Phenotypic distances of parental components as a possible indicator of heterosis

Abstract

Although the reveal of heterotic groups in maize significantly increased testing efficiency, field trials are still unreplaceable and most time and fund consumable in the process of the hybrid development. The efficiency of breeding programmes could be significantly increased if the hybrid performance could be predicted prior to the field evaluation. Although different marker techniques have been developed and included into current breeding programmes, the satisfactory results have not been obtained yet. The present study is an attempt to inexpensively and rapidly discover indicators that could even partially facilitate the selection of parental pairs in the process of the hybrid development prior to the field evaluation. The phenotypic description of inbred lines according to the UPOV Descriptor was used for the estimation of the phenotypic distances for which it had been assumed that they could, to a certain degree, be an indicator of heterosis. The phenotypic characterization according to the UPOV Descriptor was done for 28 elite inbreds, that are often used in our commercial breeding programmes, and for 24 inbreds originating from the same source, as well as, for an inbred of the unknown origin and their phenotypic distances were estimated. The cluster analysis resulted in the classification that was in high compliance with known information on the origin. It was empirically concluded that great distances of parent inbreds result in good hybrids. Furthermore, high values among certain inbreds belonging to the same heterotic groups are observed on the morphological distance matrix and crosses among them should indeed be tested in the field prior to making any general conclusion on the reliability of the morphological distance in the prediction of heterosis.

Efikasnost oplemenjivačkih programa bi se znatno mogla povećati ako bi bilo moguće predvideti proizvodne performase hibrida pre evaluacije u polju. Fenotipska karakterizacija linija po UPOV deskriptoru je iskorišćena za izračunavanje fenotipskih distanci za koje smo pretpostavili da u određenoj meri mogu biti indikator heterozisa. Urađena je i fenotipska karakterizacija po UPOV deskriptoru 28 elitnih linija koje se često koriste u komercijalnom programu oplemenjivanja u Institutu za kukuruz 'Zemun Polje', 24 linije poreklom iz istog izvora kao i jedne linije nepoznatog porekla i na osnovu rezultata urađena je Klaster i Korespondenciona analiza. Klaster analiza je dala grupisanje koje je u visokoj saglasnosti sa poznatim informacijama o poreklu. Empirijski je zaključeno da velike distance roditeljskih linija daju dobre hibride. Međutim, na matrici morfoloških distanci se uočavaju visoke vrednosti između nekih linija koje pripadaju istim heterotičnim grupama i ukrštanja između njih bi svakako trebalo testirati u polju, pre izvlačenja nekog generalnog zaključka o pouzdanosti morfološke distance u predviđanju heterozisa.