Plant defense response against grasshopper herbivory
Farha Rehman, Fareed A Khan, Shoeba B Anis and Abid A Ansari
The objective of the current work was to study the defense mechanism of Maize plant (Zea mays var.GKSF2) against the herbivory caused by grasshopper (Choreodocus illustris). Fifteen plants of the selected crop were exposed to adult grasshoppers in varying number (10, 20 and 40) and compared with the control plants protected from insect attack. Accumulation of proline in insect attacked plant increased linearly and significantly with increased population of insects (10, 20 and 40 adults). In response to the insect attack highest proline contents (34.2 mgg-1 of fresh weight) were recorded with 40 adults. But, protein content in the infested leaf decreased consistently with the increase in insect population and lowest of 8.3% observed in plants with 40 adults of grasshopper. The chlorophyll content, leaf number and leaf area also suffered damage in proportion to the insect population. The chlorophyll was lowest as 2.2 mgg-1 of fresh weight in plants attacked by 40 adults. Number of damaged leaves (27) and damaged leaf area (72 cm2) was highest in the plants exposed to 40 adults of grasshopper. The correlation and linear regression analysis showed greater degree of dependence of protein content, chlorophyll content and leaf damage on the insect population. Moreover, proline accumulation in insect attacked plant also signaled the unattacked (control plant) for marginal proline accumulation.