Indian Journal of Plant Genetic Resources

Paclobutrazol was applied to soil (0, 5, 25, 50 and 100 mg/plant) in potted plants of 12 citrus cultivars propagated by tissue culture and seedlings. Required quantity of active ingredient of paclobutrazo] was applied in 200 ml of water around the base in polythene bags and control plants were given 200 ml of water only on 4 month old seedings. Six random plants were selected for morphological observations at the age of one year. Results indicated that all citrus types were sensitive to paclobutrazol. Micropropagated plants seems less responsive to paclobutrazol than seedlings which might be due to increase in secondary roots of seedlings at early stage than micropropagated plantlets, which helped plants in absorption of paclobutrazol. Principal component analysis indicated that the cultivars, JL, AL and P registered very high positive loading in PC I which indicated that response of paclobutrazol was least on these species where as distinct response on growth reduction was observed in Citrus indica, KM, SAT, SOB, SLS and Cv. All the variables have very high positive loading except per cent of thick roots, which registered negative loading indicative of one of the most important parameters to be used. It was observed that application of paclobutrazol significantly affect the root morphology particularly root thickness.