Sohail, M.; Hussain, I.; Din, R.;Tanveer, S.K.; Qamar, M.; Abbas, S.H.
Wheat under rainfed conditions of Pothwar region of Pakistan is usually exposed to limited soil moisture during early growth period and high temperature stress during reproductive growth stage. Better yield under stressful environment is the main objective while evaluating genotypes for rainfed ecologies. A field study was conducted at National Agricultural Research Centre (NARC), Islamabad, Pakistan to evaluate the agronomic traits of three advance lines (NR-397, NR-379 and NR-400) in comparison to released variety (NARC-09) under rainfed conditions during crop season 2010-2011. Crop was sown on normal (November 15) and late (December 15) planting times to create variable growing conditions especially during reproductive growth period. The adverse effect of the late planting was significant (P<0.05) on grain yield of the crop. Late planting produced 29% lower grain yield than normal planting. Genotypes also showed significant variation (P<0.05) regarding grain yield production under both normal and late sowing dates. Under more stressful growing conditions (late planting), minimum grain yield reduction was noticed in line NR-397 (19%) followed by NARC-09 (20%), NR-400 (30%) and NR-379 (35%). Late planting conditions also signi- -2 ficantly reduced days to maturity, spikes m and 1000-grain weight in all genotypes as compared to normal sowing; however, the reduction in these parameters were significantly less (P<0.05) in wheat lines NR-397 and NARC-09 as compared to other two genotypes. Results showed that comparatively higher grain yields of lines NR-397 and NARC-09 were correlated to their better leaf chlorophyll retention and maintenance of low canopy temperature during grain filling periods particularly under late planting conditions. Findings of this study have indications that wheat sowing up to November 15 is more appropriate time and advance lines NR- 397 and NARC-09 have the genetic potential to tolerate adverse rainfed growing conditions under agro-ecological conditions of Pothwar region, Pakistan.
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