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Drought is one of the major abiotic stresses which adversely affect crop growth and production worldwide as water is vital for every aspect of plant growth and development. The present experiment was carried out during the growing seasons (September – December) of 2012 and 2013 to evaluate the response of black gram (Vigna mungo L.) and green gram (Vigna radiata L.) in terms of some important growth indices, biochemical traits and seed quality under drought stress. Four commonly grown genotypes - T9, KU 301(black gram) and Pratap, SG 21-5 (green gram) of Assam, India were grown in a randomized block design with three replications under stress and non-stress conditions. Stress was applied by withholding irrigation for fifteen consecutive days at vegetative, flowering and pod filling stages. Leaf area index (LAI), seed protein content and protein yield significantly decreased (p ≤ 0.01) whereas proline, total flavonoids and anthocyanin content increased significantly (p ≤ 0.01) in response to water deficiency. Among the studied genotypes, T9 and Pratap showed better tolerance capacity towards the applied drought by presenting higher values of LAI, plant height stress tolerance index (PHSI), dry matter stress tolerance index (DMSI), proline, total flavonoids, anthocyanin, lower percentage of chlorophyll degradation and finally producing high quality seeds.

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Propagation of dust density waves (DDW) is theoretically investigated in a collisional plasma in the presence of an external magnetic field. The magnetic field is kept constant in a direction perpendicular to the direction of streaming ions, which is an important requirement for the self-excitation of these waves. Standard stability analysis is done to predict the conditions under which ion-drift instability may drive the DDW unstable. It is found that a minimum dust density is required to excite the wave. There exists a lower cut-off value of ion streaming velocity for the excitation of DDW which may change with the applied magnetic field and neutral gas pressure. The wave is found to behave complexly with the applied magnetic field and gets damped beyond a critical value. The results of this paper may be helpful in understanding the behavior of low-frequency dust modes as well as the background plasma both in laboratory and astrophysical environments.