Biochemical and physiologicalfactors imparting olerance in safflower against aphis, Uroleucon compositae (Theobald)

Abstract

Development of aphid tolerant cultivars is needed in pest management in safflower where the crop is often grown with least plant protection measures. Sixteen recombination inbred lines (RILs) of F7 generation of the cross, CO-1 (susceptible) X EC-523368-2 (tolerant) along with parents were studied to understand the biochemical and physiological factors operating in highly tolerant RILs. Eight RILs were confirmed tolerant (A.I.I., 1.1 - 1.5) and 8 RILs were found highly susceptible (A.I.I., 4.5- 5.0) to aphid. Susceptible RILs underwent more oxidative stress through more H2O2 (4908.0+1287 nmols g-1 fresh weight) production due to aphid infestation compared to tolerant RILs. Activity ROS enzymes, Superoxide Dismutase (53.63 + 0.29 (nmols g-1 fresh weight)) and Catalase (33.73+3.3 µmols g-1 fresh weight) and amount of metabolites like total phenols (169.60+16.49 µg g-1 Gallic acid equivalent) were more in tolerant RILs than susceptible ones. The tolerant RILs were physiologically more efficient with higher chlorophyll (8.45+0.91 mg L-1), net photosynthesis (28.9+3.31 µmole CO2 m-2 sec-1), net assimilation rate (0.289+0.033 µmole CO2 cm-2 leaf area) and intrinsic water use efficiency (0.35+0.05 µmole CO2 mole-1 H2O) than the susceptible RILs.