FRITSCHE-NETO, R.

PEREIRA, A. da S.

SILVA, G. O. da

SOUZA, V. Q. de

SUINAGA, F. A.

Repository Open Access to Scientific Information from Embrapa

EARLY GENERATION SELECTION FOR TUBER APPEARANCE ANDITS INFLUENCE ON POTATO YIELD TRAITSGiovani Olegario da Silva), Arione da Silva Pereira), Velci Queiroz de Souza2,Roberto Fritsche-Neto3, Fabio Akiyoshi Suinaga)IEmbrapa - Brazilian Agricultural Research Corporation2UFSM/CESNORS - Santa Maria Federal University3UFV - Viyosa Federal UniversityAbstractThe objective of this study was to verify the intluence of selection for tuber appear-ance on potato yield traits. A potato hybrid population composed of 20 clones fromthe Embrapa Temperate Climate breeding program was evaluated. The selection fortuber appearance had a positive effect on genetic gains for yield.IntroductionPotato breeding programs constantly need new strategies to improve efficiencyby increasing the frequency of selected genotypes and reducing time and costs. Thepossibility of predicting genetic gains that can be achieved by a certain selectionstrategy is one of the most important contributions of quantitative genetics to plantbreeding.Breeders often select for several traits at each selection stage. However, it isimportant to know the selection effect of one specific trait on the others (Pereira et al.1994).The existence of genetic associations between traits indicates that selectionpracticed for one trait may lead to changes in another. Depending on the direction,the association between traits may be of interest for breeding. Knowledge on the rela-tionships between traits is therefore very important to choose a suitable selectionstrategy for a target trait. The strategy may be based on other very closely correlatedtraits, with higher heritabilities that are easier to measure or to identify (Cruz and Re-gazzi 2001). In potato, tuber appearance is normally se lected in the early and yield insubsequent generations.The objective of this study was to verify the intluence of selection for tuber ap-pearance on yield traits of potato.Material and MethodsIn this study it was used a hybrid population composed of 20 families, random-ly sorted from the potato breeding program of Embrapa Temparate Climate, Pelotas,RS, Brazil. The families were derived from crosses targeting cultivar development:C-1750-15-95/Panda, C-1485-6-87 /Asterix, Asterix/C- I226-35-80, C-1750-15-95/Canoinhas, Columbus/Eliza, C-1485-6-87/Fe lsina, Asterix/C-1311-11-82,212Agria/C-1226-35-80, C-1750-15-95/Felsina, Shepody/Eliza, Imola/C-1226-35-80, C-1714-7-94/Imola, White Lady/C-1311-11-82, C-I750-15-95/Divina, Divina/C-I226-35-80, Agria/2CRI-II49-1-78, White Lady/2CRI-II49-1-78, C-I750-15-95/Exquiza,C-I750-15-95/ Asterix, and Asterix/2CRI-II49-1-78.A population of 600 clones (30 of each family) was evaluated on the experi-mental field of the Embrapa Temperate Climate (31 oS, 52OW), using second genera-tion clones in spring of 2003, and using third generation clones in autumn 2004. Theexperiment had a randomized block design, with five plants per clone (plot) in threereplications of 200 clones (10 clones of each family/block). The recommended agri-cultural practices were applied. The following traits were evaluated: yield (g/plot),number of tubers/plot, average tuber weight (yield/number of tubers), tuber appear-ance (1= excellent: clones with smooth skin, shallow eyes, less long shape, uniformshape, and size), skin smoothness (I = smooth, 5= rough), eye depth (1= shallow, 5=deep), tuber shape (1= long, 5= round), tuber size, and shape uniformity ( 1= uniform,5 = non-uniform).The data were subjected to analysis of variance to estimate genetic parameters.The estimates of variance components were calculated according to Cruz (2001). Theenvironment was treated as fixed effect and the genotype as random effect. The phe-notypic (rp) and genotypic (rg) correlations between traits were calculated accordingto the statistical model described by Cruz (2001). The expected correlated response(CR) was estimated according to Falconer (1989). The gain from selection for traitswas estimated according to Simmonds (1979).Results and DiscussionThe analysis of variance presented statistical differences (p 'S 0.05) for alltraits, except for uniformity of tuber size. This indicates the efficiency of the traits todifferentiate the genotypes. The genotype x environment interaction was significantfor tuber appearance, number