Data/hora: 05/06/2024 01:45:53

Biblioteca(s): 	Embrapa Cerrados; Embrapa Trigo.	
Data corrente: 	18/12/1995	
Data da última atualização: 	16/06/2000	
Autoria: 	MINELLA, E.	
Título: 	Evaluation of ten generations of mechanical mass selection for seed size in wheat composite cross I.	
Ano de publicação: 	1979	
Fonte/Imprenta: 	Davis: University of California, 1979.	
Páginas: 	53p.	
Idioma: 	Inglês	
Notas: 	M. Sc. Thesis.	
Conteúdo: 	Wheat Composite Cross I, a diverse population of Triticum aestivum L., was mechanically mass-selected for small, medium and large seeds for 10 generations (F4 to F13) and for extra.large seeds from the large-seeded subpopulation for five generations (F9 to F13). An unselected control subpopulations was maintained in each generation of selection. All derived subpopulations for each seed size class and for the control were evaluated in a uniformfield trial in 1978 for seed weight (direct response) and plant height, heading date, seed color, glume color, spike density and awnedness (indirect responses). The mean seed weight of the control and medium-seeded sub populations did not change significantly during the generations of selection whereas, it was significantly increased in the subpopulations selected for large seeds and decreased in the subpopulation selected for small seeds. By the end of the selection experiment (F13) seeds from the extralarge-seeded subpopulation were 23% heavier and seeds from the smallseeded subpopulation were 39% lighter tran those of the subpopulation, respectively. The response to selection for large seeds was rapid and most of the gain was realized in the second or third generations of selection whereas the response to selection for small seeds was slow but steady throughout the selection experiment. The phenotypic variance among plants within generations was substantially reduced during the selection generations in all but the extra-large-seeded subpopulations. The variance in the control population also showed reduction indicating that natural selection was operating in this population. Selection for large seeds was associated with earliness, tallness, white seeds, lax spikes (nonclub), white glumes and the presence of awns. Selection for  small seeds was strongly associated with lateness, white seeds, club spikes, and awnless plants, and moderately associated with short stature. Medium-seeded and control subpopulations were also shifted toward earliness and tallness. The rapid response to selection suggests that selection for large seed size may be simple ans effective breeding tool in wheat improvement. 	
Palavras-Chave: 	Seed size; Selection; Tamanho de semente; Wheats.	
Thesagro: 	Melhoramento Vegetal; Seleção; Seleção Massal; Semente; Tamanho; Trigo; Triticum Aestivum.	
Thesaurus Nal: 	plant breeding.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Cerrados (CPAC)	
Exemplares: 	CPAC - (16538-1) - ADD - TS - -- - T053/79 - MIN - T053/79 - DIS
CNPT - (29959-1) - ADD - TS - -- - TS-0379 -  - 0379 - DIS