Effect of Drought and Salinity Stresses on Alfalfa Plant and Performance of Tetranychus urticae on Water-Stressed Plants
Paper ID : 1160-IPCA4 (R2)
Samira Khodayari *1, Fatemeh Abedini2
1Department of Plant Protection, Faculty of Agriculture, University of Maragheh.
2Department of Horticulture, Faculty of Agriculture, University of Maragheh
Stress is hypothesized to be one of the primary abiotic factors that influence the structuring of food webs. Drought and salinity stresses are the most serious problems of agriculture due to climatic changes. According to global warming and drying of Urmia salty lake in Northwestern Iran which could result in salinization of agricultural lands nearby, the focus of this study was to examine the effect of two above mentioned stresses on a host plant and its pest performance. Two levels of water deficit (kept dry for 5 and 10 days and received 50% and 25% the amount of water given to control plants respectively) and three levels of salinity (100, 200 and 300 mM NaCl) were induced to alfalfa plants (Medicago sativa L.) as stress factors and the following characteristics were measured before and after herbivore infection: leaf surface area, relative water, chlorophyll, carotenoid, protein and proline contents of leaves. The life table parameters of two-spotted spider mite, Tetranychus urticae Koch, reared on stressed plants were measured and compared with control. We found that drought and salinity stresses lead to significantly decrease of alfalfa plant leaf surface area, relative water content, chlorophyll and carotenoid contents and significantly increase of protein and proline contents compared to control that generally cause to a negative effect on T. urticae performance. The net reproductive rate (R0), mean generation time (T), intrinsic rate of increase (r) and finite rate of increase (λ) were significantly higher for mites grown on control host plants and were 25.66 offspring/individual, 16.38 d, 0.1971 day-1 and 1.2180 day-1 respectively. These parameters reduced significantly in mites grown on stressed host plants; the significantly lowest values were recorded for mites grown on host plants subjected to high salinity and were 0.5 offspring/individual, 14.47 d, -0.0514 day-1 and 0.9502 day-1 respectively. In terms of this experiment, the water stress had a stronger influence on the morphological and physiological characteristics of alfalfa plant compared to spider mite infestation.
Medicago sativa, water deficit, NaCl, two-spotted spider mite, intrinsic rate of increase
Status : Abstract Accepted (Oral Presentation)