of tubers, skin smoothness, and average tuber weight,indicating that the environments caused differential responses of at least one geno-type, i.e., the best genotype in one environment may not have been the best in anoth-er. The coefficient of genetic variation, which indicates the relative genetic variation,showed similar values among the traits, varying from 3.08% for uniformity of tubershape to 14.09% for average tuber weight (data not shown).The selection efficiency depends on the heritability, which indicates the pheno-typic superiority of genetic origin that can be transmitted to descents, can be used toestimate response to selection. In the present study, heritability coefficients variedfrom moderate (0.52) to high (0.73). Only the value for uniformity of tuber size wasvery low (0.06). The results indicate that this population has genetic variability formost of the evaluated traits. So, tuber appearance and yield traits can be inherited bythe descents and estimates of selection gain could be effective at predicting geneticgains (Tai and Young 1984). For uniformity of tuber size, the heritability estimate in-dicated that a selection strategy based directly on this trait would not provide consid-erable genetic gain. So, selection for other traits could promote higher gains in uni-formity of tuber size than direct selection for this trait (Goldenberg 1968) (Table 1).Environmental conditions can cause correlations of environmental nature only.Therefore, the phenotypic correlation can be partitioned into their components, envi-ronmental and genotypic correlations, which is the most important for breeding. Thephenotypic and genotypic correlation coefficients are presented in Table 1. The high-est number of significant associations are among the coefficients of genetic correla-tions, indicating that the environmental effect could be masking the effect of the ge-netic expression of correlation between traits.Table 1. Genetic (rg) and phenotypic (rp) correlation between tuber appearance traitsand yield traits in potato, direct response to selection in percentage of the mean of. Id' d h . bT (h2)Yle tralts, an enta 1 ltyTraits Yield Number of Average tuber h2tubers weightre Rp Re rp re RpTuber appearance -0.49* -0.38 0.83* 0.49* -0.99* -0.68* 60.5Tuber shape -0.17 -0.08 -0.12 -0.06 -0.05 -0.01 70.19Uniformity of tuber 0.28 0.14 0.56* 0.29 -0.22 -0.11 51.63shapeEye depth 0.22 0.20 0.16 0.09 0.08 0.14 53.44Skin smoothness -0.39 -0.23 0.68* 0.47* -0.85* -0.56* 72.22Uniformity of tuber size 0.24 0.14 1.00* -0.35 -0.21 -0.15 6.48Direct effect 81.55 92.93 120.3 -h2 65.77 70.94 72.90 -Tuber appearance showed significant genetic correlations with yield and itscomponents (number of tubers and average tuber weight). It indicates that more ap-pealing tubers were produced in plants with small number of tubers (0.83), higher av-erage tuber weight (-0.99) and yield (-0.49). On the other hand, the magnitudes forphenotypic correlations were smaller and only significant for tuber appearance withnumber of tubers (0.65) and average tuber weight (-0.68). Besides the associationwith tuber appearance, the only significant genetic correlation of yield was with aver-age tuber weight (0.71), indicating that as the yield increases so does the average tu-ber weight (Table 1).Except for the relationship described with tuber appearance, the trait number oftubers had significant genetic correlation with uniformity of tuber shape (0.56), uni-formity of tuber size (1.00) and skin smoothness (0.68). These results allow the con-clusion that the increase in number of tubers is associated with a reduction in tubershape and uniformity of tuber size, resulting in tuber roughness. The phenotypic cor-relations had smaller magnitudes and were not significant. Thompson et al. (1983)also reported significant genetic correlations for these traits, indicating that the higherthe number of tubers the less uniform they are. Besides the previously described cor-relations, skin smoothness had a significant and negative genetic correlation with av-erage tuber weight (-0.85), indicating that the selection for skin smoothness wouldresult in an increase of the mean tuber weight.The expected correlated response estimates for yield traits by selecting for tu-ber appearance traits are shown in Table 2. Considering the traits with significant ge-netic correlation, the yield would be affected only when selecting for tuber