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Title: PLANT GROWTH REGULATORY EFFECTS OF CHICKEN LITTER EXTRACT

Author
item MALIK, NASIR - USDA-ARS
item BRADFORD, JOE - USDA-ARS

Submitted to: Sustainable Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2006
Publication Date: 9/1/2007
Citation: Malik, N.S.A., Bradford, J.M. 2007. Plant growth regulatory effects of chicken litter extract. Journal of Sustainable Agriculture. 30(2):2-10.

Interpretive Summary: Organic farming is increasingly becoming popular due to its several benefits related to health and environment. Farmers engaged in organic farming usually employ indigenous techniques developed on their farms, while scientific knowledge about various organic amendments is scanty. Even when research studies are conducted, they usually involve complex systems; i.e. interactions between plant, soil, and micro flora. Therefore, it is usually difficult to assess whether a particular plant response to an organic amendment is due to the direct effect of the amendment on the plant, or is mediated indirectly through interactions with various physical and/or biological conditions of the soil system. Thus, contradictory results are sometimes reported for the same organic amendment. It would be valuable to understand individual effects of different organic amendments so that one could make appropriate management decisions in an organic farming system. In this study, therefore, we decided to study the effect of chicken litter in a soil-less system to assess direct effect of this amendment on plants. Our studies have demonstrated, for the first time, that chicken litter, which is primarily sold as plant food, also has plant growth regulatory effects.

Technical Abstract: Chicken litter is often used in organic farming as a source of plant food, and to improve soil organic matter and microbial populations. Both positive and negative effects of such an amendment have been reported. Because of the complex interactions involving soil, plant, and microbial populations in the most common test systems, it is difficult to attribute the observed plant responses to any one component of the test system affected by chicken litter. We have, therefore, conducted studies on the chicken litter extracts in a soil-less system to ascertain whether chicken litter affects plants simply by providing plant nutrients, or if it also affects plants through plant growth regulatory substances. Since chicken litter is generally rich in available ammonium nitrogen, we studied the effects of chicken litter extract on ammonium-induced rise in putrescine levels in oat leaves. Our results showed increases in putrescine levels in oat leaves floating on ammonium sulfate solution (0.033%) but not in leaves floating on chicken litter extract containing equivalent amount of ammonium nitrogen. Mixing chicken litter extract with the ammonium sulfate inhibited the ammonium-induced rise in putrescine levels, thus supporting the hypothesis that regulatory substances in chicken litter extract affect plant growth. In addition, our experiments showed that chicken litter extracts inhibited root growth in cowpeas that could not be attributed to the level of ammonium nitrogen present in the extract. In fact, emerging roots of young cowpea seedlings exhibited an anti-geotropic response more akin to hormonal effect that nutritional phenomenon.