INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY 1560–8530/2004/06–6–1003–1005 http://www.ijab.org Effect of Sowing Date and Plant Population on Biomass, Grain Yield and Yield Components of Wheat AFTAB WAJID, ABID HUSSAIN, ASHFAQ AHMAD, A.R. GOHEER, MUHAMMAD IBRAHIM AND M. MUSSADDIQUE Department of Agronomy, University of Agriculture, Faisalabad–38040, Pakistan ABSTRACT This study was conducted to investigate the effect of sowing date and plant population on biomass, grain yield and components of yield. The early sowing (10 Nov.) gave higher grain yield over late sowing (10 Dec.) by 60.6%. Differences in grain yield between 10 Nov. and 25 Dec. sowing were also significant (45%). Increasing plant population from 200 plant m -2 to 300- and 400 plant m -2 also enhanced grain yield but the response was quadratic. The higher grain yield in early sowing was due to higher number of ears m -2 and mean grain weight than late sowing. Early sowings also enhanced biomass accumulation over late sowing. The study confirmed that optimum planting time of wheat is early November for obtaining higher grain yield under agro-ecological conditions of Faisalabad. Key Words: Biomass; Grain yield; Yield components; Sowing date; Plant population; Wheat INTRODUCTION There are many components of production technology which significantly affect grain yield of wheat in a region, for example sowing date, seeding rate, etc. Sowing date affects the growth and yield of wheat by affecting its environment. Early sowing always produces higher yield than late sowing mainly due to longer duration of growth. Each day delay in sowing from 20 November onward decreases grain yield @ 39 kg ha -1 d -1 (Singh & Uttam, 1994). Similarly, seeding rate affects yield when crop is sown late in the season. Increasing seeding rate usually gives good yield (Nanaenko & Loktionv, 1991). This paper reports the effects of sowing date and plant population on biomass, grain yield and components of yield in wheat under semi arid conditions. MATERIALS AND METHODS The study was conducted at the Agronomic Research Area, University of Agriculture, Faisalabad, during 1998- 1999 and 1999-2000. The experiment was laid out in a randomized complete block design with split plot arrangement with sowing date in main plots and seeding rate in sub-plots. There were three replications having a plot size of 1.6m x 10m. The treatments were three sowing dates (10 November, 25 November and 10 December) and three planting densities (200-, 300- and 400 plants m -2 ). The crop was sown with the help of a single row hand drill. Nitrogen and phosphorus @ 120 and 100 kg ha -1 , respectively, were applied in both the seasons. Half of the nitrogen and full phosphorus was applied at sowing and remaining half of nitrogen was top dressed with first irrigation. All other practices such as hoeing, irrigation, weeding, etc. were kept uniform in both seasons for all the treatments. At maturity an area of one meter square was harvested from each plot. Spikes were threshed and grains were separated and weighed. Then the grain yield was converted into kilograms per hectare. RESULTS AND DISCUSSION Biomass. Early (10 Nov. or 25 Nov.) sowings significantly increased final biomass than the late (10 Dec.) sowing in 1999-2000, but not during 1998-99 season (Table I) and it ranged from 11.15 to 12.7 t ha -1 among different sowing dates. Increasing plant population from 200 plants m -2 to 300- or 400 plants m -2 also showed significant effect on final biomass production than the low (200 plants m -2 ) population only in 1999-2000. On an average, final biomass yields were 11.4 t ha -1 in 200 plants m -2 , 12.19 t ha -1 in 300 plants and 12.15 t ha -1 in 400 plants m -2 . Overall, biomass yields were higher (5.6%) in 1999-2000 (12.24 t ha -1 ) than the 1998-99 (11.59 t ha -1 ). The average biomass yield (11.59 t ha -1 to 12.24 t ha -1 ) obtained in this study are similar to the average values of TDM (10.6-13.5 t ha -1 ) reported by others under similar agro-ecological conditions (Hussain et al., 1997; Khan, 2000). Grain yield. Table I shows the effect of treatments on grain yield in both seasons. In 1989-99 differences in grain yield among sowing dates were non-significant. However, in 1999-2000, significant differences in grain yield among sowing dates were found. Early sowings enhanced grain yield over late sowing by 60.6%. The 10 November sowing also significantly increased grain yield over 25 November sowing by 44.9%. Increasing plant population at 400 plants m -2 significantly increased grain yield over 300- or 200 plants m -2 . Similarly differences in grain yield between 200 plants m -2 and 300 plants m -2 were also significant. Interaction between sowing date and plant population