Allelochemicals extract of star fruit (Averrhoa carambola L.) modulates wheat growth through alterations in anatomical architecture.

Context: Allelopathy is recognised as a potential technology to control weeds, and could also be a suitable approach for enhancement of crop yield. Aims: The study was conducted to investigate the allelopathic role of Averrhoa carambola leaf extract on growth, anatomical and physiological features of three wheat lines, namely 3094, 7076 and A2011. Methods: Three dilutions i.e. 0% (control), 15% and 30% of the leaf aqueous extract were applied at 15 day intervals (total five applications) on wheat lines until maturity. Key results: All wheat lines showed differential behaviour to allelochemicals of A. carambola leaf extract. Increased root area was accompanied by a high proportion of storage parenchyma tissues and enlarged vascular bundles in line 3094. Disintegration of root cortical parenchyma and complete transformation of chlorenchyma into sclerenchyma in stem was recorded in all wheat lines, particularly at the highest concentration of leaf extract. Line 7076 showed very different behaviour, as it possessed a proportionally enlarged root cortex, enlarged stem vascular bundles and increased leaf thickness, primarily at the highest concentration of leaf extract. Line A2011 was relatively more sensitive, indicating a significant reduction (P < 0.05) in root and stem area and deformed leaves. Conclusions: A low concentration (15%) of leaf extract promoted growth and development, whereas a higher concentration caused significant reduction in growth and anatomical attributes. Implications: A lower dose of Averrhoa leaf extract promoted growth and development in all wheat lines, and hence can be used as a growth promoter. A higher concentration is important for eradicating unwanted plants. Wheat lines were treated with allelochemicals extracted from A. carambola. A low treatment concentration led to increased root area, accompanied by a high proportion of storage parenchyma tissues, and enlarged vascular bundles. Using a high extract concentration, root cortical parenchyma collapsed while stem chlorenchyma was transformed to sclerenchyma. Line 7076 responded differently, as it possessed an enlarged root cortical proportion, enlarged stem vascular bundles and increased leaf thickness. A low concentration (15%) of leaf extract promoted growth, whereas a higher concentration (30%) caused significant reduction in morpho-anatomical traits. [ABSTRACT FROM AUTHOR]