Combining ability of nitrogen deficiency stress indices for plant height in rapeseed varieties

Abstract

Although an average plant height is more preferable in most of agronomic crops, less reduction of this trait in stress condition makes yield components and seed yield sustainable in rapeseed varieties. Combining ability, heterosis and heritability of plant height at application and non-application of nitrogen environments (Hp and Hs, respectively) and its related stress tolerance indices were detected in half F2 diallel crosses of six spring rapeseed varieties. Significant mean squares of general and specific combining abilities (GCA and SCA) were detected for Hp, Hs, mean productivity (MP), geometric mean productivity (GMP) and stress tolerance index (STI), indicating the importance of additive and non-additive genetic effects for them. A high narrow-sense heritability estimate was exhibited for STI, emphasizing the prime importance of additive genetic effects for this stress tolerance index. A significant correlation among Hp, Hs, MP, GMP and STI showed the efficiency of these stress indices for improving plant height in plant breeding programme. In comparison to SCA effects, most of the crosses had significant high parent heterosis for Hp, Hs and all the stress indices. RGS003 with a significant positive GCA effect of Hs was considered as a suitable parent for improving this trait and most of the combinations of this genotype had significant negative SCA effects.Iako je prosecna visina biljke pozeljnija za vecinu gajenih biljaka, smanjenje ove osobine u uslovima stresa cini odrzivim komponente prinosa i prinos semena sorti uljane repice. Kombinaciona sposobnost, heterozis i heritabilnost visine biljke u uslovima sa primenom i bez primene azota (Hp, odnosno Hs) kao i njeni odgovarajuci pokazatelji tolerancije stresa su utvrdjeni kod polovine F2 dialelnih hibrida sest jarih sorti uljane repice. Znacajne vrednosti sredine kvadrata opstih i posebnih kombinacionih sposobnosti (GCA i SCA) su uocene za Hp, Hs, srednju produktivnost (MP), geometrijsku srednju produktivnost (GMP) i indeks tolerancije stresa (STI), ukazujuci na vaznost aditivnih i neaditivnih genetickih efekata. Dobijen visok koeficijent heritabilnosti u uzem smislu za indeks tolerancije stresa ukazuje na veliki uticaj aditivnih gena. Znacajni koeficijenti koleracija izmedju Hp, Hs, MP, GMP i STI ukazuju na efikasnost tih pokazatelja stresa za dalje povecanje visine biljke u procesu oplemenjivanja. Kod posebnih kombinacionih sposobnosti (SCA), veliki broj ukrstanja je pokazivao znacajno visok heterozis za osobine Hp, Hs i sve pokazatelje stresa. Sorta RGS 003 je imala znacajnu pozitivnu vrednost GCA za osobinu Hs zbog cega se smatra pogodnim roditeljem za poboljsanje te osobine, dok su SCA vrednosti bile znacajno negativne.