Uticaj fenotipske i genetičke udaljenosti inbred linija na ispoljavanje heterozisa kod dialelnih hibrida kukuruza

Abstract

Za istraživanje je korišćeno sedam inbred linija kukuruza različitog porekla i dužine vegetacionog perioda. Odabrane inbred linije su ukrštene po metodu dialela bez recipročnih kombinacija čime je dobijen 21 hibrid. Ogledi su postavljeni u polju tokom 2017. i 2018. godine na tri lokacije: Zemun Polje, Novi Sad i Školsko Dobro (Zemun). Fenotipska karakterizacija je urađena na osnovu morfoloških osobina inbred linija i hibrida, kao i na osnovu kvantitativnih osobina u koje spadaju prinos i komponente prinosa. Najviši prinos su ostvarile inbred linije ZPL6 (4.17 t/ha) i ZPL4 (4.16 t/ha), najniži inbred linija ZPL5 (3.40). Najprinosniji hibridi su bili ZPL2 x ZPL4 (11.15 t/ha) i ZPL1 x ZPL4 (10.79 t/ha), a najmanje prinosni hibridi ZPL5 x ZPL7 (6.31 t/ha) i ZPL3 x ZPL6 (6.47 t/ha). Heterozis je računat u odnosu na boljeg roditelja (HPH) za sve ispitivane osobine. Najviša vrednost heterozisa za prinos zrna je dobijena kod hibrida ZPL2 x ZPL4 u 2017. godini (285.88), a najniža kod hibrida ZPL4 x ZPL7 u 2018. godini (31.19). Na osnovu ispitivanja opštih (OKS) i posebnih (PKS) kombinacionih sposobnosti inbred linija zabeležene su značajne i veoma značajne pozitivne vrednosti OKS za prinos zrna kod inbred linija ZPL2 i ZPL4, dok su značajne negativne vrednosti OKS za prinos zrna imale inbred linije ZPL5 i ZPL7. Najveću pozitivnu PKS vrednost za prinos zrna je imala hibridna kombinacija ZPL2 x ZPL4 (2.061), a najmanju vrednost hibridna kombinacija ZPL1 x ZPL7 (0.857). Odnos OKS/PKS ukazuje na uticaj aditivne i neaditivne (dominacija i epistaza) varijanse u ukupnom fenotipskom variranju. Za osobine prinos zrna, broj redova zrna, broj zrna u redu, dubina zrna i masa 1000 zrna je odnos OKS/PKS bio manji od 1 što ukazuje na preovlađujući uticaj neaditivne varijanse, dok je za osobine visina biljke, visina klipa, ukupan broj listova, broj listova iznad klipa i dužina klipa odnos OKS/PKS bio veći od 1 što ukazuje na preovlađujući uticaj aditivne varijanse. Za korelaciju prinosa i komponenti prinosa podaci ukazuju na najveću zavisnost prinosa sa brojem zrna u redu (0.50). Kod ostalih osobina inbred linija i hibrida je najveća zavisnost bila između visine biljke i visine klipa (0.85 i 0.83). Molekularna karakterizacija inbred linija je izvršena pomoću SSR i SNP molekularnih markera na osnovu kojih je formiran dendrogram. Na osnovu SSR markera najmanja genetička sličnost je zabeležena između inbred linija ZPL2 i ZPL6 (0.45), a najveća između inbred linija ZPL5 i ZPL6 (0.75). Na osnovu SNP markera najveća genetička distanca je bila između inbred linija ZPL2 i ZPL4 (0.487), a najmanja između inbred linija ZPL1 i ZPL2 (0.191). Rezultati su pokazali da su najudaljenije inbred linije dale hibride sa najvećim prinosom zrna i najvećim heterozisom.

Seven maize inbred lines of different origin and different growing period were investigated. Selected inbred lines were crossed by the diallel method without reciprocal combinations, and in this way we got 21 hybrids. Field trials were conducted during 2017 and 2018 on three locations: Zemun Polje, Novi Sad and Školsko Dobro (Zemun). Phenotypic characterization was done on the basis of morphological characteristics of inbred lines and hybrids, as well as on the basis of quantitative characteristics which include grain yield and yield components. The highest grain yield was achieved by inbred lines ZPL6 (4.17 t/ha) and ZPL4 (4.16 t/ha), the lowest grain yield was achieved by inbred line ZPL5 (3.40). The most productive hybrids were ZPL2 x ZPL4 (11.15 t/ha) and ZPL1 x ZPL4 (10.79 t/ha), and the least productive hybrids were ZPL5 x ZPL7 (6.31 t/ha) and ZPL3 x ZPL6 (6.47 t/ha). Heterosis was calculated in relation to the better parent (HPH) for all examined traits. The highest value of heterosis for grain yield was obtained for hybrids ZPL2 x ZPL4 in 2017 (285.88), and the lowest for hybrids ZPL4 x ZPL7 in 2018 (31.19). Based on the investigation of general (OKS) and specific (PKS) combining abilities of inbred lines, significant and very significant positive values of OKS for grain yield were recorded in inbred lines ZPL2 and ZPL4, while significant negative values of OKS for grain yield were recorded in inbred lines ZPL5 and ZPL7. The hybrid combination ZPL2 x ZPL4 (2,061) had the highest positive value of PKS for grain yield, and the hybrid combination ZPL1 x ZPL7 (0,857) had the lowest value. The OKS/PKS ratio indicates the influence of additive and non-additive (dominance and epistasis) variance in the total phenotypic variation. For grain yield, kernel row number, kernel number per row, ear diameter and 1000-kernel weight, the OKS/PKS ratio was less than 1, which indicates the predominant influence of non-additive variance, while for plant height, ear height, total number of leaves, the number of leaves above the ear and ear length ratio OKS/PKS was greater than 1, which indicates the predominant influence of additive variance. For the correlation of grain yield and yield components, the data indicate the highest dependence of grain yield with the kernel number per row (0.50). Among other traits of inbred lines and hybrids, the greatest dependence was between plant height and ear height (0.85 and 0.83). Molecular characterization of inbred lines was performed using SSR and SNP molecular markers and dendrogram was formed showing genetic distance between inbred lines. Based on SSR markers, the lowest genetic similarity was recorded between the inbred lines ZPL2 and ZPL6 (0.45), and the highest between the inbred lines ZPL5 and ZPL6 (0.75). Based on SNP markers, the largest genetic distance was between the inbred lines ZPL2 and ZPL4 (0.487), and the smallest between the inbred lines ZPL1 and ZPL2 (0.191). The results showed that the most distant inbred lines gave hybrids with the highest grain yield and the highest heterosis.