Heterotic Effects in Fls and Inbreeding Depression in F2 Hybrids of Sunflower

Abstract

Genetically diverse female lines of sunflower were crossed with male testers to get heterotic hybrids. Studies were carried-out during 2008-2010 at Experiment filed of Agriculture Research Institute, Tandojam, Sindh, Pakistan. Six female lines like T-4-0319, PAC-0505, HO-I, Hysun-33, Peshawar-93 and CMS-03 and three testers i.e., PAC-0306, PAC-64-A and SF-187 were crossed in a line ´ tester mating design, thus 18 F1 and F2 hybrids were developed for evaluation of heterosis and inbreeding depression for days to initial flowering, days to maturity, leaves/plant, plant height (cm), head diameter (cm), 1000-achene weight (g), seed yield kg/ha and oil yield kg/ha. The experiment was conducted in a randomised complete block design with four replications. The analysis of variance revealed significant differences among parents, F1s and F2 hybrids for all the traits studied. The existence of significant genetic variability among the plant traits is particularly useful because variations in these traits would allow further improvement in sunflowerseed yield and oil traits. The F1 hybrids HO-I ´ PAC-0306 and HO-I PA ´ C-64-A exhibited desirable negative mid and better parent heterosis for days to initial flowering, days to maturity and plant height. These hybrids also manifested desirable positive heterotic effects for leaves/plant, head diameter, 1000-achene’s weight, seed yield and oil yield. Inbreeding depression for phenological, seed yield and oil traits showed that desirable high inbreeding depression was observed in hybrids HO-I ´ P´AC-64-A, HO-I ´ PAC-0306 and HO-I ´ SF-187 for days to initial flowering, similarly T-4-0319 ´ PAC-0306, PAC-0505 ´ SF-187 and HO-I ´ PAC-64-A explicated maximum but rewarding inbreeding depression for days to maturity. The F2 hybrids Hysun-33 ´ SF-187 and Peshawer-93 ´ PAC-64-A may be the most desirable ones in the sense that they recorded comparatively moderate inbreeding depression with enough number of leaves to be productive if F2 hybrids are to be exploited for hybrid vigour. Low inbreeding depression for various traitsindicated that such hybrids some how favour the usefulness of F2 hybrids in sunflower.

Heterosis and inbreeding depression for yield and oil traits of sunflower genotypes under water stress conditions

“…The high inbreeding depression in negative direction can lead to develop F2 hybrids with shorter plant height. Analogous to present findings, (26) reported high inbreeding depression for plant height extended between -3% to -26% and that is the lowermost inbreeding despair designated high heterozygosity thus showed minor deprivation of dominant genes operated in F2 populations. Reports are also on higher inbreeding depression, around 23% in 4 F2 hybrids (26).…”

“…Analogous to present findings, (26) reported high inbreeding depression for plant height extended between -3% to -26% and that is the lowermost inbreeding despair designated high heterozygosity thus showed minor deprivation of dominant genes operated in F2 populations. Reports are also on higher inbreeding depression, around 23% in 4 F2 hybrids (26). These hybrids may suit better for short duration sunflower F2 hybrids.…”

“…The crossing due to additive type of genes may be suitable if on the contrary dominant genes produce high inbreeding effect (25). Stumpy inbreeding impact for different characters designated that such hybrids somehow favor the effectiveness of F2 sunflower hybrids (26). The results regarding heterosis (Table 7) and inbreeding depression in sunflower are presented (Table 8, 9) for traits under investigation.…”

“…However, the F2 hybrids such as Mehran × peshawar-93, SH-3915 × B-2 and PSF-025 × B-2 recorded maximum inbreeding depression (around 6% on average of 3 hybrids) for oil content in non-stress, whereas F2 progenies SH-3915 × UC-666 followed by HO.1 × Peshawar-93 and Thatta × Peshawar showed no inbreeding depression in water stress conditions. It was stated that oil quantity being a multigenic character is advocated by trivial genes; consequently nethermost inbreeding influence is predicted (26).…”

“…Reports are on 5 paramount hybrids with higher heterotic estimates. In case of parental mean, 4 hybrids were identified from their study (26).…”