Allelopathic effect of casuarina needle leachates on germination and initial development of legume crop seeds

摘要

Casuarina is one of the important tree species of agroforestry system. It is a non-leguminous but nitrogen fixing type and as a wind break is planted around agriculture fields in many countries, especially in Egypt, Senegal and India. In wind proneareas, planting casuarina bordering annual or perennial crops can considerably reduce the wind damage to the crops. Casuarina tree is largely planted to check soil erosion because of the network of fine subsurface roots and needles that fall on the soilsurface throughout the year. Similarly, casuarina has been planted in large areas under agroforestry system but information regarding the effects of its leaf (needles) leachates on the performance of understorey field crops is very meagre and scanty. Lack of herbaceous growth under casuarina has been observed by Storey (1967) and was attributed to allelopathic effect. Similar adverse effect on sorghum, cowpea and sunflower was observed by Suresh and Rai (1988). Keeping this in background, a petriplate study was carried out to know the existence of allelopathic action of casuarina needle extracts on three leguminous crop seeds.