appear-ance. This effect, however, would result in less than 50% of the estimated direct ge-netic gain in yield. In a similar study that focused only on indirect gain in yield, Bar-bosa and Pinto (1997) did not found superior responses than with direct selection forthis trait either.Table 2. Correlated and direct response to selection in percentage of the mean of. Id t 't I b I f fI t b t 't 2 • t tYle ral s 'y se ec mg or u er appearance ral s m po a o.Traits Tuber appearance2 Tuber shape Uniformity oftu-bel' shapeYield' -38.98 -14.33 20.22Number of tubers 71.53 -11.14 44.39Average tuber -109.65 -5.91 -22.27weightEye depth Skin smoothness Uniformity oftu-bel' sizeYield 16.17 -33.34 6.13Number of tubers 12.93 63.87 28.06Average tuber 8.24 -101.88 -7.52weightThe selection for tuber appearance, uniformity of tuber shape, skin smoothness,and uniformity of tuber size would result in changes in the number of tubers (Table2). However, it would take a toll on the traits tuber appearance, skin smoothness, uni-formity of tuber size and uniformity of tuber shape (Table 1). Besides, gains with in-direct selection for these traits would be lower than by direct selection (92.93%) (Ta-ble 1).Average tuber weight would result in higher gain if tuber appearance and skinsmoothness were selected. The selection for these two traits would result in gains of109.65 and 101.88%, respectively (Table 2). Nevertheless, these values do not exceedthe gain expected by a direct selection for average tuber weight, which would be120.33% (Table 1).The expected correlated gains expressed that the selection for less complextraits, which are easier to measure and have higher heritabilities and high correla-tions, could favor selection for yield and tuber appearance. These two traits are com-plex and influenced by several individual traits and are therefore controlled by vari-ous genes and often under strong environmental influence.ConclusionsSelection for tuber appearance modifies the genetic gains for yield positively,while yield components do not have any influence on yield due to the absence of sig-nificant genetic correlations. The expected response for yield by selecting for tuberappearance does however not surpass the direct response.ReferencesBarbosa, M. H. P. E. P.; Pinto, C. A. B. Analise de trilha e resposta correlacionada asele<;;aoem clones de batata (Solanum tuberosum L.). Ciencia e Agrotecnica, v.21, p.137-142,1997.Cruz, C. D. Programa Genes - versao windows 2001.0.0. UFV, Vi<;;osa, 2001, 642p.Cruz, C. D.; Regazzi, A. J. Modelos biometricos aplicados ao melhoramento geneti-co. UFV, Vi<;;osa,2001, 390p.Falconer, D. S. Introduction to quantitative genetics. Longman Group, New York,1989, 438p.Goldenberg, J. B. El empleo de la correlaci6n en el mejoramento genetico de lasplantas. Fitotecnia Latinoamericana, v.5, n. 1-8, 1968.Pereira, A. S.; Tai, G. C. C.; Yada, R. Y.; Tarn, T. R.; Souza-Machado, V.; Cofin, R.H. Effect of selection for chip color on some economic traits of potatoes. PlantBreeding, v. 113, p. 312-317, 1994.Simmonds, N. W. Principles of crop improvement. Longman, New York, 1979, 408p.Tai, G. C. C.; Young, D. A. Early generation selection for important agronomic char-acteristics in a potato breeding population. American Potato Journal, v.61, p.419-434,1984.Thompson, P.G.; Mendoza, H. A.; Plaisted, R. L. Estimation of genetic parametersfor traits related to potato propagation by true seed (TPS) in an Andigena population.American Potato Journal, v. 60, p. 393-401, 1983.Ll.epraqeBa H.B., CorYJlSlKC.B.CI1611PCKI1HaYLIHo-I1CCJlenOBaTeJlbCKI1HcnnyT CeJlbCKorOX0351HCTBaOMCK,POCCI151dbor@bk.ruCeJleKUI151KapTo<peJl51B OMcKe HaLIaJlaCbB 1919 r. Ha 3ananI-IO-CI16I1PCKOHce-JleKUI10HHOHCTaHUl111(HbIHe - CI1611PCKI1HI-Hi CeJlbCKOrOX0351HcTBa),rne non py-KOBOnCTBOMB.B. TaJlaHoBa HaLIaJlpa60TaTb Jl.H. BeHeHI1. B KaLIeCTBeMeTona ce-JleKUl111Jl.H. BeHeHI1 I1CnOJlh30BaJlKJlOHOBhIHoT60p 113MecTHoro MaTepl1aJla, B KO-TOpOMnpe06JlanaJl COpT PaHH5I5Ip03a. B 1937 r. CeJleKUI10HHhlepa60ThI B C116-HI1I1CX 6hIJll1npOnomKeHbI Jl.B. KaTI1HhIM-JlpueBhIM11Jl.H. HBaHoBoH. B 1939 r.no peWeHI1I-O3KOHOMI1LIeCKOroCOBeTanpH COBHapKoMeCCCP, CH6HpCKOMyHHH

Early generation selection for tuber appearance and its influence on potato yield traits.

Abstract

Similar works

Full text

Available Versions

Repository Open Access to Scientific Information from Embrapa

RCAAP - Repositório Científico de Acesso Aberto de Portugal