PROPORTION OF TOTAL NITROGEN AND FIXED NITROGEN IN SHOOTS OF LENTIL AND CHICKPEA GROWN IN A MEDITERRANEAN-TYPE ENVIRONMENT

Shoot dry matter yield, shoot nitrogen yield and amount of nitrogen de rived from fixation are collated for chickpea (Cicer arietinum L.) cv. ILC482 and lentil (Lens culinaris Medic.) cv. ILL8 grown at the ICARD A research station Tel Hadya, Syria over a period of 17 years. Regress ion analyses of shoot nitrogen yield on shoot dry matter and of the am ount of nitrogen fixed on shoot nitrogen yield were undertaken for bot h species. The intercepts for both analyses with lentil were not signi ficantly different from zero, so the slopes of the lines represented t he concentration of nitrogen in the plant tissue (20.6 g kg(-1) dry ma tter) and the proportion of nitrogen derived from fixation 0.75. Data for other cultivars of lentil grown at Tel Hadya and at four other loc ations in Syria fell within the 95% confidence limits of the original analyses. The intercept of the regression of shoot nitrogen yield on s hoot dry matter yield for chickpea grown at Tel Hadya was not signific antly different from zero, so the concentration of nitrogen in the pla nt tissue was constant (17.8 g kg(-1) dry matter). The proportion of n itrogen derived from fixation increased asymptotically as the shoot ni trogen yield increased. Data for other cultivars of chickpea grown in different locations were generally similar to those for cv. ILC482 gro wn at Tel Hadya. It is proposed that generalized relationships between shoot nitrogen yield and shoot dry matter yield, and between amount o f nitrogen fixed and shoot nitrogen yield can be established for lenti l and chickpea grown in the West Asia-North Africa region. Consequentl y the amounts of nitrogen fixed by the two crops could be predicted fr om a knowledge of dry matter production alone.