Effect of Aerosols and Drought Stress on some Physiological traits of Mungbean

Mungbean (Vigna radiata L.) is affected by some different stresses. Aerosol is one of the new problems that is accompanied by a drought stress in some Western and Southern parts of Iran (Marsafari, 2011). The increase of irrigation intervals reduces chlorophyll a and b and increases proline amino acid content of basil leaf (Gholdani, 2012). Zadeh Bagheri (2014) has indicated that the accumulation of sugar, chlorophyll, potassium and proline content in beans can be cause of drought-resistance in plants.
The objective of this study was the evaluate aerosols along with drought stress effects on mungbean photosynthetic pigments, nitrogen compounds, soluble sugars and grain yield.
The research was conducted to study the effect of drought and aerosol stresses on physiological traits of mungbean (Vigna radiata L.) in the Lorestan Agricultural and Natural Resources Research and Education Center which lies at latitude 33° and 29' N, longitude 48° and 18' E, and an altitude of 1195 m above sea level in 2015. Before the beginning of the experiment, soil samples were taken in order to determine the physical and chemical properties. A split plot design based on RCBD was used with four replications. Four different irrigation regimes after 70 (well irrigated treatment), 80 , 90 and 100 mm evaporation from pan class A were assigned to main plot, and three aerosol levels did not contain aerosols (control) and using 50 and 100 mg m-3 aerosols in clay soil sours were randomized in subplots. Chlorophyll a, chlorophyll b, chlorophyll a b, soluble sugars and protein content in leaves were measured at flowering period and grain yield was measured at harvesting time.
The data were statistically analyzed using the MSTAT-C and SAS softwares. Comparison of means was performed using the Least Significant Difference test at 5% probability level.
Result showed that chlorophyll a, chlorophyll b, chlorophyll a was significantly affected by drought stress. Aerosol only affects chlorophyll a. Drought and aerosol stresses interaction had a significant effect on chlorophyll a and decreased it. The highest amount of chlorophyll a (0.015 mg g-1 FW) in leaves was achieved by normal irrigation in different levels of the aerosol. Chlorophyll b, chlorophyll a b significantly reduced by drought stress from 0.0083 and 0.024 in normal irrigation condition to 0.0037 and 0.01 mg g-1 FW in severe drought stress, respectively.
Sugar of leaves was also significantly reduced by drought stress from 1.86 in normal irrigation condition to 4.62 mg g-1 FW in severe drought stress. Protein content was also significantly affected by drought stress and decreased from 0.15 in normal irrigation condition to 0.05 mg g-1 DW in severe drought stress. Significant and negative linear relationship was found between drought stress and grain yield, but found a significant and positive linear relationship between drought stress and leaf proline.
In addition, according to data analysis in this experiment, the synergistic effect was found in higher levels of drought stress and aerosols on chlorophyll a. Chlorophyll b, chlorophyll a b, soluble sugars and protein contents significantly decreased by drought stress. Also, Significant and negative linear relationship was found between drought stress and grain yield, but between drought stress and leaf proline was found to be significant and positive. Therefore, it seems that provision of water requirement of mungbean plant in the region, while preventing the decrease in grain yield, does not have a negative effect of aerosols on the plant.