A trial has been conducted during the winter season 199li 92, in the Research Fann, The Northern Highland Regional Research Station, AL - BOUN. TI1e main objective of this study was to investigate the effect of different sowing dates on the p<::rfonuance of different genotyyes and identify the optinnun so.,..ing date for lentil growing in the Northern Highland Region. Sowing period was sta11ed in 1st Dec. and lasts to l st March with an interval of 15 days. The results howed that the varieties precoz - 4605, FLIP 84 - l 4L and FLIP 86 - l 12L would gave the best gram yield when planted on, 1st JA:-J . to 15th JAN . On the other hand, the variety 76 TA 66005 gave a better grain yidd when planted on 15th DEC. while the local variety l AMRANI ) gave it<; best grain yield when planted on 15th JAN. to 15 FEB. Generally, the results under this study showed that the optimum sowing date for planting the promising varit!ties precoz - 4605, FLIP 84 - 14 L, FLIP 86 - 112 L and 76 TA 66005 < which have been introduced from ICARDA in 1985 ) in the Northern Highland Region ( AL - BOUN ), would be from 15th DEC. to 15th JAN( Early season ) while the best time for plan the local variety would from be 15th JAN. to 15th FEB. ( LATE SEASON ) m order to obtain

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