Yield and quality of medicinal coleus (Plectranthus forskohlii Willd.) cultivar 'K-8' influenced by organic manures

An experiment on effect of organic manures on yield attributes, yield and quality of medicinal coleus (Plectranthus forskohlii Willd.) cultivar 'K-8' was conducted at the Department of Plantation, Spices, Medicinal and Aromatic Crops at Kittur Rani Channamma College of Horticulture, Arabhavi. During kharif season 2013 on sandy loamy soil with a pH of 7.73. The experiment result indicated that the plants provided with FYM equivalent to 100% recommended dose of nitrogen (RDN) recorded a significantly higher number of tuberous roots plant^-1, length of tuberous roots, diameter of tuberous roots, fresh weight of tuberous root yield plant^-1 (81.9 g plant^-1) and dry weight of tuberous root yield plant^-1 (15.30 g plant^-1). Also highest fresh tuberous root yield ha^-1 (6.82 t ha^-1) and dry tuberous root yield ha^-1 (1.28 t ha^-1) were recorded. Forskolin content (1.037%) was recorded in pressmud equivalent to 100% RDN treatment. However, as fresh and dry tuberous root yield were concerned, in which the farmers are interested, significantly higher fresh (26.59%) and dry tuberous root (15.65%) yield were obtained with the application of FYM equivalent to 100% RDN (T₁) (10 t ha^-1) but, poultry manure (1.65 t ha^-1), pongamia cake (1.19 t 
ha^-1), pressmud (4 t ha^-1) and RDF (108.7:312.5:83 kg NPK ha^-1 + 10 t ha^-1 FYM) application also gave on par dry tuberous root yield. Hence alternatively, in the absence of FYM, the above organic source of nitrogen can be considered for getting optimum yield in medicinal coleus under Ghataprabha Left Bank Command Area of Northern Dry Zone of Karnataka.