Variability and components of variance for harvest index in wheat (Triticum aestivum L.)

Abstract

Variability, heritability and components of variance were studied in 50 cultivars from different selection centres of the world. Plants were grown in the experimental field in 3 replications during two vegetative seasons. Samples of 60 wheat plants (20 plants in 3 repetitions) were analysed in full maturity stage. Harvest index was calculated as the ratio of grain yield and total aerial part of the plant. The highest harvest index was found in cv. Peking8 (44.6%), and the lowest in cv. Jawa (23.8%). On average for all cultivars, the harvest index was similar in both years of investigation (35.4%; 35.2% resp.). Cultivars showed differences in variability of harvest index. The mean coefficient of variation for all cultivars and both years was V = 12.0%. The lowest coefficient of variation was found in cv. Peking 8 (V = 7.0%), and the highest cv. Brock (V = 17.8%). High heritability (V= 75%) was established for this trait. Highly significant differences in mean values for harvest index between cultivars were shown by analysis of variance. Differences between year and the interaction cultivar/year were also highly significant. Components of phenotypic variance showed that genetic factors (53.7%) had the highest impact on expression of harvest index, while the interaction cultivar/year showed less impact (35%). Year did not contribute significantly to the variance. Key words: wheat, cultivar, harvest index. heritability, variability, components of variance.

U radu je proučavana varijabilnost, heritabilnost u širem smislu i komponente varijanse kod 50 sorti pšenice poreklom iz različitih zemalja sveta. Biljke su gajeneu poljskom ogledu po slučajnom blok sistemu u tri ponavljanja u toku dve vegetacione sezone. Analiza biljaka su urađene u fazi pune zrelosti pšenice na uzorcima od 60 biljaka (po 20 biljaka u tri ponavljanja). Žetveni indeks je izračunat kao odnos prinosa zrna i ukupne nadzemne mase biljke. Najveći žetveni indeks je ustanovljen kod sorte Peking 8 (44,6%), a najmanji kod sorte Jawa (23,8%). Posmatrano u proseku za sve sorte, vrednosti za žetveni indeks su bile slične u prvoj (35,4%;) i drugoj (35,2%) godini istraživanja. Sorte su ispoljile razlike u varijabilnosti žetvenog indeksa. Koeficijent varijacije, prosečno za sve sorte i godine iznosio je V = 12,0%. Najmanji koeficijent varijacije utvrđen je kod sorte Peking 8 (V = 7.0%), a najveći kod sorte Brock (V = 17,8%). Ustanovljena je visoka heritabilnost u širem smislu za žetveni indeks, sa vrednošću od h = 75.0%. Analizom varijanse utvrđene su visoko značajne razlike za ovo svojstvo između ispitivanih sorti pšenice. Razlike po godinama i interakcija sorta/godina bile su, takođe, visoko značajne. Komponente fenotipske varijanse pokazale su da najveći udeo u ispoljavanju žetvenog indeksa imaju genetički faktori (56,7%), nešto manji udeo pripada interakciji sorta/godina (35,0%), dok udeo godine nije ustanovljen.