Pat analysis for popping volume, grah yield and yield components in maize (Zea mays L. everta)

Abstract

Five maize inbred lines, ZPNP11, Sg1533, ZPLP2/1, ZPK18 and ZPK6, were used for this study. The dilled cross with n(n-l)/2 combinations was performed and 10 Fl hybrids were analyzed in parallel trials in two locations (Zemun Polje and Indjija). The two factorial analysis of variance and covariance, model II, was used for data processing and therefore separation of variance components (genetic, ecological, phenotypic) and the estimation of coefficients of genetic and phenotypic correlations among studied traits (popping volume, grain yield, number of kernel rows per ear, number of kernels per row, number of kernels per 10 grams, kernel depth). The coef­ficients of variation and heritability were also computed. Beside the degree of compatibility between the two traits (correlation coefficient), the path analysis (Wright, 1934) provided a more detailed consideration of the relation.: among observed traits. The estimation of standardized regression coefficients (path coefficients) was done by the method of inversion correlation symmetrical matrixes (Edwards. 1979) Popping volume, as the most important trait in popcorn breeding is used as a dependent variable (v). The results obtained by the path analysis point to the complexity of relations between popping volume, as a dependent variable, and independent variables, as well as to the character of relations among independent variables. Path analysis is a form of the regression analysis providing comprehension of the direct and indirect effects, as well as the share of joint effects (determina­tion) of independent variables (x1, x2, ... xn) on the dependent variable (y). The purpose of this study was to determine and evaluate effects of grain yield and grain yield components on popping volume. It was assumed that some of the selected traits, as independent variables, significantly affected grain yield as the dependent variable. The highest correlation dependence (genetic and phenotypic) was detected between pop­ping volume and the number of kernel per row(rg=0.82**, rf=0.75**). The direct genetic effects (path coefficients) were higher and more significant than phenotypic ones. The highest direct genotypic effect on popping volume was detected for the number of kernel per row (Pyg3 = 1.04**) and number of kernel row per ear (Pyg4=1.00**). Negative direct genetic effect was found for grain yield (Pyg1=-1.33**) and number of kernels per 10 grams Pyg4 = -0.48**. The coefficients of determination, especially genetic one were not high (Rg2 = 0.31, Rf2 = 0.73) which indicate that studied traits do not determine popping volume at a great extent, so selection of genotypes with high popping volume could be done regardless grain yield and grain yield components. Direct phenotypic effects were lower and not significant.

Pet linija kukuruza: ZPN11, Sg1533, ZPLP2/1, ZPK18 i ZPK6 su upotrebljene za ovo istraživanje. Dialelno ukrštanje sa n(n-1)/2 kombinacija urađeno je između ovih linija, a 10 njihovih F1 hibrida je ispitivano u uporednim ogledima u dve lokacije (Zemun Polje i Indija). Za obradu podataka korišćena je dvofaktorijalna analiza varijanse i kovarijanse, model II, kao i za razdvajanje komponenti varijanse (genetička, spoljne sredine, fenotipska) i procenti koeficijenata genetičkih i fenotipskih korelacija između ispitivanih osobina (zapremina kokičavosti, prinos zrna, broj redova zrna, broj zrna u redu, broj zrna u 10 g, debljina zrna). Takođe su utvrđeni koeficijenti varijacije i heritabilnost. Osim stepena saglasnosti između dvc osobine (koeficijent korelacije), pat analiza (Wright 1934) pruža detaljniji uvid u odnose između ispitivanih osobina. Procene standardizovanih regresionih koeficijenata (pat koeficijenti) su urađene po metodi inverznib korelacionih simetričnih matrica (Edwards 1979) - Zapremina kokičavosti, kao najhitnija osobina u selekciji kokičara, iskorišćena je kao zavisna promenljiva (y). Dobijeni rezultati ukazuju na složenost odnosa između zapremine kokičavosti, kao zavisne promenljive, i nezavisnih promenljivih, kao i na karakter odnosa između nezavisnih promenljivih. Pat analiza je oblik regresione analize koji omogućuje procenu direktnih i indirektnih efekata, kao i udeo zajedničkih efekata (determinacija) nezavisnih promenljivih (x1, x2,...xn) na zavisnu promenljivu (y). Cilj ovog istraživanja bio je da se utvrde i procene efekti prinosa zrna i komponenti pritiosa zrna na zapreminu kokičavosti. Pretpostavilo se da neke od odabranih osobina, kao nezavisne promenljive, značajno utiču na prinos zrna kao zavisnu varijablu. Najviša korelaciona zavisnost (genetička i fenotipska) utvrđena je između zapremine kokičavosti i broja zrna u redu (rg=0,82**, rj=0,75**). Direktni genetički efekti (pat koeficijenti) bili su veći i značajniji od fenotipskih. Najveći direktan genotipski efekat na zapreminu kokičavosti bio je za broj zrna u redu (Pyg3 = 1,04**) i broj redova zrna (Pyg4 = l,00**). Negativan direktni genetički efekat nađen je za prinos zrna (Pyg4=-1,33**) i broj zrna u 10 g (Pyg4=-0,48**). Koeficijenti determinacije, posebno genetički, nisu bili visoki (Rg2=0,31; Rf=0,73), što ukazuje na to da ispitivane osobine ne utiču mnogo na zapreminu kokičavosti, tako da bi selekcija genotipova sa visokom zapreminom kokičavosti mogla biti urađena bez obzira na prinos zrna i neke komponente prinosa zrna. Direktni fenotipski efekti bili su niži i nisu bili značajni.