Heterosis Expression Analysis and its Impact on Different Agro-Morphological Characters in Sunflower (H. Annuus L.) Hybrids
Heterosis Expression Analysis and its Impact on Different Agro-Morphological Characters in Sunflower (H. Annuus L.) Hybrids
Ihsan Ullah Khan*, Muhammad Arshad, Muhammad Ayub Khan, Muhammad Ashraf, Ashiq Saleem, Sundas Awan, Samra Azam and Shamim Ul Sibtain Shah
ABSTRACT
This study was carried out at National Agricultural Research Centre (NARC), Islamabad during 2016-17 with the objective to assess the impact of heterosis on different Agro-morphological traits in sunflower hybrids. Randomized Complete Block Design (RCBD) was used with three replications. The experimental material consisted of nine hybrids, six inbred lines and a commercial check (Hysun-33). The recorded data on days to flowering initiation (DFI), days to flowering completion (DFC), days to maturity (DM), plant height (PHT, cm), stem thickness (ST, mm), head diameter (HD, cm), 100-grain weight (100-GW, gm), oil content percentage (OC %) and seed yield (SY, kg ha-1) revealed statistically significant differences. All the crosses out-performed the standard check in terms of seed yield (kg ha-1) with significant differences in this regard. Positive and significantly high mid-parent heterosis was observed in all the hybrids for all the studied traits except DFI, DFC and DM which showed negligibly low impact of heterosis on their expression. Comparatively higher and positive heterosis was exhibited by all hybrids for traits such as PHT (52.16-84.91 %), ST (2.83-191.85 %), HD (19.98-68.49 %) 100-GW (12.21-64.44 %) and SY (kg ha-1) (125.47-175.21 %) relative to parental average. The highest magnitude of heterosis for seed yield was exhibited by the cross CMS-77 x R-83(1) (175.21 %) relative to mid-parent values. The impact of mid-parent heterosis on the oil content (%) remained negligible. Similarly, all the hybrids showed positive and significant heterosis for PHT (61.36-101.44 %), ST (8.59-134.22 %), HD (1.87-33.20 %), 100-GW (-13.76-32.07 %) and SY (kg ha-1) (32.80-56.01 %) relative to better-parents. The remaining traits studied did not show appreciable effect of heterosis over better-parents. Overall, the heterotic effects were more prominent on the PHT, ST, HD, 100-GW and SY (kg ha-1) as compared to other traits both relative to mid- and better-parent values. The hybrid vigor (%) in the hybrids over the standard check regarding seed yield ranged from 4.84 % in the cross CMS-77 x R-18 to 20.09 % in the cross CMS-77 x R-83(1). The discovery of Cytoplasmic Male Sterility (CMS) and fertility restoration genes gave a new direction to heterosis based sunflower breeding and consequently revolutionized sunflower seed sector. The high impact of heterosis on the yield and other yield contributing traits in the hybrids, as revealed in this study, offers good prospects for the future use of hybrid breeding in sunflower if genetically more diverse germplasm is incorporated in breeding programs.
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