Effect of nitrogen fertilizer on growth of canola (Brassica napus L.) under saline water irrigation

Effect of nitrogen fertilizer providing two different doses of urea (@ 150 and 250 kg/ha) were investigated on the growth of canola (Brassica napus L. cv. Oscar) under saline water irrigation of different sea salt concentrations. Plants were subjected to control (non-saline), 0.4 % (EC 4.5 dS.m(-1)) and 0.6 % (EC 6.5 dS.m(-1)) of sea salt concentrations with and Without N amendment. Vegetative growth was recorded in terms of plant height, number of leaves and branches, fresh and dry shoot biomass per plant, while reproductive growth was noted in terms of number of flowers and siliquae per plant; siliquae weights seed number and weight per siliquae; seed number and weight per plant. Plant growth on vegetative as well as reproductive phases was found proportionately inhibited with respect of increasing salinity in irrigation water. Amendment of urea @ 150 and 250 kg/ha had beneficial effect in non-saline as well as under saline conditions. The amount of chlorophyll decreased under saline conditions without N amendment while plants supplemented with urea exhibited an increase in chlorophyll. Total sugars and proteins exhibited an increase under N amendment in control as well as in saline conditions. Among mineral composition (Na(+) and K(+)), Na(+) showed increase while others exhibited a decrease in different salinity levels with or without N amendment. Reproductive yield was comparatively more in N amended plants whereas it was considerably decreased in plants grown under salinity without N amendment.