Salinity Tolerance of Blackgram and Mungbean: II. Mineral Ions Accumulation in Different Plant Parts

Blackgram (Vigna mungo) is more salt tolerant than mungbean (Vigna radiata). This study was initiated to know whether the accumulation pattern of mineral ions in different plant parts plays a significant role in the differences in salt tolerance between the two Vigna species. Different mineral ions, viz. N, Cl, Na, K, Mg and Ca in different organs of two varieties of each of blackgram- Barimash-l (susceptible one) and Barimash-2 (tolerant one), and mungbean-Barimung-3 (tolerant one) and Barimung-4(susceptible one), were analyzed after growing with 0, 50, 75 and 100 mM NaCl solutions. The two crops showed a decreased but similar pattern of total N accumulation under saline conditions. The tolerant variety of both the crops showed a less reduction in total N than the susceptible one. Leaves showed the maximum while stem the minimum N, irrespective of levels of salinity. C $l^{[-10]}$ and N $a^{+}$ accumulation increased with the increasing salinity levels. Interestingly, similar to a halophyte, the salt tolerant blackgram exhibited conspicuously higher amount of N $a^{+}$ in the shoot than the salt-susceptible mungbean. However, the tolerant varieties showed less amount of N $a^{+}$ than the susceptible one, especially in blackgram. Seeds of both Vigna spp. accumulated the minimum amount of N $a^{+}$ than other plant parts. $K^{+}$ accumulation decreased by salinity in most of the plant parts, except seeds. Blackgram showed larger reduction in K than mungbean. The $Mg^{++}$ increased in leaves, petioles and stem by salinity while decreased in the roots, podshells and seeds in both the crops. Salinity increased $Ca^{++}$ accumulation in all plant-parts except roots of both Vigna spp. Apparently, the leaves of mungbean accumulated higher concentration of $Ca^{++}$ than blackgram. Varietal differences in the accumulation pattern of $K^{+}$, $Mg^{++}$ and $Ca^{++}$ were not clear. It was concluded that blackgram, presumably, possesses a similar salt tolerance mechanism to halophyte, and the pattern of accumulation of mineral ions in blackgram and mungbean was not fully ascribed to the differences in salinity tolerance between the two Vigna species.gna species.ies.s.ies.