BREEDING FIELD CROPS FOR ORNAMENTAL PURPOSE: A CASE IN Jatropha spp.

Abstract

Populations of F₁, F₂ and BC₁F₁ were formed from an interspecific cross between green-flowered Jatropha curcas and red-flowered J. integerrima (dwarf type) to observe for segregation in flower colors and to select for ornamental segregants. The crossing to produce F₁ and BC₁F₁ was successful only when J. curcas was used as the female parent. The suitable time for crossing was between 08:00 – 13:00 o’clock with fruit setting rate of 65-78%. The F₁ segregated into white- and pink-flowered plants. While flowers of the F₂ population segregated into nine different colors, viz. light green, green, white, very light pink, light pink, pink, deep pink, very deep pink, and red. When J. curcas was backcrossed by a pink-flowered F₁, its BC₁F₁ progenies segregated into green, light green, white, very light pink and light pink flowers. While another set of BC₁F₁ progenies obtained from a white-flowered F₁ parent segregated into green, light green, and white. The segregating progenies in both sets showed smaller plants than jatropha and bore colorful flowers suitable for ornamental purpose. Six plants were chosen and registered at Kasetsart University and the Thai Department of Agriculture as commercial cultivars, ‘Kamphaeng Saen 1’ to ‘Kamphaeng Saen 6’.

Keywords: ornamental jatropha, interspecific cross, flower color, crossing durations