Combining abilities of silage maize grain yield

Abstract

The aim of the present study was to evaluate the following parameters of maize grain yield: 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, year and their interaction. As expected, hybrids had higher average grain yields than inbreds due to the depression of this trait that occurs in inbreds during inbreeding. The highest average value of heterosis for gain yield was detected in the hybrid ZPLB405 x ZPLB406 (123.0% and 178.1% in 1997 and 1998, respectively). The estimation of combining abilities was done on the basis of diallel hybrids after the method established by Griffing, 1956 (method II, mathematical model I). The analysis of variance of combining ability for grain yield indicated highly significant values of GCA and SCA for the observed trait in both study years. Grain yield 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 inbreds ZPLB401 and ZPLB406 had high GCA effects, while the hybrid combinations ZPLB40Î x ZPLB402, ZPLB401 x ZPLB403, ZPLB401 x ZPLB405, ZPLB402 x ZPLB406, ZPLB403 x ZPLB406, ZPLB404 x ZPLB406, ZPLB405 x ZPLB406 had high SCA effects in both study years. These hybrid combinations include one parent with high GCA effects and other with low GCA effects. Furthermore, there are combinations ZPLB402 x ZPLB405, ZPLB403 x ZPLB405 and ZPLB404 x ZPLB405 with significant SCA effects that include parents with low GCA effects. This is probably the result of the additive type (additive x additive) of interaction between parents.

U radu za prinos zrna kukuruza izvršena je procena varijabilnosti inbred linija i njihovih diaielnih hibrida, heterozis u odnosu na boljeg roditelja i opšte i posebne kombinacione sposobnosti. Na osnovu dobijenih rezultata dvogodišnjeg istraživanja može se zaključiti da na varijabilnost ove osobine značajno utiču genotip, godina i njihova interakcija. Hibridi su u odnosu na linije ispoljili veće prosečne vrednosti za prinos zrna što je i očekivano obzirom da pri inbridingu dolazi do depresije ove osobine kod linija. Najveći prinos zrna su imali hibridi ZPLB401 x ZPLB406 (1997) i ZPLB404 x ZPLB406 (1998). Za većinu hibridnih kombinacija utvrđene su visoke vrednosti heterozisa (-31.7 do 178.1 %), dok je hibrid ZPLB402 x ZPLB403 pokazao negativnu vrednost heterozisa za prinos zrna (-11.0 do -31.7%). Najviša prosečna vrednost heterozisa za prinos zrna je utvrđena za hibrid ZPLB405 x ZPLB406 (123.0% (1997) i 178.1% (1998). Procena kombinacionih sposobnosti je izvršena na bazi dialelnih hibrida po metodi Griffing-a, 1956, (metod II matematički model I). Analiza varijanse kombinacionih sposobnosti za prinos zrna je pokazala da postoje visoko značajne vrednosti OKS i PKS za ovu ispitivanu osobinu u obe godine. Za nasledjivanje prinosa zrna utvrđen je veći značaj neaditivnih gena (dominacije i epistaze) što pokazuje odnos OKS/PKS koji je bio manji od jedinice. Najbolji opšti kombinatori su bile linije ZPLB401 i ZPLB406, a hibridne kombinacije ZPLB401 x ZPLB402, ZPLB401 x ZPLB403, ZPLB401 x ZPLB405, ZPLB402 x ZPLB406, ZPLB403 x ZPLB406, ZPLB404 x ZPLB406, ZPLB405 x ZPLB406 su sa značajnim efektima PKS u obe godine ispitivanja. Sve hibridne kombinacije sa dobrim PKS uključuju oba roditelja sa dobrim ili jednog roditelja sa dobrim OKS i drugog sa lošijim OKS ili oba sa lošim OKS sposobnostima. Takođe, imamo i hibridne kombinacije ZPLB402 x ZPLB405, 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.