Responses of three arid zone grasses to N deficiency: A greenhouse study

Responses of three arid zone grass species Cenchrus pennisetiformis Hochst. & Steud., Dichanthium annulatum (Forssk.) Stapf., and Panicum turgidum Forssk. to five N levels (224‐control. 112. 56. 28. and 14 μg mL‐1) were examined. Biomass production and growth rate of D. annulatum were not as affected under N‐deficient regimes as the other two species. D. annulatum maintained almost uniform shoot N concentration and chlorophyll contents at all assessed N levels, whereas a reduction in these two variables was found in both C. pennisetiformis and P. turgidum. Leaf soluble proteins increased considerably in P. turgidum (30.5–45.5% compared to control) and decreased in D. annulatum (19.58–36.98% compared to control), whereas they remained unaffected in C. pennisetiformis. Leaf free amino acids and soluble sugars decreased consistently in the three species. D. annulatum was found to be highly efficient in N utilization under N‐deficient regimes compared with C. pennisetiformis and P. turgidum. High adaptation of D. annulatum to N deficiency may have been attributable to its perennial growth habit. Common annual growth habits of the remaining two species preclude them from experiencing N deficient conditions, which might explain their poor adaptation to low N regimes.