EFFECT OF NITROGEN ON SAFFLOWER PHYSIOLOGY AND PRODUCTIVITY

Safflower ( Carthamus tinctorius ) L. is an oil-crop suitable for semi-arid agriculture, but its physiological re- sponse to agronomic inputs has yet to be fully evaluated. The effect of fertiliser on the physiology and produc- tion of Safflower grown in pots filled with standard grade perlite inside a semi-controlled glass house was studied. Plants were initially irrigated with 20-100 ml standard hydroponic solution and then one month after germination plants were irrigated using 50-200 ml complete Hoagland\u2019s solution, supplemented with one of eight levels of nitrogen (0, 25, 50, 75, 100, 125, 150, 175 kg N ha-1) in the form of ammonium nitrate. Elevating nitrogen to 100 kg N ha-1 significantly increased the assimilation rate by about 42 %, transpiration rate by 32%, stomatal conductance by 52% and LAI by 42% compared with the control. The above ground dry weight, seed yield and Water Use Efficiency (WUE) increased incrementally with increases in nitrogen rate. Above ground dry weight increased by an average of 42%, seed yield by 76% and WUE by 41% at harvest compared with the control. This study clearly demonstrates how nitrogen fertilisation can affect physiology of Safflower leading to im- provement in seed yield.Le carthame ( Carthamus tinctorius ) L.) est une culture ol\ue9agineuse appropri\ue9e \ue0 l\u2019agriculture semi aride, mais sa r\ue9ponse physiologique aux intrants agronomiques reste \ue0 \ue9valuer. L\u2019effet de fertilisants sur la physiologie et la production du carthame cultiv\ue9 en pots rempli de perlites de niveau standard \ue0 l\u2019int\ue9rieur d\u2019une serre semi contr\uf4l\ue9e \ue9tait \ue9tudi\ue9. Les plants \ue9taient initialement irrigu\ue9s avec 20-100 ml de solution hydroponique standard et, ensuite, un mois apr\ue8s la germination des plants \ue9taient irrigu\ue9s avec 50-200 ml de solution de Hoagland compl\ue8te et un suppl\ue9ment de huit niveau d\u2019azote (0, 25, 50, 75, 100, 125, 150, 175 kg N ha-1) sous forme du nitrate d\u2019ammonium. L\u2019utilisation de la dose de 100 kg N ha-1 a significativement accru le taux d\u2019assimilation d\u2019environ 42 %, le taux de transpiration de 32 %, la conductance stomatale de 52 % et l\u2019index de la surface foliaire de 42 % en comparaison avec le t\ue9moin. Le poids sec de la biomasse a\ue9rienne, le rendement en grain et le Water Use Efficieny (WUE) avait augment\ue9 avec la dose d\u2019azote. Le poids sec de la biomasse a\ue9rienne a en moyenne augment\ue9 de 42% pendant que le rendement en grains et le WAE ont augment\ue9 \ue0 la r\ue9colte de 76% et 41% , respectivement, en comparaison avec le t\ue9moin. Cette \ue9tude d\ue9montre clairement comment la fertilisation azot\ue9e peut affecter la physiologie du carthame conduisant \ue0 l\u2019am\ue9lioration du rendement en grains