* Present address: B.A. College of Agriculture, Anand, Gujarat, India
In order to study the effect of late sown conditions on the yield and nitrogen status in wheat (Triticum aestivum L.), two cultivars namely HI 977 and HI 1116 were raised in earthen pots under normal and late sowing and under natural day length and 10 h day length. The 10 h day length treatment was included to separate the effect of temperature from that of photoperiod. In the late sowing, time taken for anthesis, maturity and grain development were reduced and also the dry weights of leaf, stem and grain were lower, however, the rate of grain filling was faster. Grain yield was higher under natural day length as compared to 10 h day length. A polynomial fit of changes in NRA in relation to ambient temperatures (mean max. min.) indicated that NRA increased from 17.5°C to 22°C and decreased thereafter upto 27°C. The temperatures around 22°C were optimal for NRA. The percentage nitrogen and total nitrogen at harvest were higher in late sowing. There was also considerable increase in nitrogen content of the plant between anthesis and harvest in both the sowings which indicated nitrogen uptake in wheat during grain development period.
