The Effect of Ascorbic Acid, when Applied to the Rooting Medium, on Nodulation and Nitrogen Fixation in Gram (Cicer arietinum)

Abstract

Plants of a pure line variety, G 24, of Cicer arietinum L. were grown in sand culture. After an initial dose of a complete nutrient solution, a nitrogen free nutrient solution was supplied to the sand at intervals and a standard rhizobial culture was added twice. The plants were treated with two concentrations of ascorbic acid (20 mg/l and 100 mg/l) through the rooting medium. At suitable intervals two pots from each treatment were sampled. Observations were made regarding the earliest initiation of nodulation, the number, weight and colour of nodules and the nitrogen content of different plant organs under various treatments. Ascorbic acid (AA) treatments considerably enhanced nodule initiation. AA was found to increase the number and the fresh and dry weights of nodules tremendously and maximally under both concentrations used. The nodules were, on the whole, more pink under AA treatments and their greening was considerably delayed thus increasing their functional span. The nitrogen content of AA‐treated plants was over 2.5 times that in the control. This increase in nitrogen content fully reflected itself in growth by an increase in the weight of all plant organs. Treatment with 20 mg/l AA stands out prominently above all others in this respect. Pod formation started earlier and the pod and seed weights were also much higher in the AA treatments than in the control. Treatment with 20 mg/l AA was on the whole more promotive than that with 100 mg/l. The enhancement in the nodulation and the functional efficiency of nodules by AA treatments has been attributed to the capacity of AA to increase the loci and rates of cell division by promoting nucleic acid and protein synthesis and its action as a powerful electron donor. The results show that nodulation is yet another phenomenon wherein AA plays the role of an important hormone.

Direct detection of a globin-derived radical in leghaemoglobin treated with peroxides

“…A haem-totyrosine cross-link has been observed in Mb treated with H202 [41], and if the radical is indeed situated at tyrosine-132 in the MetLb proteins, a similar event may occur. In this context it would be expected that the above compounds, which react with the phenoxyl radical, might protect against inactivation and degradation; previous reports have shown that ascorbic acid can slow down the destruction of Lbs in root nodules [42] and that salicylate, thiourea or desferal can inhibit haem degradation [40], suggesting that such reactions may be of importance. The radical also appears to undergo further reaction with excess H202, as the intensity of this signal decreases with increasing H202 concentration (see Fig.…”

Legume nodule senescence: roles for redox and hormone signalling in the orchestration of the natural aging process

“…Moreover, while Bashor and Dalton (1999) focused their studies regarding the effects of enhanced ascorbate on protection against oxidative damage showing that lipid peroxides were decreased, these authors noted that ascorbate feeding increased the average number of nodules per plant. Earlier studies had also reported that exogenous ascorbate led to increased nodule numbers as well as earlier nodule initiation and delayed senescence, with resultant large increases in plant yields (Swaraj & Garg, 1970). Furthermore, the inclusion of ascorbate and ascorbate peroxidase in a model system containing Bradyrhizobium japonicum bacteroids and leghemoglobin resulted in large increases in nitrogenase activity and enhanced oxygenation of haem proteins (Ross et al ., 1999).…”

Effects of exogenous application and stem infusion of ascorbate on soybean (Glycine max) root nodules

“…Previous indications of the role for ASC in N # fixation can be found in the largely overlooked work from India, excellently reviewed by Chinoy (1984). These studies, which include notably the experiments of Swaraj & Garg (1970), reported that exogenous application of ASC led to earlier nodule initiation, to delayed senescence and to increases in nodule number, weight and nitrogen content as well as in the overall growth and yield of several leguminous plants. In the most remarkable case, a more than five-fold increase in ' fodder yield ' was observed in response to foliar spraying with ASC.…”