Combining ability of silage maize ear length

Abstract

The aim of the present study was to evaluate the following parameters of silage maize ear length: variability of inbred lines and their diallel hybrids, superior-parent heterosis and general and special combining abilities. According to obtained results of the two-year study, it can be concluded that variability of this trait is significantly affected by a genotype and a genotype x year interaction. As expected, hybrids had greater average values of ear length than inbreeds due to the depression of this trait that occurs in inbreeds during inbreeding. The highest average value of heterosis for ear length was detected in the hybrid ZPLB 402 x ZPLB 406 (62.3% and 48.8% in 1997 and 1998, respectively). The estimation of combining abilities was done on the basis of diallel hybrids after the method established by Griffing, 1956a (method II, mathematical model I). The analysis of variance of combining ability for ear length indicated highly significant positive values of GCA and SCA for the observed trait in both years of investigation. Ear length inheritance was more affected by non-additive genes (dominance and epistasis) as indicated by the GCA to SCA ratio that was smaller than unity. The inbreeds ZPLB 401 and ZPLB 406 had high GCA effects, while the hybrid combinations ZPLB 401 x ZPLB 403. ZPLB 401 x ZPLB 402, ZPLB 401 x ZPLB 406 and ZPLB 403 x ZPLB 406 had high SCA effects in both investigation years. These hybrid combinations include both parents with high GCA effects or one parent with low GCA effects. Furthermore, there are combinations ZPLB 403 x ZPLB 405 and ZPLB 404 x ZPLB 405 with significant SCA effects that include parents with low GCA effects. This is probably a result of the additive type (additive x additive) of interaction between parents.

Cilj ovog istraživanja je bio da se za dužinu klipa silaznog kukuruza procene: varijabilnost šest inbred linija i njihovih dialelnih hibrida, heterozis u odnosu na boljeg roditelja i opšte i posebne kombinacione sposobnosti u dialelnom ukrštanju po metodi Griffing-a, 1956, (metod II, matematički model I). Na osnovu dobijenih rezultata dvogodišnjeg istraživanja može se zaključiti da na varijabilnost ove osobine značajno utiču genotip, i interakcija genotipa i godine. Hibridi su u odnosu na linije ispoljili veće prosečne vrednosti za dužinu klipa što je i očekivano obzirom da pri inbridingu dolazi do depresije ovih osobina kod linija. Najviša prosečna vrednost heterozisa za dužinu klipa je utvrđena za hibrid ZPLB402 x ZPLB406 (62,3% (1997) i 48,8% (1998)). Analiza varijanse kombinacionih sposobnosti za dužinu klipa je pokazala da postoje visoko značajne pozitivne vrednosti OKS i PKS za ovu ispitivanu osobinu u obe godine ispitivanja. Za nasleđivanje dužine klipa utvrđen je veći značaj neaditivnih gena (dominacije i epistaze) što pokazuje odnos OKS/PKS koji je bio manji od jedinice. Najbolji opšti kombinatori su u obe godine ispitivanja bile linije ZPLB401 i ZPLB406, a hibridne kombinacije ZPLB401 x ZPLB403, ZPLB401 x ZPLB402. ZPLB401 x ZPLB406 i ZPLB403 x ZPLB406 su sa značajnim efektima PKS u obe godine ispitivanja. One uključuju oba roditelja sa dobrim OKS ili jednog roditelja sa dobrim OKS i drugog sa lošijim OKS. Takođe imamo i hibridne kombinacije ZPLB403 x ZPLB405 i ZPLB404 x ZPLB405 koje su u obe godine ispitivanja imale značajne efekte PKS, a uključuju roditelje sa lošim OKS vrednostima. Ovo je verovatno posledica delovanja aditivnog tipa (aditivni x aditivni) interakcije među roditeljima.