Guar (Cyamopsis tetragonoloba [L.] Taub.) response to organic and inorganic nitrogen sources during early seedling growth

Abstract

Guar (Cyamopsis tetragonoloba [L.] Taub.), a legume, has gained its industrial importance due to galactomannan gum in its seed endosperm. As a legume guar Rhizobium nodulation is usually inadequate. Thus, it does not fix nitrogen sufficiently in the soil. Guar seeds were germinated under five concentrations each of organic {Bovine Serum Albumin (BSA)}, inorganic {Ca(NO3)2} and combined {(BSA + Ca(NO3)2} nitrogen sources in order to analyze the morphological, anatomical, and protein concentration changes due to different concentrations of varying nitrogen sources. Low nitrogen concentration in modified Hoagland’s solution in absence of preexisting nitrogen in the supporting solution (coco peat) showed significantly reduced morphological and anatomical characteristics and total protein concentration. On the other hand, the combination of organic and inorganic nitrogen sources showed greater effect on morphological, anatomical characters, and total protein concentration than individual treatments and control. At 16.1 mM nitrogen [given through combined treatment of 0.075 g/dL BSA + 0.095 g/dL Ca (NO3)2] metaxylem number (MXN), percent of stele that is metaxylem (percSisMX) and total protein concentration (TPC) were nearly equal or higher than the control. These parameters are positively correlated with each other which indicates that MXN, percSisMX and TPC contribute to relieve guar plant from nitrogen stress by more inflow of water and nutrients. Results show despite being a leguminous crop guar behaves as non-leguminous crop toward nitrogen and is affected by nitrogen stress during germination.