralis chinensis was its strategy to answer the chemical response of cucumber. The trenching behavior of the beetle not only stopped the cucurbitacins biosynthesis in cucumber leaf tissues, but also blocked the translocation of cucurbitacins to the feeding sites. The trenching behavior of the beetle and the chemical response of host cucumber were the mutual adaptive strategies for protecting the host plant and the beetle themselves.
