Natural selection and family X location interaction in the common (dry) bean plant

Abstract

Ab stractNat u ral se lec tion takes place while ad vanc ing gen er a tions of segregant pop u la tions of s elf pol li nat ing spe cies by the pop u la tion (bulk) method. There is ev i dence that it main tains the in di vid u als with greate r grain yield. The ques tion arises whether nat u ral se lec tion pre serves the in di vid u als which are more adapted only to the en vi ron ment where the gen er a tion ad vance oc curred, that is, if it con trib utes to in creas ing the ge no type x en vi ron ment in ter ac tion in the fam ily as sess ment. This study was car ried out to check this hy poth e sis in the com mon bean p lant us ing fam i lies de rived from a seg re gat ing pop u la tion from a cross be tween the Cari oca MG x ESAL 686 culti vars. The seg re gat ing pop u la tions in crease in homozygosity was ob tained by the pop u la tion (bulk) method un til th e F 14 gen er a tion, in three dis tinct lo ca tions in Minas Gerais state: Lavras, Lambari and Patos de Minas. Forty-seven F 14:15 fam i lies were ran domly taken from the pop u la tion in each lo ca tion and later mul ti plied to ob tain F 14:16 fam i lies. These fam i lies were jointly as sessed with three con trols us ing a tri ple 12 x 12 lat tice de sign in the three lo ca tions of gen er a tion ad vance in the wet sea son of 1998/1999. All the es ti mated pa ram e ters showed that while ad vanc ing segre gant pop u la tions by the pop u la tion (bulk) method, nat u ral se lec tion acted to pre serve the in di vid u als which are more adapted to the en vi ron ment in which they were ad vanced.Key words: ge no type x en vi ron ment in ter ac tion, heritability, com mon bean, Phaseolus vulgaris L., nat u ral se lec tion. In tro duc tionSev eral meth ods to ad vance segregant pop u la tions are avail able to breed ers of self pol li nat ing spe cies. The pop u la tion or bulk method is widely used be cause it is versa tile and easy to use. From the F 2 gen er a tion, the plants are har vested (bulked) and their seeds mixed and sam pled to sow and grow the next gen er a tion. This pro cess is re peated un til F 5 , F 6 or even more ad vanced gen er a tions are obtained. Plants are then col lected and their fam i lies (prog enies) are as sessed in rep li cated ex per i ments.Nat u ral se lec tion acts on the segregant pop u la tion dur ing the bulk method ad vance of gen er a tion. The question is whether this se lec tion acts in the di rec tion de sired by the breed ers. It is known that for cer tain traits such as growth habit and cy cle it does not al ways oc cur in the required di rec tion. How ever, it has been proved that nat u ral se lec tion con trib utes to main tain ing the higher yield ing (grain yield) in di vid u als (Hamblin, 1977;Allard, 1988;Corte et al., 2002).An other per ti nent ques tion is whether nat u ral se lection ac tion pre serves the in di vid u als that are more adapted only to the en vi ron ment where the gen er a tions were advanced. Proof of this fact is es pe cially im por tant for trop ical con di tions be cause...

Homeostasis of common bean populations with different genetic structures

“…This evidenced that the population performance did not coincide in the evaluation of the 20 distinct environments. This result agrees with those of Corte et al (2001) and Pirola et al (2002), in experiments conducted with common bean in different environments.…”

Performance of common bean families after different generations under natural selection

“…Only five families of the 30 best (16.67%) were derived from the F 2 generation. It has also been reported that the action of natural selection con- Silva et al 577 tributed to preserve the best-adapted individuals (higher yielding) in crops such as in Triticum aestivum L (Gregan and Busch, 1978) Phaseolus lunatus L. (Tucker and Harding, 1974) and Phaseolus vulgaris L. (Pirola et al, 2002). All these results pointed towards the efficiency of the bulk method.…”

Implicações da origem das linhagens de feijoeiro na magnitude da interação com ambientes

“…Para a obtenção de uma nova linhagem, são feitas avaliações por várias gerações. Nessa condição, espera-se que a seleção natural atue e que possam ser identificadas as mais adaptadas àquele ambiente particular (Gonçalves et al, 2001;Pirola et al, 2002;Silva et al, 2004). Assim, esperava-se que as linhagens oriundas de um local tivessem maior adaptabilidade e estabilidade no referido local.…”