Effect of soil fertility on regrowth vigor, nodulation, and nodule physiology of Cratylia floribunda Benth

Abstract

The effect of fertility treatments on regrowth vigor, nodulation, nitrogenase, nodule enzymes and carbohydrates of Cratylia floribunda was evaluated when cultivated on a Dark-Red Latosol (Typic Eutrustox). P augmented regrowth of aerial parts, root dry weight, and number and weight of the nodules, as well as their levels of protein and glucose. Increased nitrogenase activity was observed in pots fertilized with P (µmoles C₂H₄/pot/hr), but non-significant effects were found when results were expressed as µmoles C₂H₄/g fresh nodule/hr, and a negative effect was noted if nitrogenase was calculated as enzyme specific activity (µmoles C₂H₄/mg protein/hr). The same effect was observed on glutamate dehydrogenase, glutamine synthetase, glutamate synthase, and the transaminases glutamate-oxaloacetate and glutamate-pyruvate. Mg had a beneficial effect on herbage yield, but depressed the nodule enzymatic activity. S and K increased herbage production but showed little effect on nodule enzymatic activity, and Ca augmented glutamate synthase activity, levels of α - Ketoglutarate, pyridoxyl phosphates, soluble protein and starch, but depressed herbage production on the first two clippings, root growth and levels of glucose and sucrose in the nodules.