EFFECT OF SOWING DATE ON EMERGENCE, TILLERING AND GRAIN YIELD OF DIFFERENT WHEAT VARIETIES UNDER BAHAWALPUR CONDITIONS

An experiment was conducted to study the effect of germination percentage, seedling emergence and tillering on yield of different varieties of wheat viz. Punjab-96, MH-97, BWP-97, Panjnad-1, AS-2002, Inqlab-91, BWP-2000, Uqab-2000 and Bhakkar- 2002 sown at different planting dates. The study included six sowing dates starting from 1st November to 16th January of the year 2006-07 with equal intervals of fifteen days. The experiment was laid out in randomized complete block design with split plot arrangement having three replications, keeping sowing dates in main plots and wheat varieties in sub plots. The plot size was 2.4m x 8m. The collected data were analyzed using computer statistical program MSTATC. Significant difference was recorded among dates of sowing from 1st November to 16th January with highest mean grain yield of 6292 kg ha^-1 followed by 16th November sowing (6059 kg ha^-1). After November, yield of all varieties decreased significantly. Lowest grain yield of 2020 kg ha^-1 was recorded on 16th January sown. However, all the wheat varieties gave significantly higher yields in a wide range of sowing period i.e. 1st November to 1st December. In late sown crop due to increase in temperature (6-8°C) above normal from mid March to mid April crop reduced its life cycle, resulting in decreased grain yield. Crop emergence was impaired when sowing was delayed owing to low temperature prevailing during stand establishment, which resulted in poor stand and reduced the number of productive tillers which resulted in yield reduction. With delay in planting, high temperature (32-39°C) at reproductive stage (March and April) reduced the patterns of dry matter accumulation as was evident from decrease in final yield.