In 2012-2015, under the conditions of different natural wind speeds, the single-rotor agricultural unmanned aerial vehicle was used for the supplementary pollination during seed production of 10 hybrid combinations wi...In 2012-2015, under the conditions of different natural wind speeds, the single-rotor agricultural unmanned aerial vehicle was used for the supplementary pollination during seed production of 10 hybrid combinations with big parental row ratios in the hybrid rice seed production bases of Hunan, Hainan and Guangdong Province, and the pollination effects were studied through the investigation of pollen density in the field, outcrossing seeding rate of female parent and seed production yield. The results showed that under the parental row ratio of 6：（40-60）, the seed setting rate and yields of the supplementary pollination by single-rotor agricultural UAV could reach and even higher than those of artificial pollination, indicating the single-rotor agricultural UAV could be used in supplementary pollination for hybdd rice seed production, which could promote the whole-process mechanization of seed production.展开更多
For a commutative ring R with a unit, an R-homology rose is a topological space whose homology groups with R-coefficients agree with those of a bouquet of circles. In this paper, we study some special properties of th...For a commutative ring R with a unit, an R-homology rose is a topological space whose homology groups with R-coefficients agree with those of a bouquet of circles. In this paper, we study some special properties of the fundamental groups of R-homology roses and their covering spaces, from which we obtain some results supporting the Carlsson conjecture on free(Zp)ractions. In addition, we discuss how to search candidates of the counterexamples of Wall's D(2)-problem among R-homology roses and R-acyclic spaces and propose some candidates.展开更多
基金Supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(2014BAD06B07)the Rice Industry Technology System of Hunan Province~~
文摘In 2012-2015, under the conditions of different natural wind speeds, the single-rotor agricultural unmanned aerial vehicle was used for the supplementary pollination during seed production of 10 hybrid combinations with big parental row ratios in the hybrid rice seed production bases of Hunan, Hainan and Guangdong Province, and the pollination effects were studied through the investigation of pollen density in the field, outcrossing seeding rate of female parent and seed production yield. The results showed that under the parental row ratio of 6：（40-60）, the seed setting rate and yields of the supplementary pollination by single-rotor agricultural UAV could reach and even higher than those of artificial pollination, indicating the single-rotor agricultural UAV could be used in supplementary pollination for hybdd rice seed production, which could promote the whole-process mechanization of seed production.
基金supported by National Natural Science Foundation of China(Grant No.11371188)the PAPD(Priority Academic Program Development)of Jiangsu Higher Education Institutions
文摘For a commutative ring R with a unit, an R-homology rose is a topological space whose homology groups with R-coefficients agree with those of a bouquet of circles. In this paper, we study some special properties of the fundamental groups of R-homology roses and their covering spaces, from which we obtain some results supporting the Carlsson conjecture on free(Zp)ractions. In addition, we discuss how to search candidates of the counterexamples of Wall's D(2)-problem among R-homology roses and R-acyclic spaces and propose some candidates.
