# Bacterial Indole-3-Acetic Acid Influences Soil Nitrogen Acquisition in Barley and Chickpea
## 3 Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Trait** & \multicolumn{2}{c}{**Barley**} & \multicolumn{2}{c}{**Chickpea**} \\ \cline{2-5}  & **Dim.1** & **Dim.2** & **Dim.1** & **Dim.2** \\ \hline Root fresh weight (RFW) & 0.9801 & \(-\)0.1458 & 0.9817 & 0.0430 \\ Root length (RL) & 0.9897 & \(-\)0.0874 & 0.9480 & 0.3087 \\ Shoot length (SL) & 0.9713 & 0.0506 & 0.9721 & 0.1266 \\ Total nitrogen (Nt) & 0.9438 & 0.0923 & 0.9705 & \(-\)0.2037 \\ Chlorophyll (CI) & 0.9130 & 0.2394 & 0.9893 & \(-\)0.1326 \\ Nitrate reductase (NR) & 0.9650 & \(-\)0.1917 & 0.6626 & \(-\)0.5968 \\ Nitrate (NT) & 0.9664 & \(-\)0.2451 & 0.9306 & \(-\)0.3403 \\ Protein (PR) & 0.9918 & \(-\)0.1094 & 0.8870 & 0.0474 \\ Number of secondary roots (NSR) & 0.9806 & \(-\)0.1137 & 0.7895 & 0.4932 \\ Nitrogen use efficiency (NUE) & 0.9776 & 0.1497 & 0.9938 & 0.1065 \\ Nitrogen uptake efficiency (NUpE) & 0.9632 & 0.2575 & 0.9705 & \(-\)0.2037 \\ Nitrogen utilization efficiency (NUtE) & \(-\)0.2301 & \(-\)0.9407 & \(-\)0.2182 & 0.7675 \\ Grain weight (GW) & 0.9774 & 0.1509 & 0.9945 & 0.1042 \\ Root diameter (Rdia) & 0.9629 & 0.1877 & 0.2290 & \(-\)0.7412 \\ Root surface area (RSA) & \(-\)0.1874 & 0.9773 & 0.9815 & 0.1875 \\ Root dry weight (RDW) & 0.9760 & \(-\)0.1830 & 0.9616 & 0.2426 \\ Shoot dry weight (SDW) & 0.9821 & 0.0292 & 0.9883 & 0.0800 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Correlation of the plant traits (variables) of barley and chickpea with the principal components dimension 1 and dimension 2. PGPB can modify the physiology and functioning of plant parts other than root [22]. Two mechanisms are thought to be accountable for this; first is well documented where plant roots under the influence of PGPB result in enhanced nutrient availability [22]. This will be taken up by aerial parts of the plant leading to modification in the primary metabolism which subsequently results in growth. Second, PGPB by some unknown signal triggers the systemic responses which might lead to plant growth [22]. Due to the former, general phenomenon of nutrient acquisition takes place including nitrogen, phosphorus, and other macro- and micronutrients. Nitrogen availability regulates the C and N in the plant due to the allocation of resources between roots and shoots [28]. In the present study, all the wild type strains improved the overall shoot development compared to control, especially _K.p._ SSN1 (Figure 2). These results are in agreement with [PERSON] et al. [29], who reported enhanced shoot length and biomass in wheat upon inoculation with PGPR. Experiments conducted by [30] on chickpea in sandy soil resulted into enhanced shoot fresh weight and dry weight in treated plants. The biochemical parameters (Cl, PR, and NT) that contribute to plant nitrogen were enhanced. The abundance of these biochemical traits in _K.p._ SSN1 and _K.q._ SGM81 above _K.o._ M5a1 clearly demonstrates that coupled effect of root growth-promoting traits (auxin production) and nitrogen-fixing ability of _K.p._ SSN1 and _K.q._ SGM81 on total plant nitrogen is more vital than nitrogen-fixing ability alone of _K.o._ M5a1. This is justifiable on the basis of \"multiple mechanism theory\" given by [PERSON] and [PERSON] [31], which assumes that more than one factor may be responsible for plant growth. Few studies conducted recently emphasize mechanisms other than BNF for improving overall plant nitrogen. For example, [PERSON] et al. [32] studied different non-nitrogen-fixing _Bacillus_ strains which were able to upregulate nitrate and ammonium uptake genes in _Arabidopsis_. Nitrate was being absorbed by the plasma membrane of the cortical and epidermal cells of the roots, thus bringing root structural elements to the frontline [33]. After absorbing and assimilating \(\text{NO}^{-}3\) in the root in some proportion, the remainder was being reduced to ammonium (\(\text{NH}^{+}4\)) by nitrate reductase (NR) and transported upwards through the xylem for assimilation in the shoot [34].