Effect of Neem Leaf Extract on the Mobility, Egg Hatch and Infestation Rate of Meloidogyne incognita on Tomato Plants under Greenhouse Condition Kaur Harpreet1,*, Kaur Harjinder, Rishi Praveen2,** 1Department of Zoology, Punjabi University, Patiala, Punjab-147 002 2Department of Microbiology, Panjab University, Chandigarh, Punjab *E-mail: harpreet_bimbra@yahoo.com
**E-mail: rishipraveen@yahoo.com
Online published on 16 February, 2013. Abstract Aqueous neem leaf extract was tested against root-knot nematode, Meloidogyne incognita. In vitro studies, 25%, 50%, 75% and 100% concentrations of extract significantly suppressed root-knot egg hatching and caused second stage juvenile mortality. Eggs after treatment with 100% concentration when transferred to distilled water showed maximum inhibition of hatching (0.18 ±0.60) as compared to control (6.63 ±1.20) after 6 hrs exposure time. Percentage of viable J2 decreased with increase in exposure time from 12hrs to 72hrs in each concentration. In the juvenile mortality test, exposure of J2 to 100% for 24hrs led to 97.5% mortality in comparison to 15.8% in controls. After treatment with 75% at 12hrs and 24hrs, 50% at 12hrs and 24hrs, 2 5% at 72hrs less than 50% immobile J2 were revived when immersed in distilled water in comparison to 100% revivability in controls. No significant revival (1.2%) of J2 was observed after 12hr at 50% concentration as compared to control 79.3% in distilled water. In pot experiment, the control-2 plants (infected= plant+ nematode) exhibited significant reduction in fresh root weight (2.37g) and shoot weight (11.54g) as compared to 5.14g and 22.65g respectively in control-1(plant) group. There was significant reduction in the total weight of fruit yield in control2 (2.9g) and pretreated J2 group (2.61g) as compared to the control-1(plant) (12.91g), preventive group (plant + neem + nematode) (10.3g) and therapeutic group (plant + nematode + neem) (7.03g). Comparison of preventive group with pretreated J2 group indicated that total fresh root weight (3.83g; 3.68g) and shoot weight (16.62g; 10.32g) mean values were more when aqueous neem leaf extract was applied as soil drench. Similarly total length of root (12.61cm; 7.05cm) and shoot system (31.31cm; 30.83cm) and fruit yield (10.3g;2.61g) was found to be better in the preventive group as compared to the pretreated J2 group. Furthermore the pretreated J2 plant group showed significant reduction in root gall index 2.9 as compared to infected group 3.1 (Control-2). In preventive group root gall index was found to be 1.2 as compared to therapeutic (2.4) and pretreated J2 (2.9) groups. Top Keywords Meloidogyne incognita, neem leaf extract. Top |