Genetic Variation in Allelopathic Activity of Traditional Rice Cultivars on Echinocloa crusgalli (Barnyard Grass)

Abstract

Economical and eco friendly weed control methods are very much important for the present agricultural production systems due to over usage of chemicals in agriculture. Exploitation of allelopathic potential of different traditional rice cultivars is a better solution for a sustainable weed management system. Genetic variation in allelopathic activity among rice cultivars has been extensively demonstrated. In the present study allelopathic effect of rice straw of traditional rice cultivars on germination percentage and plant height of Echinocloa crusgalli was evaluated in laboratory experiments. Rice straw of thirty eight rice cultivars were separately mixed with non-rice grown sterilized soils in four replicates using plastic cups (diameter 6 cm and height 5 cm). Surface sterilized Echinocloa crusgalli seeds were sawn in decomposed soil samples. Control experiment was carried out in non-rice grown sterilized soil samples collected in to the same sized plastic cups. Allelopathic effect of rice cultivars was evaluated according to reduction of germination percentage and plant height of Echinocloa crusgalli in soil samples mixed with rice straw compared to those of in control soil samples. Germination and growth of Echinocloa crusgalli were significantly suppressed in soil samples prepared using rice straw of the most traditional rice cultivars. There was a positive correlation between reduction of germination percentage and plant height (r=0.58923, a= 0.0001) of Echinocloa crusgalli in soil samples mixed with straw of different rice cultivars. Ingirisi Wee, Bala Ma Wee, Karayal, and Lumbini are the best allelopathic rice cultivars found in the present study. Rice cultivars those showed significantly higher germination reductions and plant height in Echinocloa crusgalli can be further tested to confirm their allelopathic effect at the field conditions.