PHYSIOLOGICAL-PARAMETERS OF BRASSICA SPECIES AS AFFECTED BY IRRIGATION AND NITROGEN MANAGEMENT ON ARIDISOLS

A field experiment conducted during the winter seasons of 1988-89 and 1989-90 showed that Brassica species had significant variations in lea f-area index (LAI), leaf-area duration (LAD) and crop-growth rate (CGR ). Oilseed rape (Brassica napus L.) and Ethiopian mustard [B. carinata (L.) Braun] showed significant differences at 105 and 120 days stage for LAI and at 120 days stage for LAD. Indian mustard [B. juncea (L.) Czernj. & Cosson] recorded greater values of LAI, LAD and CGR up to 75 days stage, followed by Ethiopian mustard and oilseed rape. At 90 day s stage all Brassica species in respect of LAD, LAI and LAD at 90, 105 and 120 days with 1 and 2 irrigations were at par, but recorded signi ficantly higher values over no irrigation. AT 120 days stage all the i rrigation levels caused significant variation in CGR. Application of N increased significantly the LAI up to 80 kg N/ha (except 45 days stag e). LAD and CGR significantly increased with 80 kg N/ha compared with lower doses, i.e. 0 and 40 kg N/ha, and could not increase further wit h 120 kg N/ha.