In vivo Application of IAA imparts resistance to siliqua shattering in Brassica napus L.

Among the oilseed brassicas, Brassica napus L. (oilseed rape) is a high yielding species but premature shattering (dehiscence) of siliquae leads to a significant loss in seed yield. The present investigation was undertaken to test the efficacy of indole-3yl-acetic acid (IAA) for suppressing siliqua shattering in B.napus cv. GSC 5. Localized application of IAA (25, 50 and 100 μg ml⁻¹) to the terminal inflorescence (TI) axis imparted significant resistance to siliqua shattering with a concomitant increase in seed yield. The length and width of IAA treated siliquae were greater as compared to control. Anatomical studies revealed that IAA treated siliquae had thick-walled cells in the dehiscence zone, greater transectional area of main vascular bundle (MVB) and increased siliqua wall thickness. The contents of total chlorophyll and phenols increased significantly by IAA application. Statistical analysis indicated that morphological and anatomical characters (siliqua length, siliqua width, siliqua wall thickness and area of MVB) of siliquae were negatively correlated with siliqua shattering percentage and, therefore, could potentially serve as markers for selection of siliqua shattering resistance.