The effect of foliar application of nano Fe and Mn chelates on mungbean yield, fluorescence and some of the quantitative characteristics under water deficit stress condition

Mungbean (Vigna Radiata L. Wilczek) is considered as one of the important tropical and semi-tropical pulses. This plant is important in terms of nutritional value, hay supply, green fertilizer and improvement of soil fertility (Al-Shaheen et al., 2016). According to the previous studies, water deficit causes morphological, physiological and biochemical changes within the plants, thereby negatively affecting their growth and yield. Various studies also suggest that water stress restricts nutrients absorbed by the plant as the absorption of nutritional elements and the water available for the plant roots are closely dependent on each other (Aghdasi et al., 2018). Therefore, spraying liquid fertilizer can be offered as an appropriate method of feeding the plant in this condition (Alipour & Zahedi, 2017). In this regard, the choice of the landraces and suitable cultivars and nutrition and irrigation management can play an important role in increasing quantity and quality of pulses and reduce negative effects of various environmental stresses. The present research aimed to study the effect of water deficit stress on some quantitative and qualitative traits of mungbean Parto variety under the foliar application and non-application of nano iron and manganese chelates.

In other to determine the effect of water deficit stress and nano Fe and Mn chelates foliar application on yield of mungbean cultivar Parto in 2013-14, an experiment was carried out in the agricultural research farm station of Tarbiat Modares university, Tehran as a split plot in a completely randomized block design with three replications. The experimental treatments in the main plots were three levels of irrigation regime [no cessation of irrigation (S1), cessation of irrigation at reproductive stage whenever 70 % of the field capacity (FC) was depleted (S2), cessation of irrigation at vegetative stage whenever 70 % of FC was depleted (S3)]; and in the subplots were 10 levels of foliar application [no foliar application of the nano fertilizers as control (F1), foliar application of pure water (F2) including 1/1000 chelated nano iron (F3), 3/1000 chelated nano iron (F4), 1.5/1000 chelated nano manganese (F5), 3/1000 chelated nano manganese (F6), 1/1000 nano chelated iron+ 1.5/1000 nano chelated manganese (F7), 1/1000 nano chelated iron + 3/1000 nano chelated manganese (F8), 1.5/1000 nano chelated manganese + 3/1000 nano chelated iron (F9), 3/1000 nano chelated iron+ 3/1000 nano chelated manganese (F10] at withholding irrigation periods.

The results showed that the water deficit stress and the foliar application of iron and manganese nano-chelates significantly affected the most of the plant traits at 1% probability level. Among water deficit stress levels, the termination of irrigation at the reproductive stage resulted in the lowest yield and yield components, whereas the highest values for yield performance yields were obtained from control (optimum irrigation). The results showed that the highest values for the plant yield and yield components were achieved with different levels of foliar spraying of iron and manganese nano-chelates at the vegetative and reproductive stage, especially at the vegetative growth stage, while control (no spray) decreased the yield and yield components in the plant. Also, the interaction between the two main treatments were significant for the most of the traits at 1% probability level. The results showed that the quantum yield of PSII, due to increased the F0 and decrease in Fm and Fv, in mungbean grown under water-deficit conditions in reproductive (60.2) and vegetative (97.4) stages declined significantly in comparison to the control group.

The means comparison for the interactive effects of foliar spraying and water deficit stress suggested that the greatest grain yield was related to the treatment of optimum irrigation and simultaneous spraying pf one per a thousand nano chelated iron and three per a thousand nano chelated manganese (1765/3 Kg/ha) and the lowest yield was associated with the treatment of the water stress at the reproductive stage and no spraying (376/0 Kg/ha). The was found to be a high correlation between biological yield and other morphological traits, especially dry weight of the leaf (r=0/90**). Thus, it is suggested that these elements can be utilized as a factor for decreasing stress and also increasing productivity in the plants.