Positive Effects of Growth Retardants on Castor (Ricinus communis L.)

The perennial growth habit of castor plants (Ricinus communis L.) limits mechanical harvest because the plant grows very tall, when the environmental conditions are favorable and produces green flush interfering with mechanical harvesting. In order to prevent excessive growth plant growth, retardant are applied to modifying crop architecture. Present investigation was designed to study the effect of growth retardants on growth and yield parameters. The experiment was conducted at the regional agricultural research station, Palem farm of Professor Jayashankar Telangana Agricultural University, Nagarkurnool district, Telangana, taking locally available tall variety PCH-111. The experiment was laid out in Randomized Block Design with three replicates in Kharif, 2019. Treatments comprises of water spray, ethrel@500 ppm, ethrel@1000 ppm, CCC@1.5ml/lit, CCC@2.0 ml/lit and CCC@2.5 ml/lit and sprayings were done at expanding leaf in the 6th node of the primary stem, expanding leaf on the 8th node of the primary stem, appearance of the first inflorescence, one expanding leaf in a secondary stem after the appearance of the first inflorescence, and appearance of the second inflorescence. Results revealed that, plant growth retardants are effective in reducing plant height, whereas no spray recorded significant superior value for plant height (70.73 cm). For leaf number, there is no much deviations though ethrel treatment enhanced senescence in older leaves, newly developed leaves compensated the number but there was reduction in LAI, which were 1.70 and 2.18, respectively, in ethrel spray of 1000 ppm and 500 ppm. The yield reduction is lower in ethrel treatment due to lower capsule formation and lower spike length at higher concentration of ethrel. Hence, it is concluded that, retardant accelerates natural senescence and thus, acting as defoliants overcoming difficulties in mechanical harvesting.