TABLE CONTENTS

SESSION TEN – SUSTAINABLE AND ORGANIC MANAGEMENT
THROUGH BIOFUMIGATION, AMENDMENTS AND SUPPRESSIVENESS
CONVENORS: GIOVANNA CURTO & RICHARD SIKORA
Impact of Green Leaf Application on the Management of Plant Parasitic
Nematodes and its Effect on the Population of Predatory and Saprophytic
Nematodes and Microflora in Soil
Sheela, M.S., K. Ajith & M.S. Nisha
Kerala Agricultural University
Green leaves of a number of plants are well documented for nematode suppressant properties.
Neem (Azadirachta indica A Juss.) and eupatorium (Cromolaena odorata L.) are two plants
with potentially nematicidal properties. However, knowledge on the impact of these green
leaves on the soil fauna is meagre. Hence an attempt was made to study the effect on the soil
fauna and their consequent effect on the yield of okra and cowpea during rainy and summer
seasons. Field experiments were laid out in a randomized block design. Chopped neem and
eupatorium green leaves were applied 15 days prior to sowing the seeds at rates of 7.5 and 15
t per ha at a depth of 30cms. Nematodes were extracted by Cobb's sieving and sifting
techniques and cleared by modified Baermann funnel method, while fungi, bacteria and
actinomycetes were isolated by dilution plate method of Timonin using different media. The
result showed that application of neem and eupatorium leaves at both doses reduced reniform
nematode, Rotylenchulus reniformis in the root zone of okra and cowpea in soil both in
summer (214 to 427 per 200g soil sample as against 727/200 g in untreated) and during the
rainy period (324 to 646 per 200g as against 933 per 200 g in untreated ). The population of
predatory (two to three fold) and saprophytic nematodes (three fold) also increased
significantly in the root zone of okra and cowpea. The rate of increase was more in
eupatorium leaves when compared to neem leaves. The pre-sowing application of eupatorium
leaves increased the population of fungi, bacteria and actinomycetes in the root zones of okra
and cowpea whereas neem leaf at higher dose (15t/ha) reduced the multiplication of
microbial population (except for the fungi) in the root zone of okra and cowpea in both the
seasons. The stimulatory effect of eupatorium leaves in the multiplication of microbial flora
and predatory and saprophytic nematode in our investigation is being reported for the first
time. The pre-sowing application of neem and eupatorium at 15t ha resulted in significant
improvement in plant growth characters which contributed the increase in yield of okra and
cowpea in both the seasons. Thus application of green leaves suppressed the multiplication of
plant parasitic nematodes by the nematicidal principles released during decomposition and it
also indirectly managed the plant parasitic nematode population by stimulating the
multiplication of predatory nematodes and beneficial microflora.
5 th International Congress of Nematology, 2008 37