5TH International Congress on Technology - Engineering & Science - Kuala Lumpur - Malaysia (2018-02-01)

Evaluation Of Heterosis For Heat Tolerance In Wheat

Heat stress one of the critical factors affecting wheat crop especially at reproductive stage. Exploitation of heterosis is considered as a vital strategy for incorporating heat stress tolerance in wheat that ultimately results in increasing over all yield. The experiment was conducted in NARC Islamabad, to evaluate heterosis regarding various morpho-physiological traits involved in heat tolerance. Heterosis was assessed by crossing five lines (Auqab-2000, Punjab-81, Punjab-85, Pak-81, Pak-2013) and three testers (Chanab-2000, Pavan, Shalimar) in Line × Tester matting design. To estimate the effects of heat stress F1 along with parents were sown in two contrasting temperature regimes, high temperature (heat stress) in green house and control (field conditions). Morpho-physiological traits were analysed and found highly significant for numbers of tillers per plant (Auqab-2000 × Chanab-2000) under control conditions and non-significant for plant height (Punjab-85 × Shalimar-88) under heat stress conditions, highly significant chlorophyll contents (Pak-2013 × Shalimar-88) were found in control while significant results were observed for cell membrane stability (Pak-81 ×Chanab-2000) under heat stress conditions. The parents genotypes, exhibited good general combining ability for plant height (Chanab-2000 and Pavan), chlorophyll content (Auqab-2000), cell membrane thermostability (Auqab-2000), fertile tillers (Auqab-2000), spike per plant (Auqab-2000) and grain yield (Pak-81). Among crosses, Punjab-81 × Chanab-2000 and Punjab-81 × Shalimar-88 presented significantly positive chlorophyll contents and canopy depression respectively while Pak-81 × Chanab 2000, Pak-81 × Shalimar-88 showed significant results for spike per plant. The crosses Pak-81 × Pavan, Pak-81 × Chanab 2000, Pak-2013 × Chanab-2000, Pak-2013 × Pavan, Pak-2013 × Shalimar-88 were highly significant for cell membrane thermostability. The cross Punjab-85 × Shalimar-88 and Punjab-85 × Pavan were the best showing highly significant combining ability effect of -2.07 and -1.41 respectively for plant height. All the crosses exhibited maximum heterosis for plant height and significant heterosis for 1000-grain weight and spikes per plant. Results showed the existence of heterosis in these lines for plant height, 1000-grain weight and spikes per plant and these lines can be used in any breeding program to exploit heterosis.
AZHAR IQBAL, RASHID MEHMOOD RANA, MUHAMMAD KOUSAR SHAH NAWAZ, NAVEED TAHIR